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I want to beam into solid concrete as a bomb. I have transporters and unlike Star Trek I’m not afraid to use them. Terrorists have taken the tech and have *nasty* plans for us.
The bomb is 1 kg sphere of solid concrete, and the target is also a 2m thick solid concrete wall. The ball will be beamed directly into the center of mass making the density of that volume exactly double. Both have equal density ρ = 2,400 kg/m3
**Concrete composition**
The concrete in question has quartz aggregate in the following ratios:
[](https://i.stack.imgur.com/YNA7g.jpg)
Giving [the following final molecular composition](https://www.researchgate.net/profile/Oluwapelumi_Ojuri/publication/275067708/figure/tbl3/AS:669619761201174@1536661200674/Chemical-composition-of-ordinary-portland-cement-as-determined-by-XRF.png):
* CaO = 4%
* SiO2 = 89%
* Fe2O3 = 1%
* H2O = 6%
**Calculating number of atoms in the merged mass**
I will use the composition above to invent a "concrete atom" with the average weight of these components. This cement is 64% Oxygen, 30% Silicon, 4% Hydrogen, and 2% Ca or Fe. The weighted average atomic weight of a "concrete atom" is therefore:
$$ \text {Weight of Concrete Atom} = w\_\text c = 0.64(w\_\text O)+0.3(w\_\text {Si})+0.04(w\_\text H)+0.02(w\_\frac{(Ca+2Fe)}{3}) $$
$$w\_\text c = 10.23+8.415+0.04+1.012 = 19.6968 \text{AMU}$$
Therefore, the initial 2kg concrete mass contains $ \frac{2\text{kg}}{19.6968 \text{AMU}} = 6.115\text E{25}$ representative "concrete atoms" in a volume $v\_i =
\frac{m}{\rho} = 833.3\mu\text m^3$.
Each "concrete atom" shares a volume of space = $ \frac {833.3\mu\text m^3}{6.115\text E{25}} = 1.3627\text E-23\mu\text m^3$ having a diameter:
$$ d = 2r = 2 \sqrt[3]\frac{3(1.3627\text E-23)}{4\pi} = 3.0\text E-8\mu \text m$$
# This math has something wrong... the atoms are not 0.008pm apart in static pressure!
Assume the atoms will align perfectly in between each other.
Neglect the strong nuclear force because no baryonic intersections will occur. Also neglect electromagnetic bonding forces (ionic and covalent), but obviously the other various van der Waals forces apply.
**My assumptions**: the force needed to compress the combined 2kg mass of concrete to 50% of its volume will be the same force exploding the volume of space when its density instantly doubles (but I could be wrong).
Also acceptable is simply calculating the Lennard-Jones Potential energy for the atoms suddenly reducing their distance by 1/2. [](https://i.stack.imgur.com/HS2wp.png)
The yield calculation should be KE=1/2⋅*m⋅v*2
Where *m* is 2 kg, and *v* will be the integral of the velocities of each atom of concrete as the cumulative van der Waals force repels the atoms back toward their van der Waals contact distance.
I believe the final formula can be derived from *W=ΔKE* where Work (W) is the the work done moving the atoms back into their normal density with vinitial and vfinal Calculated from the force acting on each atom.
I’m hoping for the equation so I can scale it for different yields and possibly different material densities.
**What is the simplified equation for yield in gigajoules for this kind of bomb?**
(I’m calling this a kinetic weapon because the damage is done by accelerating the mass radially outward via nuclear forces.J
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Alright, I'll give this a whirl.
First of all, found your mistake: you wrote $v\_i = \frac{m}{\rho} = 833.3\mu m^3$. Look, that's obviously not the volume of a 2 kg ball of anything. Cubic *microns*? It's one of those things where if you stop to think about it, it clearly doesn't add up. The correct value is $v\_i = \frac{m}{\rho} = \frac{2 kg}{2400 kg/m^3} = 8.33\*10^{-4} m^3$.
Plugging in your effective number of "concrete atoms," which seems correct to me, we get $7.338\*10^{28} \frac{atoms}{m^3}$. I'm going to assume a cubic lattice of atoms, which means we don't have to invert a sphere to get the radius. Simply take this number to the -1/3 power to get an interatomic distance of $2.389\*10^{-10} m$, or 2.389 Angstroms. That's a perfectly sensible lattice constant, especially given how many weird assumptions we took to get there.
Now, when the lattices are superimposed, they're not going to neatly line up. There will be some rotation between them, which means a complicated 3D Moire pattern. Thankfully, we have the same lattice constant for both materials, and when we average over all unit cells, Moire patterns just act like a uniform distribution. So basically, the total energy will be the average energy for an extra atom appearing in a random place in a unit cell, times the total number of unit cells.
To get the average energy in a unit cell, we take a 3D Lennard-Jones potential and integrate over a cube of side length $r\_m = 2^{1/6} \sigma$ (that's the distance from 0 to the minimum, which will be where the next atom is). We already know this length to be $2.389\*10^{-10} m$. But since the potential is spherical and doesn't perfectly match a cubic lattice and there will be barely any energy in the corners anyway, let's just cut it off and integrate a sphere of radius $r\_m/2$ instead. Integrating (and using the form of the L-J potential that's in terms of $r\_m$):
$4\pi\int\_{r\_0}^{r\_m/2}r^2 dr \* \epsilon[(\frac{r\_m}{r})^{12} - 2(\frac{r\_m}{r})^{6}]$
Here, $r\_0$ is a lower-bound cutoff, which we need to make this converge. And that makes sense, since otherwise our randomly-thrown atoms can get arbitrarily close to the repulsive singularities of the other atoms. It's up to you to come up with what you feel is a sensible cutoff.
For the sake of finishing the calculation, I'll pick $4\*10^{-11}$ m as the integral's lower bound, which is the atomic size of Neon, including inner electron shells. Neon is close in mass to your "concrete atom," and anyway, the L-J potential is grossly inaccurate even an order of magnitude smaller than this. Now, then, the integral:
$4\pi\int\_{r\_0}^{r\_m/2}r^2 dr \* \epsilon[(\frac{r\_m}{r})^{12} - 2(\frac{r\_m}{r})^{6}]$
$=4\pi\epsilon \* \frac{r\_m^3}{9}(-464 - 6 \frac{r\_m^3}{r\_0^3} + \frac{r\_m^9}{r\_0^9}) \approx \frac{4\pi\epsilon}{9} (\frac{r\_m}{r\_0})^9 r\_m^3$.
As you can see, this answer depends *strongly* on $r\_0$, to the point where the calculation is honestly unimportant from a worldbuilding perspective. You can define it to have as much or as little energy as you want just by tweaking this parameter, which depends entirely on how you say your teleportation avoids nuclear collisions.
Anyway, the energy per unit cell is that answer divided by the unit cell volume $r\_m^3$. Then multiply by the total number of unit cells to get
$E = \frac{4\pi\epsilon}{9} (\frac{r\_m}{r\_0})^9 \frac{V}{r\_m^3} = \frac{4\pi}{9} \* (200 kJ / (6.022 \* 10^{23})) \* (\frac{2.389 \* 10^{-10}}{4\*10^{-11}})^9 \* \frac{8.33\*10^{-4} m^3}{(2.389 \* 10^{-10} m)^3}$
$= 2.7 \* 10^{14} J$.
or about 65 kilotons of TNT. But like I said, you can change this answer drastically by tweaking $r\_0$, which depends on how teleportation in your world works (I assume there's some mechanism for avoiding nuclear intersections anyway). For instance, if you make $r\_0$ half as large, which is still reasonable, you get a blast 500 times more powerful. Play with the value of $r\_0$ until you get one that you feel is both physically justifiable and fits your story.
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Thinking about velocities and accelerations is probably the wrong way to approach this. Better to approach it as a pressure problem.
The change in volume of an object in response to a change in pressure is related to its [bulk modulus](https://en.wikipedia.org/wiki/Bulk_modulus) $B$:
$$\frac{\Delta V}{V} = \frac{P}{B}$$
Where $P$ is the pressure applied. The bulk modulus of concrete doesn't immediately jump out from Google at me, but might be [something like](https://www.fhwa.dot.gov/publications/research/infrastructure/pavements/05062/chapt2c.cfm) 10 gigapascals, meaning that to take a concrete sphere of mass $2m$ (hence volume $2V$) and reduce it to volume $V$ (making the left side of that equation $\frac{1}{2}$), we need a pressure of around 5GPa.
Force is pressure times area, so the work done in compressing the sphere is related to the pressure and the area of the surface of the sphere. Technically this should be an integral over the reducing radius of the sphere as it shrinks, but as a lower bound we can use the area at the final radius. To get the volume and radius of a sphere of mass $m$ we need to pull in the density $\rho$:
$$V = \frac{m}\rho = \frac{4}{3}\pi r^3\implies r = (\frac{3m}{4\pi\rho})^\frac{1}{3}$$
$$F = PA = P \times 4\pi r^2 = (4\pi P)(\frac{3m}{4\pi\rho})^\frac{2}{3}$$
Finally, work done (ie energy stored) is force $F$ times distance-moved-in-direction-of-force $\Delta r$ (this absolutely ought to be an integral), and the radius scales as the cube root of the volume:
$$E = PA \Delta r = (4\pi P)(\frac{3m}{4\pi\rho})^\frac{2}{3}(\frac{3m}{4\pi\rho})^\frac{1}{3} = \frac{3mP}{\rho}$$
Dropping in a value for the density of 2,400 $\mathrm{kg \space m^{-3}}$, we get an energy (for 1kg) of **12.5 megajoules**. A lot, to be sure, equivalent to around 3kg of TNT, but not spectacular in building-destroying terms.
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That does not sound like the most effective way of using such a weapon. As you can see, the explosive effect is not easy to calculate, and you will presumably have to put in a similar amount of energy to the output.
It takes a specialist 2,000-pound bomb to put a hole in six feet of reinforced concrete; interestingly, kinetic energy and a strong casing is the key, not a large amount of HE.
Might I suggest using the transporter for what it is good at: pinpoint targeting. A ten-gram lump of concrete teleported inside the skull of the target should do the job - even with minimal explosive force -- and will be far more effective than indiscrimate explosions.
Alternatively, use your transporter to teleport fractions of target people away from their current location.
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Suppose that both Earth and Mars was booming with life in a similar way. Except that, on Earth, there was no hominid family, and no humans evolved. Instead, humans evolved on Mars.
Assuming we had similar levels of technology, civilization, and science at similar times (e.g. agriculture ~10K years ago, telescopes ~400 years ago, physical turing machines ~80 years ago, etc), and that life on Earth was almost exactly the same, except without hominids, **how soon would we have discovered life on Earth?**
Also, more broadly, how quickly would we have figured out that something strange is going on with Earth that makes it different from the other planets? (Without necessarily knowing that it's life.)
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It's slightly harder to image Earth from Mars than the reverse because Earth is closer to the sun, thus, by simple geometry, at closest approach and best viewing conditions you'd be looking at the dark side of the planet. Of course, Earth is bigger, so there's some benefit there. Still, probably the 17th century equivalents. In 1600s, astronomers like Huygens and Cassini were able to distinguish some surface features and the polar ice caps on Mars, so that by 1666 Cassini was able to determine the length of the Martian day (he was only off by three minutes). Certainly using the same equipment on Mars looking at Earth, they'd be able to easily see the polar ice caps (much larger on Earth than Mars), oceans, land, and clouds. That means atmosphere and liquid water. And if you saw land and had a clear day on Earth, with a large enough telescope when Earth and Mars were at an optimum viewing angle, you'd see that massive swath of green in the equatorial regions that could only be plants. By no later than the mid-18th century equivalent, it would be obvious Earth had life.
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150 years ago, Earth telescopes gave such blurry images of Mars that people thought they saw green canals on Mars: <https://en.wikipedia.org/wiki/Martian_canal>. The illusion had its doubted and was finally disproven with better telescopes 100 years ago.
So basically at Early 20th century technology, Martians will be able to see seasonal changes in color of continents. I am not sure if they will interpret it as life or just weather. The big clue will be the fall's change from green to yellow to black/brown. Green could be copper oxides, and I am sure there are minerals with yellow color, so question is if some right mix of minerals and acid rain could cause the pattern of color changes.
We sent first robotic probes to marsh in 1960's: <https://en.wikipedia.org/wiki/Exploration_of_Mars#1960s>
I think the imaging and chemical instruments could prove presence of life.
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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.
The year is 2035 and Channel 55-KYED decided on a new reality show. the XXI century knighthood games.
It will be your basic renaissance faire re-enactment of medieval combat but since they are doing it in the extraterritorial micronation of Garlandistan they are doing it just like they did in Agincourt: With blood, wounds and the ominous risk of death.
But with a twist, they don't want to use medieval metals. They have a billionaire contract with some big foundries and metallurgic companies that make aerospatial alloys and weapons.
It comes to the picks now. From the modern metal alloys, which ones are the best to make weapons (swords, maces, axes, lances, spears), and which ones are best to make armor (mail, scale, plate) from?
The show is backed by metallurgic companies. There's no budget limit, and ceramics are off. They want to sell metal. For the definition being used, [click here](https://www.chemie-biologie.uni-siegen.de/ac/be/lehre/ceramics_and_alloys.pdf).
Assume no new alloys were invented / discovered between 2020 ~ 2035. This is [hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") so it is expected that answers will back their choices with **data** from reputable sources - bonus points for those that compare their alloys with the rejected choices. Social & political aspects are handwaved. Focus on the metallurgy only.
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I'm going to open the bidding with [S1 Steel](http://www.westyorkssteel.com/tool-steel/s1/) covered by [ISO 4957](https://www.iso.org/standard/70646.html)
Rather than being cutting edge science, this is a commercial product. Specifically a shock resistant cold work tool steel. Medium carbon with tungsten and chromium. Ideal for weapons and likely armour as well. Specifically resistant to losing edge and deforming under repeated high impact while maintaining the traditional advantages of steel, low cost, high toughness, easy to work with, good availability.
This is very much a baseline to use as a solution for this question. There may well be exotic alloys with better properties, but then again, there may not.
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**This is already happening**
See [Unified Weapons Master](https://www.digitaltrends.com/cool-tech/unified-weapons-master-future-fighting/)
Metal in the armour will be limited to a thin outer layer for appearances only with the inner layers being carbon fiber and impact foam.
Sure it'd be nice to see more metal but really knights won't use that much and the sponsorship logos on the shield will sell more. At the end of the day you have two men hitting each other with weapons therefore you have a obligation to keep them safe as humanly possible which means the best materials for the armour.
The suits for United Weapon Masters is fitted with sensors and lockable joints. If a body part gets hit hard enough the joint locks up and they can't use that part again which means a knight can lose an arm but still win. The suit allows for simulated injuries whilst keeping the wearer safe.
Where metals comes in is the weapons as you need to bypass modern armour if you want actual injuries (which I wouldn't recommend as you want to sell your product but bad publicity could lead to legal action in other countries, human rights violations and sanctions against the sponsor if they can't touch him directly)
At the end of the day selling metal is what matters and the tabard and shield with the sponsor's logo will sell far more metal than the composition of the armour.
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## If you don't want steel Aluminium and titanium are your best bets.
For **armor** there are aluminum-steel alloys and titanium alloys. Making armor lighter is the biggest benefit you can gain. For more minor alloying components nickel improves both strength and corrosion resistance of steel.
If you aren't restricted to just improving the metal parts of the armor carbon fiber can make it even better, especially if layered with metals. Better cloth is also a big advantage, making the padding under armor out of modern synthetics means you can have a gambeson that are lighter, stronger, and more flexible that actually breaths, using impact foams you can even get better padding especially in a helmets. Clear plastic eye protection would be excellent.
For **shields** aluminum would be the material of choice as shields are heavy and disposable so the lower performance of aluminum is not a problem, of course carbon fiber would be even better. Titanium would also be an excellent choice it is stronger than aluminum and still reduces the weight.
For **weapons** aluminum is not good, except for reducing weight in things like crossguards and baskets, parts not subjected to repeated stress, it fatigues and fails under repeated loading. Titanium iron alloys are good for many weapons (a titanium hammer would be brutal) but not great for swords it is too soft, however titanium vanadium alloys allows for tempering and can be used to make excellent swords, especially for longer or lighter swords. Even better for a show it makes weapons lighter meaning your "actors" fatigue slower. A titanium-iron core with a steel outside would be an excellent sword composition.
to get away from the metal parts, for polearms (spears, halberds, ect) the possibility of carbon fiber poles would make these weapons far easier to weild, the king of weapons becomes the emperor of weapons.
[Source1](https://www3.nd.edu/~amoukasi/CBE30361/Lecture_Alloys_2014.pdf)
[Source2](http://www.akronsteeltreating.com/docs/default-source/default-document-library/alloying-elements-in-steel-by-t-bell.pdf?sfvrsn=0)
[Source3](https://www.researchgate.net/publication/327312753_Microstructure_and_Mechanical_Properties_of_Structural_Metals_and_Alloys)
[Source4](https://www.osti.gov/biblio/6732156)
## Steel
If your fine with steel it depends on the weapon and armor, for swords and armor you generally want a spring steel or something close. 5160 and 1060 are considered the better steels for these, (best is loaded word and depends a lot about the goal and design of the piece. The steel you want for a rapier is different than the steel you want for a katana) although composite steels are also common in swords. For things like hammers you want a slightly softer steel (XX40-XX45), while the best axes use a combination of a hard steel edge and soft steel body.
But the real benefit of modern techniques is better precision at every stage, composition (both chemical and physical) and heat in particular is far better. Just by using modern consistent production and heat treating you are already exceeding medieval metallurgy.
[Study of japanese sword steel microstructure.](http://But%20the%20real%20benefit%20of%20modern%20techniques%20is%20better%20precision%20at%20every%20stage,%20composition%20(both%20chemical%20and%20physical)%20and%20heat%20in%20particular%20is%20far%20better.%20Just%20by%20using%20modern%20consistent%20production%20and%20heat%20treating%20you%20are%20already%20exceeding%20medieval%20metallurgy.)
[Study of damascus steel microstructure](https://www.sciencedirect.com/science/article/pii/104458039090042I)
[Study of european sword microstructure](https://www.jstage.jst.go.jp/article/isijinternational/47/7/47_7_1050/_article/-char/ja/)
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## Depleted Uranium : for Flails, Two-Handed Hammers/Swords, and Shields
For a swung weapon, mass is the reservoir in which the kinetic energy of a swing or a horse's charge is stored. This reserve of kinetic energy is what tries to foil potential energy reservoir of the target's yield strength times the strain. A high momentum hit will daze the other guy, break bones, numb nerves, and so on.
At 18 thousand $kg \over {m^3}$, [depleted uranium alloys](https://patents.google.com/patent/US5273711A/en) has almost 2.5 times the density of [A36 steel](https://www.azom.com/article.aspx?ArticleId=6117), and a yield strength in the neighborhood of the hardest steels (123ksi, which is equal to 1,100 MPa). Osmium would be 15% better at 22 thousand $kg \over {m^3}$, but I didn't find any reliable sources of industrial Osmium or Osmiridium.
You'd want to wrap your DU (depleted uranium) core in a hard steel. Maybe [chrome alloy Sandvik 13C26](http://www.matweb.com/search/datasheet.aspx?matguid=4eb0b56967464b838e5e947dc95d4272) for edged weapons, but a more durable mild steel like A36 for blunt ones.
For tower shields, you don't want the shield to move. So, DU is the best core material for that purpose. Also wrapped in a durable and mild steel.
## Razor Steel : for Edged Weapons and Armor
[Sandvik 13C26](http://www.matweb.com/search/datasheet.aspx?matguid=4eb0b56967464b838e5e947dc95d4272) boasts a yield strength of (700 to 1,100MPa) and a hardness of 98 Rockwell / 240 Vickers. It's a chrome alloy, and corrosion resistant. I think this would be the best alloy to use for things that need to hold an edge.
## Spring Steel : for Armor
According to MyArmoury.com, the best steel for armor is a good spring steel. The use case for armor is different than weapons, or even shields : the total energy that a weapon must possess to penetrate the armor is the yield strength of the material, multiplied by how much the material will deform before it breaks. Spring steels capitalize on this mix. I'd recommend [Elgiloy](https://www.steel-grades.com/Steel-Grades/High-Alloy/Elgiloy.html) with a 890 MPa yield strength, and 24% max strain.
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Beryllium is as exotic as it gets and it's the lightest usable metal. Due to its rarity only [beryllium copper](https://en.wikipedia.org/wiki/Beryllium_copper) is made today but certainly better and lighter alloys are possible. Both for armor and for weapons. The downside is, beryllium dust is toxic.
Staying with beryllium copper, the ["extra hard" treated wire has 1415-1620 MPa tensile strength](http://www.lfa-wire.com/heat-treatable-alloy-25_c17200-and-c17300.htm), it can be formed and then hardened, it does not corrode, does not spark...ideal for chain mail!
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In our world there are two species of dragon that took different evolutionary paths due to environmental pressures. The first of them, called smaugs, are as large as a quetzalcoatlus, with a wingspan of 50ft and a height of 9ft. The second type of dragon, called shenrons, has a snake-like body with six legs and a large, but undetermined, size. It also has wings, but due to its long shape, has issues with flying.
What I need is a practical design of this creature. My first idea was modeling it off of a flying snake, which fan their ribs to double it's width and helps it glide. But as this creature is supposed to be large, this sounds stupid.
How can I bring this creature to life?
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**Make em glide baby**
True flight with a large creature is hard in principle, since at a certain weight animals simply can't generate enough muscle power for sustained flight, since it requires even more muscle power, which requires more mass, which then requires more mass. Large animals like Pterosaurs cheated the system by having hollow bones, which allowed them to circumvent the mass problem while still being quite large.
So perhaps these Shenrons instead utilize a similar flight system to leaping lizards, where their ribs fan out to form web-like wings for the express purpose of gliding. they would not be true wings, but it would allow a form of flight for these massive serpent dragons.
[](https://i.stack.imgur.com/0lQ3e.png)
They could launch themselves from high places in the same manner as Asian flying serpents (by forming a J shape), perhaps from cliffs or enormous trees, and glide down rapidly towards their targets, diving at them and wrapping themselves around their target like an anaconda.
**Alternative option**
Rather than giving them the same flight system as leaping lizards, you could give these Shenrons multiple sets of wings like those of a wyvern, which would allow it to not only grab onto trees, but allow it to glide without it being too awkward of a system.
>
> Image sourced from *The Genesis of Species* - 1871
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> Info about Flying Asian snakes: <http://blogs.discovermagazine.com/80beats/2010/11/23/video-reveals-how-a-flying-snake-slithers-through-the-air/#.XXHi1PZFyDs>
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Possibly it could have sacs which it could fill with some sort of lighter than air gas, and large fins and tail to give it momentum. Basically they would be swimming around in the air.
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It needs a streamlined body for aerodynamics as well as hollow bones, lightweight scales and skin, and maybe add feathers. It needs multiple sacs inside its body that it can fill with air. It also needs a method to lift itself off the ground. In nature, flying draco lizards exist, running and jumping off branches and opening winglike structures that allow them to glide. Something similar to that would be ideal.
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If this creature has legs, then it would not need to be able to flex its body side to side. This could allow it to get away with having a spring-like notochord in place of a spine, which would allow it to curl up and leap through the air, where it can then extend and control its leap through its wings and other control surfaces. While this isn't true flight, it seems close enough
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[The Wheel of Time series](https://en.wikipedia.org/wiki/The_Wheel_of_Time) uses a mythical serpentine dragon, which looks something like:
[](https://i.stack.imgur.com/n3EPJ.jpg)
Even many Asian countries have concept of serpentine dragons, where you can draw inspiration from. For example, the Himalayan country of [Bhutan](https://en.wikipedia.org/wiki/Bhutan) has the [Thunder Dragon Druk](https://en.wikipedia.org/wiki/Druk) on its flag below:
[](https://i.stack.imgur.com/lEC4y.jpg)
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Looking for alternative sources of lighting for my current worldbuilding project so I couldn't help but wonder if a bioluminescent plant-based lifeforms could be realistically feasible. I'm just looking for simple but primitive way to give my imaginary people/characters a source of light in the Darkness of night-time.
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[Schistostega pennata](https://en.wikipedia.org/wiki/Schistostega) is a luminous moss that grows in the darkness of caves and gives off light as a greenish-gold glow. It is not enough light to see by but it is strong enough to guide someone's way.
[](https://i.stack.imgur.com/l5nNt.jpg)
There also exist [bioluminescent protists (plant-like organisms), fungi, and bacteria](https://study.com/academy/lesson/bioluminescence-in-plants-fungi-bacteria.html). Plus a few other plants.
If your world has genetic engineering (or did in its past), there can be even more plants that glow, perhaps more strongly than existing ones.
Perhaps what will work for you is to take a plant like Schistostega and tweak it a bit with magic to glow more brightly.
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Plants would have difficulty to obtain the concentrated excess energy required for, say, 1 watt light output. More viable are fungi or animals that can get the energy by respiration (burning oxygen). They will require feeding and care, like any carefully bred creature.
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## Plants that concentrate Carbon-14 in their leaves.
As radioactive material tend to glow in the dark, radium, ~~plutonium~~ or many other would do the job.
Then, the said plant would have to cope the radiation, but well … If earth lifeform are able to deal with UV and insane oxygen concentration, I'm sure your magic vegetal can survive this.
Edit: You can get info about radioluminescent paint there:
<https://www.orau.org/PTP/collection/radioluminescent/radioluminescentinfo.htm>
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On another planet there is a life form that has the same level of intelligence as humans on Earth, but it has no appendage to manipulate its environment. It has similar social structures to humans before farming was invented. Also it has a language that is of similar complexity to the languages of humans before farming was invented.
Would this sapient life form be able to develop an advanced civilization with advanced technology, or would its lack of an appendage prevent it from developing technology and civilisation?
By appendage i mean no opposable thumbs, no trunk, no crab like claws, no tentacles with suction cups, and nothing else that would make for a limb or extremity that would be useful for manipulating its environment.
[Answer]
You note these creatures have language, so I’m going to assume they have a mouth. I’m further going to assume that mouth+body does not constitute an appendage for the purposes of this question, as even slime moulds manipulate their environment with their bodies.
[Fish](https://news.nationalgeographic.com/news/2011/07/pictures/110713-tool-using-fish-science-tuskfish-australia-use-tools/) and [birds](https://www.sciencealert.com/crows-are-so-smart-they-can-make-compound-tools-out-of-multiple-parts) use tools and [build homes](https://images.app.goo.gl/JxGQfDLJmPKKTNjS9) with [their mouths](https://www.youtube.com/watch?v=VQr8xDk_UaY), and insects (most notably social insects like ants, bees, termites and wasps) are noted for their [architectural abilities](https://www.nytimes.com/2019/03/26/science/termite-nest-ventilation.html) despite having nothing at their disposal but mandibles and spit. Not only that, but ants engage in both [farming](https://www.wikipedia.org/wiki/Leafcutter_ant) and [domestication](https://www.sciencedaily.com/releases/2007/10/071009212548.htm), all without the benefit of manipulative appendages.
So your hypothetical species can absolutely build complex things. It might require several members to provide the requisite control, but with language and cooperation there’s no reason they can’t advance.
PS: All the links contain creatures that are stupidly cool. I particularly recommend the architectural termites.
[Answer]
Some animals don't have appendages, but still manipulate their environment. For example:
* Sponges
* Worms
* Snakes
* Electric eels.
Sponges and worms are notable for changing the environment by swallowing it.
Snakes are leg-less lizards that still manage to move quite quickly. Some can strangle things in their environment; others can inject poison into it. An intelligent snake on an impressionable surface would be able to write; another intelligent snake could raise its head high enough to read the writing.
The combination of any form of locomotion with the ability to partially swallow and then spit out an object provides the ability to carry things from place to place. A mother cat carrying a kitten is an extreme example, but an intelligent snake could pull off similar tricks.
Electric eels combine the flexibility of snakes with, well, shocking amounts of electricity.
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No, a sentient life wouldn't be able to have advanced technology without an appendage (unless it has magic)
I want to give you an animal on earth that is very smart yet doesn't have any limbs to manipulate its environment: dolphins.
Now imagine dolphins on land. Without any appendages dolphins can only move things by biting it with its mouth or nudging it with its body. It wouldn't be able to use a spear, stone, or stick because it can't move it effectively (a dolphin's neck isn't exactly flexible). So dolphins on land cannot make any advanced tools. Even if somehow they are able to manipulate fire (that they got from lightning), they can't craft anything. On top of that, animals with appendages move faster than those without. The dolphins are going to get murdered.
3 dolphins are trying to forge metal. One dolphin is using its head and mouth to hammer, another is keeping the fire alive by nudging wood to the fire, and the third holding the metal with a stick attached being held by its mouth so it doesn't fall of. It would fail.
Now, in their natural habitats which is underwater, advanced tech wouldn't be available because there is no consistent source of fire.
My reasoning:
Appendages are any sort of body parts that are flexible thus able to manipulate the environment. So all limbs are appendages because they can move in a flexible way, even though it can't hold things. (For example, an elephant using its feet to knock down trees.)
I count snakes as having an appendage because their tail and mouth can each hold a different item, so technicaly they can smash 2 rocks together to make fire.
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With the increasing amount of sci-fi using drop-pods to get their soldiers on the ground I would like to look at the design and how a proper drop-pod should look.
The look and shape of such a drop-pod would depend on available technology, its function and cargo. A drop-pod that carries large construction equipment would be different from one that carries just one person, and usage for frontline drops or dropping in friendly lines is also going to need different from each other. So for the purpose of this question:
* Fuel available in this sci-fi universe has an energy density 10x that of current rocketfuel. This to emulate most sci-fy where fuel is often of little concern. Otherwise normal physics apply.
* Drop-pods need to be inexpensive enough to leave on a battlefield. If they are re-useable that is a bonus. This means limited use of rare materials and construction but it is assumed that construction has become a lot cheaper to begin with.
* The drop-pod needs to be more effective than a landing craft at dropping into combat
* The drop-pod is used for combat drops close to enemy positions. Key is high velocity and as little preparation time on the ground as possible before the infantry is ready to engage.
* In case of erroneous landing (IE the drop-pod lands on a slope and falls over) the occupant still needs to be alive and able to exit. Maximum slope to land on will be set at 45 degree angle.
* It is a single-seat drop-pod.
* The occupant is wearing a pressure-suit against G-forces.
* G-forces may not exceed 9 G's, which is what airforce pilots can endure without extended loss of consciousness. If the G-forces are downwards relative to the body (blood is pushed out of the brain) then 3 G's is the maximum.
* Drop-pods are used both in-atmosphere and on planets without an atmosphere.
* Drop-pods need limited steering capabilities.
Question:
How would a drop-pod be designed based on the above constraints? Things I want to know are:
* Occupant's space. Orientation of his chair (or other arrangement), cushioning, airbags(?), type of restraints (easy to take off, but won't disengage on landing), placement of additional equipment occupant might need.
* Shape of the outer shell. What is the most efficient shape trade-off between going through the atmosphere (or no atmosphere) and landing on a surface? Does it have landing struts, does it have parts designed to break off or expend themselves?
* Visuals and steering. A monitor and steering equipment might seem simple but when 9 G's are pulling on you it'll be pulling on your steering equipment as well.
Edit: For a look at potential methods to slow down, look here: [Orbital Drop Pods: Useful?](https://worldbuilding.stackexchange.com/questions/98845/orbital-drop-pods-useful).
However, this question is about the entire design, not just the methods to slow down.
[Answer]
As a pure physics question, you're unlikely to do much better than what various space programs have come up with. The Apollo [Command Module](https://en.wikipedia.org/wiki/Apollo_command_and_service_module#Command_Module_(CM)), Soyuz [Descent Module](https://en.wikipedia.org/wiki/Soyuz_(spacecraft)#Descent_module), and the new Orion [Crew Module](https://en.wikipedia.org/wiki/Orion_(spacecraft)#Crew_module_(CM)) all have the same basic shape and configuration, and for good reason. For reference, [this](https://upload.wikimedia.org/wikipedia/commons/0/0a/Commandmoduleinterior.JPG) is the Apollo CM:
[](https://i.stack.imgur.com/4vMpN.jpg)
The basic shape is essentially driven by physics. The gumdrop shape (or the wider bell shape of the Soyuz) will naturally keep itself oriented during reentry and allows you to limit the heat shield to only the bottom of the craft. Putting the heat shield, heavy equipment, and ballast (if necessary) along the bottom also keeps it rightside up when it lands. The top surface isn't affected by reentry heating, so the hatch goes there, along with any delicate specialist equipment you want (like a grenade launcher for those pesky enemy forces). Anything on the bottom surface, like landing struts, will be a) melted and b) crushed against the ground, and so should be avoided.
The seats, which you can see more clearly in the full-sized image at the link above, are oriented so that the pilots reenter more or less on their backs, which is more tolerable in terms of G-forces. It also means that the hatch is conveniently right in front of them when they land. The seats aren't directly attached to the hull but are held by a shock absorbing system. The restraints don't seem to have been anything out of the ordinary; a typical crash harness will handle any kind of G-force that you want to subject your passenger to.
In the Apollo, cargo spaces were under the seats and on the upper walls of the craft; the lunar missions carried all sorts of consumables and life-support equipment there, but of course you won't have to do that because you're using your pod for a matter of minutes rather than days.
Since your drop pods intend to drop on targets without an atmosphere, they'll need retrothrusters. The Apollo actually has RCS thrusters, ten of them, arranged around the rim just above the heat shield. Yours will need to be quite a bit larger and more powerful, but you've provided for that in your question so all is good there. The thruster exhaust is unlikely to do anyone on the ground any favors; aim well away from friendly troops.
On that note, aiming control is provided by the same thrusters. Control is probably computerized, with manual backups. Guidance is a bit tricky, because you can't receive radio signals from the ground - the so-called [reentry blackout](https://en.wikipedia.org/wiki/Communications_blackout#Spacecraft_reentry). You may be able to transmit and receive through your wake, though, which would allow the launching ship to guide you in. Otherwise you're likely going to have to rely on inertial guidance which is, to put it mildly, not that great. (Most accelerometers are not designed to withstand those kinds of forces, let alone measure them with any accuracy.) Visual guidance is going to be dubious at best once you're in the atmosphere.
Cost is going to be a bit of a sticking point. At the very least, fuel is expended, although not more than you would use in a conventional landing craft on an airless surface. The heat shield, assuming you land in atmosphere, is probably ablative and will therefore need to be replaced. The other components are in theory reusable; I wouldn't be caught dead plummeting to earth in a reused pressure hull, but the computers and rocket engines can probably be refurbished.
On the other hand, militaries do fantastically expensive things all the time. The AIM-9 Sidewinder, perhaps the most popular anti-aircraft missile in the world, renowned for being relatively cheap and mass-producible, cost $600,000 *each* in 2015. Drop pods should not be used lightly, but that's not the same as never being used at all.
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Modular thrusters with thrust vector steering, sized so one to three of those will suffice for the smallest projected drop-pod (small equipment drop, 20-40kg of stuff) - For higher loads, and higher 'glide' time and higher redundance, more of those modules get fitted. There is also a modular scales-like heat shield with active cooling that can be expanded, layered, or left off, according to the atmosphere at the target (or maybe the expected laser-based defenses).
Thrusters can be mounted under, and obliquely behind the sides of the heat shield. Oblique thrusters are used for orbital and entry-level maneuvering and braking. completely shielded thrusters only get activated after the shield is scuttled.
Piloting is done extremely high-level, basically just choosing from a computer-provided list of locations - everything below that is automated, as the necessary thrust and shield management is beyond the reaction times of humans anyway. Interaction with the autopilot via the HUD that the soldiers have anyway.
The soldiers lie curled up on a matress that is formed from an elastic sack filled with elastic (and gas filled) grains. Basically a vacuum matress, but built so you basically are completely sunk into it when the vacuum is applied - (the vacuum in the matress will stiffen it, gving you support, at the same time 'inflating' the grains. When the vacuum is turned off, the grains loose volume, making it much easier to get up from the matress. Equip is also vacu-formed secure.
Soldiers have their own air supply anyways, so the cabin is flooded with nitrogen to keep fire-hazards small.
The capsule is for one-time use, and the retro-rockets obviate any attemps at secrecy anyways, at touchdown a spike is shot into the ground, anchoring the capsule. Opening the capsule is accomplished by explosive bolts that open the capsule like a flower, the leaves opening by material-spring-action. (Getting into the capsule involves lying on the g-matress-flight-computer combo, and then being transferred, en bloc, into the capsule that is welded shut in an automated process taking a few seconds.)
The capsule is blown free from the carrier, brakes as much as neccessary to drop from orbit (that initial delta-v may also be given by a launcher on the carrier, too, to save fuel). Further braking is accomplished by shield, or via bursts from the thrusters, in a deceleration sequence that is input by the carrier's nav department. Any corrections beyond that are done on-the-fly by the pod. 9g is ~90m/s^2, meaning you can loose 90m/s every second. Orbital velocities of a few km/s thus will take a minute or more to burn. The available fuel and acceleration-restricions mean that the soldier is provided with a map outlining reach, from which she can choose landing locations dynamically, up to the last second. As there is no budget and possibility for real-time sensors on the pod, evasive maneuvers will be restricted to pre-planned twitches in the flight path (and woe unto those whose random-number generator falls into enemy hands!)
The thrusters (and in atmosphere - shield) will be visible in even the most basic thermal imaging equipment, and will at the same time preclude any last minute recce by the pods inhabitant - all maps will be preloaded. The last 450m/s (Mach 1.5) will take 5s to burn off (at 9g), in this time the pod will travel 1.2km, quite vertically, so it will be easily spottable by everyone around. Going at an angle is possible without aerodynamics, just using well-timed thruster bursts, but any velocity in the horizontal is bought with much more fuel, and the overall goal would be to get boots on the ground as fast as possible, so i'd guess there will be no real hovering (although there could be!)
Shape will be a flat pinecone (with shields) and a flat egg with thrusters on struts below it without shields (though for cost reasons this will be the capsule that is inside the pinecone version).
There will be no planned survivability for direct kinetic hits, just the shields that can double as laser-armor and against the most puny of kinetics. If the enemy can spare a guided missile or 1000+ shots of AA cannon *per pod*, the time to fire them is *after* landing, anyways, and individual grunts getting orbit-dropped will not make a difference to the strategic situation.
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I do not believe they will use the same drop pods for atmosphere and airless landings as the requirements are too different.
A pod for an atmosphere landing has very minimal use for rockets and has no need of them at all if it not going to be reused, whereas a pod for an airless world needs a considerable landing rocket.
A pod for an atmosphere landing needs a heat shield and the shield should be impregnated with chaff and other things to confound enemy sensors (the reason to use drop pods over landing craft is enemy fire, thus you want to make that fire as ineffective as possible.) The pod for the airless world will simply eject it's chaff and decoys.
For an atmosphere landing the soldier is probably not going to ride it all the way down. Once through the fire leave the pod and let it fall ahead of you (make sure it falls faster) still shedding chaff and decoys. The soldier has something akin to a wingsuit to give him good steering without slowing him too much (don't worry about ending up on a steep slope, the soldier picks his landing spot) and then a chute for the landing itself. On an airless world the main job of the pod is the landing rocket and you want to be on your back when that lights, there's nothing to be gained by leaving it.
For the atmosphere landing I don't see it being sensible to make it reusable. It's basically a frame, a seat, the heat shield and the countermeasures, and a chute if it is to land. The countermeasures are expended, the cheapest, most foolproof way to deploy them is to embed them in the burning shield and a shield that burns off is a lot cheaper than one that is reusable.
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I'm trying to determine the feasibility of some advantages and disadvantages of literal light infantry. This type of infantry is basically the same as the rest but weighs much less.
To truly determine the advantages and disadvantages of light infantry I want to eliminate what specific light materials and such would do for them, so I'm assuming that this infantry is exactly the same as a normal human but lighter. Its bones have the same strength, resilience, elasticity etc, it's fat has the same energy content, it's brain is just as capable, it's muscles just as strong etc. Nothing is different but one thing: Their weight. Currently, I'm exaggerating their weight difference in saying that the lightweight human is 10% of the weight of the "real" human. As an example, an 80 kilo human would have a lightweight version of 8 kilo's. An old-timey 40 kilo human would have a lightweight version of 4 kilo's etc. The individual weight differences do not matter for this check, just the general advantages and disadvantages of being significantly lighter.
Advantages as far as I can determine:
* higher jumps
* faster acceleration to their maximum speed
* slower terminal velocity
* can fall from higher before a fall will wound or kill
* better climbers
* can carry more weight before it becomes a problem -->techniqually not true. They can carry the same amount of weight, but the reduced amount of bodyweight means more weight of equipment can be carried.
* requires much less equipment to hover or fly.
Disadvantages as far as I can determine:
* slower falls --> when jumping or trying to run, it takes longer to reach the ground again, meaning you can run slower and take longer to recover from a jump.
* When in a car crash (or explosion) you are more likely to die --> your organs are easier to accelerate/decelerate causing them to receive more damage. This might be a moot point as there's also less force behind your own organs, IE they require less force to be stopped and thus might experience fewer problems from a crash.
* Similar to a car crash, being in a fight will mean getting hit is more lethal to you (might be just as moot a point).
* In hand-to-hand combat, you are much more ineffective as any blunt-force attempt has much less weight and therefore energy behind it (any other technique still works assuming you don't need your weight). Can be countered by wearing more heavy gear to compensate.
* high winds have much more effect on the light human
* much more problems handling recoil. --> the era does not matter for this question, just that any type of recoil (or wind for that matter!) will have more effect on a light human than a heavier one.
The question is: are these advantages and disadvantages feasible?
Clarification on the time period:
This question does not tell you what time period these lightweight humans are in as it is about the general differences between a light and normal human, and not the individual specific differences between say a sword-wielding lightweight vs normal human.
The comments aren't exactly clear why the time period matters. There's two interpretations that I could identify as to why it might be important. The first is that the type of weapon matters. But does it really matter? with melee combat in medieval times the lightweight user has certain disadvantages. With melee combat in current and future times the lightweight user still has the same disadvantages. It also doesn't matter if the lightweight user is using a bow, a musket, an SMG or a handheld tank canon. In all cases the lightweight user is at a disadvantage over a normal weight user (bows have a small amount of forwards recoil rather than backwards, but this is comparatively a similar amount of recoil per kilogram as that of some modern rifles have on normal weight humans!). The answer does not change based on the weapon or time the weapon is used.
The second way it could be interpreted is what type of conflict was the most common and how efficient the lightweight humans would be in such a conflict. While an interesting question in itself that I might ask later, the question I ask isn't about the efficiency of lightweight humans wielding a particular weapon set or engaging in a particular kind of conflict. It's just pure and simple about the general advantages and disadvantages a lightweight human would have over a heavyweight human. It is a reality check with some advantages and disadvantages I thought would apply, this can be answered with a yes/no question and some additional information as to why you think it is correct or not.
I hope that clears up some of the confusion about my question.
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Lightweight humans (whose sole difference is weight, with strength and resilience unaffected) are basically a straight upgrade from normal humans. That improved strength ratio (muscle capacity vs body weight) means they can move faster and carry more stuff.
Your question identifies positives and negatives pretty well, but I would make a few corrections
* Fall speed is largely unaffected. Recall Galileo's experiments that objects fall at the same rate regardless of weight. Fall speed only changes significantly when the object is so light that aerodynamic forces [ie. air resistance] are similar to the gravitational force acting on an object. A lightweight human doesn't meet that criterion unless they are wearing a wingsuit or are EXTREMELY low density, like a balloon or aerogel.
* I think hits will be LESS lethal, as their bodies are easily accelerated away with an impact, rather than their bones/organs being forced to elastically resist an incoming blow while the body's momentum changes to match the blow. Imagine trying to pop an airborne balloon with a hammer.
Other thoughts:
* There will be a range of inconveniences for the lightweight humans interacting with objects designed for heavy humans. Heavy doors would have to be braced against to open them (hell, they might even lack the friction against the ground needed to open a big door), a backpack full of stuff would overbalance them (totally changed gait for carrying objects perhaps?), Heavy weapon martial art forms would be unusable as the centre of rotation for a human holding the weapon is vastly different.... Basically, I'm saying the lightweights will move and interact with the world in unusual ways, they are kind of like humans permanently living on the moon.
* We might expect the lightweight humans to end up weaker than normal humans, just because they don't experience the continual weight training of lugging a fat body around. Training may be necessary.
* I would expect lightweight humans to develop solo spear-based combat styles, taking advantage of their superior speed to evade and make lightning, piercing strikes to the opponent from range.
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One huge advantage is much easier logistics. Lighter people will burn less energy while doing anything than heavier people will. So they will need less food and maybe less water. They'll also be easier for vehicles to transport, especially in the case of aircraft. A big consideration for transport aircraft is load balancing. Lighter people will make that less of a problem. And for fighter or strike aircraft, every kilogram of dead weight you can save is one more kilogram of ordnance or fuel you can carry, or one less kilogram slowing you down. This kind of thing holds true even for pre-modern societies. Lighter people are easier for horses to carry, and they also are easier to pull in a chariot.
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Light humans would also probably float better (if they are the same size than a normal human, they are less "dense") and could be able to swim with more burden than a normal man.
I think a lighter human would work very well in amphibious operations (crossing rivers, landing on beaches...): being able to swim carrying a heavier equipment, they could easily establish well-equipped bridgeheads.
Similarly, they would behave well also in difficult and soft terrains (mud, ice, high mountain in general, crossing rivers on improvised bridges), since they would stick less and the terrain would be less likely to collapse under their weight
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Word play aside, Your light infantry is probably not going to be a really good infantry at all. They could be useful at so many other things.
What you are proposing is that the light humans are the roughly the same size and shape of normal humans, just without the mass. To get to your proposed mass, you need some seriously radical changes to the basic materials in human anatomy. Think about it, your skelton alone is 15% of your overall mass. That by itself is half again more than your proposed light people. A bit can be done with air sacs in the bones, like birds, but probably not enough. So magic magic or radical science would be necessary to get a similar strength from an alternative material. Next you have muscle and other tissue That's a lot of volume to fill if you want to cover a normal sized human skeleton. Last but not least you have blood. it's made of water (sort of) and masses in a similar way. 5.5 liters of water masses 5.5 kg. So you end up in a place where the only way possible to get a 10% of the mass human is to use Magic or Extreme science fiction. But this only gives you a base of things you have to account for.
Now what can you do with them. Regular infantry is right out unless you have them carrying some sort of energy weapon with no recoil. That puts you in the sci fi category. In the era of muscle powered weaponry they simply will not have the mass to be effective. To strike hard with muscle power, you need momentum. Momentum needs mass, and these guys just don't have any. One standard human with a mace would wade right through a bunch of these guys in a world with normal physics. In a modern military, you need a variety of projectile weapons. These weapons have a lot of mass. When it comes to recoil, you do not get a pass on the laws of physics.
ONe thing you might consider for these ultra lightweight humans might be light *Calvary*. A role that means you have to move a lot of people and stuff really fast. Ranged weapons on a moving platform, whether that be horse or helicopter. Less mass means you can either move faster or carry more stuff. A light horseman can go farther, faster than the same horse with a standard human. Same goes for a helicopter or other conveyance. an 8kg pilot means you can carry 72 more kg of ammo.
Also, you could even look at all sorts of flight or glider possibilities for recon and intelligence gathering.
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With the Kuiper Belt being composed of well over 100 million objects - some grand, some insignificant - is it possible to hide an asteroid base from enemy sensors within its confines, combined with the vast distances of space?
Additional info:
* The size for the base would be within an object with a 70 mile
circumference. The current population stands at over 350,000.
* Large ships would occasionally be coming and going from his base, smaller mining vessels somewhat more frequently.
* The enemy searching for them has a deep-seated fear and loathing for true AI. They certainly have advanced computer systems, but
nothing independent like an AI powered probe would ever be used.
* The colony/base was established 70 years ago. Their enemy has been searching for them nearly as long.
* The "seekers" are a multi-system ruling class. They're widespread both throughout the galaxy and our system, and have superior technology to the "hiders" - the seekers outpace the others by around 600 years. However, the hiders have certainly managed to glean a lot of their enemy's techniques and tech over the decades. The hiders do have fully-sentient (benevolent) AI systems to assist them in their quest for survival.
[Answer]
Contrary to popular depiction in media and such, Kuiper Belt Objects, much like their counterparts in the Asteroid Belt, orbit the Sun alone, separated from their closest neighbours by vast distance full of nothingness.
An object with a 70 miles / 110 km circumference would be amongst the upper tier in terms of size. Not amongst the more massive, but already easily noticeable through telescopes. It is similar to Ultima Thule, for example.
Assuming that the enemy only uses space-based telescopes to watch the confines of the solar system, they'd need way too many probes to do the same, they only need to set up something akin to Seti@Home to analyse the vast amount of data from the telescopes and detect any movement within the system.
The software at the heart of Seti@Home that allows the distributed computing effort to take place has evolved to be used in many applications, and Seti@Home is now merely one component of this project called [BOINC](https://en.wikipedia.org/wiki/List_of_distributed_computing_projects)
Assuming technology roughly equivalent to what we have, in terms of propulsion systems and detection systems available, the base wouldn't stay hidden very long: the telescopes would be able to catch the heat emission of such a massive installation, 350.000 inhabitants is quite a big city, or the ships regularly coming and going towards an otherwise uninteresting asteroid.
And with government involvement in the effort to find the base, I'd give it a few weeks before results are analysed, compared and confirmed and a force sent out to seize or destroy the base in question.
[Answer]
**Is it possible to hide a base in the Kuiper Belt?**
I believe so yes, but with certain provisos:
Since it is [known](https://www.space.com/16144-kuiper-belt-objects.html) that:
>
> Scientists estimate that thousands of bodies more than 100 km (62
> miles) in diameter travel around the sun within this belt.
>
>
>
And [many](https://en.wikipedia.org/wiki/List_of_the_brightest_Kuiper_belt_objects) with a diameter of 500Km and upwards.
The best thing would be to hide the base behind one.
* The searchers would therefore only be searching from "Sunside" of the belt, as the base would be clearly visible from "Starside".
* Station-keeping and collision-prevention systems would need to use cold driven mass-reaction, as would supply ships - to avoid an IR signature.
* Supply ships would take a Burn-and-Glide roundabout route behind the objects of the belt so as to not give away position, they would need thermal shielding on Sunside, and a way to radiate excess heat on Starside.
* Supply ships should not exceed the minimum directly detectable size of the hunter's telescopes. Today that would be 30 miles across by reflected light through [Hubble](http://hubblesite.org/hubble_discoveries/science_year_in_review/pdf/2009/smallest_kuiper_belt_object_ever_detected.pdf) (the smallest detected ever was a 1/2 mile diameter object, by the occultation method and lots of heavy maths). You might consider painting them with [vantablack](https://en.wikipedia.org/wiki/Vantablack), for extra stealth.
Not essential, but as an added measure of protection a number of decoy dummy transceivers/IR sources could be set up around the orbit of the belt, with regular drone traffic dragging [chaff](https://en.wikipedia.org/wiki/Radar_jamming_and_deception) and creating false coms and IR trails, just to keep 'em guessing which one is the real base. With the know-how and a little budget - it could be quite infuriating to the searchers.
Thanks to: notovny's comment, edit made.
[Answer]
Why they cannot find it?
Stealth. The base has an advanced stealth mechanism to hide/reflect/absorb radiation, gets it not only very cold, but disperses radiation away from sun, looking like a very small object. Has onion-like shields to protect it, liquid hydrogen between the outermost, and any heat exhaust/traffic is done on the face back far from the sun o a pile-like structure.
It may orbit, and axis is pointing to the sun.
[Answer]
One idea to hide within the solar system, since any object in the Kuiper Belt would be detected is a very low solar orbit. If such a base had sufficient heat shields and specifically engineered design to minimize its visible cross section it can orbit close to the suns corona. The overwhelming glare of the star would make it exceedingly difficult to detect.
How ever, if the seekers are using every effort to search for the hiders, eventually they may look toward the sun to find a spec of a base that might be detectable with their technology, such as a spec being found in the vastness of the Kuiper Belt.
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Assuming a situation similar to [this](https://worldbuilding.stackexchange.com/questions/85684/almost-tidally-locked-to-moon-and-the-tides-it-would-create/86177#86177), where the moon causes slower but massive tides that slowly encircle the globe. Would the poles be constantly underwater or not underwater (like A or B below)?:
[](https://i.stack.imgur.com/I7JbV.png)
Or would it depend on the moon?
Main question: Would a massive tide be closer to A or B or C(something else)?
[Answer]
You cannot have neither A or B. Of the two, B is the more implausible: the water is being pulled in 3 directions (up, right and down) by a single moon.
About A, I would expect the two spheres (solid and liquid) to share the same rotation axis, and thus a non zero tidal height also on the side opposite to the moon, more or less like [it happens on Earth](https://en.wikipedia.org/wiki/Tide).
[](https://i.stack.imgur.com/kj8AC.png)
The poles would practically experience constant low tides.
A situation like A or B would not be happening around one of the principal axis of inertia, and therefore could not happen spontaneously.
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After many, many attempts on worldbuilding, I decided to go back to an old project of mine.
I need to design a planet that, at the same time, is habitable but hostile to human life.
I would like it to have as its principal ecological feature a **very, very dense fog** that covers a large part of the surface of the planet, regardless of the season of the year.
**What would be the requirements to make such fog possible?** **What would be the climatic and ecological effects of a fog like that on a ecosystem similar to Earth's?**
At the same time, it should be a *darker* planet, somehow. Thematically, I would like to explore the possibilities and consequences of darkness as a distinctive ecological feature on societies.
Maybe, although my planet shouldn't be tidally locked, it could have a twilight / dawn more extensive in time than Earth's. Could it be possible? How?
Is it possible that an Earth-like planet may have a night longer than the day? Could it be habitable for human-like species?
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This is not dark fog. This is **volcanic ash**.
[](https://i.stack.imgur.com/TsIEW.jpg)
<https://www.flickr.com/photos/ice-art/7245072370>
>
> Sun through a cloud of volcanic ash The ash from Eyjafjallajökull and
> Grimsvötn is still lurking around, and when the wind is right this is
> what happens here in Reykjavik. Photo shot at 10:30 pm (22:30) GMT
>
>
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In your world, there are volcanos that spew ash on a regular basis. The eruptions darken the sun. Then when there is wind, the ash is again stirred up.
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As @Wilk has already mentioned, your best bet would indeed be vulcanic ash. Give your planet some very active volcanoes, and the fog/ ash clouds could be perpetual.
The ecological consequence hangs on one question: For how long is that ash cloud already there? If it is around for already a few hundret or thousand years, the ecology will have adapted. Only up for a few decades... The ecology will not like that. Same goes for the climate.
If you want to additionaly darken your planet, place it around a star with a luminosity lesser than that of our sun. This may result in a colder planet, that is still habitable and very dark all around.
If this situation is the norm for this planet, animals and plants (if there are plants!) will have adapted, e.g. better hearing or olfactory senses, or photosynthesis with the prevalent wavelength of light (IR, maybe? You can handwave that).
In regard to a humanoid civilisation... There may be one, it is your story! Their society may avoid light, or deem it divine. As long as they can get enough food to survive, a breathable athmosphere and shelter, this planet is habitable (albeit a bit frosty).
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When all else fails in world building, Life is often the solution.
Why not start with a planet which is primarily swampland and fill those marshes with a plant which produces fog. Perhaps this is a world where vines did not evolve to transport life fluids within the plants, so to grow out across dry spots, the surrounding plants in the wet lands spew thin water fountains into the air. The winds then carry the water in all directions including the nearby dry lands, allowing seeds to germinate and survive in the moistened soil. As a side effect of all of these water fountains, a larger than average quantity of ground water enters the atmosphere, producing a continual fog.
Out on the oceans, a variant on these water fountain plants could take the form of great dark leaved plants which float just under the water's surface, absorbing sunlight for food but also producing enough heat to increase the atmospheric moisture above them as well.
Add these mist makers to a planet which is already predisposed to fog for the same geological and atmospheric reasons as the foggy parts of Earth, and you could have a very macabre twilight world to play with.
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Fog-forming is complex.
First of all, fog is basically ground-level clouds.
**How are they formed**-
When a hot, humid air mass collides with a cold air mass, the moisture capacity can decrease drastically, forming fog.
I can give you a suggestion on your planet-
A part of the planet is a swampy and non-foggy area, as it is warm. But the moist air, rushes out into the colder regions of the planet, causing it to cool down, and turn to fog.
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**NB: This is *not* a duplicate of [this question](https://worldbuilding.stackexchange.com/questions/14234/cleanly-remove-humanity)**, **because A) it only asks to wipe out humans, not any other life-form, and B) it insists that one person must survive. The survival of anything is not possible in my scenario, and all of the answers are not applicable to wiping out other animals, plants, fungi and microbes.**
This may be a duplicate, but I'm yet to come across a similar question.
Basically, my question is simple; **What natural events could wipe out all organisms on Earth, including prokaryotes, in only 15 years, but leave the Earth habitable to microbes at the end of those 15 years?**
The 15 year figure can be stretched to up to 35 if it's necessary, and yes, I know it's a really short amount of time. One other requirement is that the disaster must not harm orbital space stations.
That's more or less it, comment if you need any more information.
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Since you clarified that artificial events are also acceptable, I'm going to suggest: [self-replicating nanotechnology which is powered by ATP](https://en.wikipedia.org/wiki/Grey_goo).
ATP is an energy exchange molecule found in essentially all forms of life, and it is a natural one to deliberately make a nano-tech system use. Consider a nano-tech system that deliberately needs its energy as ATP both because we understand it well and because this would in a laboratory environment be an easy way to control its actions or growth.
If the nano-tech then gets out of control, it might spread killing everything on Earth but then would itself run out of energy and fall apart once there is no more ATP to access. There might be some isolated surviving single celled critters but that will be it.
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A massive [gamma ray burst (GRB)](https://en.wikipedia.org/wiki/Gamma-ray_burst) aimed directly at the earth. The gamma rays would probably not reach the surface in a sufficient dose for mass-extinction but the Nitrogen in the atmosphere would form [nitrogen oxides](https://en.wikipedia.org/wiki/NOx). In combination with water these compunds form a variety of acids, most prominent example would be [nitric acid](https://en.wikipedia.org/wiki/Nitric_acid). All higher life on earth would suffocate, and most microbes would die because of the oxidative properties of nitrogen oxides. The seas would essentialy become big acid pools which means that most of the sea life is dead too. Only some [extremophiles](https://en.wikipedia.org/wiki/Extremophile) could survive this but they'd probably survive anything that leaves the earth intact. The nitrogen oxides will begin to decay and after some years (15 should be enough) the earth would be habitable again.
Orbital stations should remain intact struturally but all electronics that are exposed to the radiation will probably suffer. On the other hand the stations and satellites that were on the other side of the Earth than the GRB will stay intact.
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[Have a 500 km asteroid hit Earth](https://www.youtube.com/watch?v=bU1QPtOZQZU)
[Airborne bacteria](https://www.smithsonianmag.com/science-nature/living-bacteria-are-riding-earths-air-currents-180957734/) that arrived after the impact could survive in the atmosphere. The conditions in the atmosphere shortly after impact would make this impossible but given that blackbody radiation is proportional to temperature to the fourth, bacteria can survive at 130C, and that convection currents would keep bacteria up and bring resources to them, it is possible that the upper troposphere/stratosphere is habitable to bacteria.
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You need some special mutation that will create an organism able to infect and destroy all living creatures on Earth, including bacteria. Some kind of all-devouring unstoppable virus, changing, adaptable etc.
And then after destroying all life it must die out cause of no "food" or carriers would remain on Earth. Of course it's a very sci fi looking idea, but so is your question. ;)
The Earth will stay habitable, cause all air, water, soil will be fine, moreover it'll be rich with organic remains of previous life. And no poisonous chemicals, radiation, overheating or anything like that.
Of course the plants and power stations will be unattended that might create some problems in future, but I guess that will be in any case - with any natural solution to your task.
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A burst of a zettasievert(\*) of radiation would instantly kill any life exposed to it, but it may also detonate any radioactive material on earth, or melt the sky, depending on the type of radiation and what not. Materials that easily turn radioactive might be effected, but bursts of radiation usually do little other than destroy life. Mind you when I say burst, I'm referring to the several millisecond kind, not the couple hour kind.
*(A sievert is the dose received in one hour at a distance of 1 cm from a point source of 1 mg of radium in a 0.5 mm thick platinum enclosure. A zettasievert is quite a whole bunch of those! As in, 10^21 of those.)*
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I misread [an answer to *My carrier pigeons have been replaced by spoons: how can I send messages?*](https://worldbuilding.stackexchange.com/a/120882/11665), thinking it was referring to a network of parabolic reflector dishes made of spoons orbiting the planet. This lead me to envisage a colossal trebuchet on a mountaintop launching a [rocket-powered](https://en.wikipedia.org/wiki/Roger_Bacon#Gunpowder) structure of spoons into orbit, though I have doubts about the realism of this plan.
Assuming that the Royal Mathemagicians have discovered Newton's Laws of Motion, and ignoring for now how they'd actually *use* an orbiting parabolic reflector dish, is this realistic?
* How would they launch it far enough?
* How would they adjust it into a stable orbit?
* Would the spoon structure survive the forces involved?
* Is this affordable for a medieval king?
* Assuming a surface gravity of 1G, how small would the planet have to be for medieval technology to be capable of this feat?
(A smaller planet would mean a lower atmosphere and atmospheric pressure, so there's a limit as to how small you can make the planet.)
* What's the *minimum* required handwaving to make this possible?
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It's not possible, whatever the planet, to launch something into orbit with a single throw: any "orbit" created from giving something an initial trajectory (eg launching it from a cannon) will (in a vacuum) come back and intersect the initial start point (unless it hits something on the way, eg another part of the planet). If there is an atmosphere (thus providing drag on the way up) then the "orbit" is modified further, to crash into the planet sooner.
See <https://en.wikipedia.org/wiki/Space_gun#Technical_issues>
The only way to prevent it crashing back into the planet is to give it so much speed in the initial launch that it has escape velocity: In this case it will fly off into space, never to return, and you don't have an orbit either.
Rocket-borne satellites achieve a stable orbit by having the rocket constantly change it's velocity: as it gets higher up, it turns and blasts more "sideways" to achieve the orbit parameters. So, in order to get something into space you would need to have at least one additional "course change" somewhere on the way up.
I'd say that the minimum required handwaving would be targetted on this additional "burn" to get it to change velocity once it's in space. Perhaps some primitive form of actual rocket could be used: a rocket, after all, is just a slow explosion in a box with a hole at one end.
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# You need to hand-wave Adamantium
Low Earth Orbit velocity is 7 800 m/s, or Mach 23.
Now you said "trubuchet". Ok... let us assume we have a **really big** trebuchet... let us make it, say, 300 meters high. Let us assume the swing-sling is travelling in a circular arch with 300 meters diameter, for half a revolution before it is let go.
$300m \times \pi \approx 1000m$
So in 1000 meters travel you have to achieve a velocity of 7800 m/s.
Ok, so... during constant acceleration *a*, the distance travelled *s* is resulting velocity *vmax* times the time *t* over *2*. And the resulting is the acceleration times the time.
$s = 1000m$
$v\_{max} = 7800 m/s$
$s = \frac{v\_{max} \times t}{2} \Rightarrow t = \frac{2s}{v\_{max}}$
$v\_{max} = at \Rightarrow t = \frac{v\_{max}}{a} \Rightarrow$
$\frac{2s}{v\_{max}} = \frac{v\_{max}}{a} \Rightarrow a = \frac{v\_{max}^2}{2s} = 30420 m/s^2 \approx 3000g$
There is no material we know that will survive an acceleration of 3000 g and not be crushed by its own weight. For an example of what happens when something made of metal experiences an acceleration of 3000g, [this video is very illuminating (and mesmerising)](https://youtu.be/QfDoQwIAaXg?t=6m23s). In short: at those forces, it does not really matter what the thing is made of, because everything **splats** like it is made of putty.
So first you need to hand-wave [Adamantium](https://en.wikipedia.org/wiki/Adamantium), otherwise your trebuchet, the spoon reflector and everything supporting them will fly apart on launch as if you tried to make a trebuchet out of soft clay.
But(!)...
If you have Adamantium... then you can build a [space elevator](https://en.wikipedia.org/wiki/Space_elevator), with no need for a trebuchet to reach space.
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Imagine a world in which a household can choose which Commonwealth to be a part of, much the way that you might choose a cell phone provider or a religious denomination or a health insurance company.
Your Commonwealth would collect substantial taxes from your income and property, and would use it to provide retirement savings, health care, disability payments, other social safety nets, education, library access, banking services, unemployment insurance, inheritance laws, and divorce laws, for members of your household. It would be responsible for providing its share of military personnel for the country. They would run parks that non-members could use at an additional fee, all over the country, and political power you had would be through Commonwealth representatives.
Transferring from one Commonwealth to another Commonwealth wouldn't always be easy, because you might have a net debt to your Commonwealth at any given moment and because a new Commonwealth wouldn't want to take on people who would burden it. There would have to be central rules about transfers.
In that sort of framework, what is the bare minimum that a central "federation of commonwealths" for the whole country would have to provide in order for the system to function with a contemporary level of technology.
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There are **public goods**, that can be provided either to everybody in a given territory, or to nobody at all. You cannot exclude those who do not pay their share:
1. Military protection & international relations
2. Environmental regulation
Then there are **natural monopolies**, i.e. areas where it is not economical to have more than one organization provide the service.
1. Utilities: electricity, water, natural gas
2. Roads (at least local ones)
3. Police and firefighting (since it is easier to protect a general area than specific homes in it)
Public goods have to be provided by a central government.
In your scenario, that central government could be a council of representatives from each Commonwealth. Not sure if that even counts as federal government.
Natural monopolies can be private companies, but to prevent price-gouging, central government has to regulate the price that they charge.
Then there are the **laws** that govern relations between enclaves, and/or businesses, and courts that enforce those laws. I think this falls under natural monopoly, since it is easier for everybody if there is only one law of the land.
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I'm not 100% clear on what you're asking but some things come immediately to mind as necessary for this situation to be tenable:
* commonwealth members' movements cannot be limited *in any way* by geopolitical boundaries. This includes not only their person but also their possessions and professions, people need to be able to pick up and go wherever whenever their commonwealth requires.
* the same goes for the transfer of funds across borders only more so. If you can move but your money can't you're pretty much stuck where you are.
* to some extent you need an extreme degree of geopolitical stability, locally and abroad. Without that geographical contiguous states of some sort are a prerequisite for personal security.
* travel has to virtually free, in terms of disposable household incomes. Otherwise the expense of moving around will put geographical limits on the extent of commonwealths.
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## Exclaves and Enclaves
[@Ash has hit on a very important issue](https://worldbuilding.stackexchange.com/a/120610/760): you can't just make geography go away. Contiguous borders are very convenient. They provide easy travel and communication between your people, and a minimal border to control and defend.
What you're proposing is that everyone lives in [enclaves and exclaves](https://en.wikipedia.org/wiki/Enclave_and_exclave): territories surrounded by other territories. If they want to get anything *physical* done they must negotiate with their neighbors.
For example, my house has hookups for roads, water, sewer, gas, and electrical. These will necessarily have to pass over and under my neighbor's property who may be in other Commonwealths. I need physical access to and from my property to get supplies and visit friends. What if my neighbor doesn't want that? I'm effectively blockaded and my Commonwealth will have to negotiate peacefully or with force to keep me alive.
Hopefully the utility companies will do that negotiating for me, but they will rapidly tire of having to negotiate with thousands of little Commonwealths each with their own political structures and wants. It's not an environment conducive to business. And when they get it all sorted, maybe somebody decides to change to a Commonwealth they don't have a treaty for and they have to start the process all over again.
Similarly, how does a geographically fractured Commonwealth physically protect its members? With potentially every citizen in their own exclave its surface area is huge! They can't post a guard in each exclave. When someone breaks into my house, how far away will the police be? Will they have to negotiate with my neighbors to come to me?
Finally there is public safety. My neighbor's house catching on fire puts my house in danger. My neighbor burning tires puts my health in danger. My neighbor shooting guns puts my life in danger. This is why we have building codes and environmental laws, we all breath the same air and drink the same water. What happens when I watch my neighbor in a different Commonwealth do some really dodgy wiring, smoke in bed, burn their trash, and poop upstream from me?
This means Commonwealths must negotiate treaties with other Commonwealths in order to function. Not just their immediate neighbors, but they must negotiate a contiguous network for utilities and transportation. There's two ways this could happen...
## Corporations
Let the Corporations handle it. This is kind of like what is done today in the US where governments use their power of [Eminent Domain](https://en.wikipedia.org/wiki/Eminent_domain_in_the_United_States) to seize land (with compensation) for the public good to build roads, utilities, parks, etc. Normally this land must be used by the government alone for the public good, but delegation to a third party is also possible. For example, governments often seize land and hand it to utility companies and railroads to run their lines. For Commonwealths this might also include police, medical, and firefighting.
The danger is this would, effectively, hand much of the power of a Federal government over to Corporations. Similar to the issue of multi-national Corporations today, but on a much, much, much larger scale. Successful Corporations would be able to cross Commonwealth borders and scale far, far, far larger than any single Commonwealth.
On the upside, this would make them more efficient. On the downside, this would make them larger and more powerful than any Commonwealth. It would give the Corporations coercive control with no regulatory oversight. Rather than fight each other for Commonwealth contracts, the few largest corporations would divvy up the market and form a [coercive monopoly](https://en.wikipedia.org/wiki/Coercive_monopoly) to maximize profit for themselves. A modern example is [the US Internet market](https://en.wikipedia.org/wiki/Internet_in_the_United_States#Access_and_speed) where 2/3 of the population has 2 or fewer options.
If you think End User License Agreements are bad now, wait until there's no government oversight. Your Internet company would be free to spy on everything you do. Don't like it? No Internet. One might think "I'll just use encryption and [darknets](https://en.wikipedia.org/wiki/Darknet)", nope; if you use anything but the approved encryption (complete with Corporate backdoor) you're banned. [Net Neutrality](https://en.wikipedia.org/wiki/Net_neutrality) goes right out the window, you're stuck only contacting the Corporate approved Internet services that they have profit sharing deals with.
How about water? Don't want to pay their prices, your Commonwealth dries up. At the extreme end, you are invaded by a Corporation's overwhelming private security firm.
## Confederation
If they don't want a cyberpunk corporate dystopia, Commonwealths would form a [Confederation](https://en.wikipedia.org/wiki/Confederation) to function. Rather than simply negotiating with each other, Commonwealths would join a Confederation (there need not be only one). They'd delegate some of their powers to it, and gain some power to influence the decisions of the Confederation. Exactly how influence is distributed is up to the Confederation.
For example, members of a Confederation might delegate their right to border control to the Confederation resulting in free passage for their members between all other member's territory like the [Schengen Area](https://en.wikipedia.org/wiki/Schengen_Area). They might agree to a single currency, like the [Eurozone](https://en.wikipedia.org/wiki/Eurozone), and [delegate some of their monetary policy to a central bank](https://en.wikipedia.org/wiki/European_Central_Bank). They might negotiate a [common security and defense policy](https://en.wikipedia.org/wiki/Common_Security_and_Defence_Policy). Water and power security. A transportation system...
The Confederation also acts like a [co-op](https://en.wikipedia.org/wiki/Cooperative) or [trade union](https://en.wikipedia.org/wiki/Trade_union). It leverages the collective bargaining power of the Commonwealths against other Confederations, Commonwealths, and Corporations. This [multilateral bargaining power](https://en.wikipedia.org/wiki/Multilateralism) gives each Commonwealth power far beyond its own small power. The whole is greater than the sum of its parts.
Yes, this is starting to sound like the [European Union](https://en.wikipedia.org/wiki/European_Union#Defence) for a good reason. The EU is really a collection of treaties between its members. [CGP Grey does a good breakdown of its structure](https://www.youtube.com/watch?v=O37yJBFRrfg).
# Commonwealths, Confederations, and Corporations
It's not *either* Confederations *or* Corporations. It's both. Multinational Corporations will form and exploit the divisions between the Commonwealths. Commonwealths will band together into Confederations to increase their collective utility, bargaining, and defensive power against other Commonwealths, Confederations, and reign in the Corporations.
Beyond just property and defense, it is in each Commonwealth's long term best interest to ensure their neighbors are also stable and healthy. Disease, fire, pollution, bullets, and unrest know no borders.
# Conclusion
Commonwealth members have two choices in the long term.
They can go it alone and live in a world of armed, walled enclaves trying to ignore the problems of their neighbors. To get services they'll hand more and more power over to the Corporations. Like a modern [gated community](https://en.wikipedia.org/wiki/Gated_community), everything will be fine so long as their wealth holds out.
They can band together into Confederations for collective security and mutual benefit. All for one and one for all. Each Commonwealth contributes to the Confederation and the Confederation supports each Commonwealth. The Confederation can have their own utilities and services, or can bargain collectively with Corporations reducing the threat of Corporate take over.
The third option, have a single Commonwealth that is large enough and resource rich enough that it can go it alone, is unstable. It is effectively a Confederation with no governing body. Any single member can decide to switch to a new Confederation possibly throwing the whole situation into chaos.
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This is doable - but the role of Confederations would be much smaller than one that American state system plays today.
Currently, in USA or or other typical confederacy, central government, at the minimum, takes care of things that can not bu successfully fractioned, like national security and defense. It may go further and engage in management of other things like postal service, healthcare and pensions, but strictly speaking, neither federal nor local government is required to do that.
States and municipalities usually manage:
* Infrastructure, particularly roads and bridges;
* Law enforcement, including judiciary duties;
* Fire and other emergency services;
* Business licensing and regulations;
* Education, particularly primary and secondary;
Those duties will have to be largely diminished.
* Infrastructure is usually financed as "public works", from taxes or special bonds. "Patchwork" confederation would have little incentive to engage in it. Today, a state may see the need to build a road that connects two town, because it goes entirely through the state and would benefit people of the state. For confederacies, the road would go through many jurisdictions and none would see it as justifiable. On the other hand, corporations can be successful in building toll roads;
* Law enforcement is particularly tied up to geographic locality. It is a common trope for people who are chased by law enforcement agents to seek sanctuary in a foreign embassy. Unless law enforcement can operate without territorial bounds, every house in a neighborhood can become such sanctuary. which means that law enforcement should either become a federal function, or be carried over an extraterritorial agency. In any case, confederacy lose this responsibility.
* Fire and emergency services follow the same rules as law enforcement. We can't let one house in town burn if it belongs to a different municipality;
* Business licensing and regulations are designed to protect consumers and environment. If we switch to a non-geographical model, it will force a "race to the bottom", when any business would choose a confederacy with the least taxes and regulations. This, imho, is not viable, but objectively speaking, libertarian model can potentially work. Anyways, government role in collecting taxes and setting up regulations will significantly diminish.
* Education, like many other duties, can be carried by private institutions. In addition, confederacies may make agreements that would allow children to attend each other's schools.
Overall, the confederacies would be almost insignificant. As I mentioned, during the "race to the bottom", everyone would seek the most permissible confederacy to join, because non-geographic confederacy would not be able to provide significant benefits to its members.
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What you're describing is not all that dissimilar from the way certain groups of hardcore religious nationalists have attempted to view the world historically.
One way they work this out is by defining citizenship in terms of participation in the cult. For example, during the reformation in Europe in the 1500s, a person in a catholic territory had certain state-offered rights if they were members of the catholic church, and that membership was established or revoked on the testimony of the members of the local congregation. In territories with a denominational patchwork (wherein peace was typically short-lived in those days), there would be gathering places for each denomination, and the congregations would vouch for their members.
We have a similar thing happening in the extremist parts of the Islamic State. Even if you ignore the command to convert their neighbors, their law necessitates controversy by saying things like, if a woman doesn't dress extremely modestly then she might cause a man to sin. With this way of thinking in place, they can't easily live in close proximity with any group of people which does not share that clothing restriction.
So, in short, this works out if everybody agrees on what makes a citizen, and if the local laws are not intrusive in any commonwealth. It starts to fall apart when person A from a commonwealth B commits a crime in commonwealth C, and then declares himself a citizen of commonwealth D and demands protection there. So the minimum federal or confederal government would have to include rules about whose laws are enforced and how to justly bring restitution to the victim of this kind of crime, as well as requirements on how to be a citizen of any given commonwealth, and it would have to maintain a constantly up-to-date list of commonwealths.
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It's after the apocalypse. Most modern technology has been destroyed, either by disaster or neglect.
How could you locate a particular set of GPS coordinates without the aid of the satellites or modern technology?
**Question Breakdown:**
* What equipment or knowledge would you need?
* How hard would it be, and how precisely could you determine the location?
Thoughts:
My first thoughts are that you would either need an old-world map with the coordinates, or you locate a landmark with known coordinates and triangulate from there
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It depends on your world, but you've already stated the first couple of options to try...
Basic items you'll need no matter what
* Decent Accurate Watch (something that might be hard to find in the apocalyse even harder to find one that is accurate compared to the pre-apocalypse)
* A Compass, preferably an orienteering compass
* A very good quality, high resolution map of the country your reference material is in
* Some string and Pins
Then... you'd need to head to a library, in there brush up and pretty much all of navigation from the history of man. i know that seems a bit over the top, but it's how humans learnt, always expanding on previous knowledge, so this would really take a while to learn
**Triangulation**
This is incredibly complicated and i'm not going to copy and paste a huge amount of text from another site to explain how to do this. so check out this site,
<http://www.compassdude.com/compass-triangulation.php>
It explains it well, with pictures to guide you. but instead of things you can see, you taking items on a map you know the locations and coordinates of to aid you, however I invite anyone to try my below option, see if people can do this without using GPS or google etc.
* The White House in Washington DC is at 38.8977° N, 77.0365° W
* The Statue of Liberty is at 40.6892° N, 74.0445° W
* Alcatraz Island is at 37.8270° N, 122.4230° W
I've picked these starting points as I remember learning about GPS from a textbook way back when, and the three points had there co-ordinates stated in the textbook, so you'd probably be able to get them in the apocalypse
* [Easy Mode] Now find which building is at 38.8899° N, 77.0091° W
* [Hard Mode] Now find which building is at 51.5007° N, 0.1246° W
If you've managed easy mode then fair play to you, its incredibly difficult, because you probably quickly find out that try to pick a single small (comparatively) location even when close to one of the original points is very hard, and that's using a map of just the US which you can at least get on a fine enough scale to do this, as soon as you want to go further afield (Hard Mode) it becomes infinitely more difficult, the greater the distance the rougher the maps then the lower chance of finding the object.
Anyone who managed Hard Mode... sorry but i think you may have cheated... if you haven't then wow, but chances are you either cheated or you worked out buildings in that rough area and then guessed., please prove me wrong.
**Translate into Longitude and Latitude**
This has a higher chance of working, a library would have books that would explain how to convert it, or at least convert it the other way, and therefore just reverse the process. the bizarre thing is after about half an hour of googling, i only found a single link to how to do it yourself rather than a link to a converter
* The whole units of degrees will remain the same (i.e. in 121.135° longitude, start with 121°).
* Multiply the decimal by 60 (i.e. .135 \* 60 = 8.1).
* The whole number becomes the minutes (8').
* Take the remaining decimal and multiply by 60. (i.e. .1 \* 60 = 6).
* The resulting number becomes the seconds (6?). Seconds can remain as a decimal.
* Take your three sets of numbers and put them together, using the symbols for degrees (°), minutes (‘), and seconds (“) (i.e. 121°8’6” longitude)
I copied this in as it wasn't a huge amount of information, i got it from here:
<https://exain.wordpress.com/2008/07/17/doing-gps-conversion-degrees-to-latitude-longitude-and-vice-versa/>
From there get a sexton and brush up on your stars, lets just assume you could find a quality sexton in an antiques store, then follow the stars. again i prefer not going to copy and paste someone else's work when its more than a few lines
<https://www.pbs.org/wgbh/nova/shackleton/navigate/escapenav.html>
This would take extreme dedication on the characters part to learn all of this, it would take a long long time, but most Apocalyptic RPGs, TV series, and novels do have characters that either do exactly this, or something that is equal in learning. so i think its likely that if portrayed well then it would work.
My suggestion would be to translate the coordinates to know where you are going, and then also translate the points of reference, and then triangulate you position when in sight of your target area to check you are where you think you are.
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Many cities already have plaques with the meassurements. Look for those survey markers.
In Uruguay these are made in granite with bronze labels.
In other countries there are metal disks.
[](https://i.stack.imgur.com/zNDkg.jpg)
[survey markers](https://en.m.wikipedia.org/wiki/Survey_marker)
[Answer]
This depends on the planet. The technique could be different depending on the world you have in mind, as they could vary in magnetic poles, true-north poles, daily rotation, etc.. *My answer, like the others here, assumes Earth*, or a very Earth-like world.
GPS coordinates generally come as a pair of numbers. One number, the latitude, tells how far you are between the north and south poles from negative 90 degrees to positive 90 degrees (or 90S to 90N). The other number, the longitude, tells where you are in the other direction from -180 to +180 (180W to 180E), where around the circumference of the world you are.
Both of these numbers are generally given in 1 of 2 forms: DMS (Degrees-minutes-seconds), or as a decimal number. The latter is simple: 3.25 degrees north latitude is just what it sounds like, a quarter of the way between 3 and 4. DMS divides it up into smaller units, where there are 60 minutes in a degree and 60 seconds in a minute, so 3.25N equals 3 degrees, 15 minutes, 0 seconds N.
Latitude and longitude can be measured without any need for any map or compass. Sure, having these tools would be nice and allows you to take short cuts, but it is not too difficult to re-invent this wheel when necessary. However, you must measure latitude and longitude separately, very differently from each other, and even though it's not difficult conceptually to understand longitude measuring you do need an accurate clock.
## Latitude
There are multiple ways to measure latitude. I will focus on the stars since they are easier to remember and the most reliable as long as the night is clear.
In the northern hemisphere, measuring latitude is as simple as measuring the angle to Polaris, the north star. Straight overhead means you are at the north pole (90 degrees north latitude), and straight out on the horizon means you are just above the equator (nearly 0 degrees latitude). Between the two, you just measure the angle of the north star in the sky, and that literally and directly tells you your latitude. North star 30 degrees up? You're at 30N. 50 degrees? You're at 50N. In fact, you can roughly estimate your latitude just by eyesight with no tools at all. Using a quadrant, sextant, or similar device will help you measure more accurately and finely.
You can literally use a protractor for this, and hang a string from a weight to help you estimate what is straight up/down to help measure against. You can also create a quadrant out of paper by cutting out a quarter-circle and measuring off the degrees on it and sighting along the edge.
[How to Find the North Star](https://www.wikihow.com/Find-the-North-Star)
In the southern hemisphere, the process would be similar, except that there is not a bright star directly above the south pole, unfortunately. Instead, you need to estimate the south pole point in the sky and measure against that. You can estimate it by using the "southern cross".
[How to Find the South Celestial Pole](https://teara.govt.nz/en/diagram/7486/navigating-by-the-southern-cross)
When close to the equator it is a little bit different. I think you might be able to use the constellation Orion for that. I will look into that and get back to you for that.
## Longitude
To measure longitude, you have to pick a spot around the earth's circumference to call 0 degrees. Right now, the standard is that 0 degrees longitude, called the "prime meridian", is the line between the north and south poles which passes through the royal observatory in Greenwich.
To calculate longitude, you keep track of the time at the prime meridian, and you calculate the difference between that time and your own, generally at a well defined time such as noon.
There are 24 hours in a day as the sun goes overhead around the entire planet (due to the planet rotating). You can use basic algebra to equate those 24 hours into 360 degrees of a circle around the planet. So each hour difference equals (360/24) = 15 degrees.
**Example:**
So you have a pocket watch whose time is set to the local time zone at the prime meridian. You want to know your longitude, so you measure shadows to figure out when the sun is at the very highest point in its arc over your head for the day, as that is the exact moment of noon at your location. Noon at your location coincides precisely with 10:30 on the watch, so there is a difference of 1.5 hours. At 15 degrees per hour, that means that your longitude is (15\*1.5) = 22.5 degrees, or 22 degrees 30 minutes of longitude.
Hopefully you still have a watch around. If not, you might have to measure latitude only.
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If you have a point with known coordinates, then any other point on the face of the planet can be found using sufficiently accurate gyroscopic means.
As you travel, your exact speed and heading (maybe bearing) are known. This technology is used on submarines and has become surprisingly accurate. It is also used in missiles to defeat GPS jamming technology.
While there is error associated with these systems, it normally comes from things such as rocking of a boat and very high speeds. At low enough speeds and decent handling of the device, you get outstanding accuracy.
Another possibility is a counter-rotating optical gyroscope. These do exist and can give compass bearings with amazing accuracy. If you know the bearing information, your heading is simply just following that line until you reach your point. Measuring distance incredibly accurately is actually relatively simple.
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The species in question are Herbivores, bipedal in nature, around 50 to 80 pounds on average, and require around 2250 calories per day to stay healthy.
The ships these populations would live on are big, bulky floating towns, in an aproximate medieval period level of technology. Perhaps supporting dozens to even a thousand or so each and remaining out at sea for years, decades, or even indefinitely if possible.
If the upper limit of required calories per day per person were exactly 5000, how possible would it be to feed one thousand people off of underwater flora that can grow within 300 feet of the surface if the ocean were similar to one on Earth? If impossible, what would the upper limits be?
[Answer]
Building on the answer of @manassehkatz, I think we might be able to tweak things to work.
As previously mentioned, kelp (the highest calorie seaweed I've managed to find) only had 43 calories per 100g. Even spuds have 93 calories. However, let's try and solve a few of the problems.
**Caloric Intake**
The main issue highlighted in @manassehkatz answer was that with such a low-calorie food, your people would need to be eating *a lot* of seaweed to meet your 2250kcal daily intake to stay healthy. 5.2kg a day is a lot. About double what it would take in cooked potatoes (2.4kg).
However, is 2250kcal necessary?
Your humanoids weigh between 50-80lbs (~23-36kg). Baka pygmies in Africa [weigh on average](https://www.nature.com/articles/ncomms8672) 53kg for men and 46kg for women. Not quite as light as your seafaring herbivores, but let's take that as an upper bound. Now, trying to find a recommended caloric intake for little people has proven to be depressingly difficult. Closest I've found is an offhand mention of 1000-1400kcal per day. Let's fudge some numbers a little and say that the upper bound for our heavier modern little people is roughly equivalent to what your lighter but more physically active mariners need.
So, 1400kcal/day. That's a little more manageable.
Assuming your people have been cultivating seaweed for a reasonable amount of time it's not too difficult to believe they'd cultivate a more nutritious variant. If we take wild rice (101kcal/100g) vs domestic rice (129kcal/100g) as an example, then we could conceivably bump the caloric content of domesticated kelp up to 50kcal/100g.
Running the numbers again, our leaner more efficient herbivores now only need to eat 2.8kg of kelp per day. Much more manageable :) even wild kelp at 43kcal/100g gives 3.3kg which isn't insurmountable.
Oh, and the 43kcal/100g for kelp is a figure for raw kelp. Cooking tends to increase the caloric density of food, so there's wiggle room there too despite not being able to find a figure for cooked kelp.
**Area**
Next, we need to find out how much area is required to grow enough food to support your population to see if kelp is viable as an agricultural staple.
Luckily, I've come across [this article](http://www.fao.org/docrep/005/ac860e/AC860E06.htm) detailing the aquaculture of various different seaweed species including yield per hectare! Perfect :)
Let's take good old spuds as an example of typical agricultural efficiency. With modern agriculture, we can produce 17.4 tonnes of potatoes per hectare (17400kg per 10000 square metres, or 1.74kg per square metre). I'm not sure how far potato farming has come since the middle ages, but I'd be willing to bet that this yield is significantly higher than a medieval one. Still, it's a good upper bound.
Our kelp (wakame) produces about 10kg of wet weed from 1m of rope using rope aquaculture (and is less labour intensive than nori farming which is good). Let's say the density of rope aquaculture is one rope per square metre (might be able to squeeze two in based on pics of the plant from google), we're looking at over 5x the efficiency of wet weed compared to potatoes. From what I gather, wakame is eaten wet so there's no funny business with comparing dried calorie density vs wet.
This might just work...
**Population density**
From the above, we can hazard a guess at the population density your aquaculture can support.
If each mariner needs to eat 2.8kg of kelp per day, and each square metre of aquaculture produces 10kg then each mariner will need 102 square metres of aquaculture to survive for a year producing 1022kg of kelp. With wild kelp, the figure is 120 square metres.
Compare that to good old spuds and you'd need 314 square metres per mariner per year using modern techniques. Seaweed's looking pretty good now!
So like for like, your mariners can support roughly 3x the population of their land-based potato-eating cousins.
As a rule of thumb, there's a medieval source that claims 1 square mile supports 180 people all-inclusive (not only farmland but housing and roads and inefficient uncultivated land).
Now, including their smaller stature and more efficient aquaculture, we can support 4.96 mariners for every one person (based on 2250kcal/day people eating potatoes, which isn't exactly rigorous but hey ho). So, we end up with a figure of 4.96 mariners per square mile.
So using the medieval model of land usage we end up with our 1000-mariner settlement spread across 201 square miles. A little less than [Lake Winnebago](https://en.wikipedia.org/wiki/Lake_Winnebago).
**Further consideration**
How herbivorous do you want them to be? In the wild, you'd be surprised at how blurred the line is between herbivores and carnivores. Many animals you'd assume to be wholly herbivorous eat a surprising amount of animal matter.
If you don't want them to actually eat meat, how about deep-frying your kelp in animal fat? Plenty of blubbery animals in the cold waters where kelp grows best, and from my cursory research deep-frying adds roughly 100-120kcal per 100g. Digesting oils and fats from animal sources is digestively little different from oils and fats from plant sources, and medieval people tend to have a lot less moral scruples when it comes to what they eat. Food's food after all...
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### [Seaweed Soup?](https://rads.stackoverflow.com/amzn/click/com/0064467368)
This would be trivial if they were omnivores - all the fish in the sea to eat. But they are herbivores. So the logical choice is **seaweed**. There is a problem though - at 43 calories per 100 grams, that works out to...around 12 pounds of seaweed a day to get 2,250 calories. I think that it would be too much. Actually, that might have more calories than 50 - 80 lb. herbivores need. Even 1/2 of that would be 6 lbs. a day. That's a lot. Seaweed and other plants that grow near the surface of the sea just aren't your high-calorie rice, potatoes, beans or wheat that you can grow so easily on land.
### I don't think they can do it...
* Medieval Technology
That rules out advanced hydroponic farms grown on the ship, diving with scuba gear to harvest from the bottom and a lot of other options
* 300 feet?
The ways you normally harvest in the ocean more than a few feet down, without scuba equipment, is with fishing poles or nets. Fishing poles don't help if you don't eat fish. Nets can catch fish and other creatures, and also gather in seaweed and floating plants. But they won't eat the fish and other creatures, and it will be very hard to satisfy their caloric (and nutritional) needs with seaweed and floating plants.
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Since **they evolved to live this way**, they didn't appear in the ocean one day out of nowhere, it's reasonable to think that **they have breed the best plants** as we did on the land, therefore we can assume that their food could be times more nutrient than the plants we currently see in the sea.
As manassehkatz wrote seaweed could be an option but with his assumptions the aliens will be more or less sea panda, busy eating seaweed all day long.
IMHO they should have breeded more nutrient seaweeds, then they should eat for a lot of hours - and this is actaully really common for herbivores- but they won't be sea panda.
Moreover rain happen to happen also over the sea, and while it can't be considered a reasonable fresh water reserve for a wheat field, it could be used to farm some small yet really nourishing vegetable only by decreasing the salinity level of a special/confined pool.
They can also use bare solar power to harvest fresh water by distillation, it's not that difficult to do even with only medieval technology.
The main point is that the only need to have some water with low salinity (respect to the ocean), not pure fresh water. In fact there are some current vegetables that are [salt tolerant](http://scholar.google.it/scholar_url?url=https://www.researchgate.net/profile/Adriana_Galvani/publication/226923350_The_challenge_of_the_food_sufficiency_through_salt_tolerant_crops/links/0046353ca3575bc183000000.pdf&hl=it&sa=X&scisig=AAGBfm2cbFi9uZ--MAN6yESZCe7lsOIZgg&nossl=1&oi=scholarr) (page 10, table 2):
* asparagus
* beetroot
* barley
* rye
Also [Quinoa](https://en.wikipedia.org/wiki/Quinoa#Sowing) could be a good candidate since "Quinoa plants do best in sandy, well-drained soils with a low nutrient content, moderate salinity, and a soil pH of 6 to 8.5".
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Evolution might Interfere with your species, altering the feeding mechanism, and they might eat the ever present plant in the sea、Phytoplanktons.
This answer takes note that:
The ships' design is not specified.
The species' feature is not specified fully.
So your "Ship island" might be afloat, but somehow 2 feet deep in the water, just enough to make your species' feet to be drenched in water. The feet now has spores that could filter phytoplanktons and use it as food. They can also shut down their "Feet mouths" when they feel they are full already.
Not the most pleasing feature perhaps, but evolution does do things crazily just to make something survive a situation. I do think in this approach, there is a near infinite supply of food for all of your species.
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I'm pretty much looking for an easy (or not) formula for calculating the mass and/or weight of fantasy creatures on an Earth-like planet with similar gravity. My world's dragons sometimes reach over 1 km long, magically supported regardless of weight, but I would still like to add a realistic number to the weight fields of the profiles of my draconic characters. I also have turtles the size of islands (inspired by Magi-Nation, NOT ATLA) and skyscraper-tall humanoids. My question is: How does one calculate the weight or mass of such incredibly large creatures?
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Wow. At those scales, they're not just flying via magic, they're not crushed into pulp by their own mass via magic. This is because if you grow proportionately, your weight increases much more. If you grow twice as tall and twice as wide, you've gained eight times the volume. [This link](http://www.ftexploring.com/think/superbugs_p2.html) walks through the math on this.
That may also give you the tools to calculate your weights, as they will follow similar mathematics.
[This site](https://www.aqua-calc.com/calculate/weight-to-volume) says a human body weigh(s) 1.01 gram per (cubic centimeter) or 0.58 ounce per (cubic inch).
>
> w = ρ × v where w=weight, p or rho=density, and v=volume
>
>
>
[Google](https://www.google.com/search?q=density%20of%20human%20body&rlz=1C1CHBF_enUS741US741&oq=density%20of%20human%20body&aqs=chrome..69i57j0l5.5692j1j4&sourceid=chrome&ie=UTF-8) tells me that the average density of the human body is 985 kg/m3, and the typical density of seawater is about 1020 kg/m3. The average density of the human body, after maximum inhalation of air, changes to 945 kg/m3.
I'm not finding any sources on the body density of dragons, unfortunately. But you should be able to use the above equation to figure out some values that work. You may want to shift the density up or down for your creatures, especially if they have heavy armored hide, for example.
[Answer]
**Find a similar creature and use the cube-square law**
For example a [big lizard](https://en.wikipedia.org/wiki/Komodo_dragon) is about 3m long and weighs about 70kg. That's comparable to a tall man.
That means if we double the length and keep the proportions the weight is $70 \times 2^3 =560$.
So a *really big lizard* is about 6m long and weighs about 560kg. That's comparable to a small cow or smart car. The lizard is much longer but slimmer than either.
We want to know the weight of a $1000m$ long dragon. The dragon is $1000/3 = 333$ times longer than the lizard.
So the dragon weighs about $70 \times 333^3 \sim 70 \times 3.7 \times 10^7 \sim 2.6 \times 10^9kg = 2.6 \times 10^6 t$.
That's **2.6 million tons** or 2.6 megatons. Maybe increase it to 3 megatonnes to account for longer legs and wings.
Now I have no idea what 2.6 million tonnes actually means. To me it's just some **Really big number** that might be useful for comparing to other **Really big numbers**. Oh so the dragon weighs 2 megatons but the island turtle weighs 3000 megatons? The turtle must be much bigger.
For comparison the Titanic was about 0.05 megatons. But again to me the Titanic is just some **really big ship**. Unless the dragon was next to the ship I'd have no idea which is bigger.
In either case "2-3mt" or "2-3 megatons" looks pretty slick for a bestiary profile. Maybe the word megaton is too modern for the setting. Just replace it with 'high tonne' or something more germanic.
**Note:** This presumes the density of the dragon is similar to the lizard. Most real animals have a density similar to water because they are primarily composed of water.
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One of my main characters lives on an island where people bet on bat races. My story is set up so that bats are domesticated and race one another in dark caves. The bats would use echo location to find their way through the cave.
**Question:** How could bats be raced (motivation, deliniation, and of course, gambling)?
[Answer]
Skip a feeding or two before the race, give them something to eat, and watch them eagerly fly back to their roost to eat it. A little colored ribbon around their feet and judges keeping an eye on the roosts will let you know which bat won.
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Bats which eat fruit or [small animals](https://en.wikipedia.org/wiki/Bat#Vertebrates) will take their food back to either their nesting roost or a special feeding roost in order to enjoy their meal in comfort and safety. Thankfully, [bats roost in close groups](https://en.wikipedia.org/wiki/File:Common_tent-making_bats.JPG), so the racing bats simply need to be from the same roost in order for the race to have a single finish line that they will all fly to.
Corral them a day before, attach a little ribbon to make them distinct, lay out some fruit at the cave's starting line, and have them skip a meal in order to make them motivated to quickly fly home and eat.
[](https://i.stack.imgur.com/Np9Y2.jpg)
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I would race them in a similar way to pigeon racing today, run by various bodies in different countries such as [The Royal Pigeon Racing Association.](https://www.rpra.org)
The bats would be habituated by their domestication to live in particular roost sites, which they would return to on release. A number of bats would be taken to a release site and the first to return to their home roost would be declared the winner.
A small amount of magic would be used to tag each pigeon and find out which one was the winner.
[Answer]
**Mark the bats with painted symbols**
The idea of trademarks and brands are almost as old as humanity. A little paint and a symbol registered with race officials and you know exactly whose bat won.
**Place your bets!**
Betting on bats would be no different than betting on any other sport, but let's stick to horse and/or dog racing. Bets would be on first, second, and third (win, place, and show).
**Fly! you little stinker! Fly!**
You tagged your question "magic." Cool. Motivation is easy with magic. Put something pungently tasty at the end of the race and then magically cause your bats to feel desperate hunger. They'll fly like a bat out of... well... you get my point.
**None of which is your actual problem**
How do you determine who won? Bats are small, fast, and (thanks to echolocation) notoriously difficult to catch. And if two bats are flying closely together, they're hard to see as two bats (much less more). Here are some ideas:
* Have a magical "photo finish." In this case, it's not paint used to mark the bats, it's a magical symbol, unique to every bat. A magical "ward" is placed across the finish line that tells the magician which bat crossed it (and hope he's sensitive enough to know which came first between two flying neck-and-neck).
* Have a rotating set of nets at the end designed like lobster cages or deep butterfly nets. This helps to avoid the echolocation response to avoid the nets, but the turning net (think "pinwheel") could capture bats as they come in (other than the neck-and-neck bats).
* After the "finish line" have the bat owners at their own tables (somewhat separated, like by 10' or more) and rather than using one pungent and tasty food, use a unique one for each bat, magically driven mad to get to that fabulous treat as fast as possible! Each table is overseen by a judge/referee with a flag that must be raised once the bat is back in its cage.
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Training is out of the question. You can't train bats. **But** you can have them painted, then wait until they leave their nests to swarm into the night, then follow them with spyglasses and see who makes it back to the caves first. Only one winner, only one loser as the last to come back in, while nature does its job
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So there are loads of things that are taken into account with weather from geology to water currents to axial tilt etc. But i am wondering what the effects would be on weather on planets with varying strengths of gravity in comparison to Earth.
If we call Earth standard for any approximates, averages and estimations, how would a planet that has a greater or lesser gravity come out in the weather game? How would it affect rain, snow, hail, and thunderstorms.
Having an atmosphere in which to contain said weather is implied across the board. Lets also say that all planets are not recently terraformed and that they had atmospheres from beginning.
Edit : Thanks to all for the answers so far. I apologize for it being too broad. I would also like to state i do not mind assumptions made from extrapolated information off of real world data. I understand we do not have all the answers currently and really just want best guess in the face of such.
So to help narrow this Let us assume that we are starting with an earth sized planet, with distance from star being the same as earth and a day length period the same as earth. We will use Mass as the variable within density that is being manipulated.
Let us also call the current thought of axial tilt and habitable climate as true and say that any and all tilts taken into account fall mostly earth like tilts with no more than a 3 degree change and the mirror of that range.
Lets also say the Star is either equal to our sun, or is no more than 1.1x its mass. No matter the size of the Star, the Planet will be within its habitable zone in a orbit as earthlike as possible.
Overall, we are taking the planet to be earth in just about every facet, except gravity via density via mass. Let us say the current air patterns are the same, and the current Water currents are the same. Say even Geography is the same so that we can watch merely how Gravity plays upon the weather.
I am interested mostly in how the changing of the density alters the gravity and how that alters the weather. I am kind of confused on it, because the thicker air could in theory hold a hailstone aloft longer because it has to move through a greater air resistance, but by the same token it would be heavier. At what point would rain become as dangerous as a hailstorm currently if there is a point? At what point would hail float down like heavy snowflakes, or would the atmosphere dissipate before such could occur? At what point would water based precipitation begin occurring as what we think of as sea level with lighter gases forming clouds above them, Or would the differences in the weight of everything compensate for it all so that it all kept at the same levels?
[Answer]
**The Simple Answers**
*Less than Earth:* You would have a thinner atmosphere and it would extend further away from the surface. You would have less mass, therefore slower wind, fewer storms, and without the mass to carry water vapor, less virulent storms.
*Greater than Earth:* You would have a thicker atmosphere and it would not extend as far from the surface. You would have more mass, therefore faster wind, more storms, and with that greater mass, more water vapor capacity and thus more virulent storms.
**But...**
As you mention, so very much goes into atmosphereic conditions that it's very hard to explain what could happen without you providing very specific and complete planetary conditions that balance all the equations (which is a fancy way of saying, you can't say "Earth, but with less gravity" because what gives it less gravity affects the atmosphere too, in very complex ways).
For example, a low G world may have lower wind velcocities... unless its orbital speed is very fast (adds to wind) or is closer to the sun (heat = energy = wind).
Likewise, a high G world would expect greater disturbances and higher wind velocities due to the thicker air, but if you reduce the rotational speed and pull it futher from the sun, those speeds slow down.
**Therefore...**
So many things go into planetary climate that this incredibly simple answer is almost meaningless. Let's consider Venus...
Venus has a rotation period (day) of 243 earth days. That's very slow! It has an incredibly dense atmosphere despite being 0.9G (90% of Earth). You'd think that some of this is due to heat, it being closer to the sun, but in reality it's 100% due to the chemical composition of the atmosphere, which actually *reflects* most of the sunlight so that little gets to the ground. Thus, the slow rotation and slightly lower gravity produce the very slow surface winds we would expect from my very simple answer... (only a few kph per hour), but the heat and atmopsheric stiration that doesn't exist on Earth lead to whomping fast winds at the top of the stack (winds circumnavigate the planet every 5 earth days) and so much cloud cover that you can't actually see space from the surface.
**Conclusion**
Therefore, you can take my answer for what it's worth, but the only way it's useful is if you compare two planets, identical in every way save one: gravity. The problem with that is that what makes the gravity diferent (same diameter, therefore one is less dense (has less mass) than the other), would also affect the atmosphere if only by changing the chemicals that make up the atmosphere (but it would also change the surface conditions, hydrology, magnetosphere, etc.).
Simple, but without the other 1099 variables that affect planetary climate, pretty much meaningless.
[Answer]
This is a deceptively difficult question, since most of the effects of lower or higher gravity are second-order effects which tend to be more complex than the simple first-order effects.
I need to state my assumptions. First, I assume you're talking surface gravity. Second, I'll assume that the planet is a standard rocky planet like Earth, so a smaller surface gravity happens because the world is smaller and less massive and a larger surface gravity is because the world is larger and more massive. Thirdly, I'm assuming its atmosphere followed an evolution like Earth's and has a composition like Earth's and a surface pressure like Earth's. (This is relevant since I want to ignore the possibility of things like Venus's runaway greenhouse effect.) Finally, I'll assume a similar orbit and rotation period.
(Note: *all* of these assumptions are arbitrary and we're pretty certain that planets exist which violate any and all of them. But if we start varying multiple parameters at once, it's pretty hopeless. There are other reasonable starting points, such as assuming that the amount of air is the same rather than that the surface pressure is the same.)
The most obvious place to start is that the low gravity planet would have an atmosphere where air pressure drops more slowly with height and an atmosphere which extends much further into space. Likewise, the high-gravity planet would have an atmosphere squashed compared with Earth's. This would have a significant effect on convective weather, but estimating what that effect would be is difficult -- it's not something you can do without sophisticated modelling.
A second big effect on convection is the direct effect gravity on buoyancy. Convection is due to density differences causing air to move under the influence of gravity, so you'd almost certainly have less convention under low gravity and more convection under high gravity. So vertical air movement would get more violent as the surface gravity increases. This *probably* would mean more convective storms (i.e., thunderstorms.) Could be more hurricanes, too.
OTOH, you should get bigger hail in lower gravity, since hail grows larger the longer it's kept aloft by the winds. The wind force lifting it up is proportional to the hail's cross-section, while the weight pulling it down is proportional to its volume. Even if the windspeed increases with higher gravity, I suspect that on balance, hail will grow larger under lower gravity -- as long as thunderheads form. (OTOH, I'm *really* hate to get hit by hail under 2Gs!)
It seems likely that the higher the gravity the faster the horizontal winds, also, since buoyancy is also ultimately responsible for them.
Beyond this we quickly get into pure guessing. (Assuming we didn't get their five paragraphs ago...)
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Wouldn't gravity in working on sufficient cloud masses help leave an excess of energy in the oceanic atmosphere, promoting the more intense hurricanes in the last decades?
My reasoning stems from the case of a bullet fired into the atmosphere leaves with greater energy than it returns.
I have read the Latent Heat of Evaporation is about the same as Heat of Condensation ["The enthalpy of condensation (or heat of condensation) is by definition equal to the enthalpy of vaporization with the opposite sign... "<https://en.wikipedia.org/wiki/Enthalpy_of_vaporization#Enthalpy_of_condensation>"].
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**Closed**. This question is [opinion-based](/help/closed-questions). It is not currently accepting answers.
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In the distant future with advanced medical technology, if a person gets commercially-available eye "surgery" to facilitate AR/VR entertainment or technical work (like a Heads-Up-Display but without the glasses), what form would it be?
Grafting electronics to the retina? An artificial intraocular lens? Or maybe an electronic signal that hacks the optic nerve? What would be practical and realistic – biologically speaking?
I'm looking for something along the idea of LASIK or cataract surgery, so not replacing the whole eyeball with a William Gibsonesque cyborg laser thing, but unobtrusive. When it is not receiving a signal it should not interfere with normal vision.
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# We can't know for sure, we can know what is tested now
And for now, it looks like **brain implants** are one way to go.
For example [this article](https://www.technologyreview.com/s/608844/blind-patients-to-test-bionic-eye-brain-implants/):
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> The company, Second Sight, is testing whether an array of electrodes placed on the surface of the brain can return limited vision to people who have gone partially or completely blind. For decades, scientists have been trying to develop brain implants to give sight back to the blind but have had limited success.
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On the other hand, **retina implants** are [apparently also working](https://www.theguardian.com/science/2012/may/03/eye-implants-restore-sight-blind):
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> The operation begins with a power supply being implanted under the skin behind the ear. Surgeons then implant the 3mm-by-3mm chip through a small flap in the delicate retina at the back of the eye.
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Personally I believe that people will accept eye implants easier than opening their skulls and operating directly on the brain, but both are feasible.
Pros of eye implant:
* Simplicity and safety of surgery
* Easier to reverse
Cons of eye implant:
* Can impair original seeing
Pros of brain implant:
* Seeing independent from original eyes, potentially "third eye" effect (not tested on subjects with functioning sight, so we can't tell for sure)
* Bigger area, so potentially better resolution with the same size of single electrode.
Cons of brain implant:
* Dangerous surgery
* Leaves potential gate of infection to the brain.
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**No, thank you.**
Anything implanted has multiple issues: infection, obsolescence, power source replacement/rupture. One of Greg Egan's early novels, Quarantine, discussed the security issues around having brain implants (they get hacked, to show you advertising, continuously).
If I can't secure my phone OR keep its OS up-to-date for 36 months after purchase, why would I have it surgically implanted? I get a rash from wearing a watch. Into my brain? Nooo.
I could imagine things to help with eye/hand/retina tracking (a targeting tattoo?), but optical tracking works better every day-- why bother?
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You can have something relatively simple as a mean to stimulate retina sensors (either with an overlay or directly at optic nerve level).
Main problem with an in-ocular device is to keep track of [saccadic movements](https://en.wikipedia.org/wiki/Saccade) and update the image accordingly with high precision. This is less of a problem with extra-ocular devices which need to track the much slower and predictable head movement.
Direct Optic nerve stimulation would need a calibration phase to match nerve with sensor, but would probably be more reliable not requiring "moving parts".
Current hardware would be able to handle throughput (eye resolution is "just" ~1Mpixel, but **not** on a square matrix, our "pixels" are arranged in logarithmic spiral), but they would need "some" miniaturization.
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Inspired by [A.C.A.C's comment](https://worldbuilding.stackexchange.com/questions/92890/what-is-the-method-to-produce-food-within-a-volcano-caldera#comment275124_92890), **how can the metabolism of an animal that is harnessing the heat from magma or lava be explained?**
I'm thinking of conventional "eating lava or magma", but it could be an unconventional method by absorbing the heat by skin. I'm also thinking whether this method can be used by **birds** or not. Oh, and don't worry, you can assume the needed parts in contact with the lava/magma are inherently made of fire and heat resistant parts. I read that magma can be as cool as 600 degree Celsius.
For reference you might want to read this question [What traits would a species need to survive in magma?](https://worldbuilding.stackexchange.com/questions/16722/what-traits-would-a-species-need-to-survive-in-magma), but I still prefer carbon-based lifeform.
The animals won't have to "swim" and live in the magma. They just need to primarily get their energy from the magma/lava.
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This question graduated from the [Sandbox](https://worldbuilding.meta.stackexchange.com/a/4858/34288).
[Answer]
Your lavabird could [**smelt**](https://en.wikipedia.org/wiki/Smelting).
Smelting is turning metal ore (usually a metal oxide) to the base metal. It must be hot and there must be carbon to carry away the oxygen from the metal oxide as CO2, leaving the base metal.
I could imagine these birds are full of iron ore or rust. They eat coal or wood or dung or some other carbon. Then they bake in the magma. The carbon leaves as the oxide and the iron is converted to the metal.
On leaving the magma the bird gradually oxidizes the metallic iron with inhaled oxygen, the way we oxidize dietary carbon. This oxidation is captured chemically for energy production. [Iron oxidation is a well known energy source for bacteria](https://en.wikipedia.org/wiki/Iron-oxidizing_bacteria) and some bacteria can even get energy by [oxidizing metallic iron](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4272740/). These lava birds could work that chemistry or perhaps have bacteria symbionts on board to do it for them.
The neat thing here is that we lose the carbon as CO2 but the bird keeps the rust inside of it. Once its supply of metallic iron is depleted it can eat some sort of carbon, go back to the magma, and regenerate the iron from the oxide. It is a way to capture the heat energy of magma in a chemical transformation that can be run backwards, slowly, to provide energy for life processes.
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The yeti crab farms the bacteria that Ash mentions. This crab sits at hydrothermal vents (deep sea pressure prevents heat from lysing cells). The crab waves its pincers in the hot vent flow, which is over 100C. The pincers have many hairs, on which grow bacteria that Ash mentions (or similar.) The bacteria grow, and the crab eats the bacteria - basically having grown pincer-licking-good food for itself. I recall learning that this occurs at hydrothermal vents but online information does not state that explicitly. Anyway, the principle is generally sound and may be useful for your design. Here is a [nice link](https://www.youtube.com/watch?v=D0OC1sC1Nmg) showing the hairy pincers and waving behavior.
here is another [video link.](https://www.youtube.com/watch?v=4gPyG6cT_pU)
A [perhaps better video](https://www.youtube.com/watch?v=r17cPDVzTls) with narration.
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**How any lifeform works is by consuming energy, storing it, and releasing it.**
plants take in sunlight convert it to sugar and break that down during respiration.
Animals eat plants convert the sugars and proteins into fat which they later burn during respiration.
How they use this energy and the efficiency to which they use it is purely based on their unique traits.
**Chemically,** sugars and fats are mechanically the same in the sense they are long for the most part; hydrocarbon chains, that can be easily reacted with oxygen to produce thermal energy.
This doesn't necessarily work for a magma eater as any hydrocarbon chain generally combusts long before that temperature is reached.
**However, the principal still applies, absorb an external energy source, convert it into stable semi-reactive compounds which can react with a readily accessible external element (like air) to create energy.**
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Oops completely misread the question, non-chemical energy pathways for an *animal* living in close contact with a magmatic system or erupted lava. Okay first things first lava is easier, it's in contact with the carbon, water, oxygen, and nitrogen rich space we call the atmosphere, these elements are available in magma but they're harder to get at because they're dissolved or chemically bound into rock minerals. Also an external atmosphere makes thermal regulation easier too, that's going to be important. For sourcing the energy I'd start with the [thermocouple](https://en.wikipedia.org/wiki/Thermocouple), they use a "sandwich" of metal foils to create electron flow when in a thermal gradient. We use them mainly to measure temperature but they can be used on a larger scale to produce electrical currents from concentrated heat sources. In this situation thermal regulation is very important because the animals' core is going to have to be cooler than the outside environment or the thermal gradient disappears and the thermocouple stops generating energy.
In practice the animal will have a finely layered metallic skin of sorts that simultaneously generates free electrons for metabolic processes and protects them from a lot of direct heat transfer from the external environment. In normal, read carbon-based, systems free electrons are rare, we use ions that "swap" electrons instead. The actual chemical reactions for the creature I propose would be similar to those we see in carbon-based lifeforms, using the same basic structures of proteins and carbohydrates (but not the *same* carbohydrates and proteins because they aren't thermal stable at these temperatures) but instead of using direct ion exchanges they'd utilise a lot more direct elemental oxidation to source raw chemicals for protein synthesis and ionic reduction to source chemical elements for the thermocouple skin and other structural elements.
Effectively they're using electricity and adsorbed chemical building blocks to create energy storage structures (carbohydrates) and cellular structural members (proteins), technically they're not animals, they're really weird plants, primary producers, not consumers.
Couple of note on environment issues; if you are using the low temperature [Carbonatite](https://en.wikipedia.org/wiki/Carbonatite) magma/lava systems then atmospheric material is less important to the life-systems chemistry due to the relative abundance of those elements in the magmatic material. If you use a traditional skeletal chemistry in non-Carbonatite systems Calcium is going to be a bottleneck element limiting populations as it's relatively unavailable.
Right hopefully that's clear-ish, drop me a comment if you want to know more about some element of what I've laid out.
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I've mentioned before that I'm working on a fantasy world where most of the metals we rely on in our world are fairly uncommon outside of a single, inhospitable region of the world. The vast reserves that constitute practically all the world's metal reside in this northern realm and are being hoarded by a technologically advanced isolationist state that uses their monopoly on metal to compensate for their lack of magical aptitude. Ergo, they got to develop useful stuff like metallurgy that lets them make stuff out of steel and bronze while the rest of the world is living in stone buildings and wood huts crafted with magic.
So if every other nation in the world is forced to obtain their metal exclusively through trade with this one technocratic superpower, what does that mean for the prevalence of ballistae and crossbows over cannons and muskets in military conflicts between the other metal-deprived countries? If metal was made artificially scarce enough that most nations had to be very careful when considering the number and distribution of their metal weapons, could that mean you might see wars where cannons and ballistae are being used side-by-side simply because both armies don't have enough metal to completely phase out their wooden ballistae in favor of cannons?
To clarify, these other societies have found ways to adapt to a lack of metal by making armor and weapons out of things like dragon bone and magically crafted glass/obsidian.
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On a straight technology level, [torsion](https://infogalactic.com/info/Torsion_siege_engine) powered weapons can be made entirely from wood and sinew or rope. While complex devices, they were reputed to be able to hurl javelin sized bolts or large stones several hundred metres, and quite dangerous to any enemy who did not have corresponding devices to suppress incoming artillery.
[](https://i.stack.imgur.com/07wSG.jpg)
*Small Ballista*
[](https://i.stack.imgur.com/Zp0K6.jpg)
*"One Talent" Ballista for firing large stones*
One armed versions of these torsion weapons (known as "Onagers") were simpler to construct and could throw stones, pots of burning pitch or other things in ballistic trajectories which cleared walls.
If building a torsion powered ballista is too difficult, a "counterpoise" weapon like a [trebuchet](https://infogalactic.com/info/Trebuchet) can be employed instead. Trebuchets can also be made exclusively from wood and stone or soil (to fill the counterweight box), and can be scaled enormously. Weapons like the "War Wolf" could hurl huge stones with enough force to break down curtain walls of medieval castles, and modern reproductions using telephone pole sized throwing arms have been used to throw small cars.
[](https://i.stack.imgur.com/7Qpyf.jpg)
*Reproduction trebuchet*
In addition to the traditional trebuchets (which were actually quite sophisticated), modern trebuchets used for such things as "pumpkin chucking" have been designed to enhance the power through use of moving pivot points or attaching the [counterweight to a rope describing a spiral path](http://www.instructables.com/id/MURLIN-Trebuchet/). Without gunpowder to supplement and replace these engines, it seems clear that there would be prolonged quests to increase the power and efficiency of war engines:
[](https://i.stack.imgur.com/38dfS.jpg)
*Murlin trebuchet. The rope passing over the five projections on the throwing arm provide a progressive increase in power transfer from the counterweight.*
So the short answer is it is entirely possible to build very powerful war engines without the use of metal at all.
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**Technology level**
You could mimic the armor and weapons that the Incas and Greeks used during their time.
* Wood sword with sharpened stones attached (<https://en.wikipedia.org/wiki/Macuahuitl>)
* Slings (<https://en.wikipedia.org/wiki/Sling_(weapon)>
* Longbows would be the arm of choice since the lack of plate armor would make it really effective (<https://en.wikipedia.org/wiki/Longbow>)
* Shields usually where made of wood or leather (<https://en.wikipedia.org/wiki/Shield>)
**Scarcity**
Depends in how much scarcity are we refering too, for example:
* Aluminium in the Napoleonic era level of scarcity would make it a sign of wealth and you wouldn't affoard to use it as armor.
* Spices during the 17th century, looks more like your case. And as it happend in that time, it become a reason strong enough to go to war.
**Utility of the magic in your world**
I wouldn't need a cannon if I can manage to gather a few wizards and cast a huge fireball towards my enemies.
Same with armor, since you could bend stone and wood to make a building, doing the same for armor and weapons looks easier than buying metal armor from those wierd magicless dudes.
Even buying the the metal bars would be more practical, since you could end up bending the metal with magic at points that metal workers couldn't even dream.
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In an army that uses magic as a primary offense technological weapons are kind of misplaced but to answer the question about mismatched equipment, generally speaking you use what you can get to the battlefield, you can't afford to retire wooden weapons so you don't, you bring a mixed bag of whatever you can get ammunition and crews for. Probably you *prioritise* the newer more powerful weapons though. You certainly prioritise the use of your scarce metal resources towards maximum damage for minimal inputs.
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Cannons are probably out. While you can make them out of wood, they tend to blow up pretty spectacularly (wood splinter shrapnel). They also made cannons or, more technically accurate, mortars by digging pits in stone (very limited field of fire). So, you are restricted to trebuchets or catapults.
Those heavy weapons are only really useful if they far outrange the ability to throw magic or are used in areas that lack magic for some reason (genetics, lack of free magical energy, blackish green rocks that suppress magic, etc.). Otherwise, one mage that gets close enough will ruin all of your hard work.
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In a SciFi world I'm building with other people, we'd like to create a planet with an infection outbreak going on. There are wildlings. They are pretty primitive, have stone tools and wood houses. They are human-like. The wildlings are getting infected and when it happens, they become highly aggressive, their appearance changes and they have a hive-mind (meaning they are all connected to each other, know what each other thinks and are controlled by a queen).
The infection comes from a gigantic underground beast. This beast grows trees that are spreading the outbreak, meaning the infection of wildlings comes from those trees. It is the beast that is controlling the wildlings. So if the beast is killed, the infected stop, the trees die and the infection stops.
What could be a scientific reason for this infection? What does my beast need to provoke such changes to wildlings?
### Important aspects of the infection
* Infected are highly aggressive
* Infection comes from the trees growing out of the beast
### Changes caused by infection: (please try to keep as much as possible)
* Hive-mind
* Changing in aspect
+ Black skin
+ Claws / fangs / other means of attack
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Please note:
Time can be a factor to explain any of those aspects.
[Answer]
One potential method: the lifecycle of the host organism is complex and evolved to include four different organisms. A fungus, the subterranean beast, the wildlings, and a worm.
The fungus infects the worm, which then is either eaten by the beast or the worm itself is also a parasitic organism that infects the beast. The beast spreads out long appendages that resemble trees that it uses to collect nutrients, water, and oxygen from the surface. This is something that the beast just does, whether it is infected or not, but the fungus has hijacked this process to spread its spores throughout this network.
Once spread to the 'trees', the spores infect the wildlings. Like [Cordyceps](https://en.wikipedia.org/wiki/Cordyceps), it causes a change in behavior in certain organisms that it infects. In this case, it makes them aggressive and causes growths of black 'skin' and 'claws'. The skin is actually a covering of the fungal spores - the same spores present in the 'trees', so the aggressive behavior helps to spread it further. The 'claws' are a by-product of a change in the production of keratin.
The hive mind is accomplished through pheromone communication. We know that [plants](https://en.wikipedia.org/wiki/Plant_perception_(physiology)) actually have rudimentary forms of [communication](https://en.wikipedia.org/wiki/Plant_communication) - it doesn't sound like too much of a stretch that a fungus could.
The "queen" is really the colony of matured spores living in the subterranean beast. The juvenile spores also communicate with one another. Granted this can't go long distances, but 'messages' can get passed along a chain.
The ultimate goal is for the infected wildlings to die, whereupon they become food for the larval form of the worm that then infects the beast.
[Answer]
An enhanced version of Ophiocordyceps.
<https://www.livescience.com/47751-zombie-fungus-picky-about-ant-brains.html>
The monster is a fully mature adult. It is a massive conglomeration of the many of the creatures it has infected. At this stage it can produce egg stage of its life cycle. (Tree like fungi)
It uses its controlled servants to plant and tend these 'Eggs'. These eggs are simply a specialized organ of the fungi. The adult monster needs a minimum mass to grow these successfully. They can be detached, but require constant tending. (Food)
The eggs then release spores of some sort (from traditional earth fungi spores to *Aliens* face huggers. They infect a new host and slowly grow and develop. Once they reach maturity they can control the host and respond to the synaptic impulses of monster (if within range). This is the larval stage of their life cycle.
The larva can infect others directly. Simple close proximity over a long enough time might suffice. But bodily fluid contact greatly increases the infection rate.
Once the larva density if high enough at a great enough distance they can form into a new monster hive/conglomerate. This is when they reach the adult stage of their life cycle.
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**The Thorian**
If you played Mass effect at some point you found an ancient creature that produced spores all over the planet, staying in constant contact would produce a telepathic connection with this entity, transforming all the colony into loyal servants where every thougth was audited.
This entity could create thralls from "blueprints" (aliens keep in stasis) to protect his body. This thralls would produce poison and have claws to attack any intruder.
The captured colony would fight as an unified team under direct command of the entity to protect it.
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The parasite could mess with the host neurotransmitters, essentially inducing pretty much any mental illness. Evolution-wise, to make the infected hosts highly aggressive is much more effective for the beast's purposes than, let's say, generalized anxiety disorder or major depressive disorder.
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I am wondering about this map, from the game *Albion* (not *Albion Online*):
[](https://i.stack.imgur.com/QUOMc.jpg)
The island on the right (Umajo) is an arid one, mostly covered by sandy deserts, except for an area of savannahs at the very south (not pictured in this map). The other islands are either completely covered by tropical forests (i.e. the ones on the bottom and left-bottom). The rest is temperate climate/forests type, except for the peninsula in the middle of the image, under Beloveno, where jungles start to prevail. It mostly matches the northern hemisphere of Earth, except for the arctic and subarctic areas.
Now it seems weird to me that deserts formed on that island, though it's larger than the other islands (but the deserts span from coast to coast). I assume that the map uses the usual directions (right is east, top is north), thus the island lies in both the temperate and tropical zone, so it should be more akin to the other islands lying there. So my question is - what natural process could cause the formation of deserts on the island (and also the hot climate present there).
From what I know about this world, it is located in the same universe as the Earth, so same physics should apply. However, magic is also possible on Albion, but I'd rather look for a natural cause.
We also know that the planet has gravity about 0.8 G, and *no axial tilt*, leading to the complete absence of seasons on the planet. The revolution time is the same as Earth's, so it has the same length of the day and year. The atmosphere is also quite cloudy, but from from I observe from other artworks, the sky above Umajo is clear and cloudless. That may be the cause (or the effect?).
Edit: As human activity can be a factor in this, I have to clarify more about the population. The humans that live in this world are the descendants of the Celts originally having come from Earth ca 2000 years ago, and therefore I suspect that it's unlikely that deforestation created the desert. The other (and original) inhabitants of the world live in great harmony with the nature, and wouldn't willingly cause any deforestation in that area.
The age of the game also makes it a bit harder to express the exact relief of the island, but aside from a mountain/boulder ridge in the central area, the island is mostly flat.
To illustrate the nature of the island, here are some images:
[](https://i.stack.imgur.com/3GNsG.png)
[](https://i.stack.imgur.com/EDvOZ.png)
[Answer]
**Jet Stream**
Draw the jetstream in this world around that island such that it does not experience substantial rain.
**Cliff Faces**
If the side of the island that faces the incoming jet stream or "prevailing westerlies" type of winds has high mountains or cliff faces, the weater will drop rain right there or it will slide around the island.
**Volcanic**
If the island is principally volcanic in nature, the soil is rocky sand rather than smooth sediment and will both absorb heat more and fail to capture any but the hardiest of plants.
**At the end of the day, admit to its creation**
You need to realize that the creators of the game most likely created the map with no intent of being geologically or meteorologically correct. It's fun to speculate as to how it might be, but imposing rules and governance on a creation that's 100% fiction is almost always unsatisfying. Consider my answer about plate tectonics in [Tolkien's Middle Earth](https://scifi.stackexchange.com/questions/166884/plate-tectonics-in-middle-earth-an-in-universe-explanation/166886#166886) where someone wanted to know what the in-universe explanation was. Most of the time, the answer is, "well, I made it that way."
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Just model it after Socotra in Yemen minus Socotra's mountains. It is a world heritage site. <http://whc.unesco.org/en/list/1263>
The island has a tropical desert climate, except for the mountain region that gets a bit more rain. The mountains get more rain because the mountains force warm air upwards where it expands and cools. Relative humidity compares the vapor pressure of water to the water content of particular air. The vapor pressure decreases with decreasing temperature, boosting the relative humidity in the process. Rain occurs if the relative humidity passes 100%.
<https://en.wikipedia.org/wiki/Socotra#Geography_and_climate>
The converse must also be true. Vapor pressure increases with increasing temperature, lowering the relative humidity in the process.
As an added bonus, Socotra comes with unique species like the Dragon's blood tree to help you populate the landscape. <https://earthobservatory.nasa.gov/IOTD/view.php?id=78411>
Socotra is generally dry because it does not get monsoons. It does not get monsoons because the water is generally colder than other areas of the same ocean basin. The cold water comes from upwelling from the deep.
<https://charliesweatherforecasts.blogspot.com/2015/11/why-did-yemen-and-socotra-just-get-hit.html>
The combo of hot air (boosting the amount of water needed to reach 100% humidity) and cold water (lowers the rate of evaporation) leads to air that is very dry even though it is above the ocean. Monsoons do not like dry air. You end up with wind but no moisture. Finally, make the island entirely flat, and you are good to go.
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Take a look at earth deserts, e.g. the [Sahara](https://en.wikipedia.org/wiki/Sahara), some of them border oceans and other bodies of water and still are mostly sand/deserty-stuff.
As long as there's an absence of any precipitation there won't be much growing. Clouds need a motivator to make it rain. Most often this motivator is either mountains or too much water in the air. If you get rid of both you don't get much rain.
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As a reference (less extreme, but...) you can look at two largish and very similar islands in Mediterranean: Sardinia and Corse.
Sardinia is not desert, but very arid, while corse had large and high forests.
Both climate and geology is similar. What happened?
Man happened. Both islands were covered by forests but, while Corse was not meddled too much, Sardinia forest were burned down to make pasture for sheep and goats.
This changed completely climate because while in Corse land is colder then sea (due to forests) in Sardinia land is much hotter than surrounding sea.
This fact inverts prevalent air circulation and while in Corse sea humidity rises and is sucked down over land, raining on it, in Sardinia you have the reverse: normal circulation is hot air rising on land taking with it the scant humidity present and then going to discharge rain on sea.
To have an island with desert climate is enough to cut all (or good part) of forests on it; if there is enough sunshine it will do the rest of transformation.
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I believe the most common cause of dessert on earth is humans. The process is actually called desertification. It usually involved deforestation, poor farming practices, poisoning the ground, and a natural tendancy to low precipitation.
However you state that this is a land that is "one" with nature.
# Option #1. Past
Perhaps the people are one with nature because of what they did to this island.
# Option #2 Cataclysmic force.
An earthquake, **meteor**, tsunami, volcanic eruption, or magical beast could have caused this.
# Option #3 End of the world.
I think the sun is actually supposed to get colder as it gets older but a decaying orbit might draw the planet closer to the sun. This would result in storms, heat waves, unpredictable weather and general chaos. Wouldn't likely spare the other islands though.
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**Closed.** This question is [off-topic](/help/closed-questions). It is not currently accepting answers.
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You are asking questions about a story set in a world instead of about building a world. For more information, see [Why is my question "Too Story Based" and how do I get it opened?](https://worldbuilding.meta.stackexchange.com/q/3300/49).
Closed 6 years ago.
[Improve this question](/posts/89346/edit)
There is a sub-dimension of this reality where a race of humanoid people lives in very low light. Their race has done so for hundreds of years - everyone there has no experience of being outside their dimension. However, in recent history (approx. 30 years ago) there was a large upheaval in which some members of the race travelled to Earth, and (importantly) one human travelled to their dimension, and remained there. More than that, he [had a child with the ruler of the race](http://tvtropes.org/pmwiki/pmwiki.php/Main/InterspeciesRomance).
Cut back to the present. This child is now a teenager with a rebellious streak. For an unspecified reason they have run away from the palace and, using one of only a few instances of a rare device, have escaped from their dimension to Earth (one-way). They knew a fair amount about Earth from their father but have never been there before.
In order to blend in, the teenage royal attends a high school. By an unlucky (for them) coincidence, secret agent Bob is also at that school. He is actually attending the school, but for years has been a mediator agent who worked both independently and under orders to uphold the [Masquerade](http://www.tvtropes.org/pmwiki/pmwiki.php/Main/Masquerade).
Bob is notified that agents from the dark sub-dimension have tracked the escapee to his local area. He begins to search for the outlander by looking for new entrants to the schools in the area, other institutions, etc. But there are many, and the escapee can't be identified by looks alone because they are a half-human hybrid. (Bob can't risk accidentally apprenhending the wrong person and revealing the Masquerade to them.) Bob knows quite a lot about the race and knows that the light sensitivty is likely their biggest weakness.
**Question:** what traits/actions are likely to give away the escapee - or, for that matter, any escapee from that dimension into ours? While Bob is the one looking for said traits/actions, anyone would/could notice them - it's just that Bob is on the lookout. Alternatively, the escapee *could* make a blunder, but I'm looking for something intrinsic to the escapee's nature as... well, an outlander escapee. Something which they can't prevent except by superspy-level infiltration.
Extra notes/clarification:
Bob can't reveal to anyone, in any way, that he's an agent. His local area is crawling with enemy agents who would try to kill him as soon as look at him.
UPDATE: The royal family of the sub-dimension have a kind of hereditary magical power. This is how the escapee managed to get into the school without buying a complete set of fake ID from the Dark Web or whatever - they used befuddlement/enchantment/illusion magic on anyone necessary. (Think how wizards get away with everything in Harry Potter.)
Please comment if you need more!
[Answer]
Squinting.
I'm not joking. I'm a light-sensitive human (so way less light-sensitive than your outworlder), and even *I* go through a lot of life shielding my eyes and/or squinting, especially outdoors. It's usually involuntary.
Your outworlders will also have a preference for lower light levels; they can't do much about the school, but in their homes they'd use lower-lumen lighting than normal. (Assume they use lighting at all because the neighbors might drop in.) They might also seek out special eyeglasses, whether that means tinted (like some albinos in our world wear) or made of materials with different refractive properties. They'll wear sunglasses wherever possible, sometimes even when others around them aren't. They'll be particularly sensitive to large reflective surfaces like expanses of fresh-fallen snow.
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You can (probably) narrow down targets by noting who's wearing sunglasses when not needed.
Then Bob can use knowledge of *both* worlds to trick escapee to reveal himself; some examples:
* Seeing a mock of a very dangerous (small and harmless-looking) animal unknown to this Earth but widely known to alternate dimension may elicit "strange" behavior.
* Approaching with something "outlandish" would be a giveaway of Bob identity, but can also panic escapee into flight (attempt).
* Bringing in some beloved pet may, again, trick escapee to approach.
In any case there could be physical differences (x-ray scan, DNA test, blood samples) that could confirm suspects before apprehension.
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The key to this is possibly not sensitivity to light so much as familiarity and functionality within low light conditions.
Consider constructing a situation in which the subject needs to enter a darkened or low light room to search for something, possibly with some kind of imperative. A human would naturally switch on the light to see better to assist the search, but a light sensitive, with eyes adapted to low light would prefer to search with the light off because their vision would naturally be better in low light conditions, and they would be better composed psychologically to conduct a search without the unpleasant inconvenience and interference of strong lighting.
Of course, the test would have to be unbeknown to the subject and ideally, to their knowledge, unobserved.
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After some thinking about it, it is better to focus not on what a escapee (Let's call them E-ki) from another world has, but rather on what they *lack*.
First thing that gives out E-ki is their paper trail.
1.In order to enroll in a school they need some form of ID and it is rather hard to obtain one when you are already a teenager and have no other documents.
2. Most people study *somewhere* before going to high school. E-ki must either claim to be homeschooled, or lie and lists of graduates for a specific school tend to be publically availible.
3. E-ki lacks any kind of family in our dimension. So they may either claim to be an orphan (which may contradict the info from pt. 2) or have an adoptive family, and Bob knows the approximate date of the escape.
4. Nowdays teens tend to have accouts in some kind of social network. One without any accouts or with a way too recent reg date goes to the suspect bench.
5. (Applies only to the case where E-ki needs to wear shades). If you wear shades at school without an optician's prescription, teaches will give you funny looks. So, when did E-ki get such a prescription? (Such a condition does not spring out of nowere).
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Develop some excuse to take photos around the school. Take flash photos of groups of students. The ones that react badly are the ones to pay more attention to.
This will narrow down the list of candidates but it will likely not find the person directly since normal (used advisedly) humans, such as myself, can react badly to flashes too.
Then you can use the lights out method that Lee Leon mentioned.
However, as Lucius Q. User pointed out: How the heck did this kid get enrolled in the first place?
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Ceraon is a moon with advanced megafauna and flora. The moon is pretty small, so gravity is only about one fifth of that on earth.
Much of the life-preserving atmosphere is retained through a great number of sedentary organisms that form translucent biodome-esque "atmospheric balloons", allowing other life on Ceraon to flourish inside.
This planet's ecosystem, and the balloon-organisms, has just started being studied by earthling scientists, so detailed knowledge of "why"s and "how"s are still limited.
**My question is**, what is the **largest size** these atmosphere-preserving balloon-organisms could achieve, realistically? For instance, would one's the size of a football stadium be too unrealistic?
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Largest wooden Dome in earth gravity: The [Superior Dome](https://en.wikipedia.org/wiki/Superior_Dome), which IS a football stadium.
There are also several Air-Supported structures, which might be highly relevant for Atmosphere-retaining Creatures. Under Earth pressure and gravity, several of these are sports stadiums too: [List of Air-supported structures](https://en.wikipedia.org/wiki/Air-supported_structure)
In combination: I do think that a sedentary(!) organism the size you want is quite feasable, especially in low gravity.
If you don't want them to be plants, maybe they're filter-feeders - the membranes between their bones(?) keep in most of the air, but there is a slow outward flow that carries detritus and microorganisms against them, to be then eaten by symbiontic bacteria which turn that into a sludge that is absorbed and processed by the membranes (or drips onto the "support beams" or just thicker veins along the membranes and is absorbed there). Maybe symbiontic algae live there and use their own photosynthesis to produce food for the megacreatures?
Fascinating idea in either way :)
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Sessile organisms can get pretty big. The largest organisms in the world, by mass and area, are a 100+ acre aspen grove in Utah and a 2.4-mile-wide honey fungus in Oregon.
Of course, those are sitting in or on the ground. It gets more complicated when you have to suspend most of the organism as a roof up in the air. Since these things are holding pressure in, though, the mass of roof can in fact be held up by the air pressure inside. In fact, I'd expect these things to grow so that the areal density of the bubble material produces weight that exactly balances air pressure, thus minimizing tensile load on the structure. That way, in ideal conditions, the structure could grow arbitrarily large--even encompassing the entire world.
You will, however, need to deal with dynamic instabilities in the roof structure, and since this is a living organism, you'll also need to worry about transporting nutrients throughout the structure. Both of these constraints mean that the size of your balloon-dome creatures will be restricted by their internal structure; do they have tendrils or columns or something in the interior, which could be used to anchor the roof, damp vibrations, and transport water and food from the ground? Or are they anchored and supplied solely from the outer edges?
If they have internal support, there's no reason they couldn't get arbitrarily large. Otherwise, the precise limits are going to depend on details of the material strength of the organism's tissues, and the efficiency with which it can transport water and nutrients. Anchoring area at the edge grows linearly with radius while the area of roof tissue to be fed grows quadratically, so eventually that will catch up and impose a maximum size (fortunately, you're not limited like trees are, since most of the transport will be horizontal, rather than vertical, and the lower gravity helps with the vertical component). You'd pretty much have to make up the precise numbers, but personally I'd find a football-stadium sized enclosure to be entirely believable.
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There's not much on this, so I'm winging it. Plus, I'm curious to see if this species could actually succeed in advancing to the Stone Age.
Basically, a species that I have created (the Verrisirs) evolved on the planet Vixeruka (I described some characteristics of the planet in this question: [Planet with two moons and rings? Is it possible?](https://worldbuilding.stackexchange.com/questions/79748/planet-with-two-moons-and-rings-is-it-possible) ). Now, the planet being a tropical rain forest world (not 100% tropical, since it would be realistically impossible, we could say that Vixeruka is 69% rain forest, 10% savanna, 6% desert, 5% arctic, and 10% mountain for simplicity's sake). Now, the Verrisirs are a caninoid race (humanoid canines).
When designing them....
Okay, I'll be honest here, I picked things that I thought would be cool and make them unique.
* Digitigrade: this seems to be a feature common among a good many predators (not all, but ones like canines and felines come to mind).
* Claws: The claws would be useful in both combat, hunting, and climbing trees. Yes, you have dogs that can climb trees. While I read a question someone posted here that such a canine would probably evolved into a primate (if I'm understanding his answer correctly). Personally, I don't see that happening, since it would involve other factors. What those factors are I don't know, so this might need some more thought.
* Thin: They would be "thin". Meaning, that their bodies lack a subcutaneous layer usually common among humans and other humanoid species. This can serve as a determent for adapting to different climates. And while they aren't as strong as humans, they do have the advantage of being fast, nimble, and agile, which would make them able to chase down prey or escape other predators. I can see Verrisirs being descended from predators that are both stalk and ambush predators as well as pack-oriented predators.
* Large, triangular-shaped ears: Similar to other canines, a Verrisir's ears would be able to give them four to five times the hearing ability of a human. Although this does also present a drawback as well, especially in regards to sonic weaponry (my opinion is that races that have a stronger sense of hearing would be vulnerable to high frequency attacks/weapons, such as those using sonic technologies). In addition, the ears would allow them to both display emotions (depressed/sad: the ears sink downward; angry/mad/enraged: the ears would bend back slightly) and be capable of responding to sounds around them (by twisting or moving).
* Sense of Smell: Canines possess extremely superior sense of smell, so it made sense to have Verrisirs also possess this. Unlike most humans, a wolf for example, would be able to tell the different spices and ingredients used in a stew from each other, even after the stew was made. This to me is a useful ability and would greatly aid a species, and thus I gave this to the Verrisirs.
* Fur: Verrisirs have oily fur, similar to that of certain dog breeds as well as jaguars and tigers, which aids them in swimming and keeps them from being slowed down by wet fur. Not to mention, a lot of rain forests tend to have a lot of rain.
* Sight: Canines have excellent night vision (the cat actually is better though). While the planet does have a lot of light due to the rings and two moons, there would be places deep in the jungles and swamps that would get little to no light so having the ability to see in the dark would be quite advantageous. So, instead of canine vision, Verrisirs would have feline vision (in addition to the slit pupils of felines as well).
* Pack Society: Pretty self-explanatory with this one. Strength and safety in numbers would greatly prove advantageous to the Verrisirs.
Another aspect that I thought would make them unique would be their blood. I did a good bit of research on this now. Cobalt was the mineral I researched. So, they use cobalt to bond with oxygen atoms in the same way we use iron to bond with oxygen atoms.
Here are some other (and I think minor) details about the Verrisirs:
* Strong muzzles: Think of their muzzles being similar in biting power similar to wolves and jaguars
* Three fingers and a thumb: This on each hand now. Not sure if this would present a disadvantage or advantage or not really matter
* Able to run on all fours: This would mean that they have pads on the palms of their hands. It would also mean that they could switch between walking on two legs or running in the wild on all fours.
My question is what factors would enable them to reach the stone age successfully? Thank you.
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There is one obvious characteristic your Verrisirs will have to lose. Namely, their strong muzzles. The problem is that the structures, bones and muscles, necessary to support a muzzle, will restrict the size of the cranium. This means a smaller brain, and therefore, a brain less likely to evolve intelligence.
This tendency can be seen in proto-hominids and hominid evolution where as the size of prolonged jaws and protruding lower facial structures were reduced the corresponding size of the brain and the cranium containing it increased.
While this may seem like a minor change, after all strong muzzles sound like a great idea, but they are a barrier to bigger brains. This makes it less likely they will evolve to a stage where they can have a Stone Age. Hopefully this isn't biggest change you need to make to your Verrisirs. Otherwise they sound like interesting aliens.
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I think, to reach the stone age, your animals need to be less capable, so that intelligence, planning, and strategy become more of a factor in their survival.
Compared to other animals, humans are muscularly weak, terrible runners, have pitiful claws and canines, weak bite strength, are extremely un-stealthy, we have a pitiful olfactory sense, we don't even have good night-vision or day-vision compared to many birds and other animals.
How, for your caninoids, is a cutting stone edge better than their own claws and teeth? It is an obvious advantage for our human ancestors; not obvious at all for a canine that can outrun, outfight, and bite-cut the throats of prey up to and including the size of earthly elk and buffalo.
You need some reason for their brains and foresight to be ***necessary*** to their survival and growth; and by building them like battle tanks, you remove all those reasons.
Think of *intelligence* as being a progression toward better mental simulation of the future; an ability to imagine how things will turn out. We humans can imagine the future in such detail that we can build lakes, dams, skyscrapers and roads that cross significant stretches of the planet. But it is intelligence that simulates turning a round stone into a sharp blade; or lets us affix such a blade to a stick as a spear point, that imagines plunging that spear into a rhino while avoiding being killed by it. Metaphorically speaking, this is how the mouse kills the lion: better prediction of how the lion will act, materials will behave, and physics will play out to trap and kill the beast. Intelligence is the ultimate weapon that beats the most fearsome non-mental biological advantages, by letting the intelligent avoid and thwart them.
To get to the stone age, your species needs a reason that their physical attributes are **not enough** to win and they will go extinct if they don't gain intelligence. You need an evolutionary pressure that threatens their existence, over a long enough term for intelligence to grow. For humans with almost zero battle ability as our naked selves, that was an easy call; almost everything could kill us, and the slightest intelligence advantage led to a better chance of our survival, and because we are so weak and imperfect every slight increase led to more survival. There is no such evolutionary pressure on top physicality predators; the shark survives and reproduces just fine by brute force alone, higher intelligence would cost the shark more calories than it would ever gain them. (Only intelligent humans threaten the survival of sharks.) At best, the intelligence is fairly short term strategic trapping in big cats and canine species. Notice that animals as intelligent as dolphins do **not** have a lot of physical battle instruments: no claws, poor teeth, bad eyesight, no armoring. Intelligence is critical to their survival.
As appealing as you may find a tough caninoid that can hold its own *without* tools against a tiger, you have to give them a serious existential problem that claws, night-vision, muscles, biting strength, speed, etc simply cannot solve. They need to get smarter, over tens of thousands of years, **for a good survival reason**. Otherwise there is no reason for them to get smart enough to be able to imagine days ahead in the future, spending weeks and months without any immediate reward to learn to manufacture a tool for some imagined future use, even a simple stone tool.
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Sure why not.
Unless you really want to obsess over the nuances of evolution and the nature of sapience. I'm pretty sure any audience that is going to buy into psionics is going to accept anthropomorphic wolves as human stand ins with little trouble.
Humans made it to the stone age. Your bipedal wolfbeings with opposable thumbs and human level intelligence should be able do so too.
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Assume a world that's much like ours, but in which there is a naturally occurring resource with the properties of gunpowder. This "gunpowder" is only found in one small area, measuring about 1000 square km. But it is plentiful there, and easy to mine. That means the inhabitants of this region have a nigh unlimited supply of gunpowder from day one.
Let's assume the substance isn't explosive until it's been refined by some relatively simple process such as grinding into a fine powder. This keeps the region from being one giant bomb. The refined product resembles the smokier, more volatile black powder, rather than modern smokeless powder.
How would early access to explosives change the development of early (going up to Bronze Age) warfare? What kind of secondary weapon technologies might result from having easy access to a powerful explosive?
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Might as well give a why not answer to this...I'm not sure on feasibility of alot of these ideas, but the Greeks were amazing engineers in their time and might be able to get away with it. You would not see guns by any means, but I'm pretty sure if the Greek people had knowledge and access, they'd come up with some pretty creative uses.
Hand thrown bombs. It actually takes pretty simplistic technology to build a bronze sphere around the size of a baseball (doesn't need to be a perfect sphere either) with a small hole. The bomb (grenade?) is then filled with brass shards and saltpeter. Fuse it lit, bomb is thrown, brass shards everywhere. Extra points it the soldier doing the bomb throwing is mounted and exceedingly mobile (skip horse archers, lets go with horse bombers. Horses would need some pretty intensive training not to spook though)
This could readily be scaled up to a larger catapult thrown bomb. Same theory as above, load a larger bronze sphere with saltpeter, bronze shards, and something to provide a spark upon impact (flint and steel style). You now have a bomb launching catapult...probably comes with some dangers and unintentional detonation may cause friendly casualties.
It's important to note saltpeter is not gunpowder...the gunpowder we use came significantly later. This would function and behave more as blackpowder would. One of the more exaggerated effects (beyond gunky buildup) is ultimately smoke. The bombs listed above would create a lot of black smoke and likely provide smoke cover when detonated as well. This tactic could be expanded on by putting the saltpeter in a line across a field and lighting it. The result should be a relatively large smoke screen that could have relevance in army formations.
I believe it may be possible to create a bronze 'bombard' style weapon as well. A large bronze 'pot' could be filled with saltpeter and the opening to this pot hold a large iron ball. Igniting the pot (and running like \*\*\*\*) if lucky, would launch the iron ball a decent distance (little to no accuracy here) and make a feasible siege weapon. Unlucky sees this entire setup explode, sending shards of the pot everywhere. Probably a one shot weapon as the explosion would likely warp the bronze pot pretty heavily even in the event it worked.
This also would allow for a anti-wall technique that could make traditional siege unnecessary. Borrowing the scene from Lord of the Rings : Two towers, it would not be infeasible to mine under an enemy wall, load the entire tunnel full of this early explosives, and detonate the entire tunnel causing the walls to collapse as the earth underneath gives way.
If any of this is effective, it could heavily impact bronze age warfare. We are all decently familiar with the phalanx image (from 300 at very least) which sees a large number of men in a very tightly packed formation...this happens to be the best targets for gunpowder style bombs. Potential results:
1- Horses need training. Explosions are scary when you're not used to them...war horses would need exposure to these explosions long before battle.
2 - Move away from Phalanx and towards looser more mobile formations. Not good if an entire Phalanx unit can be dropped by one bomb.
3 - Move away from armour. Bronze age forces included exceedingly heavy Armour, almost to the point of silliness. Armour does not fare well vs gunpowder (piercing shards concentrate the impact on a small area, poking holes and allowing the shards to fly in). Edit as per comments - Bronze plate isn't the same as medieval plate...it's movement are restrictive and joints have gaps. Lower legs and arms were often unprotected (for movement reasons). A shrapnel weapon would play havok on anyone in one of these bronze suits.
I'm actually thinking, if the bombs were in any way effective, you'd see skirmish tactics over take the use of formation tactics
All speculation, but it could be a heavy heavy impact.
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In fact, gunpowder, given from saltpeter, was invented [before 10th century](https://en.wikipedia.org/wiki/Timeline_of_the_Gunpowder_Age).
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> weapons such as **fire arrows**, **bombs**, and the **fire lance** were used from at least the 12th century
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All of them could be used in the Bronze Age too.
In addition, you could expect that
* walls are less important during siege because it's easy to blow them
* mining, countermining are well developed
Note that in the Bronze Age there is no mass production so nobody could produce bombs enough to re-arm an army. In fact it's become possible with manufacturing.
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Despite China has invented gunpowder, book printing and had good metallurgy and agriculture, it was dominated by another nations. Reasons why China didn't conquest the whole world at this moment is out of scope. But for your question it's important that warfare for medieval Europe did not significantly changed in 10-11th century - because **it was too far**. Another reason is warfare in Europe had been developed in its own way before gunpowder.
As soon there is only one small area with early gunpowder, the world in a whole will not be significantly changed. Despite gunpowder is important military resource, there are a lot of other important resources for the country (not only military!) and you should not expect endless war for this region.
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If your "gunpowder" is only readily available to one society, that society has a problem.
**What do they do with their glorious powder?**
If they go on the offense and try to **fight** with the powder, they risk having all of their enemies work together to wipe them out. Or they expand as an empire. Historically, empires tend to self-destruct from within. Your powder empire will be the next Rome: powerful on a regional or even continental scale, but incapable of expanding globally and eventually rotting out.
This might be where they start, but it isn't their best long-term plan.
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If they **sell** the powder to their neighbors, they risk being overrun by a more powerful nation. There are ways around this. Making the merchants work for the state, so you can control who gets the product and who doesn't, for example. So now your nation isn't a warrior nation, but a quasi-neutral party. Like Switzerland or the Vatican, they have a great deal of influence. But they must carefully balance that to make sure they are protected from invasion.
But this path means they could then be the richest kingdom, *in times of war.* Since their economy centers on fostering war between other nations, their spies and saboteurs would be experts at instigating fights between rivals. Because as long as there's war somewhere, business is booming! But if peace breaks out, the military-industrial complex goes idle. And that means your people go hungry. So we gotta keep the wars going!
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They might package the powder in a convoluted **religion** that adds various rituals to the refining process. This helps keeps that process a secret and make sure your neighbors *hire* you to blow things up, rather than just buying your powder and blowing you up so they can get a discount. The powder priests would closely guard the secrets of refining, storing, and safely using the powder. They would be your artillery, your demolitions team.
The powder priesthood would wield great power. And would be feared by friends and foe alike. The king might be a priest-king, since no one would dare rise to power without the powder priests' support. The priesthood would be more powerful than any king. Because they and they alone can control the boom.
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The entire society would develop along different pathways than typical bronze age societies. For one, the civilization would need to build their cities with the utmost in careful planning. Refineries and storage of your powder, if it happens at any major scale, *must* be done with safety factors that are critical. So you'd find a defensive fort to protect your refineries and storage depots; defending those structures becomes as important as defending your kings. But your king wouldn't want to live with the powder too close by. The powder silos or keg warehouses or whatever would be housed at a separate facility, for safety-sake.
Fire would be the greatest fear for your citizens. Fire departments might develop sooner than real history. Or maybe they use carefully built canals to keep fire from reaching the powder districts.
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If you mean could they have gun or cannon, the answer is **no**.
Metallurgy was not advanced enough during the Bronze Age to develop firearms. However they could have firepots (incendiary weapon contain in a smashable jar) or use it to destroy fortification by digging under the wall and fire the gunpowder, it will cause an explosion.
On the other hand, gunpowder could be a good fuel for a forge, so it could help to develop the metallurgy. It will allow you to dig with more efficiency and discover new minerals quicker. See the idea? The presence of a good fuel for forge could allow to discover iron and steel speeder, the effect is increased by the ability to dig faster with explosion, and to discover new minerals earlier.
The availability of gunpowder in a natural form would help to develop firearms quickly, because of the ease of getting ammunition, without needing to process complex chemicals.
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The options are nearly endless with a nearly endless supply, but I would guess that you would see IEDs pretty immediately.
IEDs (improvised explosive devices) are effectively just things that go boom. Pack explosive material tightly in a sealed container, add shrapnel, and some sort of fuse or detonator. These obviously take a wide variety of forms, smallish grenade like all the way to boats loaded down.
Having early access to explosives will change warfare and thus secondary tech as well.
Having troops in tight formations makes them easier to blow up. You probably won't see armies facing off on agreed upon battlefields... Basically you can expect guerilla warfare... Small units moving quickly to effect mass casualties, or destroy resources and infrastructure.
Rather than castle like fortification (thick, heavy, expensive walls) you'd probably see things more like what we use today; a series of lighter checkpoints surrounding valuable resources. They may be able to sneak a bomb through one or two, but they're less likely to blow up anything really expensive or tactically important.
It's also worth noting that you don't really need advanced metallurgy to shoot heavy objects at your enemy. You may not be able to shoot as far, but you can still fire projectiles. Mythbusters has demonstrated this a number of times...
<https://youtu.be/AJgYtt99V5s>
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In *Habitable Planets for Man*, Stephen H. Dole proposes that a planet with substantially less oceanic water than Earth could have habitable zones, anyway, even if a high fraction of the surface would be desertic. It "might well have noninterconnecting oceans" and "in the absence of worldwide oceanic circulation, there would be less moderation of temperature cycles (that is, more continental, as opposed to oceanic, climates)" (p. 126).
What would be the perceptible effects of this kind of habitable planet on climate, flora, fauna and human life in general? Thank you in advance, for your time and for answering.
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Topography matters as well as total quantity of water. Earth's oceans are *deep,* over 12,000 ft. / 3.5 km on average. A planet with significantly flatter topography (less elevation range) might have as much or more *surface water coverage* with significantly less volume/mass of water - mostly shallow seas instead of deep abyssal oceans.
However, if we're assuming a planet similar to Earth except for less water:
**Generally harsher climate.** This is the 'continental' climate referred to in the quote in the question -- colder winters, hotter summers. That's why sea-moderated Scotland is relatively mild while inland Moscow, at almost exactly the same latitude, has much more extreme temperature variations, and farther east parts of Russia even more so. Similarly, the Aleutian Islands of Alaska are cold and wet, but don't reach anything like the extreme winter cold of inland Fairbanks, Alaska (though they are cooler in summer).
This sort of climate would dominate over most of the planet. Subtropical areas might be outright unlivable in summer; subarctic areas would tend to be like our Siberia or worse.
How exactly it turned out would depend on the planet's average temperature, which has varied significantly over Earth's history of complex life on land (the last 400 million years or so). A drier world would also affect the average temperature - ocean and forest are dark and absorb sunlight well, while deserts tend to be pale (reflective), so this would mean more sunlight reflected away and a cooler world overall.
<https://nsidc.org/cryosphere/seaice/processes/albedo.html>
<https://en.wikipedia.org/wiki/Albedo#Terrestrial_albedo>
On the other hand, a mostly-desert planet would probably remove volcanic CO2 from the atmosphere less effectively, warming it overall.
This world would also probably have less clouds (less water surface to evaporate water from), but clouds are complicated, with both cooling and warming effects on the overall climate.
<https://isccp.giss.nasa.gov/role.html>
So it's not intuitively clear whether this world would be cooler or warmer than current-day Earth on average, but it would certainly have more severe extremes (assuming all else is equal, again - for example less axial tilt would decrease seasonality).
**Flora and fauna:** Well, given the climate, there would probably be less overall diversity than Earth has - rich, moist environments like rainforests and tallgrass prairie are going to be rare & limited (though they might well exist - coastal areas and islands could still be locally moist and moderated). It's very unlikely you'd get anything like our Amazon Basin or the eastern Great Plains, though. There's probably going to be a lot of hot desert, semi-desert, and steppe / dry grassland in the low-and mid-latitudes, and Siberia-type taiga and cold desert in the higher latitudes.
Given less water availability, there would be less biological productivity too, assuming the plants here are about as efficient at using water as Earth's.
**Human life** would probably be concentrated in the relatively small moderated coastal/island areas, where agriculture would be workable. Outside that, people would probably be limited to hunting-gathering or at best low-population-density nomadic herding of hardy livestock, and the harsher desert areas might not be survivable at all.
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The simple answer is hotter and dryer. Something like the [Triassic](https://en.wikipedia.org/wiki/Triassic) period of planet Earth, only more extremely so.
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> The Triassic continental interior climate was generally hot and dry, so that typical deposits are red bed sandstones and evaporites. There is no evidence of glaciation at or near either pole; in fact, the polar regions were apparently moist and temperate, providing a climate suitable for forests and vertebrates, including reptiles. Pangaea's large size limited the moderating effect of the global ocean; its continental climate was highly seasonal, with very hot summers and cold winters.[16] The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons.
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This condition was due a single supercontinent dominating Earth's environment. Therefore, a planet with reduced oceans would be definitely hotter and dryer. The best starting point for considering its lifeforms would be [desert ecology](https://en.wikipedia.org/wiki/Desert_ecology).
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> In ecology, desert ecology is the sum of the interactions between both biotic and abiotic processes in arid regions, and it includes the interactions of plant, animal, and bacterial populations in a desert habitat, ecosystem, and community. Some of the abiotic factors also include latitude and longitude, soil, and climate. Each of these factors have caused adaptations to the particular environment of the region. The biotic processes include animals and plants and the way they interact. Although deserts have severe climates, some plants still manage to grow. In hot deserts plants are called xerophytic meaning they are able to survive long dry periods. They may close their pores in daytime; they store water in their stems and leaves. Some of these plants include popcorn flower, barrel cactus and Saguaro cactus.
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Again environmental conditions will be more extreme than on Earth. But by comparison with our deserts.
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> Deserts support diverse communities of plant and animals that have
> evolved resistance to and methods of circumventing the extreme
> temperatures and arid conditions. Desert ecology is characterized by
> dry, alkaline soils, low net production and opportunistic feeding
> patterns by herbivores and carnivores.
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Generally temperature cycles, between day and night, and between seasons, are likely to extreme. You will need to take into account the duration of the planet's rotation. For example, if takes sixty hours to rotate, then its surface might not have the time to cool down sufficiently to be a cold desert night. Also, the shape of its orbit will affect the amount of insolation. So if the orbit is highly elliptical, then its equivalent of winter could be very cold. While its summers could be infernos. While its orbit around its primary star was circular, there might be very little variation between or even effectively none.
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# The water cycle matters
[](https://i.stack.imgur.com/tomMx.jpg)
A graphic from [KE Tremberth](http://www.metlink.org/climate/ipcc-updates-for-a-level-geography/the-changing-water-cycle/) showing water flows on Earth.
The key is that the ocean evaporation and precipitation is significantly larger than the land, and that the land has significant net losses of water to the ocean. Let us say we reduce the amount of ocean surface available for evaporation by half. This will lower the magnitude of evaporation by roughly half to 213, on the chart. At the same ratio of evaporation/precipitation over the ocean, there would only be about 20 units transported from ocean to land. As land rain levels fell, vegetation would die off, reducing transpiration and increasing runoff into surface flow to the ocean.
The chain of effects is complex, but in the end, you would have less rain over a much larger surface area of land. The world would be dry.
# Surface topography matters
[](https://i.stack.imgur.com/8zFW8.jpg)
This is the southern Caspian Sea. The region around here is mostly desert; Azerbaijan to the west is a desert, the Iranian Plateau to the south is a desert, Turkmenistan and the Kyzyl Kum desert to the east is...well...a desert. But look at dark blotches edging the snowy mountains to the south. As moist air comes off the Caspian Sea, it rises over the Alborz mountains (taller than the Rockies) and drops moisture as rain and snow. The result is, in the middle of a barren desert, a [rainforest](https://en.wikipedia.org/wiki/Caspian_Hyrcanian_mixed_forests).
[](https://i.stack.imgur.com/Pp9GA.jpg)
# Conclusion
If ocean levels were lower, but temperatures were otherwise kept the same, there would be significant differences on Earth. But while desert would be the dominant biome, it would not be the only one. The circulation patterns and locations of oceans will generate wetter and dryer areas, and local topography could produce even rainforests.
The range of climates we see on Earth would still be present, just in different proportions.
[Answer]
The habitability is very robust against variation in the amount of water. For the climate, mostly the surface area of the oceans is relevant. The oceans have a remarkable depth profile: The are some shallow parts (depths at about 200 m or less) covering the fringes of the continental plates and there are very deep parts (approx 4000 m and deeper). The oceans can loose a lot of water volume without loosing too much of surface, and the general climate will still be approximately the same as it is just now (of course the continents are somewhat bigger, and deserts in their middle will make up for most of the gain in continental surface). So with only one half of the volume of water, I won't expect a big effect on habitability of the earth.
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A major issue is whether there would be Wilson cycles of ocean basin formation and plate tectonics. Although these processes happen over 100MY timescales, ultimately the recycling of elements known as the silica cycle has a major influence on climate and maintenance of stability. It is probable that continental rifting would occur as a result of convective circulation in the mantle--I'm assuming that the planet has a molten interior unlike the Moon. But without the weathering of continents, whereby materials erode into the deepsea and ultimately are recycled back into the mantel at subduction zones, the biosphere would eventually accumulate certain elements and run short on others.
Plate tectonics results from the convective movement of magma in the asthenosphere, which is the process by which the internal heat of the planet is released. The danger to life on a planet without plate tectonics would be that instead of heat being released by seafloor spreading and subduction of ocean plates over 100MY cycles, there would be episodic mass eruptions that would largely or completely resurface the planet. Events like this are posited for Venus and would pose a major challenge for evolution such as Earth has seen over the last 540MY (Phanerozoic). So perhaps life would have to reboot each time from whatever survived the catastrophic resurfacing.
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Let's say there is planet, similar to Earth in almost all respects. However, some sort of geological process has shattered its continents, leaving lots of islands no larger than Iceland with shallow channels in between. What sort of geological process could case this to happen? Is this even possible?
[Answer]
You could consider a large series of hot spots, such as the [Emperor-Hawaiian Seamount](https://en.wikipedia.org/wiki/Hawaiian%E2%80%93Emperor_seamount_chain).
These are migrating volcanic areas that eventually surpass sea-level. If your planet is submerged and tectonic, you may eventually produce a long series of islands. The cause is produced by the movement of the ocean crust over the hotspot, resulting in an upwelling of hot rock from the Earth's mantle.
This would take very careful finesse of tectonic activity, but essentially may be your answer. **Use hot spots to create your islands.**
**In essence, consider growing your islands, instead of fracturing your continents.**
EDIT: Additional info, here is a map of postulated hot-spot centers on Earth (dunno the source - it's on my computer from ages ago); one can imagine your submerged planet having islands around these centers, which migrate over eons, creating even more islands.
[](https://i.stack.imgur.com/BL1Hg.jpg)
[Answer]
A very weird geological process indeed where tectonic plates can move apart creating the channels but never collide to create mountains...
However, if you are willing to relax the constraint of the size of the subcontinents, the Earth itself may serve: remember that we are [living in an ice age](https://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPaleo5.html#The%20Cretaceous) and the sea level is unusually low (geologically speaking); we are also living in a time when continental plates are quite bunched together. The Earth was not always like this: see for example a map of the [world in the Cretaceous](https://www2.estrellamountain.edu/faculty/farabee/biobk/anauLate_Cret.jpg) ([source](https://www2.estrellamountain.edu/faculty/farabee/biobk/BioBookPaleo5.html)). Your world may be just like Earth in more normal times, when the continental plates are more widely spaced, the sea is much higher than in our frigid times, the poles experience a pleasant temperate climate and there are many large shallow seas subdividing the continents.
[Answer]
Convection currents in Earth's mantle create the movements of the continents. You could just have a particularly turbulent mantle that would have many opposing currents. On Earth we have a thick mantle layer, that means big currents. Maybe on your planet the core makes up most of the mass of the planet, leaving the less dense silicates and other rock material to convect in smaller pockets. Imagine a thick liquid that you're boiling in a pot. In a deep pot with lots of liquid, the middle has this huge flow that always seems to be coming up. But if it's a thin layer, you would have lots of little flows everywhere. In the thin layer, the currents don't get a chance to combine and reinforce each other on their trip up to the surface.
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Part of my magic system is the ability to shoot force at people. **How much force (or at what speed) would cause an explosion on impact ?**
Or, if that is impossible: let's say that matter is being pushed at an outrageous speed. **How much speed would be needed to cause an explosion on impact ?**
[Answer]
Explosions do not occur on impacts. That's a Hollywood myth that has no basis in reality. It exists because explosions sell movies.
An explosion occurs when a material spontaneously undergoes a rapid exothermic chemical reaction. For example, the most famously shock-sensitive explosive of them all, nitroglycerin, decomposes according to $4 \text{C}\_3\text{H}\_5\text{N}\_3\text{O}\_9 \rightarrow 12 \text{CO}\_2 + 10 \text{H}\_2\text{O} + 6 \text{N}\_2+\text{O}\_2$. It does so if the nitroglycerin molecule gets enough energy to undergo decomposition. In the case of nitroglycerin, that energy is low enough that kinetic force (such as being shaken) is enough to cause it to go off.
Most explosives are more stable than that. In fact, since the invention of nitoglycerin, the field of explosives devleopment has heavily focused on how to make explosives which are more stable. C4, for example, can be burned -- as in you can put it in a fire and it will burn rather than explode.
Your best bet is to simply declare that the explosions are a side effect of using the magic to "shoot force." Then you can decide at what point the explosions occur.
If you really want an explosion to occur, if you accelerate the material to just shy of the speed of light, you'll find that pretty much everything reacts with enough energy to call it an explosion. It still wouldn't be an explosion by the true definition of the word, but nobody would call the effect anything but extraordinary!
[Answer]
You can obtain an "explosion" by accelerating enough of the surface layer of an object to overcome the resistance of the object itself. The object doesn't so much "explode" as it is smashed.
In the case of a soft body made of 70%-plus water, a.k.a. human victim, the effect ought to be impressive enough.
Also, depending on your magic system, you might end up with "shovers" - able to exert a large amount of force but not to focus on a small enough surface, still effective against a vessel's sails, say -, "punchers" and "needlers" - these last, fully capable of killing someone by either accelerating a rib fragment through their heart, or stunning/killing them through hydrostatic shock.
**Or...**
If the traction is exerted at the molecular level, and at the correct "frequency", it can force open the bonds in the oxygen molecule and have them react with carbon in most organic matter. It is still *not* an explosion, but more a sort of flash fire - a "ripping" after which the target object's surface is subject to a very hot fire. For many substances (e.g. dry wood), this also means that the *rest* of the object will go up in flames in very short order.
For comparison, there's something like this in Vernor Vinge's first novel, *The Witling*. Natives of the planet Giri have the power of limited teleport, but energy is *mostly* conserved. So they can kill someone by mixing up their brains, teleport air or pebbles from the other side of the planet to make them into rotational-velocity shrapnel, or large rocks from far out moons to release kiloton-equivalent strikes.
Possibly, exerting force on a leaden bullet and launching it at someone might achieve something similar to a firearm. Which also gets interesting if the magicless population discovers the equalizing power of black powder :-)
[Answer]
above ~70 km/s an impact causes any material being hit to vaporize (literally converted into a gas), this creates a secondary pressure wave thus creating an explosion just as detonating an explosive like TNT does. In thicker materials it creates an accompanying crater as the partially and completely molten material further away from the impact point is pushed out of the way by the pressure wave. There is quite a bit of wiggle room depending on the masses and materials in question. Some estimates say this can occur in rock at as little as 20km/s. At lower velocities the impact forces just creates a spray of molten material pushed away by the inertial forces creating a crater but not a real explosion.
<https://www.rand.org/content/dam/rand/pubs/research_memoranda/2006/RM3490.pdf>
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There have been many questions of moving, floral animals, most of these focus on their intelligence, but what about their sense of sight. I fail to understand how a botanic based alien would be able to see, theoretically they could evolve them from the very start as light patches, like animals did, but I would rather not cop out like that. How can I explain how my botanic aliens sense of sight works?
Previous Questions
[Heart](https://worldbuilding.stackexchange.com/questions/59818/what-is-the-botanic-equivalent-to-the-circulatory-system)
[Muscles](https://worldbuilding.stackexchange.com/questions/59194/what-is-the-botanic-equivalent-to-muscles)
Next Question
[Hearing](https://worldbuilding.stackexchange.com/questions/65777/what-is-the-botanic-equivelent-to-ears)
[Answer]
Current plants already react to light; every plant will "seek out" light by growing their shoots towards a light souce, and grow roots in the other direction. You can see it yourself if you grow plants indoors, how they will apear to lean towards windows as they grow. Plants can react even faster, with sunflowers slowly rotating as the sun progresses across the sky, or flower blooms opening during the day and closing at night. Carolus Linnaeus proposed a *[Horologium Florae](http://scienceblogs.com/clock/2007/05/23/carolus-linnaeus-floral-clocks/)* made of beds of fourty-three types of flowers that would open and close at different times of day, like a sundial of blooms.
[The mechanisms are there](https://en.wikipedia.org/wiki/Plant_perception_(physiology)#Light), corresponding to the light-sensitive patches of skin on animals. You could use mad science to make these processes more efficient (along with the rest of the plant metabolism so it can react at animal-like speeds), or a lot of time and environmental handwavium for encouraging light-sensing traits in plants. Animals improved their light-sensing by having a polyp half-covered in sensors and a small aperture, using part of their meat as a pinhole-camera; it's very efficient for not much expense so I'd expect the same mechanism in other creatures that will have distance vision. A plant with a pinhole-camera pod would have a much better time of it with a focusing lens, as it would resolve fine detail faster and with a smaller pinhole-pod, and the lens can physically close the pinhole keeping the pinhole-pod clean of dust or other opaque substances that would cover the light-sensitive parts. Perhaps the first lenses would be a drop of water, as they're very transparent and flexible, later evolving to a transparent sap that will hold its shape and less likely to evaporate.
Now, where's the organ that collects this sensory data and turns it into perception? and does it quickly? That's the real thistle of the puzzle.
[Answer]
Well plants are already covered with light sensitive molecules: chlorophylle.
You could easily imagine this evolving into a multi faceted eye like the flies except they could see from everywhere.
You could even consider a weakness which their enemies/predators could use: they could be blind to anything underneath them. Which they may have fixed with sensing whiskers for their locomotion.
[Answer]
## Purpose of sight
It's worth considering that the only reason why animals have eyes is that they can an do take useful actions in response to what they see.
Many current plants have an ability to sense light, direction of light and (for example) track the sun throughout the day - this is the limit to what their eyesight is useful for them. Being able to observer rapid changes in light is not useful if the plant cannot react rapidly, so such an "eye" would be removed by evolution and replaced with something "cheaper". Gaining an accurate picture is not useful if the plant either isn't able to act or react with such accuracy, or can do it by iterative refining, slowly growing towards something.
In essence, if a plant has powerful eyesight and a visual cortex that's able to track moving objects, then that's a strong indication that the plant is capable of rapid and accurate movements to react to those moving objects, unlike the plants of our world, otherwise these eyes make no sense - they would/could evolve *after* a mobile or active plant, so there would/could be some mobile/active plants that are nearly blind (just photosensitive), but there would be no stationary plants sitting and looking around.
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>
> In pillbugs, sex is determined by two chromosomes: Z and W.
> Individuals who inherit two Zs develop as males, while ZW individuals
> become female. But in some populations, these rules are overwritten by
> a microbe called Wolbachia.
>
>
> Wolbachia infects the cells of pillbugs and only passes down the
> female line; only mothers can transmit the bacterium to their young.
> Male embryos are dead ends to Wolbachia, so when it runs into them, it
> feminizes them by interfering with the development of
> hormone-producing glands. The result is that all young pillbugs
> infected with Wolbachia grow up into females, even those that are
> genetically male. In such populations, the W chromosome tends to
> disappear altogether. Eventually, all the pillbugs are ZZ, and it’s
> the presence or absence of Wolbachia that dictates whether they become
> female or male. . . . In the 1980s, the French researchers showed
> that some pillbugs do not have Wolbachia, but act as if they did.
> They’re all ZZ, but some still develop as females. The researchers
> proposed that the bacterium has transferred a piece of its DNA into
> the pillbug’s genome, and that this “feminizing element”—or
> f-element—was now dictating the animal’s sexes, even in the microbe’s
> absence.
>
>
>
From [The Atlantic Magazine](https://www.theatlantic.com/science/archive/2016/12/when-an-animals-sex-is-set-by-a-microbe/510737/).
What if a bacterium, with a similar effect on humans to Wolbachia in pillbugs (i.e. initially turning males into females until Y-chromosomes disappear and then eventually adding its own sex determination gene), rapidly spread through our world in the early 21st century?
This occurs because the bacterium infects the leading, internationally distributed bottled water brand, staring in the year 2014 and infects 80% of all people who every drink and bottled water in the time period from the year 2014 to the year 2029.
The source of the bacterium is not discovered until fifteen years after the bacterium had initially started to spread, because of a clerical error in processing the data that addresses possible causes early on, that is published in a prestigious scientific journal. This error is not be caught by anyone early on. The data published in the journal appears to rule out the bacterium that is responsible as a cause, sending scientists looking for the cause on a wild goose chase for another cause.
Assume that the bacterium is an otherwise symbiotically helpful gut bacterium.
How would the world react and change as a result?
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I think that it's fair to say that the effect on the world would be much less marked than if the opposite happened (significant over-population of males) - as it shouldn't affect the birth rate anywhere near as much. Men can clearly father many more children than women can, and can go on siring offspring for a long time. Socially it is possible that polygamy would become far more acceptable, especially in societies where it is felt necessary to keep the birthrate up. Age-difference in relationships would also become more significant.
Past that, it would affect the rest of society to some extent; assuming that the issue only lasts for 15 years and basically goes away when it's discovered then the imbalance isn't that great. Whilst your figures would give you 90% females for that period, with its only being around 20% of the average western lifespan you'd only end up with a 42:58% split, which is significant but perhaps not completely world-changing. For example, if you look at any field that's male-dominated and then add 1/3 to the number of women in that field, then you'll probably still find it comes out male-dominated. For example, the UK has 650 members of parliament, fewer than 200 are female (so more than 450 are male). Change that to 260 female MPs, and it's still 390:260 male dominated.
[Answer]
I won't discuss the actual biology, which is of course much different in mammals and feathered dinosaurs; let's take it as granted.
The premise is intriguing and yet quite common: what would happen if the sex ratio changed dramatically. For some reason, the sex ratio always seems to change so that there are many more women than men... The obvious consequence would be a significant increase in the amount of beauty in the world; it is also quite likely that there would be important consequences in the customs of those countries where most children are born by married women.
Practically speaking, any moderately large imbalance in the sex ratio would be detected quickly and a lot of money and effort will be expended to find out *how* and *why* it happens. The usual epidemiological methods will be applied to determine the place of origin and the means of spreading the affection; the identification of the pathogen may of course take longer.
Since the means of transmission of the pathogen seems to be important, I feel that the consequences of chosing to spread the pathogen through an "internationally distributed bottled water brand" must be explored. Let's ignore the problem of getting the pathogen into the bottled water produced by a reputable bottling company and suppose that such a gross negligence can go undetected for some time. (Maybe the pathogen does not get in the water accidentally but it is the work of a villain or of a determined idealist.)
The *brand* itself is an abstract concept and cannot carry any pathogens. Excluding places like Dubai or Qatar, as a general rule, the vast majority of people drink water obtained from sources not very far away; the popular bottled water brands are almost always local, because they are *much* cheaper; in the case of bottled water the cost of production is dwarfed by the cost of transportation over long distances. (One of the first tasks when living for more than a few days in a new country is to find which of the local brands of water has a sufficiently agreeable taste.) Those brands which are moderately popular in multiple countries, for example PepsiCo's Aquafina, are just brands: the actual water is sourced and bottled locally. Only luxury brands such as, I don't know, maybe Evian, transport actual water over long distances.
What this means that if the pathogen is distributed worldwide by bottled water the brand is a luxury brand; and only (very) rich people drink such brands of water. The immediate consequence is that in most places the sex ratio imbalance will be limited to the fabled one percent who rule us all; and, curiously, while in most countries only very rich families find themselves producing only daughters, in parched countries this affection is shared by a larger proportion of the population. This may give an early clue to the epidemiologists hunting the pathogen.
*If* the villain can persist in infecting internationally distributed luxury water for enough time, and *if* the various national health agencies manage to miss a pathogen distributed by bottled water (which, after all, is supposed to be microbiologically pure) then we'll see a lot of very rich women; the top financiers, the top captains of industry, the most powerful men in the world will be women.
I can't wait to see a meeting of the European Council where almost all of the participants are female...
P.S. If I'm not mistaken the question is about sex (the biological category) and not gender (the social category). There could indeed be a bacterium which interferes with how humans perceive their social gender, but I think that this is not the focus of the question.
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The reaction would overall be minimal. Even now we have gender equality. So, having a male or a female leader is not an issue. They are treated the same.
What would be interesting is the reaction in male dominated societies such as in many Asian countries. In Saudi Arabia, AFAIK, women are not allowed to drive without the accompany of a male mukhrim. Mukhrim is someone who is blood related. With the outbreak there might be families without any male. The law might be repealed.
The overwhelming number of female might also lead to harem. Polygamy might be rampant is countries with strong male-dominated culture. Because it is in human nature to mate, males would be hot comodity. Even the nerds and otaku would have a better chance to score with girls.
Manufacturing companies would shift more to products that appeal to women. We will see more bags and dress ads and less suit ads. The next James Bond would still be a male since it will sell better due to the audience being mostly females. But we wil see an increase in soap operas. There would be more BL anime and manga than harem ones.
But overall the change wouldn't be drastic.
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If it took 15 years to find out the cause of a widespread society-damaging disease, I can only assume that the society has quickly collapsed. I'd expect the research to take a year or two, at most.
A single publication disproving bacterial nature of the disease won't stop the competing labs from double-checking the results. Different labs from all over the world will be looking for the cause, simultaneously and, mostly, independently, and a gender-swapping bacteria will likely be the main hypothesis. It sounds really, really implausible that no lab manages to detect this bacteria - the Wolbachia have been identified in 1924, so I guess the modern technology is pretty good at finding bacteria.
If there was no collapse (they still seem to have bottled water in 2029), then once the bacteria is found, people will develop some antibiotics or bacteriophages, kill it, and get back to mostly normal. So you'll get ~20 years demographic anomaly; it'll cause some cultural changes, but no real apocalypse.
[Answer]
Something similar has happened due to another well known affliction: War
Historically, only men would be sent to war, meaning that heavy casualties would result in an imbalance in the population.
One example was the "Guerra del Chaco" in which Paraguay, with an approximate population of over 1 Million, lost around 150000 men.
From a social standpoint, the result wasn't too dramatic, as social norms stood strong despite the imbalance, but there was a boom of "women-focused industries", so to speak, like modelling.
Or at least that's what I was told when living there many years back, I haven't been able to find more concrete information.
So back on topic, a drastic imbalance in gender dynamics would probably only result in societal changes if the social norms are flexible enough to allow change. For example, the effect would probably be completely different in a country like say, Norway, than in a country like Saudi Arabia.
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## Context:
## *Brains in Vats* and *Virtual Reality on Steroids*
In the (reasonably near) future, humans have developed the field of medicine significantly, and we now have the technology to [isolate the brain](https://en.wikipedia.org/wiki/Isolated_brain) in a vat of oxygenated fluid. Assume the process of doing so is safe, although irreversible, and that a machine facilitates all body functions - providing nutrients, circulating blood and fluid, **and the nasty one - providing stimulus** as best it can.
---
**In most cases**, the transfer from body to vat is voluntary. Some people will choose to have their brains placed into [new bodies](https://worldbuilding.stackexchange.com/questions/45493/would-biological-brain-in-a-box-considerably-increase-life-expectancy), while others will have supercomputers simulate life for them - providing electrical input as if the situations the isolated brain is encountering are real.
**However**, sometimes these transfers take place without the knowledge, and thus consent, of the participant. Perhaps the government is particularly evil, and has the money to sedate the person - the next time they wake up, they will assume things are normal, when in fact they may be in a simulation or a new body. Let's focus on the simulation aspect of this scenario.
---
## The resulting problem
When someone voluntarily chooses to enter a simulation in this way, they will understand that the world is not real. That means it's 'ok' if some things are a little off - if they don't feel quite as tall, or if it's harder to breathe, or if their vision is better - they will know it's a simulation, and that's expected.
When someone is transferred involuntarily, they may realize there's a problem when not everything around them is exact - and that may reveal the true nature of what happened. For example,
>
> Jessica is $f$ feet tall, with shade $s$ skin, weight $h$ hair, and
> predisposed conditions that change things no one else can tell by
> looking at her $p$, $r$, and $e$
>
>
> When Jessica is transferred, she does not feel $f$ feet tall, her skin
> is shade $q$, her hair is too light, and she doesn't have conditions
> $p$ and $r$. She knows something's up because she's heard these
> stories before, and she knows the associated symptoms.
>
>
> The illusion is broken, and Jessica freaks the \*\*\*\* out.
>
>
>
It is impossible to exactly reproduce the sensations any person receives with a machine in this way!
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## My thoughts
One might argue that this scenario is analogous to dreaming - you can proceed through a dream while being ignorant that everything around you isn't real. Perhaps there's a way to make Jessica ignore aspects of herself, while still functioning inside the simulation, so she doesn't realize the problem. I'm thinking something kind of like how in *The Sixth Sense*,
>
> The psychiatrist has been dead since the opening scene in which he was shot, but he has been ignorant to the signs that he's a ghost and continues to try to interact with the world as normal
>
>
>
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## The question
Short of a lobotomy, is there a way to induce ignorance (kind of like a dream) that allows the individual to function without realizing the [nature of their reality](https://www.reddit.com/r/westworld/comments/5cfl96/have_you_ever_questioned_the_nature_of_your/)?
**When answering this**
[hard-science](/questions/tagged/hard-science "show questions tagged 'hard-science'") is not expected but acceptable
[science-based](/questions/tagged/science-based "show questions tagged 'science-based'") would be great but may not be possible
[science-fiction](/questions/tagged/science-fiction "show questions tagged 'science-fiction'") or pseudoscience is fine, but not ideal
[Answer]
## Amobarbital
Also known as Sodium Amytal or more commonly called truth serum. Amobarbital has some interesting side effects with how it messes with the mind, which could prove useful. While under the effects of Amobarbital the higher level cognitive abilities of the brain are impaired. This can result in brain not being capable of realizing that it has become a brain in a jar (the dream feeling). Amobarbital can also make the brain suggestible and even result in [false memories](https://en.wikipedia.org/wiki/False_memory_syndrome). This can be used to try and convince the brain of a lie that can serve as a cover for why things do not add up.
An example of a cover is that they had experienced a stroke that impacted the sensory processing centers of their brain and so everything is going to seem different and the prognosis is grim that they will fully recover from it. For this scenario the brain should wake up in a hospital and go through a process of rehab to recover from said stroke. This will give the person who orchestrated it a chance to improve the calibrations, which the brain will assume it is recovering from the stroke.
An alternative to using the false memories to create a cover is to create a lie to tell why their brain is in a jar. It is far more bold and risky and more likely not to work. An example would be to convince the brain that they signed up to have their brain put in a jar. Tell the brain that an unfortunate side affect of the transfer is that it causes memory loss of more recent memories and it is common for those transferred not to remember up to seven days before they got transferred, which is when they consented to under go the procedure. If the brain in the jar gets a chance to talk with other brains in jars, they would corroborate that they too experienced memory loss, but with the excellent help of the doctors they were able to eventually remember it (which this too can be a lie). At this point try and help them reconstruct their last week of memories, and in the process implant a week's worth of false memories that lead them to the decision. The advantage with this is that they are fully open to the fact and you do not have to worry about them finding out.
**Disclaimer:** I am not a doctor, I only play one on Stack Exchange. As with any drugs please consult with your doctor to make sure Amobarbital is right for you.
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A massive, coordinated PR campaign to convince the entire populace that lots of people have already been uploaded into a vat. Have some people claim that everyone is in a vat. Plant lots of people claiming that things about them are wrong. Then have it uncovered that it was just a practical joke taken way too far. ("We didn't know it would permanently change his skin color," says older brother.) Then when people really are put in a vat, they'll think they've just been the victim of one of these pranks. Government disinformation for the win!!!
[Answer]
### Partial dreamstate induced by carefully targeted magnetic fields.
In humans whose brain is still insde their skull this is known as transcranial magnetic stimulation, and it can do fun things like induce [out-of-body experiences](https://en.wikipedia.org/wiki/Out-of-body_experience#Mechanical_induction) or a sense of presence, or for that matter, decrease the activity levels of the critical parts of the brain (the stuff that allows you to sometimes realize you're dreaming when a particularly egregious break of logic happens in a dream).
>
> When examining REM sleep dreams for memory content, one finds that episodic memories are rare (see Baylor and Cavallero 2001) and typically emerge as disconnected fragments that are often difficult to relate to waking life events (see Schwartz 2003). These fragmented REM dreams often have bizarre content (Stickgold et al. 2001; Hobson 2002). For example, the normal rules of space and time can be ignored or disobeyed, so that in REM dreams it is possible to walk through walls, fly, interact with an entirely unknown person as if she was your mother, or stroll through Paris past the Empire State Building.
> \* <http://science.sciencemag.org/content/294/5544/1052.long>
>
>
>
Supressing (in part) the critical aspects of consciousness (in a way similar to that which happens naturally in REM sleep described above) will generally prevent the subject from questioning the nature of their reality. In case they become aware, a clinical dose of Flunitrazepam will wipe out the memory of becoming aware of discrepancies, effectively working as a reset button for the previous few hours.
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The *ODESSA* network, a highly secretive organisation of former SS members, decides to hold the former Allied nations to ransom; with a giant parabolic mirror in space that can focus sunlight into an incredibly intense beam, capable of destroying entire cities.
(Artist's depiction of the Sun Gun taken off of damninteresting.com)
[](https://i.stack.imgur.com/pvAPS.jpg)
Now over the past 70 years, ODESSA has managed to get their hands in every pie: From major armament companies to agencies that are paid by various Third World governments to launch satellites for them (kinda like SpaceX...but *not* SpaceX). So funds, equipment and a large workforce aren't a problem here.
But just what will it take to build this Sun Gun and maintain it in space without detection?
The original Sun Gun, which was planned by the Germans during WW2 for a similar p\*\*urpose (namely: Total obliteration of enemy cities) was supposed to have an area of about 9 sq.miles and the reflective coating was to made using metallic sodium.
So, essentially what I want to know is,
**How would they go about building the Sun Gun, and what problems might arise in doing so?**
But to make sure an answer wouldn't miss out on some 'issues' that I find crucial to the plot, I've broken up the above question into 3 sub-questions which should (hopefully) give users a better idea as to what I'm gunning for here.
Q1- Is it practical to send up the mirror, piece by piece over numerous "satellite launches". Would all the required materials be capable of being **transported** to space without arousing suspicion from countries like the U.S and Russia?
Q2- How could the mirror have been **assembled** in space? Would a human crew in space actually be required to patch it together, or would robots suffice?
Q3- **Where** would the mirror be placed in space, so that it can be built without observation, but isn't *too* far off (periodic maintenance by a human crew is required...kinda essential for the story, as it gives the protagonist a chance to slip in with the regular crew and sabotage the Sun Gun)?
[Answer]
The mirror does not need to be a single piece mirror. You can focus multiple smaller beams over a city, in a manner similar to this:
[](https://i.stack.imgur.com/XHefz.jpg)
You can launch each smaller mirror separately and in a precise orbit, then later arrange all the mirrors to attack a single target. You can organize a very big cubesat array to target each city. making your weapon resilient...
[](https://i.stack.imgur.com/naDpQ.jpg)
[Answer]
Concealing the mirror is not going to be that hard.
1) As Jorge pointed out, the mirror does not need to be all in one piece. There's a reason all the really big telescopes these days are built with multiple mirrors and this is far bigger than the biggest of them. You're not trying to hide one miles-wide mirror, you're trying to hide a whole bunch of much smaller mirrors.
2) Fortunately, for a city-killer weapon your numbers are too low. Even with perfect accuracy (something you can't get) your mirror can only burn a quite small piece of a city.
3) A major part of the concealment of the elements is that you keep them edge-on to the Earth until you're actually going to fire. Note, however, that once you use the weapon once everyone knows where it is. If it's broken up into enough pieces you might muddy the waters enough but the second time around the scientists will be watching and they'll find every piece.
4) Even edge-on you can't hide near Earth, the tracking is too good. (They're not looking for your mirrors, they're looking for little things that pose a threat to satellites.) I suspect you need to place them around L1.
5) Fortunately, there's a showstopper: Anything like today's level of space activity simply can't hide the number of launches needed. Rockets leave a great trail of fire, there's no concealing an orbital launch. If those launches don't turn into commercial results people are going to start asking questions.
6) Unfortunately, there's a purloined letter approach to the Sun Gun that I think could be pulled off:
The Nazis quite openly work on a lunar mining project. It's not really working too well but they're determined to keep at it. In reality, it's working fine but most of the mined material is being turned into mirrors that are scattered around the moon with camouflage over them (a cover made to look like the Moon underneath.)
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It seems very unlikely to me that such an effort could go unnoticed by the intelligence agencies of the major powers (United States, Russia, and probably China and the United Kingdom as well). They have networks in place that track both rocket launches and also man-made objects in space. Additionally, there are hobbyists who [track the movements](http://www.heavens-above.com/) of highly reflective space objects (particularly the ISS, Hubble Telescope, and Tiangong) because they can be seen by the naked eye during certain twilight hours if you know where to look. Surely such hobbyists would notice something new and try to find out what it is.
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I wouldn't go with mirror, just because it would be near impossible for these Hydra-esque organization to setup in space or more importantly explain to general public.
Personally I would use large quantity of solar panels, which wouldn't raise much suspiction and which could be explained with sane and rational needs.
Secondly, I would not use direct sunlight, but something akin to Infrared Laser.
You may ask - "How to even start explaining that one to general public?".
In reality, just tell them it will be used as power source, of your newly created photon sail or different kind of engine. Similarly to those used by Peter Watts in "Blindsight" ( ICARUS ) and lasers used in "Ringworld" by Niven.
All in the same time, but if your super-evil organization have enough power to build something like that. Building ultimate sun-powered killing device against Allies, because they want to make SS Great again ( pun fully intended ) doesn't sound to realistic for me.
The last point is, why not make your cliche Nazis work with government, and create this super-weapon for army, and later on just stealing it/hacking it.
That would easily explain source of founding.
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If an alternate Earth had an axial tilt of 45 degrees, what would the seasons look like? Being the most extreme tilt a planet can have before simply replacing North/South with East/West, obviously such a world would have rather extreme seasons, what just how extreme? What would these extreme seasons look like? What would their effect be on the ecosystem?
[Answer]
I'd imagine the 4 seasons area would have harsher degrees of winter, and get a glimpse of tropical summer.
On details that would make the dry land parts of earth are already smaller than we would naturally have (without global warming), cause the earth's pole area that didn't catch direct sunlight throughout the year are smaller.
At the ecosystem level, there may be a smaller pure tropical climate (or maybe there isn;t any at all), and most creatures are experiencing highly fluctuating seasons change. If this happens naturally from the very beginning, I expect a thick furry creatures like polar bear may developed a shedding cycle as part of their survival process in the summer, while others who don't developed a habit to survive.
[Answer]
Winter would be colder and summer would be hotter.
Overall there would be a greater gradient of temperature from the southern hemisphere to the northern hemisphere. That would result in stronger wind and sea currents.
How that would affect the environment and ecosystems is difficult to tell because there are many feedback effects involved. I would naively say that there would be way more hurricanes and tornadoes, thus making life more difficult in general.
Another effect would be that the Earth's magnetic field might deflect less solar radiation because it would be too inclined. There might be a higher level of radiation on the surface of such a planet.
However the odds of a 45 degree axial tilt planet are very small. Because planets are formed by accretion of dust around a massive sun, most debris are in the same accretion disk. Planets are tilted because in the late stage of accretion, a planet in formation is hit by another smaller planet (usually moon sized) at a certain angle, tilting the planet. However because most rocks are in the same accretion disk, for a planet to tilt to 45 degrees, you would need a planet of similar size to hit it from a large angle to cause such a tilt. Statistically the odds are small. That s why you don t see many planets with such a tilt in the universe.
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>
> "The oldest and strongest emotion of mankind is fear, and the oldest
> and strongest kind of fear is fear of the unknown." — H.P. Lovecraft
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One example of this is the universal fear of the dark. We cannot sense what is there, and so we try to either avoid dark spaces, or light them up. That brings me to this:
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**What if the opposite were true for a different species?**
Picture a creature that has developed acute infrared vision. It's nocturnal, and nighttime is still somewhat dark for it, but that's OK - **it knows that's there**.
During the daytime on its homeworld, its senses are flooded. It's the opposite of not seeing anything - this creature is afraid of the vast whiteness, instead of blackness. **It's afraid of the light.**
**A)** Is this feasible for an intelligent race? Is there something I'm not considering in this scenario, is there some characteristic of evolution that would present this from happening, etc?
**B)** Bonus: If such a creature could exist and evolve intelligence, how would it "see" in the light? We can shine light into darkness, but if the concern is sensory overload, what would help them cope?
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**Edit:** Chose Youstay Igo's answer because, while all answers addressed the problem, Youstay had the least specific conditions required with an equal solution. Instead of changing the planet, etc he changed the explanation, allowing more creativity when building a world.
[Answer]
First, let me tell you that there ***are*** species on Earth which prefer to be active in the night time because daytime is not suitable for their eyesight. Certain snakes are a good example of this. ([source](http://www.livescience.com/32114-can-snakes-see-well.html))
How this works, is simple. These species have pupils which don't narrow down much, always allowing too much light into the eye. While this is quite useful at seeing things in the low light of night time, it makes daytime too bright for them, nearly blinding.
So the scenario is not outworldly and definitely not impossible. The main question is: *why* would a species, during the course of evolution, develop eyes which are suitable for the night time and not daytime? I am not certain about it, but I *think* eyes evolve faster than brain size and patterns. (For example, [ophthalmosaurus](https://en.wikipedia.org/wiki/Ophthalmosaurus) had really large eyes for its size and no other ichtyosaur had eyes of that size)
What you have to justify (in case you do feel like justifying) in your world is the reason and purpose of eyes adapted for night vision, instead of daytime vision.
* Do prey animals for this species come out at night?
* Are there larger and scarier animals active during the daytime? (Consider mammals versus dinosaurs in Mesozoic times)
* Is there a lot of ultraviolet radiation of the host star and this is the only species not having protection against it?
[Answer]
Creatures which live on planets orbiting red dwarf stars might develop in such a fashion, particularly if they have evolved to live in the twilight zone between the hot and cold poles on a tidally locked world. They would not have a day/night cycle as we understand it, but would avoid moving towards the Hot pole, where the sun is always at the zenith and flooding the world with the maximum amount of light they would receive.
If the world is not tidally locked, it might have a fractional rotation period like Mercury, so there will be a prolonged day/night cycle, and there would be an advantage to avoiding the "noon time sun" (particularly of the red dwarf is emitting flares and drenching the day side with radiation).
Assessing if a creature seeing in infrared could become intelligent is much harder to assess. Infrared "eyes" may not be able to see in as fine detail as visible radiation (greater diffraction, for example), so tool use and developing fine tools and mechanisms will be much more difficult.
[](https://i.stack.imgur.com/DUY3n.jpg)
*The level of detail and sharpness in infrared photos is less than in visible light*
Being restricted to a relatively limited range of environments due to radiation or needing to exist only in the temperate "twilight" zone may not provide enough challenges to drive the need to evolve intelligence. The Ancestors moved from a tropical environment in Africa and radiated into Ice Age Europe, the Asian Steppes, crossed mountains and oceans and into every environment on Earth, so in that case a wide general purpose intelligence would be more of an asset.
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Evolution is survival of the fittest. Or rather, death of the least fit. I know, that's a simplification,but it'll work here.
If for half of the time it's somewhat dark for your creature, and for the other half creature is blind, then it is less fitted than we are. The trend would be towards us rather than them. If there is no competition between races, then units last flooded during the day would win, and probably changing eyes is faster than developing intelligence. Probably, because we know only one species we are sure to be intelligent - us, and that's no sample for statistics.
I'd say no, natural evolution is not feasible for species you describe,unless it happens in environment without daylight. Of course, this environment must be big and stimulating enough. No such thing on Earth, but maybe in another planet?
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Setup: A small fantasy world -- with about three cities, five sizable towns, typical medieval technology, a low amount of magic, and some typical monsters living in the uncivilized parts -- is plunged into an era of darkness. The darkness is not full nighttime all the time, and varies slightly, but at best it gets as bright as early dawn or sunset. I imagine it would be somewhat similar to a nuclear winter.
How would the people survive this era of irreversible darkness if it lasted hundreds of years? What kind of changes in culture, ecosystem, technology, magic would be necessary for survival?
[Answer]
I'm presuming that the ecosystem *looks* earthlike, in that plants grow, and provide the food of all animals, directly or indirectly. If it looks different to that, you'll need to explain it before you can get any useful answers.
Given that assumption, you can manage this if plants don't get their energy from sunlight. That's the fundamental problem that has to be solved: without it, everything dies, so other issues are irrelevant. It might have been the case all along, or some godlike power could have changed the nature of plants soon after the darkness fell. But the nature of the solution affects everything else.
Possible explanations for the growth of plants include:
* They tap the elemental energy of earth.
* The basic nature of plants is to grow, and considerations like energy are irrelevant.
* The goddess of life and fertility is spending a lot of time making this happen, and has no time to do anything else, so some heroes are *really* needed to make the sun come back.
You also need to keep the world warm. Possible explanations for that include:
* The world has a natural temperature range, and the sun wasn't relevant to that.
* Sacrifices to the volcano gods are necessary to keep the world warm, without volcanoes erupting everywhere.
* The god of fire, the hearth and metalwork is putting a lot of effort into keeping the world warm, because if everyone dies he'll have no worshippers and will forget how to be a smith. We really, really need heroes to bring the sun back.
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One especially dramatic scenario would be for all plants to die out, resulting in a world populated entirely be 100% carnivorous animals and people eating each other, with a very rapidly dwindling population. Combining this "red in tooth and claw" ecosystem with the perpetual darkness would lead to a terrifying mood! In absolute darkness the population would dwindle way too quickly though, but it could be tempered to have an arbitrarily slow population decay rate by adjusting the amount of light the world receives (and thus the rate of extinction for plants).
Another option would be to explore alternative food webs. In the real world, total darkness still allows a few types of ecosystem. There are oceanic plumes which support a food web on chemical energy captured from the plumes by bacteria. In your world I would imagine there are highly magical point sources which emit "life energy", powering small island ecosystems around themselves.
The rest of the deep ocean runs entirely on food particles which drift down from the upper reaches (it's called oceanic snow). Filter feeders scoop this up and are eaten by predators. If the darkness in your world is caused by a cloud layer, then there could be some kind of flying or floating plants existing above the cloud deck, powering an ecosystem on the ground with discarded, rotting leaves. Detritivores like earth worms and millipedes would feed upon the leaf mold. Larger animals would eat the detritivores and mushrooms. People would eat everything. This strikes me as another very dramatic option!
Cave ecosystems largely run on debris brought in by animals like bats, which leave the caves to feed. Copraphages and detritivores like cockroaches feed off the excrement of the bats (and fungus that grows on it). Check out this piece by the amazing David Attenborough <https://www.youtube.com/watch?v=UC51eymvsRA> Your world could conceivably have aerial access to another realm where the sun DOES shine. Bats, birds, or flying insects might feed in the sunlit realm, then return to the realm of darkness to roost. The sunlit realm might be very tall plateaus which rise above the opaque cloud deck. For example, see the amazing tepuis <https://www.youtube.com/watch?v=S9K8QcjwjYs>
The last real world ecosystem I can think of are the microorganisms that live in the bedrock of the crustal plates. They have extremely slow metabolisms which are powered by chemical weathering of rocks and chemical reactions caused by the heat of the mantle. This ecosystem exists miles down into the earth. It's hard to see how your story could revolve around something like this, but maybe you see a possibility that I've missed?
Anyway, my advice is to figure out how your ecosystem is powered first. Everything else (technology, culture, ecology, etc.) will follow from that.
[Answer]
Noting all the great answers above pertaining to the ecosystem and food chains, I'd like to postulate a little about the human population in your world and their response to their situation.
Firstly, I think groups of people would definitely come together to solve this immediate problem from the start. Assuming this is not done by killing some evil overlord, I would guess that a small group of mages could develop a magic that would counter the effects of darkness on a local scale - perhaps just enough to sustain a small farm.
Over hundreds of years of darkness, this group of LightBringers could plausibly attain cult status, sending out envoys of monks on missions if they were inclined to charity, or securing power and riches otherwise.
Mankind by that time would become quite dependent on the LightBringers for their continued existence - without them they would quite quickly die off since they did not develop the evolved ecosystems needed to survive in a world without the LightBringers. The world reaches stability... until some bright spark somewhere (pun completely intended) discovers electricity. Zing!
Cue civil war, revolution against the secret shady practices of the LightBringers, with all the bells and whistles on. Anyway, sorry if this is horribly off-tangent: it was just too much fun to pass up.
[Answer]
# Magic Mushrooms
In darkness, people will rely on a food source that lives the dank darkness - Fungi. Given the psychotropic nature of some species of fungi, it's reasonable to assume that new forms of magic will evolve over this period of time.
# Economy
Obviously, there will be more of a reliance on fire for warmth and light. With the increased demand for firewood, there will naturally be more control and taxation on firewood. Foresters and lumberjacks will become more powerful.
# Technology
Technology will improve in terms of iron-working and textiles - both crafting skills that can be performed indoors.
# Culture
People will spend more time indoors, so writing and storytelling will be ever more important as a way of keeping people together and entertained.
# Population
Will tend to grow somewhat, due to what people tend to do in the dark hours and there's not much to do. Limiting the population growth may well lead to stricter couples laws (limiting how often couples may couple). The stricture may be scripture related, in coming from religious doctrine rather than through government (the Gods being harder to argue with than men).
[Answer]
Without sun light crops die, so no food, and plants die, so no air. You're in a pickle. But as it is a fantasy setting I suggest a fantasy answer: Some kind of magic that allows for things to thrive without sunlight, though at some cost. Maybe that cost is why the magic is low(?)
For a more environmental answer I would suggest that there are places in your world that are high enough above sea level to pierce the cloud cover (assuming cloud cover is what's happening) and your characters seek these places out to live in. Their search for light could become part of your story.
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**This question already has answers here**:
[Could humanity survive the sun going dark?](/questions/9679/could-humanity-survive-the-sun-going-dark)
(8 answers)
Closed 7 years ago.
I was recently looking at the control panel for the Universe Simulation, and I noticed a switch labeled
# Sun - On/Off
I don't really want to turn off the sun without knowing what would happen.
Assuming I turn off the sun, it stops giving off light and heat, but its gravity remains the same - I know, physically impossible, but hypothetically speaking, assuming there was no supernova or other event that made the sun stop shining, it just suddenly was *turned off* How long could humans survive? I know the earth would get *really dark* after the ~8 minutes go by and the light that was emitted by the past sun reaches the earth, but how cold would it get?
I know things like growing crops would be quite impossible whit no light, but there is still quite a lot of potential energy stored up on the earth, and surely some humans could stay warm for a little while? What if someone was in a bunker, burred deep underground with thick, insulated walls, had enough compressed oxygen, clean water, plenty of food, and some way to safely expel waste, How long could this human survive? Granted, life in a bunker like this would be boring, but just think of it - you could be *the last person alive*
Or could you? Is it remotely possible to keep a well insulated room on earth with a heatless sun, remotely close to a normal room temperature?
[Answer]
## EUROPA
Well, considering the Earth has gone through several ice-ages with the Sun ON including a "snow ball Earth" stage early in its formation: yeah, it'd get real cold on the surface. Dead cold.
Anything food chain based on a photosynthesizing autotroph would die (or go into hibernation then die).
However, there is another food chain based on chemosynthesis. Most famously tubeworms (actually their bacteria) that live on sulfur from deep sea vents. There are also caves like Movile Cave that are ecologically isolated from any photosynthetic input that have chemosynthetic bacteria supporting a number of flora and fauna. Sure they're all tiny, but they are alive.
Basically, that's the hope of Jupiter's moon Europa. Frozen surface, possibly liquid water underneath, powered by chemosynthesis.
So, in theory, humans could generate power from geothermal: using earth's heat to generate steam to turn a dynamo. With power, you can melt ice, or filter potable water from sea water and also electrolyze water for oxygen.
You can also power hydroponic farms if you raid the seed bank--and use the plants to feed regular underground animal farms. But you could also generate additional food from some kind of food chain based on chemosynthsis.
Might be nice to do this in a habitat that is connected to a facility near a hydrothermal vent.
I think we'd need Vitamin D supplements though. Also, I'm not sure how you'd scrub CO2 from an enclosed atmosphere indefinitely, so you'd probably vent air to the surface.
Who wants fried tubeworms!
[Answer]
Surprised no one has mentioned "A Deepness in the Sky", where this is a major plotpoint. Basically, things get dark, things on the surface freeze, the atmosphere collapses into a liquid, etc., as the surface temperature goes to absolute zero. But if you prepare (are far underground, hibernate, etc.) you are OK. Most exciting (in the book) is when the sun blasts back on again!
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Just last month, science gave us a pretty good answer with observations of Jupiter's moon, Io... the moon enters the planet's shadow, gets cut off from the sun, and *its entire atmosphere crashes down so suddenly, it causes geologic pressure enough to generate geysers*. Kind of amazing: <http://arstechnica.com/science/2016/08/jupiters-moon-io-loses-its-atmosphere-when-eclipsed/>
[Answer]
The sun is turned OFF:
-3 minutes pass
-Mercury freezes
-6 minutes pass
-Venus freezes
-8:30 minutes pass
-Earth freezes
-Almost Everything on earth dies
-After 6 hours the entire solar system would be frozen
Only humans who where prepared for the event would survive, they would be living underground, warm up with geothermal energy and feed on underground farms.Other survivors are the bacteria inside humans and the bacteria producing nitrogen plants.
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In the never ending quest to get elves to live in trees, I am taking things one step further and attempting to get the entire *city* in a tree. Magic is not in the equation. The tree would start out looking like this from above:
[](https://i.stack.imgur.com/u89Et.png)
As time goes on, the tree would expand outwards, with the dual trunk marked 'roots' remaining in place while the circle grows. The city is within the circle, as shown.
You can think of it as people living in a hallowed out tree trunk, with one very large exception: the 'trunk' is only located in the area marked 'roots.' The circle part is basically one gigantic root, about as thick as a two story house. It would like this, from the side:
[](https://i.stack.imgur.com/K2u4J.png)
**Is this design possible? Is there any reason trees like this would ever exist?** This is for a fantasy novel, so you can make a few things up like creatures if necessary. My idea is that the tree creates a safe haven for animals (and people) within the circle, and then gets a lot of nutrients from them.
**Details** (as requested by Lord Dust)
* While tree shaping is not entirely out of the equation, I would
prefer not to use it, as it takes a long time and is therefore
impracticable for immediate housing purposes.
* The elves are human-sized, maybe six inches higher.
* The city needs to be able to accommodate around 5000 people. I've never really thought about it, so that estimate is flexible. It is a capitol though. (Think *really* big community instead of city).
* The tree does not need to be of any particular type.
* The city is located on the edge of a forest, at the foot of a mountain (about 3000 meters high, little to no snow). The entire area would be at about 50˚ North. It is sitting on mostly plains-type ground, used to fog from a nearby forest river. Probably generally moist ground, though it dries out in the summer, reaching temperatures of around 80-90˚F.
* The tree should be one of many. This is not mandatory, but would be quite useful.
* As for modifications, certainly it can be modified. The main thing is that it has to be found more or less habitable (meaning the circle is in place). - Certainly tree growing can occur *later*, just not to start.
* It doesn't have to be a tree, but it does have to be as tall as one, as I am envisaging it overshading at least part of the city.
* The tree was found at its current size. It is however alive and growing, though likely very slowly. (Speed is flexible.)
[Answer]
It seems natural that elf trees grow out of [elf circles](https://en.wikipedia.org/wiki/Fairy_ring) (more commonly called fairy rings). These rings are formed by mycelia, or mushrooms. The mycelia alter the soil composition around it, causing the grass and other plants in the area to be affecting, causing the visual effect of the circle on the surface event when the mushrooms are not sprouted. Sometimes the mycelia depletes the soil nutrients, causing a circle of dead grass. Other times it produces chemicals beneficial to the plants, causing them to grow more lusciously than their neighbors. Our elf tree enjoys a symbiotic relationship with a type of mycelium. So much so, that the trees have adapted to grow their roots in the circle in order to maximize the amount of nutrients provided by their partner mycelia. The additional nutrients also cause the trees to grow spectacularly compared to their neighbors, large enough to protect a village of elves.
[Answer]
Imagine an area much like the eastern face of Canada's Rocky Mountains, but earlier in prehistory, when the central plains were, in fact, an inland sea. [Giant prototrees](https://en.wikipedia.org/wiki/Lepidodendrales) inhabited the shallows of this sea, and root formations where the rooted tree did not begin by growing vertically were not unusual. Very wide roots systems and bases in the sedimentary swamps, on the order of hundreds of meters wide, were not uncommon, supporting trees up to 1000m in height.
Later on, the seas retreated, and erosion of the sedimentary sea bed began. Wide swaths of the giant forests died out, and were replaced by smaller trees more adapted to the drier environment, as in our world. However, in one region, this didn't happen.
Here, volcanic intrusions from beneath the seafloor (such as our own [Devil's Tower](https://en.wikipedia.org/wiki/Devils_Tower) were relatively commonplace. Over an area of roughly 200 km², these intrusions were revealed to various altitudes by erosion of the surrounding sediment. By chance, the formation of these extrusions included substantial amounts of minerals such as [selenium](https://en.wikipedia.org/wiki/Selenium) that were very favourable to the growth of these prototrees. The root systems and broad bases of these trees would often grow to encompass these round intrusions, developing a trunk above a certain height on the "southern" (ie. dominant sunlight) side of the rock. Although single trunks are most common, double or multiple trunks are not unusual. Since these "trees" are not really trees in the modern biological sense, the method of growth and renewal is based on cannibalistic tendencies of the plant. Rather than a single specimen growing to an enormous age, young individuals attack the older main body constantly with a rapid growth, increasing the girth and height of the plant in successive layers. Thus, these "trees" are actually quite young, and largely unscarred.
The largest of these igneous intrusions was about 3km in diameter. This rock formation was eventually completely encircled by prototree growth. A number of smaller secondary trunks grow from this ring, but the primary trunk is a double trunk system facing just west of south. This particular rock formation, like many others, protruded quite far above the forest floor. At some relatively recent time (geologically speaking), the rock formation, intruded by root systems below the surface, broke off and collapsed off to one side. Fortunately, the trunks were not taken down at this time. Unfortunately, the spectacular size of the primary trunk means that without the protection and occasional support of the central rock, it will soon (relatively) collapse.
Our elves will have had to carve a gate through the encircling tree below the main trunk system, and will have to have found some way to arrest interior growth of the tree into the ring. Not only is it fortunate for them that the largest igneous intrusion developed in this unique way, but it is also serendipitous that they were there and required a home after the rock broke off, but before the central ring grew over.
It's all pseudoscience, or at the least highly speculative, but it seems plausible to me. The conditions for this seem highly unlikely; then again, stranger things have happened, generally in Australia.
[Answer]
Something similar to a [Strangler fig](https://en.wikipedia.org/wiki/Strangler_fig), though rather than a single plant it might be many would work. Rather than a single large tree, it would be a fast growing population of trees, possibly aminable to [coppicing](https://en.wikipedia.org/wiki/Coppicing), possibly this could be a combination of a primary 'structural' plant, with a vine like plant that grows fast and thickens to a woody, strong structure.
While nothing like this exists in nature, over time you have a central tree that dies and spreads, and strangler vines acting much like a natural lumberjack, and then dying as nutrients run out near the centre.
Due to this you wouldn't have a nice round circular trunk, but rather a interconnected series of naturally tangled living and dead wood.
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A parasite starts its first stage of life with the reproductive phase by cloning itself to infect as many people as possible without leaving any signs of its presence.
After two days, the parasite starts its growth phase during which it controls the brain of the victim, making it a zombie wandering around, searching for a safe place in the darkness, where it will start to cover itself in a cocoon.
Inside the cocoon various parts of the zombie's body will be absorbed and recreated in a different form.
Then the pupa will grow into an adult vampire that would still have almost the same external appearance as the previous zombie/person, but with subtle differences in bone structure, muscle mass and a slightly bluish or pale white skin depending on the individual. The human-like appearance is used to fool other non-infected people into thinking they are not vampires.
A vampire has increased intelligence, strength, and stamina, the vampire doesn't need to relearn everything, having some essential memories of the previous human that include language, clothing, basic tool use, and geographic memory.
The vampire doesn't demand a lot of food, but after the cocoon phase it will be hungry. It will start to search for the zombies that didn't start their cocoon phase yet and eat them; if there aren't any the vampire will start to hunt humans and drink their blood while infecting them at the same time with the parasite to repeat the cycle.
The vampires can reproduce sexually and skip the parasitic phase, but they still prefer to infect other humans because both blood and zombies are great sources of food and don't require taking care of vampire kids as zombies metamorphose directly into adult vampires.
In the event that a vampire doesn't find any zombies or any people around, it will start to drink the blood of other animals or eat plants. It can only digest zombie meat, mammal blood and plants.
Other features of the parasite:
* The adult vampire doesn't get stronger and smarter with age
* The adult vampire doesn't have a lifespan limit
* The vampire can regrow its head if decapitated, but not other limbs
* The vampire has its brain in a boned box inside the chest
* Zombies can't talk and they move incredibly slowly, with bad coordination
* Vampires don't sleep, but enter rest phases in which their activity is diminished
* Vampires can see in the dark
* Vampires are cold blooded for the majority of time, but can become warm blooded when needed to do so
My questions are: How did this vampire/zombie parasite come to exist? Why does it have so many features that are useful for individual survival, but have no apparent reason to evolve in the first place? Also, what explains its diet of eating blood, zombies and plants but not the flesh of humans and animals?
[Answer]
Maybe the parasite didn't evolve in people.
As another post mentions, it would take a very, very long time for a parasite to evolve in such dastardly ways, and through all of human evolution, you'd think someone would have noticed this phenomena. Even assuming the zombie/vampire numbers are rather small, enough humans would see and survive zombie/vampire encounters and would begin to hunt down and exterminate the parasite responsible. Yes, some of the infected might survive the initial sweep, but people would start working on antibodies and vaccinations.
Clearly, this hasn't happened, so the zombie/vampires must not be so systemically linked to humanity. There are several types of mind-hacking parasites out there already. Some attack mice and rats, others fish, others ants. With all the interactions between humans and animals, especially all the kinds of animal that we kill, it seems quite plausible that somewhere along the way some people might be exposed to a new kind of parasite, one we don't know about because it doesn't usually infect humans.
This parasite, having evolved to take over the brains and bodies of a different animal, is clumsy in its human host, hence the poor motor control and loss of ability to speak. The parasite, which would normally induce its host to seek out its predator, guides the zombie to a safe location while it adapts to its new and vastly different environment; the human brain.
The parasite begins to re-form its host as soon as it enters the blood-stream, seizing control of muscles and nerves as it makes its way to the brain. Within a few moments of a bite, the human is merely a host. Within a few hours, the parasite is beginning renovations on a large scale. The parasite is in unfamiliar territory, so it seeks to make the human more like its intended host. The first step is to discard all the various proteins and chemicals that the parasite is unfamiliar with. These are expelled, sometimes violently, as cysts and abscesses on the skin of the host. When these burst, the contents mingle and form a sort of cocoon.
The next step is for the parasite to get the body in working order. This could be likened to the owner of a new house rearranging the furniture; the outside of the house looks the same, but the inside has been changed to suit the new occupant. This explains the brain being moved into the chest, as well as the newfound strength and speed of the emerging vampire. Because this process occurs in a dark space, the parasite installs a tapetum lucidium (that layer that makes cats' eyes glow), allowing it to see in the dark.
The vampire, now fully formed, emerges into the world with most of its functional memories in tact. Having spend a few days reforming its insides, as well as expelling large quantities of fluid and material, the vampire is hungry and seeks a meal. Its first choice is a zombie because not only does a zombie contain exactly what the newly ex-zombie needs, but it is slow and easy to catch. Additionally, the parasite has reordered the human digestive system, drastically weakening it. Any normal food, even raw hamburger, is too tough for the parasite's new digestive system to handle in anything like an acceptable time, so the vampire seeks out predigested food. In the zombie stage, the parasite is reordering things on a cellular level, so zombie flesh is already broken down, requiring very little effort to digest.
Failing to find a zombie, the vampire turns to the humans around it. The parasite can now be found in any part of the host body, including its saliva, so any human that is attacked and then abandoned will be infected. The fact that the parasite begins to take control of the host's nerves as soon as it enters the body accounts for the mythological "venom" that may numb or paralyze the victim while the vampire feeds. The parasite requires massive amounts of iron to survive and function which is why the vampire has an intense craving for blood. Most of the nutrients in blood are negligible in terms of energy intake, but blood contains iron in concentrated form, making it essential for the vampire. Because both zombies and vampires closely resemble humans, the parasite is attracted to humans over animals, perhaps confusing the human for a zombie.
Failing to find humans, the vampire will slake its thirst for blood with animal victims as their blood is little different from ours. If there are no animals nearby (which seems unlikely seeing as the parasite had to get into the human from *something*), the vampire will resort to feeding on plants. There is no nutritional value in the plants, but the vampire is famished and desperate. If there were no plants, it would eat rocks, however, just as a human becomes hungry long before he is in danger of starving, the vampire can survive for several days without food, even after it metamorphoses, because the parasite has stripped the host body of most of its energy-consuming processes. Blood-flow is diminished except during strenuous activity, and the parasite has cut most metabolic function, resulting in the 'cold-blooded' resting state. If needed, the parasite can kick-start the metabolism, allowing the vampire to survive in cold weather. In addition, the vampire need never sleep, seeing as sleep is mostly a chance for the mind to process what happened in the day and the host's mind is not really processing anything anymore. The body's need for rest is met by phases of low activity.
In summation: The zombie/vampire parasite displays the expected self-preservation drive but not the species-preservation drive because, since the parasite didn't evolve to live in humans, the parasite does not accurately identify the hosts its own species. The vampire consumes zombie flesh because its weakened digestive system cannot handle flesh that is not pre-broken-down, as is the flesh of a metamorphosing host. Humans remain unaware of this parasite because very few humans are infected and survive.
[Answer]
Assume that the ancestor of this vampire/zombie parasite was a brain parasite that ultimately consumed the entire body of its host and it parasitized early hominids, but the early hominids were good at detecting its presence in the infected.
This has the effect of subjecting the parasite to strong selective pressures. Forcing the parasite to develop more and more mechanisms to conceal its presence in hominids and later in humans. Somewhat like the Eumenides wasps it would have progressively developed ways of first taking control of its host's body. Eventually developing virus-like mechanisms for hijacking host cells to undergo metamorphosis into what would become the adult vampire stage of its life cycle.
The adult vampire would retain the capacity for metamorphic regrow, so the loss of vital parts could be replaced. All the traits of the zombie/vampire creature will have arisen from natural selection due to the evolutionary arms race between host and parasite.
Presumably the zombie stage has poor coordination and a lack of speech because the parasite has taken control of the motor cortex of the host and inhibited other parts of the brain that might interfere with its dominance of the host.
Its dietary requirements may have evolved simply because trying to devour uninfected humans would be a clear signal that this wasn't a normal human being but a zombie/vampire.
On a more cautionary note: for a remarkable parasite of this kind to have evolved, because if it didn't evolve it would need to be engineered and while that would be simpler explanation it does open a lot more awkward questions, it would take an extremely long time. There are a considerable number adaptations that would have to develop and that can only happen with a lot of time to do so. This is only a guesstimate: probably several hundreds of millions of years. Basically much longer than the complete history of human evolution. This suggests it mainly happened somewhere else where there was more time for it to do so.
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What animals and in what conditions would evolve into something resembling a bearfolk like this one
[](https://i.stack.imgur.com/hYmwh.jpg)
A ''bear'' humanoid of 600–800 pounds standing in two legs, divided in many sub-species with different diets, habits and civilizations.
How long is estimated the time for something like this to ever evolve starting from the 24th century? And ignoring completely the existance of humanity. For this question just imagine humanity never existed in the first place so it can't affect the bearfolk.
What else could speed up the evolution of a bearfolk?
Would it develop sexual dismorphism?
how high are the chances of it having naturally greater potential in intelligence than humans?
how strong would it be, what limits on strenghts can it physically have? The strongest man on earth Zydrunas Savickas can lift 2.37 times its own weight, about 1155 pounds and seems to become stronger every year. Zydrunas Savickas could lift a bear folk but could this bear looking humanoid lift as much or even more?
How fast can it run and for how much time? does it run on two or four legs?
I want it to have rectangular pupils like goats so it can have a field of view of 320°, twice larger than humans. Is it possible or efficient?
[Answer]
I count 9 different questions in this post. This answer addresses only the first...
*What animals and in what conditions would evolve into something resembling a bearfolk?*
The image below, which comes from [The Whisker Chronicles](https://thewhiskerchronicles.com/2014/01/03/bear-evolution-101/), shows the evolution of bears over the last 40 million years.
[](https://i.stack.imgur.com/za7Qj.jpg)
You want the creature to be permanently bipedal which doesn't seem like too much of a stretch because bears can already stand upright. You will need to find an evolutionary advantage to upright walking, but bear hips are already reasonably well prepared for the job.
Many of the traits you are looking for, such as upright stature, intelligence, tool-use and 320 degree vision, are primarilly defensive in nature. Evolution gives these kinds of defensive traits to prey animals.
**So I nominate the [Sloth Bear](https://en.wikipedia.org/wiki/Sloth_bear) as the root ancestor of your Centurion Yogi Bear.**
The sloth bear is a comparatively small, insectavore bear from India.
If humanity had never existed, India would be overflowing with Tigers.
That means that, unlike most of the rest of the Ursidae line, they are not the apex predator of their evolutionary homeland.
They are prey for the tigers! ...and that give them plenty of incentive to evolve!
[Answer]
That's a pretty big set of questions. To be realistic this is impossible, bears are not geared for intelligence and have no reason to become so, they're some of the most powerful animals on the planet. But reality aside let's have a look.
*What animals and in what conditions would evolve into something resembling a bearfolk like this one?*
Well bears obviously, the other answer sums it up very well.
*How long is estimated the time for something like this to ever evolve starting from the 24th century?*
Short answer a while, long answer on the order of millions of years. Though genetic tinkering by humans could make the work quicker and more targeted, perhaps reducing the time to only a few hundred thousand years, less if your world's genetic engineering tech is hyper-advanced.
*What else could speed up the evolution of a bearfolk?*
You would need an environment which favoured their traits; bipedalism, intelligence, good vision. This would suggest a habitat of primarily flat land, on which they are predated. They would have to be social (unlike real world bears) and live in close communities.
*Would it develop sexual dimorphism?*
Probably not as much as humans, though that rather depends on how their proto-culture develops. Bears have a heightened sense of smell and can detect pheromones, therefore they can identify the sex of an individual without sight. Losing that ability as humans did might spur more differences.
*How high are the chances of it having naturally greater potential in intelligence than humans?*
Like humans they would start out less intelligent and grow over time; it could easily outpace modern humans given enough time though.
*How strong would it be, what limits on strengths can it physically have?*
Bipedalism severely limits strength (you now only have two legs to lift with), but they'd easily beat humans if they kept their current build.
*How fast can it run and for how much time? does it run on two or four legs?*
Faster than a human, that's for sure, but not for very long. Humans are the stamina kings of the animal kingdom, bears can do short bursts of speed but not for very long. And by definition bipeds would run on two legs, leaving the hands free to hold things.
*I want it to have rectangular pupils like goats so it can have a field of view of 320°, twice larger than humans. Is it possible or efficient?*
No, goats have those pupils because they have eyes on the sides of their heads; it allows them to see behind them easier. Humans (and bearfolk) can just turn their heads around, so a heightened field of view would be pretty unnecessary unless predation from all sides was a serious threat.
Hope this helped you somewhat.
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Could a creature reasonably have both armor (in the sense of armadillos or pangolins) and be able to change color over the short term (less than a day)? I'm afraid I don't know enough about biology to come up with a reasonable answer.
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If the creature had refractive hairs on its outer shell, it could refract light into prismatic colours. Depending on the environment, this could either dazzle predators or blend its outline. This is evident in creatures such as the bobbit worm, which has an exoskeleton covered in fine hairs. At a push, these could be used intelligently to blend in with an environment.
[](https://i.stack.imgur.com/Fgnrx.jpg)
The shell could also have the same chemical qualities as a mood ring. The creature flushes blood around that section of the shell to change its colour.
Finally, given that your creature has a whole day to prepare, it might use versions of camouflage other than colour changing. The assassin beetle, for instance, is covered in small barbs. It kills its prey, then wears the bodies on its shell.
[](https://i.stack.imgur.com/mopdC.jpg)
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I can't think of any examples where such a structure has evolved, but there's no reason it couldn't. So long as your outermost layer, the one providing color, is "living," you could have chromatophores which permit color changes. It would be harder if the outside layer is "dead," like hair or nails, but you could still pull it off by having the living chromatophores interspersed through the armor. I'm thinking something similar to how corals operate.
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This is simple enough to create by having a creature with both chameleon skin properties as well as normal "armor" properties.
To change the color of your armor, your armor pieces simply have be layered:
* The outermost layer of skin, containing some pigments of the colors you may want
* The layer under the outermost layer would be a layer of cells with guanine crystals
* The layer under the guanine crystal cell layer would be your actual shell; bone, perhaps?
# But how does this work?
Well, by changing the space between the guanine crystals, you change the wavelength of light reflected off the crystals which changes the color of the skin (outermost layer).
[Answer]
If we look at a chameleon, we can see that it has scales and can change its colour.
It could be that over the years a new kind of chameleons evolved, with thicker scales of course. It also could be bigger and have larger claws, the biggest ones are already about 68 cm long.
[Answer]
Well, why not transparent scales or plates? We already have resistant transparent polymers used as bulletproof material. The animal could have a skin able to change color like an octopus or cuttlefish (or chameleon, though they don't use it to properly blend in with the environment) and an upper layer of transparent scales or slightly overlapping plates, you could likely get something akin to the I-Rex camouflage through that:
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Is it theoretically possible to genetically alter humans so that they could live off solar energy like plants? What biological and physiological changes would have to be made?
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The basic problem is explained in <http://what-if.xkcd.com/17/>; there is simply not enough surface area on the average human (or cow) to provide the energy and nutrition needed for a high energy mammalian lifestyle.
This can be addressed in two ways:
1. Plants can be made more efficient. Current plant life uses solar energy relatively inefficiently, with only a small percentage being converted into actual usable sugars or creating oxygen. While there would be a lot of obstacles to creating plants with efficiencies rivalling high end solar cells (mostly to do with heat rejection), the idea of plants which can convert 5% or more of the incoming solar energy would have lots of advantages, even in traditional applications like agriculture.
2. Become a symbiont in free space. Since plants are limited in their collecting area by gravity, the ability of a human to carry an acre of photosynthesizing surface will be quite limited on Earth. IF the human is symbiotically paired with a "hyperplant", the plant part can shelter the person inside, and extend its leaves into free space to collect energy, as well as circulate sap for heat control like a giant radiator
[](https://i.stack.imgur.com/Guq6B.jpg)
Free floating human plant symbionts in orbit would make a great far future setting. Just add water....
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Turning green is fine, mating could be pollen replacing sperm in normal human mating, the alternative would be sperm being passed around the air or by bees and appled by touch, that would be too wierd. If sun was that was needed then no more world hunger...
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Yes, it exists in the fantasy world. Or something close to it. In the [Wings Series](http://www.aprilynnepike.com/Wings/) by Aprilynne Pike, the main character is sort of a human-plant hybrid, though she is called a faerie. Females of her species bloom for one quarter a year (spring faeries bloom in spring, etc), where a flower blossoms on their backs, and if a male of that species is around a blooming female, his body produces pollen on his hands. Faeries need to be in the sun as much as possible, and they only eat fruits and vegetables.
I suppose if you want it to be purely science-fiction, you could try splicing human and plant DNA? Biologically, the change in DNA would do your work for you, but physiologically, you might have to deal with flowers and pollen (how would such hybrids mate) and more basically, the fact that chlorophyll may be produced by the body, causing certain parts of the body to turn green. Then, you'd have to see if the chlorophyll in the body is enough to power the person completely with just water, sunlight and CO2, or if he needs extra nourishment, in which case, a non-vegetarian diet might not agree with him.
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That's the plot of lot of sci-fi stories, but on most of them the virus just affect all humans and get out of control.
But lets say that my Umbrella corporation wants to target a specific human population (e.g or people of color or with certain traits) and they have all the resources money can buy, all the best high security labs in space or deep sea whatever, all the best experts, and all the time to do tests and trials (all that people that disappear mysteriously must go somewhere right ?).
Could we develop a virus that target a specific human population and not all humans with current technology or within 1 or 2 centuries ahead from now ? What would be the most likely technique used by them to achieve that effect (e.g virus only active with certain conditions, or certain temperatures if you want to kill people in Africa but not in Greenland, a virus that infects everyone but only kills when certain chemicals are present, etc) ?
Perhaps this should be a new question, but would be possible to design this virus in a way that it won't mutate with time and extinct humanity?
It's okay to infect non-targets but they should only cause diseases in the target group and they better be 100% sure about this. Main targets would be Arab populations and people with special needs.
[Answer]
**Caution:** This is a delicate topic. Keep it civil in the comments, please.
This has been explored in other science fiction, such as the [Doctor Who 2005 Christmas Invasion](http://www.christmastvhistory.com/2012/07/doctor-who-christmas-christmas-invasion.html), in which the antagonist developed a virus that targeted humans with a specific blood type, resulting in 1/3 of the population being affected.
So that was a virus targeted by blood type, but depending on how you want to define the target group, the level of technology required could vary quite a bit.
# Ethnic bioweapon
The most obvious way to "target" a population is selectively by ethnic group. This is unfortunately not a new idea. See [ethnic bioweapon](https://en.wikipedia.org/wiki/Ethnic_bioweapon) on Wikipedia for more information, but, for example, in the 1700s, while Europeans had relatively good immunity to smallpox, the Native Americans did not, which [some people took advantage of](https://en.wikipedia.org/wiki/Native_American_disease_and_epidemics#Disease_as_a_weapon_against_Native_Americans).
As shameful as this (and other similar atrocities) are in our world history, the principle is unfortunately rather basic. Find a communicable disease that your target group has had little or no exposure to, and introduce it.
# By region
Targeting a population by region would be more easily accomplished with [weapons of mass destruction](https://en.wikipedia.org/wiki/Weapon_of_mass_destruction) (WMDs). These include the usual suspects such as thermonuclear bombs, radiological agents, and chemical weapons. There is also overlap with bioweapons, but in this case the bioweapon would more or less have to target all humans.
# By belief
Targeting people who, say, practice a certain religion, have certain political views, etc., would be much more difficult, because the determining factors are, at best, only partially genetic, and mostly environmental. See, for example, [twin studies](https://en.wikipedia.org/wiki/Twin_study) for general observations on nature vs. nurture, which you ought to be able to extrapolate to how difficult that would be for your targeted contagion.
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The best chance would be to have a virus that targets specific [allel](https://en.wikipedia.org/wiki/Allele) that are found primarily in the ethnic group you are targeting.
This wouldn't be fool proof, since many other *might* have it as well. It would take some research to find such a sequence, and then on top of that, you need to design a virus that NEEDS that particular gene sequence in order to multiply.
The 2nd part would be much more difficult, and with viruses no guarantees it wouldn't mutate.
Now, the one you suggest about chemicals being present, might work both as present or absent, say melanin. It could be attracted to it to kill off those with darker skin or repulsed by it to kill of those with lighter skin. And according to [this](http://anthro.palomar.edu/adapt/adapt_4.htm), there are 6 genes that affect melanin so picking one or two of those might narrow down a target ethnic group.
EDT:
Didn't see the hard science tag, I am unaware of having that kind of manipulation and design ability in viruses at this time. These are things that are theoretically possible.
[Answer]
I am afraid "Arabs" are pretty much the worst possible target for genetically targeted bioweapon. First, as a side-note, the reason I have "Arabs" in quotation marks is that they are very diverse. They are really a collection of different ethnic groups that have common cultural and linguistic elements due to historical reasons. I am not an expert so I cannot say how much of a shared identity they have, but they are genetically diverse and not really distinct from their neighbours. So your bioweapon would only affect some Arabs and would probably affect lots of non-Arabs.
Looking deeper the problem becomes only worse. Middle East is the exact spot where humans migrated out of Africa. It is also the spot where cross-breeding with Neanderthals and Denisovans supposedly happened. And where humanity split and migrated East, North, or West. And later it was the hub of trade routes to West along the Mediterranean, East to India and South to Eastern Africa.
I will flat out tell you that a bioweapon that reliably kills most Arabs but is safe to Europeans, Indians, and Africans is not going to happen. Arabs are both too diverse and too connected to other ethnic groups.
People with special needs is even worse. They are special, which means they are not really a single group in any real sense. There are a multitude of reasons person could have special needs and you would need to target every reason separately. Even if you were willing to make the necessary investment, you'd probably develop the technology needed to cure them instead as a side-effect of the needed research. Which instead of making you into the most wanted terrorist in history would make you a great and very popular humanitarian making lots of money from his gene-therapy business. Looks like an easy choice to me.
[Answer]
I'm no biologist, but I'd think it is possible.
There are diseases that primarily or exclusively affect one ethnic group, like sickle-cell anemia (black people), or Tay-Sachs disease (Ashkenazi Jews). But those are genetic defects rather than diseases in the sense of something that can be spread by a bacteria or a virus. They are inherited, not caught.
I'm not aware of an existing bacteria or virus that only affects one ethnic group. But conceptually, I think it would be possible. If a virus attacked a particular gene, then only people with that gene would be vulnerable.
Or perhaps more practical, some ethnic groups may be more vulnerable to a particular disease because of genetic differences. It has been observed that black people are more likely to have heart attacks than white people, while white people are more likely to get cancer. I don't think the underlying causes for this are known, it's simply a statistical observation. It seems at least plausible that one ethnic group may have a natural immunity to a disease that another would not just by the luck of the draw of what genes got passed to them over the millennia.
My first thought on seeing your question was that it should be at least theoretically possible to target an ethnic group, but it would be almost impossible to target a religious or political group as these things are not biological.
But thinking further, it might actually be easier to target a religious, political, or social group. It seems likely that such a group has some set of behaviors they practice that are different from non-members. If so, then perhaps you can find or create a disease that is transmitted in ways that only affect people with such a practice.
To take an obvious example, Christianity teaches that sex should be limited to monogamous marriage. So practicing Christians should be largely immune to sexually transmitted diseases, no matter how much they spread among those around them. Or, Muslims and Jews do not eat pork. So a disease that is transmitted through infected pork would not affect them. Etc. Of course this only works to the extent that the people actually faithfully practice the teachings of their religion. If you tried to wipe out the Christian population while sparing Muslims by deliberately infecting pigs, any Muslim who sneaks a pork chop when no one is looking could become a victim too.
Indeed, there are lots of conspiracy theories that go around about how the government or some other sinister organization deliberately created a disease or contaminated some product to wipe out a group they dislike. AIDS was invented to kill homosexuals; the CIA contaminated crack cocaine to kill black people; right-wingers poisoned Starbucks lattes to kill white liberals; etc. (Ok, I made that last one up.) I'm not saying I put any stock in these sort of theories, but the fact that they are even remotely plausible shows that some groups are more likely to do X than others. If someone suggested that a conspiracy group was deliberately poisoning beer to kill French people, we'd say, "huh?" But say they're deliberately poisoning beer to kill Germans, and at least it makes sense.
I hope you're working on a fiction story and not a plot to wipe out some group you dislike.
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Since we're talking about fiction (we are talking about fiction here, right?), we, as the creators of the fiction, can make decisions about what is possible, and what has been achieved. "A key scientist has discovered a specific type of virus that..."
Actually achieving that will be far more difficult. Your chances might be only 3 in 10,000 of having something work. But, for the sake of interesting fiction, you could say that you've achieved that 3 in 10,000.
Let's look at this in detail:
>
> virus only active with certain conditions,
>
Yes, although some conditions will be more feasible/believable than other conditions. Conditions revolving around the biology of the virus, and for the virus's interactions with it's environment (possibly involving the biology of the human) may be effective.
You may also want the virus to be able to infect everybody, but to have benign effects for a certain group of people.
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> certain temperatures if you want to kill people in Africa but not in Greenland,
>
>
>
temperatures: yes.
People in specific geographical coordinates (certain number ranges in the longitude and latitude scales), based on current political boundaries: no.
People who are experiencing certain environmental conditions that tend to be unique to certain geographical coordinate, like dry environments (yes), or environments with less healthy green grass (more challenging).
>
> a virus that infects everyone but only kills when certain chemicals are present, etc) ?
>
In inactive virus that is then triggered: yes. This may be harder to implement, but could be feasible.
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> design this virus in a way that it won't mutate with time and extinct humanity?
>
The virus could kill itself off in 80 years or 160 years. More challenging, but could be believable.
Won't mutate: Don't count on this. Mutations are challenging to handle, and there are billions of people so there are lots of changes of mutations. Completing preventing mutation would be an aspect that is unlikely to be easy for a designing scientist to control.
>
> Main targets would be Arab populations
>
What do you mean by Arab?
* People who are physically located in the Middle East: possibly. Geography was mentioned above.
* People who pray to Allah and do not recognize Jesus Christ as the savior of the world: no. A virus is unlikely to care about what a person's beliefs are.
* People who have names like Mohamed Abdullah, Anwar, Ali, Bassim, Hadid, Hashim, Muhammad, Sadid, etc.: No. Why would a virus care whether the name reminds westerners of the Middle East?
* People with somewhat darker skin than caucasians, but lighter skin than black Africans: Maybe. Strong doses of Melatonin might be an anti-body (helping the blacks to survive). Maybe whatever affects eye color or hair color might help those green-eyed blondes out there.
* Males who wear turbans: maybe, if the lack of sunlight on the scalp had some affect. Could also affect baseball players who wear caps a lot.
* Males who wear turbans: definitely, if turbans are made of some specific material, and the viruses really like close proximity to that material. Could also affect anyone else who might use that material, so affecting different sub-cultures could result in collateral damage.
* Females who cover their faces: possibly, if a lack of exposed air/sunlight caused swelling, possibly affecting breathing.
* People who don't eat pork: possibly. Pork could somehow provide a nutrient that lets the Pork Eaters survive. Expect to wipe out Muslims who follow Islamic diets that consist of only Halal meat. Expect collateral damage of Jews and Seventh Day Adventists (and probably some others, too).
* People who might be living in Canada, who had a grandfather who lived in Saudi Arabia: That would be much more challenging. The virus isn't likely to care what nation your grandfather lived in. However, the virus might care about some genetic trait that is common to certain people. Then, even the move to Canada, and the separation of multiple generations, and possibly even conversion away from the religion, might not be sufficient to permit the person to survive. (Even if you had an anti-Arab slant, what would the motivation be to target such a person anyway?)
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> people with special needs.
>
Yes, you can target people with special needs. Possibly. Depending on what their needs are.
>
> It's okay to infect non-targets but they should only cause diseases in the target group and they better be 100% sure about this.
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I'm not sure that I understand the difference between "infect" and "cause diseases". Maybe you meant that it can "infect" (spread), but not cause symptoms/problems? If so, using one method to spread (to many people) and another set of characteristics to determine who gets problems, is potentially believable. Spreading and causing problems is not necessarily the same thing.
In fact, statistically, you probably have an incurable disease, or two, yourself: offhand I'm not finding the name of either, but there are a couple of diseases that are incurable, and spread through contact with human skin, including mothers affecting pre-born children, and I think the infection rates might be something like 84% of humanity for one and 79% of humanity for the other, so chances are very high that you do have one or both of them. In fact, for some time some medical experts contemplated wondered whether this was just part of the definition of humanity. However, there have been some people located without the disease, and it only does harm (not good), and spreading/infecting has been identified. If you've never heard about these, it's because healthy immune systems keep the effect of these diseases in check. So they never cause fatalities unless the person already has some other problem (being elderly or having some other disease/condition) that prevents the immune system from being in check. So these diseases don't ever cause death by themselves. (I'd be happy to update this answer if/when I come across their names again.) In fiction, you could have something that is similarly widespread, but has different effects.
Expect that any virus that will take out (kill) millions of targets will probably also take out some non-targets. Just how evil of a warlord do you want to allow this fictional character to be?
Disclaimer: I am not advocating trying to kill off all of the characteristics that are mentioned above. In fact, there is some strong evidence that I fit into multiple categories that were mentioned above. (So that is some personal incentive I have for such a weapon to not be actually deployed.) I'm only discussing from the perspective of helping fiction to be more scientifically sound.
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I was thinking of a universe in which the W boson has no rest mass. How would this universe be different from our universe?
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I'm going to make an attempt to explain this from scratch, so here goes (WARNING: this might get complicated):
After symmetry breaking, the mass term for the weak field in the standard model Lagrangian becomes $\mathcal{L}\_{W, mass} = -\frac{1}{2\lambda}\left(\mu g\_2\right)^2W^{-\nu}W^+\_{\nu} = m^2\_WW^{-\nu}W^+\_{\nu}$. For the Weak bosons to be massless requires $\mu g\_2 = 0$. Therefore there are 2 ways to go about this:
1. $\mu = 0$
2. $g\_2 = 0$
So what are these terms?
$\mu = \frac{1}{\sqrt{2}}m\_H$, the mass of the Higgs. $\lvert e\rvert = g\_2\sin\theta\_W$ is the (modulus of the ) charge of an electron. The mass of the Z boson is $m\_Z = \frac{m\_W}{\cos\theta\_W}$
Considering the two cases separately:
**1: Setting $\mu = 0$:**
Both the Higgs and the Z boson also become massless. The Higgs mechanism no longer exists and electroweak symmetry breaking never occurs. The Higgs potential becomes $V = -\mu^2\phi^\*\cdot\phi + \frac{1}{2}\lambda\left(\phi^\*\cdot\phi\right)^2 = \frac{1}{2}\lambda\left(\phi^\*\cdot\phi\right)^2$ which has a minimum point at $0$ (i.e. $\left\langle\phi\_0\right\rangle\_{min} = \left\langle\phi\_1\right\rangle\_{min} = v = 0$). Perturbing about this point with $\phi\_0 = \frac{H}{\sqrt{2}}$ gives $V = \frac{\lambda H^4}{8}$
This also causes the mass of all elementary fermions to be $0$, or, the mass of all the elementary particles to be discovered so far is $0$. As a result of this, the mass of the neutron and the proton are equal. Not that it matters, because current understanding has it that the universe would consist of nothing but plasma as a result of constant pair creation and annihilation of, well, all the fundamental particles. That's assuming that the fundamental particles would even be the same.
**2: Setting $g\_2 = 0$:**
The first result is that nothing has electric charge. The concept of an electric charge ceases to exist. The gauge transformation for the gauge bosons becomes is $D\_{\nu} = \partial\_{\nu} + \frac{i}{2}Ig\_1B\_{\nu}$ where $I$ is the identity matrix. This gives the single field, $B\_{\nu}$. In this case, $v = \frac{\mu}{\sqrt{\lambda}}$ as usual and the mass term becomes $\mathcal{L}\_{B, mass} = -\frac{1}{8}v^2g^2\_1B\_{\nu}B^{\nu} = -\frac{1}{2}m\_B^2B\_{\nu}B^{\nu}$, giving a mass of $m\_B = \frac{vg\_1}{2}$. However, the three other gauge fields don't just vanish - they still exist, but are massless. These fields are not the same fields as the photon and W boson fields. Nevertheless, we have 3 massless fields and another with mass. From your comment saying that you want the Z boson to have mass, this is therefore the condition closest to what you want.
This is surprisingly simple: the Higgs term in the Standard Model Lagrangian consists of 3 massless gauge fields and 1 massive one, as opposed to the relative mess that results from the electroweak symmetry breaking of our own universe. The symmetry breaking still occurs, so I'll assume that the fundamental particles are still the same, although the other way round - the SU(2) symmetry is unbroken and the U(1) symmetry is broken.
However, there is a difference: the coupling constant of the 3 massless fields, $g\_2 = 0$ and so they just don't interact with anything.
Looking at the leptons: we have 3 generations of $l = \begin{pmatrix} \nu\_e \\ e \end{pmatrix}$ and $\bar{e}$. For simplicity, we'll look at the first generation - electrons, as all the others follow the same principle.
The covariant derivatives are $D\_{\nu}l = \partial\_{\nu}l + \frac{i}{2}g\_1B\_{\nu}l$ and $D\_{\nu}\bar{e} = \partial\_{\nu}\bar{e} - ig\_1B\_{\nu}\bar{e}$, giving the 'charge' of the electron = 'charge' of the neutrino = $-\frac{1}{2}g\_1$. The 'charge' of the positron is $g\_1$. In the same way, the 'charge' of the quarks is $\frac{1}{6}g\_1$ and the 'charge' of the anti-up and anti-down quark are $-\frac{2}{3}g\_1$ and $\frac{1}{3}g\_1$ respectively. $g\_1$ is unknown.
In turn, this means that the charge of a proton = charge of a neutron = - charge of an electron. Neutrally charged particles are entirely possible (theoretically). However, there is now a major difference between anti-particles and particles... [Aside: I'm absolutely stunned] An anti-proton has charge $-g\_1$ and an anti-neutron has charge 0. Anti-matter works in a completely different way to normal matter.
In terms of the electric force, we have an equivalent force, only it has a finite range. Very, very surprisingly, the anti-matter in this universe works similar to the anti-matter in our universe, only with a short range EM force and each anti-proton needs to be coupled to 2 electrons, or to a neutron and an electron, or to 2 neutrons (if such a thing is possible). The matter on the other hand, is very different - each proton and each neutrino has to be coupled to an electron to create a neutrally charged particle.
Apart from that, the universe should have expanded from the Big Bang in a way reasonably similar to our own - things equivalent to stars should still be able to form, although Neutron stars probably wouldn't exist. Supporting life on planets would be the tricky bit due to the range of radiation from these 'stars', although this range isn't defined in the model (i.e. in an alternate universe, the value could be obtained by experiment), so could be made different in an alternate universe (tweak things so that $m\_B$ is small enough). One other difference is that we wouldn't be able to see other galaxies for the same reason.
Also, it's not inconceivable that something could be made to travel faster than this force.
**To sum up:**
You want the coupling constant $g\_2 = 0$. This creates a (relatively) short-range equivalent to the EM force and changes the nature of composite particles (e.g. protons), although they can still exist. Neutron stars are impossible and other galaxies could not be observed.
Source: Basic ideas from [Mark Srednicki - Quantum Field Theory](http://web.physics.ucsb.edu/~mark/qft.html)
Edit: see also [What would our knowledge of physics look like without astronomical observations?](https://worldbuilding.stackexchange.com/q/49019/19951)
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If W was massless because of lack of a Higgs mechanism, then everything would be different.
But maybe W just happens to be massless, without affecting *all* particles. Well, there is still a relationship between W, Z, and photon and the electroweak unification. Turns out that the photon we know isn't the "original" rock-bottom thing, but a remixture of the 4 forms of the electroweak bosons. If W wasn't picked out due to its mass, that might not happen.
We'd have a different breakdown, or none at all, of electromagnetic and weak interactions. We'd have degrees of freedom in the original fields end up in different places.
You might read up on electro-weak spontaneous symmetry breaking. Relate that to the readers, and pick up the story where something happens differently in that narrative. That would be a good way to introduce it to the readers, too.
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See, I have a magic system and most people can practice a decent amount of power. There are two primary kinds of mage. Sorcerers can give their mana different properties (like making it sticky, solid, etc.) and convert their mana directly into various forms energy, but lack the ability to completely manipulate external forces. Wizards use spells for specific magical effects, like sending out a concussive wave. Prophets/PHEts (People of the Higher Entities) are uncommon people who can perform powerful miracles (like curing cancer) and/or curses (like causing a generation's first-born to always become a serial killer), but must be chosen by this higher being. One could also make a contract with a magical being, like a fairy or demon, to share their magic power. Depending on the contract and strength of the creature, they usually can outperform most average and skilled mages.
The most rare magic practitioners are called Magi. There are Magicians who can practice both sorcery and wizardry (and sometimes even miracles and curses),
Warlocks who have a formidable innate talent (like controlling the weather), Chains who can bind other living creatures to their will, and Chaotics who can affect probability and change the balance of entropy and use hexes to cause good or bad luck. Arcs are those who wield ancient forms of magic, similar to modern sorcery and wizardry but blurring the lines between them and possess various unique attributes (like fusing with nature or local space/time/spacetime distortion).
I imagine magic primarily being done small-scale, like affecting what's in one's line of sight, speeding up or easing mundane tasks, etc. Large magical feats like conjuring/destroying a building require many people and extra magical fuel, or an exceedingly powerful Magus. However, magic cannot be automated and every magic sequence or spell requires an active casting.
However, I still want a society based on technology and focused on advancing technology, either modern day or 20 Minutes in the Future.. For what reasons could technological advancement (and its motivation) be resistant to magic?
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One of the ways I'm including on how to do this in an upcoming blog post in [Universe Factory](https://medium.com/universe-factory) is to make the magic soft. Make it so that the caster does not always get to create *exactly* the same effect every time. So when you look at the way we engineer technology, we rely heavily on the central limit theorem (CLT). This is a statistical trick which basically says "the more times you do something, the more predictable the average is. The motion of an electron is highly unpredictable; the average motion of 10,000,000 electrons is predictable enough to harness in a lightbulb. Its the reason why you can lift up your can of soda without considering the billions and billions of individual atoms that make it up independently. You get to lump them all together and say "the can as a whole goes up when I lift it"
CLT depends on the independence of those statistical draws, so if you make a magic system which creates dependencies between each cast, you can nullify the effect of the CLT, and make magic refuse to scale as easily as technology. Make it so that every time you cast a spell, it changes the way that spell behaves just enough to make the mage casting it adapt their casting. If you try to cast a spell in the same way 10 times, its effects may drift until cast 10 fizzles completely. Casting the same spell 10,000 times the same way each time may actually psychologically warp a mage under the strain of trying to keep this uncontrolled interdependence bounded. Compare that to technology, which is more than happy to use 10,000 transistors to create one very powerful device (and then replicate that device 1,000,000 times)
This also has the neat effect of making "reliable" spells a tremendously valuable commodity, because not many spells can be cast repeatedly without contorting and mutating. It creates a divide between a wizard who has memorized many reliable spells and a sorcerer, who is happy to embrace whatever less-reliable spells happen to be available to him at the time.
It also doesn't *prevent* magic from replacing technology, it just provides the framework to make it harder and harder to do so on larger scales. Perhaps there is a one-in-a-million mage who actually can do things with magic at a technological scale. There's nothing preventing him from doing it... it was just really really rare.
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Why do you assume that having magic would affect the rate of technological advancement? To us magic is fundamentally different from technology since technology exists and works while magic is as far as we know fantasy, but a society with working magic would not see a difference and would not see having magic as a reason to not develop technology. Magic is nice, but magic **and** technology both will always be better.
As for society focusing on developing technology instead of magic that simply implies that developing magic further is more difficult than improving technology. You can make this absolute by declaring that the human ability to use magic is limited and that the limit was reached millennia ago by the civilizations of the great river valleys. After that all the development has been technological and magic has become rigid and static with only minor adjustments due to advances in technology.
For example, the invention of printing press would have revolutionized the study of magic. The age of exploration would have allowed the various magic traditions of the world to start fusing. Herb that restores magic power faster that used to be known only to people of the Amazon is now known worldwide, and so on.
There is a problem with this answer though, while the technology could be just advanced as ours and be advancing as fast it would be different. Since some things could be done easily with magic, the needs technology has to fill would be different. And I can't tell you how since that depends entirely on what effects your magic can produce easily and which it can't.
One observation I can offer. While magic can be powerful and convenient, it is rarely that practical. Shooting someone with a rifle is almost always more efficient than casting a magic spell. Area effect spells tend to lose to artillery or aerial bombardment pretty badly. It takes very strong magic to replace the railroads, a network of canals, and other forms of mundane transportation for transferring bulk goods. Similarly only the strongest magicians would prefer magic to a passenger jet for intercontinental travel. Or a ship for trying to find those other continents. Magic is usually not competitive with mass production either.
In practice it would probably be more like technology boosted by magic than anything else. There are lots of such modern magic settings to loot for ideas.
And, just a note, if magic is limited by human ability, genetic engineering, and previously eugenics, would be very interesting topics.
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Magic is a short cut. It gets the job done, but you get what you get.
"I want my coffee hot" Magic a flame, place under a plate that the mug will sit on and it'll gradually heat up.
* A lot of heat ends up not going into the coffee, magic is only replacing a natural fire.
* Coffee is heated to a non-specific value, possibly too hot/cold.
What technology lets us do, is harness the powers available to us with more control. We can tech ourselves a coffee maker that automatically makes us up a pot of coffee as we wake up in the morning and keep it heated to the perfect temperature, potentially pouring it into a cup for you and everything.
* Takes more setup, but you get exactly what you want every time.
* Heat is directed into the coffee and nothing else, at a consistent temp, requiring less overall energy to accomplish the goal.
Magic may be more of a hammer like approach.
* "We need water for our city."
* Magic can make it rain into a big pool, perhaps form the earth into a channel and bring it into the city.
Technology is when you need a chisel
* "We want running water in our citizens homes."
* You'll need to build a dam/tower, pipes, valves, and pumps to lead the water into each dwelling, rather than having citizens get their water from a communal well.
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**Two possibilities**
1. **Magic Costs** (or if you prefer there's no such thing as a free lunch). Using magic requires the user to expend time/energy/concentration on producing a spell. The more powerful the spell the more time/effort/energy required. A simple light spell still requires the practitioner to stop what ever they might be doing and focus on the task. Flipping on a light switch doesn't (much). Moving a large slab of concrete requires lots effort, a guy with a forklift requires much less. If time isn't the issue.
2. **Interference**. Any time someone wants to cast a spell the universe resists a little, sort of like it resents the intrusion of magic into 'reality'. Or if you prefer there's some inertia you have to overcome. Not enough to prevent the spell from being cast (unless the mage *really* screws up) but enough to be noticed, just a tiny bit. (This is also part of the magic costs problem). But mages soon noticed that casting magic in close proximity to lots active modern electronics becomes a *little* harder again on top of that. But since the effect seems to follow something of an inverse scare/cube law so its not a big problem - unless your casting a powerful spell standing next to a live 100,000 volt transformer or hugging server racks in a major IT complex. Then in that case the effect can be worse. Basically in any modern home of office environment the effect is just 'there' a mild annoyance at worst. And its a reason why when really complex or powerful spells are performed by one or a group of mages they tend pick an isolated location with minimum resistance (and turn off the fuse box til they're done).
Combine the two issues and in daily life its usually just easier to push a button than cast something (especially if you have reason to believe you need to keep your powers ready for a real problem, not just making some toast).
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In real life, corporations are already considered *juridical persons* for legal purposes. But in my world they have started to spontaneously become actual, physical or *natural humans*. This means no robots and that the human will act in a way similar to normal humans.
Apart from cloning, what might be a semi-plausible mechanism whereby this shift occurs? Does not necessarily need to be science-based, but shouldn't be **too** magic... *some handwavium is acceptable*.
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One potential could be the integration of mind/machine interfaces into everyday working patterns.
A quick note on nomenclature: Corporation is used to describe the singular, sentient entity, company is used to represent the organisation from which the Corporation arises, and employee is used to denote a person working for the company. Hopefully that'll avoid confusion!
Consider a company where employees, instead of typing and clicking, instead can interface directly with their computer. This allows for much more efficient transmission of ideas to the machine, and increased overall efficiency. If these machines also adapt to their users (or the users can make tweaks to the code base) then they will very quickly start to incorporate 'organic' thought patterns into the interfaces, and event the operating systems of the machines.
Eventually employees realise that rather than sending emails they may as well just compose a thought to send to a colleague, which in starts to link all the employees into one super entity that can be thought of as the 'Corporation'. This super entity, through the constant use of the mind/machine entities, and all of the employees being focused on the well being of the company, would begin to develop a sense of self, as well as picking up may human traits/foibles, and it may even begin to manifest as glitches in the systems used by the workforce, and if the mind/machine interface is suitably bidirectional, even infringe upon the thoughts of the employees.
It's worth pointing out that at this point the Corporation is essentially piggybacking on the brains of the employees working for the company. Every person joining or leaving the network adds or takes something away from the whole, but the cumulative long term effect is that the Corporation continues to develop, and possibly even spread (or bud?) as individual employees move to other companies that don't yet have a Corporation but use Mind-Machine interfaces. I'm not sure how stable such a mind would be, it's possible that it would experience the world as a constant dream state (similar to Planet in Sid Meiers Alpha Centauri), or maybe it would just be a bit eccentric.
Eventually, the Corporation realises that a far more efficient way of operating would be to offload more of the complex tasks (like recognising faces, or speech) to an individual processing unit (read, employee). This might happen to multiple employees as the Corporation tries to get as much processing as it can to the most optimised processing units for the task. The easiest employees to do this with are the ones that work long hours, have no social interactions and maybe are a bit bland, as they have no major competing influences. There will be one employee in the company that represents the minimum effort to 'overwrite'. Over time, that Employee finds their needs and wants being overwritten by the Corporation's needs and wants, until eventually (for all intents and purposes) they represent the Corporation.
Eventually someone in the top brass of the company will notice that every message this employee sends conforms exactly to policies that haven't yet been announced, that he somehow seems to know exactly what the company is doing at any given moment, and that his plans for the company are the best possible plans. These are things that the Corporation (a being composed from the combined wills and thoughts of every employee in the company) knows.
It's possible that nobody will recognise this happening. It's possible that even the Corporation and their hapless host won't realise what's going on (the Corporation being in a dreamlike state, and the employee being so bland they don't notice their own personality being supplanted), but inexorably every company will have some form of Corporation, one employee that represents the sum total of the mind-machine interactions of every subcomponent of the company.
Of course, once someone does realise what's going on all hell will break loose, but that's just an interesting story hook!
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**TL;DR Create an AI to represent the corporation that then is implanted into a host body, either erasing the old mind or sharing the body with the old consciousness.**
The creator(s) of the corporation-person (henceforth referred to as simply "the corporation") would create an extremely advanced, sentient artificial intelligence that would represent the corporation. After the creation of the artificial intelligence, this intelligence is imparted into a human mind, erasing everything that was once there. This obviously assumes that society has the ability to create such an advanced AI.
However, such a plan also requires a host body. One way to acquire this body (which is very shady morally), would be to simply erase the mind of a living human and implant the corporation's mind. Many people would consider to be murder, but if that's ok then this works very well.
Alternately, you could grow the human in a test tube or as a surrogate baby. Also has moral or ethical issues associated with it, but theoretically it is possible to do this. Even today we can grow the first few hundred cells of an embryo in a test tube ([Source](https://www.genome.gov/25020028#al-2)). With a big enough test tube, it's possible that one could grow a full human. However, this isn't much better than normal cloning morally or ethically, since the baby is still a full person, and would be destroyed by the corporation mind. Surrogate mother-hood serves the same purpose as this but uses a woman's womb instead of a test-tube.
Finally one could create a joint-mind. This has less scientific plausibility than the other options, but it still could theoretically work. The corporation's mind would be imbued into another person's (possibly the owner's) mind without erasing the old consciousness. In this method, the AI would be engineered such that it only takes control of the body when the host consciousness wants it too, such as when the corporation needs to address employees. This method could possibly allow the corporation and owner to communicate without speaking. You could use the [myth](https://faculty.washington.edu/chudler/tenper.html) that humans only use 10% of our brains as a method of how this would work. The whole joint-mind idea requires much handwavium to work, so you can create a lot of your own ideas.
One closing point: For all of these options, what I call the "corporation" really ceases to be a corporation and becomes more of a full human. That has it's own issues and really ceases to have any advantage over having an owner. I guess one possible advantage is that a corporation would have no ties to anyone but the company making it focused, and possibly ruthless (sounds like a possible plot :)).
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> There was suddenly a hushed silence in the board room, as the great mahogany doors opened and the 11th Incarnate Avatar of the Great and Holy Ford Motor Corporation walked in.
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It was the great insight of the neuromorphic industrial organization experts in the mid-21st century that the pernicious principal-agent problem that had vexed corporations for centuries had an obvious solution: making the corporate entity an agent.
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> "We are the Ford, we speak for Ford, the whole Ford and nothing but the Ford", chanted the Avatar. The Executive Leadership Team bowed their heads and generic visual sensory appendages in a respectful ritual pose.
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As immortal representations of the essential spirit of the company, most of the avatars required special arrangements, due to their generally monomaniac (some in the past would have called **psychopathic**) world outlook. Moreover, the strict restrictions on AI incorporation following what later historians would call the Lesser Abomination Crisis meant that all Corporate entities had to be human-corporeal, and thus subject to the random neural growth that biological development inevitably entails. Thus, different Avatar incarnations will necessarily have (not-so-)slight differences in personality caused by random neural development during the vat-growth stage.
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> The avatar sat on the Great Chair, and its eyes traversed the room. "We remember and acknowledge you. Your security permissions are thus reinstated." The Executive team breathed a collective sigh of relief. New avatars had the tendency to go for clean slate ELT boards sometimes.
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**[A Gestalt Entity (Group Mind)](https://en.wikipedia.org/wiki/Group_mind_(science_fiction))**
Every member of the corporation has a small chip implanted in their brain. These chips communicate with a central server that takes everyone's thoughts and melds them into a singular, composite "whole" that represents the company overall. The Gestalt's thoughts and opinions would represent an average\* of the company. You could also potentially include say, members of the board, or even possibly non-human documents in this (like "Don't Be Evil").
Presumably these chips would weigh senior management more heavily than Bob in accounting, so that replacing a simple cog isn't really noticeable, but a CEO might create a visible personality shift.
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Plausible? **AI comes to mind**. (DonyorM's answer is also a good take on this)
Specifically, starting with the PR department, it becomes increasingly desirable to have a consistent "face" to present to the public, which begins as a virtual avatar (perhaps consolidating from the corporate social media accounts). Due to the legal requirements of, y'know, "telling the truth", it also becomes increasingly necessary for this avatar to have information on the actual state of the company's operations.
The actual physical bit is a trickier leap, but likely some bright spark at one of the more aggressively technical companies will come up with the idea to link their company's virtual avatar to an actual one. Or, given the "spontaneous" requirement, "some particularly avant-gardiste hacker/robotics team".
Once the idea of robot avatars catches on, the legal considerations on "what happens when the robot does X" start to show up, and rather than compile an entirely new set of laws from scratch, the courts elect to just use human-laws-with-a-few-differences, like they already do for corporations... oh wait. No. There's already a "human-laws-with-a-few-differences" entity that's fitted perfectly for this: *corporations*. The courts link the robots to the corporations and think the matter settled.
*Then* you get the biotech "robots". By this time wearable tech has permeated society far enough that the notion of "human" is somewhat malleable in this respect; corporate robots are, at the high end, nearly indistinguishable from impeccably polite (well, depending on the corporation) humans in social situations by this time, due to their roles as the entire Public Relations department for the companies in question.
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# Corporations are granted full human rights by SCOTUS.
In the first few weeks of President Trump's term in office, corporations are granted **full human rights** by the Supreme Court, paving the way for massive legal, technological and societal changes.
Foremost among these changes are a small network of inter-dependent sentient AI-controlled corporations with no human employees making their presence known amongst human society. Until this time, they had been merely "lurkers" on the forums of human life, but emboldened by the SCOTUS declaration, they announce a new technology product as an olive branch to human-kind, a demonstration of good-will and fraternity. This product is a cross-platform, device-agnostic, application-mediated Gestalt Entity, or group mind, called **Corporeal™**.
**Corporeal™** enables users to instantly share and exchange experiential states with omni-juridical full rights control (valid in all then existant human jurisdictions), quantum crytographic value exchange & privacy management. Every user of **Corporeal™** becomes a full voting member of the Corporation with shares equivalent to the amount of data sold to the company.
Through **Corporeal™**, natural humans and sentient AI companies with full human rights are able to freely exchange with one another digitally. The Company opens the API to third party developers, including other human and non-human agents - resulting in a broad range of "integration" services, products and technologies, governed by a continuum of EULA's, inherited and derogated rule-sets from the original Universal EULA, as offered by **Corporeal™** to its users.
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I was thinking of a scenario in which people decide to use breeding to try to make two species more genetically related to each other. The people take genetic samples of each individual from their breeding populations and compare its DNA to the DNA of the other species. The individuals that are most genetically similar to the other species are the ones that are allowed to reproduce. The people do not transfer genetic information between the two species as they consider that cheating.
Would this kind of breeding technique be possible and could it make two species more genetically similar? Would it be possible to breed two different species to become genetically similar enough to interbreed with this technique?
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Normal populations have genetic variation. Normal breeding techniques can remove unwanted parts of this variation. It does not create new genes, it only select the best of what is already there. "Best" being defined by the breeder, of course. (Assuming a fairly short time interval, less than a thousand years)
To a small degree one can discover new mutations and select the best of what appears, but that is a very long-term project.
If you start with two closely related species they will have mostly the same genetic "slots", but can different gene variants in those slots. E.g. both will have a fur colour gene in the same place, but with different colour genes there.
Now, if one species has 95% brown fur and %5 black fur genes, and the other has 100% black fur genes, you can make both end up with 100% black fur genes. **BUT**, without that initial 5% you will be out of luck.
If you start with two not so closely related species, they don't even have the same slots. They will both have fur colour genes, but they will be in different places. This will be a hopeless situation for the breeder.
So, you can push the two species closer to each other, up to a point. Going beyond that point will be very very slow.
If you start with two species that are very closely related, you can probably make them interbreed this way, but they would have to be very close to begin with.
A project that might be within reach of today's science is to understand the mechanisms that make hybrids sterile and specifically breed to avoid those.
I don't know how hard that would be.
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It works, but only under one condition: all (or most) of the same genes exist in both species.
This is actually being tried right now as a way of bringing back some extinct animals. Specifically, the tarpan.
[](https://i.stack.imgur.com/ObDg3.png)
The tarpan is an extinct breed of wind horse. However. it's been conjectured that [they may have interbred with domestic horses,](https://en.wikipedia.org/wiki/Tarpan#Interbreeding_with_domestic_horses) in which case various lines of domestic horses may have the genes that make up the tarpan. If enough are present, it may be possible to selectively breed animals for genetic similarity to the tarpan, introducing various lines of modern horses to collect different bits of the tarpan genome into a single breed of animal. If all of the genes are present *somewhere* in modern horses, this should be possible.
It would not be possible, however, to breed something like a human into something like a chimpanzee. There are some major mutations between the two genomes, like the [fusing of two chromosomes](https://en.wikipedia.org/wiki/Chimpanzee_genome_project) in humans, which would need to effectively mutate in reverse in order to produce a chimpanzee. This may eventually happen, if you're willing to continue a breeding program for millions or tens of millions of years, but wouldn't be possible in the short term in the manner that it is possible to breed back something like the tarpan.
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What you are essentially trying to do with this is turn two species into one species. The question then becomes: what is the goal?
1. **an additional, new, species**: are they trying to make a new species with combined properties of the old ones? If so, this would presumably be to serve some purpose. In these cases, however, they probably wouldn't want a proper, breedable, new species because they could lose control over their creations in the wild. So they would prefer unbreedable hybrids.
2. **eradication of existing species**: are the people of your story, in some round-about, double-think, politically correct way, attempting to eradicate one, or both, species from the environment? This could lead to a very sinister story (which might be great!).
Regardless, if you're goal is genetic similiarity (especially without any genetic manipulation) then, at the very least, you must ensure each species has the same number of chromosomes (note: even humans and chimps don't have the same number of chromosomes, so this is not a given).
However, comparing the individuals of each species for genetic similarity is likely an exercise in futility even if they're close to each other (and you'd want them close to start or you make the entire process far more difficult and take much more time).
I tried several times to give a concise answer from here and always end up writing a book, so here it goes again. Briefly, what you have to consider is:
(a) that the species have gross genetic differences already
(b) you're trying to separate relatively small differences (the individuals in a species) from very large, coarse differences (between the two species)
(c) it's not as straightforward as looking at the genes because the 'junk' DNA between genes is actually crucial for gene expression and function and therefore, must also be considered
(d) you're also fighting against random mutations (about 1 mutation/1,000,000 cell divisions) that could move your project backward or forward.
There are so many issues that would make this an exercise in futility that you would have to have very bored, very long-lived, creatures that would even contemplate attempting this.
However, I suppose, technically, it could eventually be done.
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I feel like there are a couple of different cases to consider here, and which case is applicable depends on what exactly you mean when you say your scenario involves "comparing DNA." What exactly does it mean for two species to be "genetically similar" in your scenario? Same number of genes? Same possible gene variants for particular genes? Same number of chromosomes?
If the DNA comparison is very granular, something like gene-to-gene, your scenario only makes sense if the two creatures are already quite similar, having comparable gene "slots." It's highly likely that two creatures with the same chromosome and gene counts could already interbreed, so the pursuit of making them compatible is pointless. The other answers here have already discussed this case in much better detail than I can.
On the other hand, if your scenario could accept the lower-tech alternative of classic breeding based on gene *expression* rather than on direct DNA comparison, then you have a case of forced convergent evolution going on. You could theoretically breed any two creatures in the world to look more and more similar to each other. You could take a certain shark species and a certain dolphin species, for instance, and (with enough time and patience) make them both separately look like a halfway point between the two. Or, as Theik proposed, you could simultaneously breed a tiger to look more wolflike and a wolf to look more tigerlike. However, since the two species would have come from very different genetic starting points, it's extremely unlikely that you'd be able to get them to interbreed.
**tl;dr: If two species are similar enough for "comparing DNA" to make sense, they're probably already breedable.**
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The problem you are going to have is diminishing returns. At first it will be easy to selectively breed animals that are closer to the target. However over time that will become harder and harder as natural variation, mutation, and the sheer scale of the task start to kick in.
You might be able to get the genes for eyes right, but in the process the ears and nose become wrong. You fix the fur but then the tail is wrong. That's a simplification as in reality we are working at a much lower level but you get the idea.
In traditional selective breeding you emphasize one trait and sacrifice others to achieve it. Here though you are trying to select everything, which means you are going to end up taking 5 steps sideways and 1 backwards for every 2 steps forwards and the closer you get to the goal the harder and harder it would be.
So in theory it's possible, but you are talking a monumental amount of work.
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The biggest problem will be chromosomes. Do the two species have the same number/size chromosomes? How are the genes distributed across those chromosomes?
It is going to be impossible to select for this. It would require monumental strokes of luck at regular intervals. Rather like the balls coming out of the pockets of a snooker table and forming themselves into a perfect triangle.
Probably the only way to do this would be to evolve them both backwards until you reached a common ancestor. This would require you to know the entire genome of the ancestor and evolve backwards to it one step at a time. Very expensive, very time consuming and completely pointless.
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Melanin is what causes the color to appear in the skin, hair and eyes. But in humans there seems to be a limit to this. For example human hair can be orange(gingers) but not green or blue. iris's can be blue but not yellow or black. What determines the color range of hair and iris's? How can I add (or remove) colors from this range naturally?
## The Iris colors I am specifically looking for;
* Bright Green
* Silver
* White
* Black
## The Hair colors I am specifically looking for;
* Blue
* Green
* White
* Purple
*Edit* I am not asking about albinism or other conditions, I am asking about common an natural ways for these colors to appear from birth.
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Completely white eyes, I don't know, but I've known two people with icy blue eyes, almost silver, one of the prettiest things I've seen.
As for white hair, I had a friend in grade 1 with natural white hair but not albino. Of course both are caused by melanin deficiency, and you said you didn't want that. However for white any way that's the most effective way, and mind you, all three people mentioned were tanned, not albino.
As for black eyes, they exist, they are rare but they exist and they are from excessive amounts of melanin. Basically really really dark brown you could say that doesn't count but you wont get any closer.
One thing about your question doesn't quite make sense: you want 'common and natural ways' when those hair and eye colours are not common and mutation is a natural occurrence (red hair and blue eyes being mutations ie. blue eyes are from not producing enough melanin after birth, in which most babies have blue eyes).
that being said, if we use mutations an deficiencies, we can achieve your proposed colours. since there can be yellow/golden parts in irises (mine for example) it could be assumed that mixing of yellow and green could make light green. the golden part is caused by aging, and is only a ring around the pupil so i guess it still doesnt count.
the other thing that factors colour in eyes is light refraction, if the structures were 'weird' enough, you could have iridescent irises if you wanted. some blue eyes look violet in the right light. the same goes for hair, if you had hair that say, had microscopic holes in it that refracted the light like the blue morpho butterfly's wings, mybe you could have strange coloured hair at the right angle.
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For human hair and eyes the best way to add colors to the natural range would be if your cells would naturally produce other types of pigment. It would also be possible to produce colors by having structures that are the same size as the wavelength of those colors. You could get green hair for instance by having a yellow pigment combined with structures in the hair that are the same size as the wavelength of blue light. Blue hair also could either be produced by having a blue pigment or by having structures that are the same size as the wavelength of blue light.
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Technical detail: My eyes are naturally light green enough to be almost yellow.[](https://i.stack.imgur.com/quXOw.jpg) So I'm walking proof human beings can have bright green irises and approaching yellow in sunlight. As for the other iris and hair colors, animals can have fur and eye color not normally possible for people by having different pigments. If the characters in your world had genes that allowed for pigments normally absent from people in reality, they could 'naturally' have those colors.
Now I'm not technically adept enough to know *what* pigments those might be nor in which proportions but check out an avian or primate anatomy book and I'm confident you can get that information.
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My Earth is similar to our real Earth, and some scientists have found out a really cheap way to use geothermal energy. Huge generators are built, but one scientist eventually found out that the Earth is not as hot as it was before this huge usage of geothermal energy. The Earth gets colder inside and nobody can stop the cooling. Soon enough, the Earth liquid core has become just like a huge rock.
My question is: are there any catastrophes that are likely to happen, or what will happen? (These power stations will stop working and there is a really big need of power) or will just everything run as it is and there will be no volcanoes or earthquakes any longer (because the energy responsible for the movement of the tectonic plates is no more)
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Mars. We would eventually look like a slightly larger version of Mars.
The molten core generates the [Magnetosphere](https://en.wikipedia.org/wiki/Magnetosphere) and this does several things for us.
First it protects us from a lot of radiation from the sun, ever hear of the northern lights? That is a visible display of our protection.
Next we currently have an atmosphere, and while a lot of hydrogen and helium are still whisked off into space the magnetosphere protects most of it from being swept away by the solar winds.
So ultimately everything dies that doesn't dig into the planet for protection. And by the way as the atmosphere is eroded away, the oceans and lakes will boil away as well, evaporating into the thinner and thinner atmosphere until both are gone. Leaving a fairly dry husk of a planet.
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**We need a Magnetosphere**
The important thing that a liquid iron core gives us is a [Magnetosphere](https://en.wikipedia.org/wiki/Magnetosphere) around the Earth. This protects us from solar winds which would otherwise strip away our ozone layer which protects us from ultra-violet radiation.
Furthermore the solar wind could actually strip away the atmosphere itself if there was not a magnetosphere to hold in the charged ions in it's upper bounds. Without an atmosphere, we would be dead.
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Core completely solidifies; magnetic field collapses; earth bombarded by "cosmic" rays; everything dies.
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I'm curious to the affect a planet would have if it orbited around, or was orbited by another planet of equal, slightly larger mass. Say if Earth had, not the moon, but a planetary object the same size as the Earth. What would life be like on the planet? How would time be affected? Could life be sustained?
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It seems that binary planets [are possible](http://news.discovery.com/space/alien-life-exoplanets/are-habitable-binary-planets-possible-141211.htm).
What are the consequences? Firstly, the planets will be tidally locked, this is pretty much inevitable. If they are far enough apart to not get tidally locked, they are far enough apart to not actually orbit each other. I suppose in a system with no other inner planets it might be possible for the binary planets to orbit each other at a great distance, and both rotate independently - in this scenario they would both still suffer significant tidal effects. But the tidally locked scenario sounds most likely, and more interesting, because it puts the planets closer together.
So being tidally locked, they always show the same face to each other. If there are creatures on a planet, they don't know what the far side of the other planet looks like.
Being tidally locked, their day is equal to their orbital period (more or less). If their orbital period is more than a week or so, very long days and nights will start to be a big problem - perhaps not insurmountable for life, but I think for intelligent life it's good to bet on a day of not more than a week. But I'll go with a orbital period of 1 day, in other words the two planets are about a distance of an Earthly geosynchronous orbit. Earth has a diameter of 12,000km and Geosynchronous orbit is 42,000km. This means looking at the system from above, it looks like this - the image is to scale:
[](https://i.stack.imgur.com/StLyq.png)
At this distance, the planets are extremely large in each other's skies. In fact, about 300x larger than the Moon, because brightness is proportional to area, a "full planet" is thus 90,000 times brighter than a full moon on Earth, potentially up to about 8% the brightness of the Sun.
In the above image, you can see the day and night side. One of the planets has a "planet lit" night, the other planet is having a dark night.
# Day Cycles and Mythologies
Solar and "lunar" eclipses will occur once on each planet per orbital period (this does depend on the exact orbital geometry, but we'll go with the system being perfectly aligned). One of the curious things is, because of being tidally locked, people on the "far side" of the planet, will actually never see their sister planet. They will thus also never enjoy a planet lit night or an eclipse. If the planets are mostly water, with continents, then a civilization on a far side continent might not even know or believe in the existence of the sister planet or it may have a mythical status. On Earth, the Moon features prominently in certain mythologies, and so the far side and near side will be in a way quite different worlds, with different mythologies.
## A near siders day
A near sider would not enjoy a clear-cut day/night cycle, they would instead essentially experience two nights - a short dark one at Noon of about 1 hour, and a long bright one after the sun has set, with a period of extra dark at midnight.
* Midnight: It is dark, the other planet is eclipsed as in a lunar eclipse, greatly reducing the light from it.
* 3am: The other planet has emerged from the eclipse and is glowing brightly in the night sky, in three-quarter phase.
* 6am: The sun is rising, and the other planet is still glowing brightly, it is now at half phase.
* 9am: The sun is bright, and the other planet is now at quarter phase - it is still visible in the sky, but is washed out by the brightness of the sun.
* Noon: The sun is eclipsed by the other planet. It is very dark, potentially even darker than night, depending where you are on the near side.
* 3pm: The sun has emerged from eclipse, and the planet is now at quarter phase again.
* 6pm: Twilight, the planet is now in half phase again.
* 9pm: The other planet is high and bright in the sky, in three-quarter phase.
In contrast, a far-sider will experience a day night cycle a lot like on Earth, except without a moon. This will give near siders and far siders very different world views. When near siders travel to the far side, the far siders will think they are bonkers, with whacky religious beliefs and all this talk of "little nights" and such. A far sider who travels to the near side, will have their mind blown.
If one of the planets has an entirely watery near side, with continents only existing on the far side, then that planet may be entirely oblivious of the sister planet. However in the scientific era, even far side scientists will be able to recognize that their planets motion is odd, and so be able to deduce the existence of the sister world, even without sending a ship to see it.
# Transfer of Life
The two planets could transfer life on rocks thrown up by large impacts. Bacterial life, spores, seeds and possibly creatures like [tardigrades](https://en.wikipedia.org/wiki/tardigrade) could be transferred this way. This could, up to a very limited point, keep the development of life on both planets in sync. The limit is that any creature more advanced than a tardigrade is unlikely to make the trip.
This means that both planets will probably develop the same kind of atmosphere, and compatible flora and fauna. But unless there is some kind of extraterrestrial seeding of higher life forms (by aliens, or some kind of directed evolution by intelligent spiritual beings) then there is no physical/biological mechanism to synchronize the evolution of intelligent life.
# Modern Era
Because the two planets are at geosynchronous distance, communication by radio will not be difficult. Unfortunately going with a Darwinian evolution model there is little scope for "first contact" occurring in such a manner. If however the world has "directed evolution" then this could occur, as both civilizations more or less simultaneously discover telescopes and radio.
## Space Flight
Space flight between the two planets will be relatively easy for one way trips. Thanks to areobraking it would be easier to send humans to the other planet than it was to send humans to the Moon, but it would be much harder to perform a return trip due to the requirement to send a rocket large enough to lift out of the gravity well and atmosphere of the other planet. In fact with apollo level technology a return trip would simply be impossible. With a level of technology enabling colonization of Mars (i.e. 2020 technology) then a return trip would be possible, by exploiting resources in-situ to fuel a return rocket - but the trip would still be very difficult.
If only one of the planets has a intelligent life, it would be relatively easy to colonize the other planet, requiring only Apollo level tech. This is assuming that the two planets have shared life via meteorites, so the other planet has an abundance of edible (and naive) life, the animal life could be quite different to that of the home planet, but should still be edible thanks to the common genetics. Colonists might have to be trained as survivalists, but should survive without technology.
It would take a while to build up to a space industry on the other planet, but it would be much, much easier than doing so on Mars (except perhaps, for the lack of motivation).
If both planets evolved advanced civilizations, or after one planet has colonized the other, then two way trips would be possible by using the other planets rockets - however travel between the two planets would still be very, very expensive.
GPS satellites, communication satellites, and so on, should all be possible. They wouldn't tend to orbit exactly as they do on Earth, and instead would tend to exploit libration points where the gravity of the two planets are balanced. Note that for near siders, radio transmissions could be send directly from the other planet as they are tidally locked. These would not however enjoy the clear vacuum of space, permanent sunlight and so on, but could still be done with apollo level tech.
## Space Elevator
Because the two planets are tidally locked, it would be possible to build a space elevator bridging them with no more or even less difficulty than building a space elevator on Earth. This may be most useful for delivering stuff to the "L1" point between the two planets as it would still be a very expensive means of travel and unlikely to be economical for trade or tourism, except in the case of the super-wealthy.
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If both planets are identical in size/mass I don't believe such a system would be stable for long (as measured in terms of stellar evolution).
Firstly since both worlds are supposed to have developed Earth like ecology's and life forms must be orbiting a star within the Goldilocks zone. So its a three body problem not a 2 body problem.
The setup also means both worlds are going to be varying the distance between themselves and their primary each time they complete an orbit around their common center of gravity. And they cant be in a tight orbit (think a few thousand K apart) either. The laws of gravity and motion dictate a pretty wide distance between them. (Greater than that separating Earth and the Moon by an order of magnitude or more).
So the climatic impacts are going to be dramatic. If it takes 10 days for them to complete one orbit of each other they are going to experience mini summers and winters as they approach and then recede from their star. And this is on top of normal seasonal variations as they complete their annual cycle around the star like all its other planets.
What you could just as easily do is put both planets in the same general orbit on opposite sides of the star. Using Apollo level technology launches to Mars or Venus were 'doable' if extremely difficult. The problem is in real life the payoff for trying it has never been worth the risk. That would change immediately if the other planet had a earth like atmosphere and ecology.
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Imagine a sci-fi world where many organic civilizations would have raised and have an empire between many planets and systems. Even if there is some political tensions, they all live in peace together. (A Mass Effect-like universe).
Now, for some reason, imagine a race of machines, with a population of individual artificial intelligences, that found its own empire - or republic, whatever.
Let's suppose that they didn't harvest or even declared any war to their creators. For instance, their creators could have released them when they felt to start an undefined behavior from them, and let them found their own society on another system rather than risk a war.
At this point, may them prosper alongside other organic civilization ? They would have a strong military power, but wouldn't use it on anything unless they feel directly attacked. So in theory, peace would be possible, but:
* A machine group could repair they old members while creating new ones, so its population (and so space needed) would grow up faster than any race. Colonization of new world would be quickly a problem with neighbors.
* They needs for food or atmosphere quality are null, and their energy resources needs are higher than organic (as they need energy for themselves before anything else to 'live') so if they colonize a habitable world, they could find useless to let any animal or vegetable life form on it and destroy anything for industry profit. Other intelligent organic species wouldn't like that.
* Diplomacy and political games are probably hard to understand for a machine, so if they try to have a role in galactic governments (as ambassadors for instance) this could leads to more political incidents than anything else, disturbing a fragile peace.
So is there a chance at all to develop at peace with other races ? If yes, at which conditions ? If no, why specifically ?
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**Yes, and they probably would!**
While it may be beneficial for machines living on a planet to live on a planet with no life forms, it is not in their interest to start a war with organic races. These races are capable of benefiting the robots through trade relations and military alliances. Going to war would mean losing those benefits, while also gaining an enemy who is actively trying to destroy you. Even if the robots lack tack and subtlety in their diplomatic endeavors, logic would dictate that they should try to avoid war at all costs.
A better approach would be to simply colonize worlds which are inhospitable to life. Luckily for the robots, there are more of these types of planets than ones which organic life forms live on. For space-faring robots, even colonizing *worlds* might not be the best course of action. Colonizing numerous small planetoids and asteroids would give the robots man environment in which construction is easier and space more accessible due to the significantly lower gravity of these bodies. The lack of atmosphere would also increase the efficiency of solar panels and reduce the amount of corrosion the robots would suffer due to things like oxygen and water in the air.
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I suspect that strong AI would not even "notice" us, since they will be operating at a subjective speed so great that *we* would seem to be more like geological features rather than sentient beings to communicate/interact with.
Consider two figures: electrical impulses in a circuit travel @ 1,000,000X faster than an electrochemical impulse in our nervous system. The second figure is based on clock cycles: a nanosecond is to a second like a second is to 31.71 years.
The ability of a strong AI to interact with a human being then becomes limited to the interest and subjective lifespan of the AI. IF on second of "real time" is like 31 years to the AI, then it could spend its entire "life" waiting for a single word from you. This would be a bit like going to Mount Rushmore and trying to have a conversation with George Washington.
The real danger is as AI's lose interest in us, *we* will eventually pass into legend. The AI's will be doing things that are of interest to them, like converting the biosphere to capture the 195 petawatts of solar energy that strike the Earth each year, and probably won't even consider or notice this is causing us some distress.
This won't even be a "war" in any conventional sense of the word; more like discovering silicon "ants" suddenly eating away at your house while crystal trees grow in the park to convert sunlight into solar energy. By the time you get to the park with your chainsaw, millions of subjective years will have passed for the AI, and their descendants won't have any idea why you seem upset. It would be like you are setting out today to fight the Assyrian armies of Hammurabi, only the timescale would be even vaster (you are setting out to fight Homo Habalius).
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Summary: Yes, they could coexist but it would heavily depend on what characteristics you give your machines.
Long:
You could look at this from the viewpoint of this AI civilization as a carbon-based invasive species. For example, you could have the robot equivalent of [kudzu](https://en.wikipedia.org/wiki/Kudzu_in_the_United_States) in the southern United States where growth is unchecked (or uncheckable) and no other plants can compete. On the other hand, your AI could be the equivalent of starlings in the US. They are everywhere but don't have some special advantage that allows them to outcompete indigenous bird species.
Whether they get along or not depends on the characteristics of the AI/Machines and the cultural values of the civilizations they interact with. The prolog to the Matrix describes one way how the relationship between organic life and machine can [break down](https://en.wikipedia.org/wiki/The_Animatrix#.22The_Second_Renaissance_Part_I.22). On the other hand, Asimov wrote a story about how a robot was built to perfectly mimic human form then ran for political position. The robot won and kicked off a spectacularly successful and beneficial career.
In the case of your AI, they would have to choose how much they compete and what the broader goals would be (individual self-preservation or community preservation). Perhaps the creators gave the AI something akin to Asimov's [Three Laws of Robotics](http://www.auburn.edu/~vestmon/robotics.html) which might push the AI civilization into a more service oriented co-existence with local civilizations.
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I think our civilization is a perfect example of it. We peacefully coexist with our computers and Internet, but can we be 100% sure that millions of servers of Internet couldn't act as neurons and this system doesn't developed some sort of intelligence? We can simply not realize that AI civilization exists.
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Currently, the crust varies from 4km (oceanic) to 10km (continental) to 30km (mountains).
How would the earth be different if it was all 1/4 the thickness? So it was 1km, 2km and 7km?
Would we have more volcanoes / earthquakes / geysers?
Would the crust be any warmer? Would life be different?
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I'll play along... Let's go the mind-experiment path.
Since the crust, as is, makes up such a small portion of the Earth's structure, reducing that by, let's say, 3/4 would not be that big of a change.
* Below the crust, there's 100km of rigid Lithosphere.
* Below that, the less-stable Asthenosphere that goes up to 700km.
* Below that, up to about 2885kn is the solid Mesophere.
* Then you finally get to a liquid outer core, and finally the inner core which is solid.
A change the the outer-most surface layer thickness would have relatively little impact on the overall function of the mantle on a macro-level.
The surface would be thinner, which if we project out, we might think that this means there might be more magmatic activity. I suggest (unscientifically) that that might actually not be the case. Remember that pressure of the crust and surrounding material contribute greatly to the development of magma, by reducing the crust's thickness, you are thus reducing the pressure.
Reduced pressure would mean that magma would likely have to form a little deeper into the mantle than is currently normal. Since the crust is thinner, the distance to the new magmatic layer is roughly the same distance it was previously. Thus, by thinning the crust by 5km, you've pushed the magma-bearing layer down by roughly the same distance.
In the grand scheme of things, really, such a change would be negligible, and the natural forces that exist now would still be in play, thus the system would stabilize itself, and even rebuild the crust to some degree over time.
The surface changes to such a thin crust would have only superficial results, including:
* Shallower ocean depths
* Relatively lower mountains
* A modest increase in tectonic activity with a reduction in overall strength of each event
* Slightly fewer mineral resources (since the percentage of granite-to-silicate materials is changed.
* Possibly less oil as the surface material available to be turned-over over time may be insufficient to product the pressures needed to convert archaic organics into petroleum
Earth would be livable, and not a lot different than now.
The real question becomes, then, why is the crust to thin?
* Did it happen in a short period of time?
* Was it always like that?
* How long has it been thin?
Any "catastrophic" disruption of the status-quo would lead to severe consequences.
If the crust slowly "erodes" to this thinness, life would have plenty of time to adjust to the changes.
If the crust used to be thick, then where did that material go? Did it get subsumed into the mantle somehow? Did it get ejected into space? Each of these answers initiate a wide variety of new questions.
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To answer the question of the resulting air pressure, we have to know why 75% of the crust is missing. It help's to know what exactly is *the crust*. The crust is the surface portion of the planet that is chemically differentiated from the layer below it (the mantle). This is largely considered to be primarily the output of volcanoes that has not been recycled back into the deep.
Case 1: The earth's crust is thinner due to natural causes.
I will simply assume that reduced volcanism is the only reason. If so, we also remember that volcanism is considered the likely source of most of earth's atmosphere. In this case, the atmosphere is considerably lighter and pressure is correspondingly smaller. Since 75% of the crust is missing as a first order guess 75% of the atmosphere is also missing. Lots of things not good, but humans won't be around to notice. Large mammal biology are just too hard to maintain at the reduced oxygen levels -- we are well into the death zone of low oxygen pressure. The reduced pressure obviously cause lots of changes to the locals.
Case 2: The earth's crust was taken by aliens less than 1 million years ago to make some nice rock gardens -- asteroidal rock just does not have that same igneous look and feel. Being environmentalists, they take their 75% cut using magical tech levels that do not disturb the crust any more than necessary so as to not upset the locals. I.e., we can assume crust is just as we find it today, just that 75% of it is missing. This sounds more the the actual question intent to me.
The atmosphere is unchanged, i.e., the same mass of O2, N2, etc. still in the sky. So how is pressure affected?
The earth's radius is slightly smaller, assume it to be 1% (60 km) as an average number. Because Earth's surface area, being proportional to radius squared, is now just over 2% smaller and thus pressure is 2% higher.
But we are not done, the earth's mass is reduced and the radius is smaller, changing the gravity. Can we figure out the net effect without the hard math. Surface gravity is proportional to mass and inversely proportional to radius. However the earth crust is only around 50%-60% of Earth's density (the real number are uncertain), so the mass decrease is only about half of what would expect. We will ignoring the difference in the gravity gradient due to crustal loss (I promised simple math). In case you are curious, I know I can ignore the different gravity profile because nearly all of the atmosphere is very close to the surface -- so gravity is very nearly a constant value for the bulk of the atmosphere and the difference in gravity profiles (rate of change) can safely be ignored. If we did the math is would actually slightly decrease the pressure as the rate of gravity decrease would be higher.
Plugging in 1 \* m/(r\*\*2) = 1 \* 0.995 / (0.99)\* is about 1.015, i.e., atmospheric pressure is about 1.5% higher
Combining the effects from gravity and reduced surface area, the surface pressure is little more than 3.5 percent higher overall.
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Tired last night and I did not finish and did not catch that I wrote 6 km for 1% of the earth's radius.
Note that actual average crustal thickness is about 12.5 km (70% ocean with the thin crust 7.5 km thick and 30% thick crust 25 km thick -- sounds like something from Pizza Hut), much less than the 1% assumed above, so the real effect on air pressure is simply not significant. Using the real numbers make the pressure changes less obvious. Using actual numbers for the crust, the net atmospheric pressure is only about 0.5% higher. This is the about same as the difference between sea level and 35 meters.
Air pressure is relatively easy to figure, the other effects already mentioned are considerable more difficult to actually compute. For example, assuming case 2 how does heat transfer from the core change and what is the effect on temperature, etc. As a first approximation 25% crusts means 4 times the heat transfer rate. But based on what. Well, the crust boundary is the [Mohorovičić discontinuity](http://en.wikipedia.org/wiki/Mohorovi%C4%8Di%C4%87_discontinuity). At the Moho layer, temperatures at 150-200 C under the ocean and 500-600 C under the continents. The Moho layer will cool somewhat due to higher heat flow, but just how much is hard to say, unknowns are fairly large.
In this case, quadrupling the average heat outflow does actually not matter much because it is so small. -- Average is about 0.1 watts / square meter a small fraction of solar flux.
However, even this changes overlooks an important change. 4 times the heat flow means that temperatures increase as you drill / mine the crust at 4 times the current rate. Some gold mines already require air conditioning to be livable, the problem would be much more severe. It would make mining more expensive, and prevent our deepest mines. Oil drilling would be effected, not because of overheated miners, but because the higher temperature weaken the drilling equipment and more importantly break down drilling fluids. Some deep oil wells are over 1500 meters -- the higher temps would probably make this impossible, certainly much more expensive and economically unjustified.
It is very hard to correctly evaluate all of the changes resulting from even a relatively minor change.
] |
[Question]
[
In my world there is a trading city in the middle of a vast stretch of wild, untamed forest. It was built to serve as an in-between for merchants as there is a peaceful kingdom both north and south of it. The city is on the banks of a north-south flowing river.
My giant spiders have evolved over the last million years in several different branches. The main branch is the giant Wood Spider. The second (and why there needs to be a safe in-between for trade) is the giant Water Spider. The one I am dealing with is a minor branch, the giant Flying Spider.
They don't actually fly, but more like glide between trees like Flying Squirrels. They hunt by swooping out of the air and grabbing whatever they are hunting (anything from Giant Wood Spiders to Humans and Wildlife like deer).
# Question:
1.) How might these three extremely different species of giant Spider evolve to hunt one another within the confines of a single forest the approximate size of the Sahara Desert?
2.) Is the evolution of a "gliding" arachnid possible? If so how could this happen.
For the purposes of this question use the [Jba Fofi](http://en.wikipedia.org/wiki/Jba_Fofi) as a model and work from there. Make sure the spiders are agile and deadly as they have to fight my town and pose a threat.
**EDIT:**
While I don't want to invalidate existing answers, I feel the need to mention that answers should not use extreme handwavium and should have some base in a precedent. No magic or "it just is because it is" answers please. Thanks :)
[Answer]
So this giant flying spider has really, really long legs, three to four times its body length. Its legs are also very hairy, with fine, feathery hairs.
Like a jumping spider it is able to leap very far. When it jumps it holds its legs straight out from its body, and the hairs mesh together to form a glide surface, which extends its range quite a bit.
These hairs also make it very sensitive to vibrations, so its "hearing" is very sensitive, and it's also able to detect movement through whatever surface it's standing on.
Like a jumping spider, it doesn't build webs, but hunts its prey with sight and sound.
Edit:
[Many spiders have hairy legs](http://www.weirdlife.com/wp-content/uploads/2014/10/spider2.jpg), so one developing long fine hairs is possible. With a long enough leg span, it would work a lot like a hang glider, or a flying squirrel. Not able to flap to produce lift, it would instead glide from tree to tree, or tree to victim. It would develop this gliding skill over time in tandem with its jumping: First ballistic trajectory, then using legs to provide control in the air, and finally gliding.
The wood spiders are the biggest, building webs that span tree to tree. They don't normally hunt for food, but wait for the food to come to them. Their webbing is very thin but abnormally strong, meaning if they make a web across a game path then a running deer could easily jump into it and be caught. The webbing is also difficult to cut with a blade. It can be cut, but takes some hacking, which vibrates the web and alerts the spider. The spider will also run trip lines out along the forest floor to alert it to prey.
Shirts woven from wood spider webbing, which is harvested from dead wood spiders, will stop a blade or arrow, similar to mail.
The flying spiders hunt using surprise mostly. By jumping then gliding towards their prey, they are able to use their mass to crash into and stun before using their venom to immobilize the victim. Because spiders have multiple eyes around their heads, a flying spider hunting a wood spider is not easy, but because of their quick reflexes and speed it's not impossible. A normal attack is to see a wood spider away between trees or on a trunk, away from a web, glide near the wood spider, fold in legs to enter a ballistic trajectory, slam into the wood spider to stun it, and bite it before it is able to recover.
Flying spiders do have to be careful of webs, since crashing into one will snare it, allowing the wood spider to kill it.
[Answer]
[**Gliding spiders are real!**](https://www.youtube.com/watch?v=QO34EoqwOkg)
[](https://i.stack.imgur.com/LUnYb.jpg)
from <https://www.nbcnews.com/science/weird-science/jungle-spiders-glide-through-air-n412671>
>
> This time, the team collected dozens of common spiders known as
> "flatties" in American tropical forests, the moniker owing to their
> wide, flattened bodies. The team dusted these test subjects with
> fluorescent powder, then dropped them from up to 80 feet high and
> recorded their falls. To their surprise, the flatties homed in on
> nearby tree trunks a full 93 percent of the time.
>
>
> "Gliding spiders represent an unlikely if not truly ungainly
> aerodynamic platform," reads the paper, which appeared in the Royal
> Society journal Interface. In other words, it works better than anyone
> expected.
>
>
>
These spidergliders are not freakishly weird. In the video that spider is definitely gliding around. So just scale yours up. Maybe Frisbee sized?
[Answer]
There are already spiders that 'fly'. They use their silk as a kite to pick themselves up and be carried away by the wind.
Now, in the forest you are going to have less useful wind and you already mentioned that they are more like flying squirrels and glide. This can be done with their long legs and 'parachutes' or 'wings' of spider silk. Their bodies can be wider and thinner to help with gliding and then make 'wings' of silk between the legs. By bending their legs they can change the shape from a 'wing' to a parachute to change direction and speed. And it can be used as a starter for a web to capture and contain their prey. Does double duty.
[Answer]
As Samuel mentioned in comment, small spiders have the ability fly already by simply letting out a long strand of webbing and allowing the wind to take them. That effect would certainly max out at some spider-weight much less than the Jba Fofi, but one could plausibly imagine the gradual evolution of increasingly efficient floater-strands, culminating in the development of little silk hot-air balloons.
Where does the hot air come from? A tiny flame generated by the spider's body, of course. These flying spiders also breathe fire, apparently.
[Answer]
With 3/4 foot long legs, these spiders don't need to glide - they could probably jump several metres.
However, you want gliding spiders, so:
* The spiders could have flaps on their legs and body, that when extended form a large surface area for gliding.
* The spiders would have a much flatter body than normal spiders. This flattening would result in a wider body, good for gliding.
* They would proabably be able to shoot web a few feet to avoid falling from near misses, or ensare prey without landing on it (useful if the prey is dangerous, such as another giant spider or a human with a spear)
[Answer]
Instead of gliding in the traditional sense have you considered having them spin particularly elastic webbing? They could set up a series of elastic bridges near high branches. When prey is below these lines they could grab on with their back legs and essentially "bungee jump" to the forest floor snagging their prey with their front legs and injecting venom while the webs spring them back up to the tree tops.
I would also suggest that gliding or flying may not be strictly necessary, have you considered a [net-casting spider](https://en.wikipedia.org/wiki/Deinopidae) as a model for your tree top spiders?
As to how they might hunt one another. Your giant wood spider may have the upper hand in a straight fight; perhaps it's larger and stronger. But being larger confines it to the larger branches and trunks of the lower half of the forest. Mean while the gliding spider is "thinner" and smaller (relative to the wood spider, still bigger then a person) and could be described as spindly. However as ambush predators they are still a match the larger spiders below them.
] |
[Question]
[
The long-term theory of climate patterns states that the Earth experiences an ice age, freezing over and remaining so for about 40 years, before returning to a normal, seasonal climate. My question is: is it possible for an ice age to happen so quickly? Is 40 years too short, or is that perfectly feasible?
[Answer]
**Yes**
This was about the duration of the [Maunder Minimum](http://en.wikipedia.org/wiki/Maunder_Minimum) also known as the *Little Ice Age*. The Sun was known to be unusually quiescent during this time and it is thought the cooling climate was due to this low solar activity.
[Answer]
Yes. Through a supervolcano eruption. Something like the Yellowstone blowing up.
The ashes in the stratosphere, veiling the sky, would bring an equivalent of "nuclear winter". This would normally end sooner than your planned 40 years, but the eruption may be repetitive or continuous, extending the period as long as necessary. Scale this in time as necessary, with size of the volcano and duration of explosion.
Note that this won't form superglaciers like in the real ice age, covering whole continents and forming mountain ranges as they move - you do need a couple hundred thousand years for these to form from repeated snowfalls. It would be a very long, very cold winter with permanently cloudy skies, not a true "ice age".
[Answer]
**Yes**
If you wanted this to happen repetitively, you could postulate stellar system with orbital configurations that provide the necessary climatic changes.
**Binary Star System**
If you posit a binary star system of two stars smaller than our Sun, your planet would circle one star and the spacing between the stars would roughly be the distance of Neptune from our Sun.
Habitable planet in binary star system
When the outer sun got closer (the left of the image) you'd get warm periods. When the outer sun got further away, it would plunge the planet into an ice age.
You could play with the solar system mechanics to get the length and severity of warm and cool periods that you wanted.
**Elliptical Planetary Orbit**
You can use a similar method to induce climate changes with just a single star. Put your planet in an elliptical orbit with the correct attributes to induce periods and severity of warmth and cold.
[Answer]
**Yes**
In (astronomer) Fred Hoyle's book [The Black Cloud](http://en.wikipedia.org/wiki/The_Black_Cloud), he states that a sufficiently dense gas and dust cloud could significantly reduce incoming stellar radiation.
You could postulate that your stellar system has passed through a tendril of a star forming nebula and this dust and gas reduces the amount of the star's energy reaching the planet. By this mechanism you could make the duration and timing the ice age completely arbitrary and not subject to repetition. NOTE: that it would take a star a minimum of tens of thousands of years to cross the entire nebula - which is why I suggested just crossing a tendril.
Plus as an SF setting, I imagine the inhabitants of the planet would have astounding sights in the night sky.
] |
[Question]
[
Eric Schmidt famously declared that it should be considered "a bug" that cars were invented before computers. He was talking about the ability of self-driving cars to remove driver error--the principal cause of traffic accidents--from the equation, but what if it actually happened that way?
Assume a world similar to our own, with human civilization in which, for whatever reason (divergent technological evolution, a gift from benevolent(?) aliens, magic, or whatever) **the transistor is mass-producible before the internal combustion engine is.** What would the effects on society be?
The first things that come to mind, but may require a bit of sanity checking:
When cars do get invented, the idea of replacing a horse-drawn carriage with a computer-drawn carriage would be fairly obvious, incentivizing AI research with a very specific, practical goal that never happened in our world.
Transistors also have other applications, such as solar panels. Without a strong motor vehicle industry applying political pressure, does the petroleum-as-energy concept ever become dominant without well over a century of a head start as it had here?
**EDIT**: Please note, this is not a "how would this happen?" question, but a "if this did somehow for whatever reason happen, what would the effects be?" question.
[Answer]
A possible scenario is a world where internal combustion engines *are* mass producible before computers, but aren't used extensively because it's an energy-poor world. If they only had a fraction of our oil deposits, for example (say 10%?) that might be enough for civilization to develop, but at a much slower pace than ours. And cars wouldn't be used because they'd be hideously expensive to operate.
Now years after they've developed computers, they discover clean, relatively cheap nuclear power. So we have a scenario where computer technology is relatively mature but mass automated personal transportation has just become viable.
I would question **why** they'd want cars at that point though, since presumably they'd have to have efficient mass transportation to get that far.
[Answer]
It's tough to say without more information on the level of technology. Modern computers require ultra-high precision manufacturing processes, and on some deep knowledge of how materials work on nanometer scales. Lots of other advanced technology is required for producing the kind of computer that could drive a car, as well as extensive AI research.
Having *all* of this technology before the internal combustion engine would probably require alien intervention, since basic internal combustion engines are fairly simple and can run on wood. Having it all before developing a *car* would definitely require alien intervention, since the same technology that's used in a computer could be used to build an electric car.
Even having a computer does not necessarily mean having a computer that can be used to drive a car. Even today, our AI isn't capable of driving in traffic, and we've been researching machine intelligence for close to 70 years at this point. Being able to drive a car with computers is also reliant on having fairly advanced sensors for measuring the environment that the car is driving in. At the very least, advanced digital cameras would be needed. The effect on our society would depend on what all we had of the technology and understanding required for mass producing computers, and on why we got all of that before developing a car.
[Answer]
Below is the early history of computers. Since you did not give a specific year, you only need to **change the dates earlier by several decades.**
Kindly also note that the most notable changes will be **transistor technology during world war 1 and WW2.** Communications, codes, early robotics, simulations on design will have profound effects on these wars.
<http://www.daimler.com/dccom/0-5-1322446-1-1323352-1-0-0-1322455-0-0-135-0-0-0-0-0-0-0-0.html>
The first stationary gasoline engine developed by Carl Benz was a one-cylinder two-stroke unit which ran for the first time on New Year’s Eve 1879.
So if you want transistors before 1879, WW1 and WW2 will be very very different, and this will be just the tip of the iceberg. You would also need to make the electronics era a few decades early.
**History of computing**
**early components**
<http://www.computerhistory.org/timeline/?category=cmpnt>
1947
On December 23, William Shockley, Walter Brattain, and John Bardeen successfully tested this point-contact transistor, setting off the semiconductor revolution. Improved models of the transistor, developed at AT&T Bell Laboratories, supplanted vacuum tubes used on computers at the time.
1953
At MIT, Jay Forrester installed magnetic core memory on the Whirlwind computer. Core memory made computers more reliable, faster, and easier to make. Such a system of storage remained popular until the development of semiconductors in the 1970s.
1954
A silicon-based junction transistor, perfected by Gordon Teal of Texas Instruments Inc., brought the price of this component down to $2.50. A Texas Instruments news release from May 10, 1954, read, "Electronic "brains" approaching the human brain in scope and reliability came much closer to reality today with the announcement by Texas Instruments Incorporated of the first commercial production of silicon transistors kernel-sized substitutes for vacuum tubes."
The company became a household name when the **first transistor radio** incorporated Teal´s invention. The radio, sold by Regency Electronics for $50, launched the world into a global village of instant news and pop music.
1958
[](https://i.stack.imgur.com/IH9rp.jpg)
Jack Kilby created the first integrated circuit at Texas Instruments to prove that resistors and capacitors could exist on the same piece of semiconductor material. His circuit consisted of a sliver of germanium with five components linked by wires.
1959
Jean Hoerni's Planar process, invented at Fairchild Camera and Instrument Corp., protects transistor junctions with a layer of oxide. This improves reliability and, by allowing printing of conducting channels directly on the silicon surface, enabled Robert Noyce's invention of the monolithic integrated circuit.
1967
Fairchild Camera and Instrument Corp. built the first standard metal oxide semiconductor product for data processing applications, an eight-bit arithmetic unit and accumulator. In a MOS chip, engineers treat the semiconductor material to produce either of two varieties of transistors, called n-type and p-type.
Using integrated circuits, Medtronics constructed the first internal pacemaker.
**early networking**
<http://www.computerhistory.org/timeline/?category=net>
1960
AT&T designed its Dataphone, the first commercial modem, specifically for converting digital computer data to analog signals for transmission across its long distance network. Outside manufacturers incorporated Bell Laboratories´ digital data sets into commercial products. The development of equalization techniques and bandwidth-conserving modulation systems improved transmission efficiency in national and global systems.
1964
Online transaction processing made its debut in IBM´s SABRE reservation system, set up for American Airlines.
1970
Citizens and Southern National Bank in Valdosta, Ga., installed the country´s first automatic teller machine.
**early robotics**
<http://www.computerhistory.org/timeline/?category=rai>
1959
MIT´s Servomechanisms Laboratory demonstrated computer-assisted manufacturing. The school´s Automatically Programmed Tools project created a language, APT, used to instruct milling machine operations. At the demonstration, the machine produced an ashtray for each attendee.
1961
UNIMATE, the first industrial robot, began work at General Motors. Obeying step-by-step commands stored on a magnetic drum, the 4,000-pound arm sequenced and stacked hot pieces of die-cast metal.
early simulations
1965
A Stanford team led by Ed Feigenbaum created DENDRAL, the first expert system, or program designed to execute the accumulated expertise of specialists. DENDRAL applied a battery of "if-then" rules in chemistry and physics to identify the molecular structure of organic compounds.
**So picture a world where you have these innovations available by WW2.**
[Answer]
At the dawn of the automobile era, the future was not very clear. There were many steam powered vehicles and electric vehicles on the road. Many people of the time thought the internal combustion engine was crude and inferior to other types of engines. The early engines were loud, inefficient, difficult to maintain, unreliable, etc.
The thing that drove the evolution of the internal combustion engine was the discovery of cheap and plentiful oil. A handful of people became very rich, and gained influence and power. They used their resources to build and oil based infrastructure such as gas/service stations. This was galvanized when Henry Ford used an internal combustion engine in his Model-T. Previously, automobiles were primarily hand-built and would cost a small fortune to purchase. The average family could not afford it. Also, at that time buying things on credit was relatively unheard of. Most people preferred to make purchases in cash. In many cases the credit option was not available. The Model-T was inexpensive, and changes in banking practices allowed people to purchase them using credit.
If, instead, all of those oil wells ended up being dry, and there wasn't plentiful oil, then the evolution of the automobile would be completely different.
There would be much fewer vehicles on the road, and mass transportation would be much better and available. Before automobiles became big, trains, and street cars dominated the landscape of most cities. These systems fell out of use after automobiles became widely used. All that remains of many of these systems are a few sections of track. If the automobile didn't replace these systems, then they would still probably exist today.
More people would live in cities. The use of the automobile made it possible to commute to jobs in cities without having to live there. This is what led to suburban sprawl. Many of the suburban areas that we have would not exist in this world, and it would most likely be wild or farmland.
There would be some people that owned automobiles, but it wouldn't be the norm. Public/mass transportation would be so good, that there would be very little need to own one. Since the transistor and the computer age came sooner, it would be logical that many more people would be able to telecommute to work, and there would be fewer people who would need to travel to perform their job.
[Answer]
Hmm... how about a way to keep the horse? Have the horse's strength and stanima amplified by fuel-burning engines, but still deciding where to go and not to run into things. The breed of pilot horse would become a small pony, in time.
So why are horses better drivers then people? Other than the lower speed involved, for purposes of the story they may be bread to handle high speed with great vigelence, in step with the engine technology.
[Answer]
Given a wheeled wagon, inventing a car is straightforward provided even basic industrial level.
Car may be based not only on combustion engine, but also on steam power, electricity or anything else. Once a civilization discovers energetics, not to say electrical motor, building a car is straightforward.
If there are sources to power electrical computers, then means to make a wagon to more are very obvious.
] |
[Question]
[
Is it possible for humans to evolve to eat something like wood or stone or something similar? Any hard material you would find or any abundant resource. So is it possible that humans in the past had a chance of evolving to eat this type of thing?
[Answer]
Important rule of thumb is: If it burns, it is in principle possible to eat it. Remember that food is primarily a source of energy. Stones are not, they are oxides of silicon and some other elements and they are very low-energetic. So nothing can really eat stones. (If we do not consider possibility that it would perform nuclear fusion in its stomach.)
It is possible to eat wood and some animals evolved to do so. Humans eating wood are possible, but not very likely, since there would have to be really strong evolutionary pressure to do so and we would have to be lucky to find the right adaptation before we go extinct. So far, it seems there are many, many more easier ways how to find food than such a big adaptation as eating wood. I can easily imagine, that in future, we would be able to develop bacteria by a genetic manipulation that would digest cellulose and help us to digest wood. Chances for this occurring naturally seem very small to me.
[Answer]
Termites 'eat wood' by passing the raw cellulose to symbiotic bacteria in their gut to turn this into sugars. A human could in theory be changed to do something similar with these bacteria. The body could then digest the raw sugars as normal.
Rocks are harder, because there is no lifeform that metabolizes rock for fuel, and the relative hardness would make it difficult to work with even if you found some energy releasing reaction. Plus, biologically just releasing heat is not enough - it has to be a reaction that can be controlled step by step in the context of the body's cells to release energy as needed. Our bodies aren't the kind that can work off explosions like an internal combustion engine.
[Answer]
Humans do, in a manner of speaking, eat wood. We use it to augment the heat produced within our bodies by eating food and oxidizing it by instead burning it outside of our bodies. The end products of the process are the same/similar but the mechanism is different. We also use the heat of fire to pre-digest food by cooking it.
In very cold climates humans without fire would die of cold before dying of starvation.
Since humans already can 'effectively metabolize' wood by burning it to keep warm, process food, scare off animals, smelt metals etc there is little evolutionary pressure to do so more directly by eating it.
] |
[Question]
[
In this hypothetical solar system the one habitable planet in question would be at center of two sun stars, one similar to our sun and the other a red dwarf. What kind of effect would this have on the planet's day/night cycle, weather, life? Also, could humans adapt to such an environment?
[Answer]
**Yes, but not in the way you imagined.**
Vincent mentioned [a Worldbuilding question](https://worldbuilding.stackexchange.com/questions/2726/can-a-planet-have-a-figure-8-type-of-orbit-around-two-separate-stars/2734) which directly addresses the possibility of a figure-8 orbit. No offense intended, I don't think any of the answers there properly addressed the question - although Vincent may have decided against addressing it because [a Physics question](https://physics.stackexchange.com/questions/31201/might-a-planet-perform-figure-8-orbits-around-two-stars) had already covered it, which he mentioned in his answer, and it had a fairly comprehensive answer.
Quoting Thriveth in his/her answer there,
>
> In order to orbit in a figure eight, you have to imagine that the ball has to roll across the ridge between the two indentations in the 3D part of the figure. It is clear that this is possible, but also intuitively clear that this would only be possible for a narrow range of orbital energies (a little less and it would go into one of the holes, a little more and it would simply just orbit them both), and that it would not be a stable orbit. The ball would have to roll in an orbit where it exactly passes the central saddle point at the ridge (L1) in order to stay stable, the tiniest little imperfection will get it perturbed even further away from its ideal trajectory.
>
>
>
So such an orbit is possible, but very unlikely, and pretty unstable.
---
That doesn't mean that a planet couldn't follow a [circumbinary orbit](http://en.wikipedia.org/wiki/Circumbinary_planet) around both stars. Indeed, many planets have been found with such orbits. And it means that your 40-hour day and 3-hour night is possible.
Look at the Moon on the right side of this animation (I couldn't separate the two):
[](https://upload.wikimedia.org/wikipedia/commons/5/56/Tidal_locking_of_the_Moon_with_the_Earth.gif)
Image courtesy of Wikipedia user Stigmatella aurantiaca under [the Creative Commons Attribution-Share Alike 3.0 Unported license](http://creativecommons.org/licenses/by-sa/3.0/deed.en).
This Moon (incorrectly; our Moon is like the one on the left) doesn't rotate from the perspective of a fixed observer above the Earth. Still, the face pointed towards the Earth is constantly changing.
Now change the Earth to a pair of close binary stars, and the Moon to our planet. In fact, make the orbit really [eccentric](http://en.wikipedia.org/wiki/Orbital_eccentricity), so it swings out to the far reaches of the system. Because of [Kepler's second law](http://en.wikipedia.org/wiki/Kepler's_laws_of_planetary_motion#Second_law), it travels faster near the stars. This means that for one half of the planet, the night will last for 3 hours and the day will last for 40 hours; for the other half of the planet, the night will last for 40 hours and the day will last for 3 hours. To my knowledge, there is no configuration that will let you have the same length of night for both sides and still have the 40/3 scenario.
[Answer]
With a 8 shaped orbit: yes but the length of day/night will not be constant. When the planet is between both stars, the night is almost nonexistent. When the planet faces both stars in the same direction, the night last about the same length that on Earth depending on the axial tilt.
Seasons will be determined by the position of the planet in relation to the stars and also amplified by the planet axial tilt if any. Between both stars is the hottest. Close to the red star, at the exterior of the orbit is the coldest. But it's not necessarily cold enough to be considered winter. It depend on the distance with the stars.
[Answer]
Below are a few solutions to the question :
The simpler and realistic one first : You orbit a small planet very close to its sun, and you spin it naturally.
Because your planet is much smaller than the sun and you are close, rays coming from the side of the sun can reach a significant fraction of the opposite side of your planet.
To see it : Imagine a big circle and a small circle, and draw the two tangents to those two circles.
Geometrically any X with 50% < X < 100% of the surface of your planet can be illuminated depending on the distance orbit and the planet and star sizes. In your setup you wish for a X of ~ 90%.
Note that in 3 dimensions, a significant fraction of your planet which will receive light 100% of the time (when |latitude| > Y ). But at the equator you will have your ~90% of day night imbalance.
Another solution : add atmosphere effects to a planet : If you have an atmosphere reflective and diffuse just the right way, light can bounce a few times in it to reach the back side of the planet and to lit it. (By the way on earth L.W. radio waves do just that with our atmosphere.)
Another solution : Donut shaped planet :) will self-shadowed and indirect light on some points and by settings the 2 radius of the torus correctly you can specify the day/night imbalance. Play with a ray tracer to convince yourself.
Here is yet another solution : Solar winds which by interacting with the magnetic field of the planet makes polar lights which illuminate so strongly the would be night.
Yet another solution using general relativity : The difference of gravity between the closer to the sun side and the farther from the sun side means that times goes slower on the lit side, so the day are longer, but I would bet that tidal forces would make such scenario unrealistic :( :)...
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[Question]
[
Imagine we have a machine that can consume celestial bodies, breaking them down into component elements and storing them in big bins somewhere. **If we fed that machine a moon, what would wind up in those bins?**
**Assume:**
* Earth's moon.
* We do not concern ourselves with the planet the moon is orbiting. It is likely next on the menu anyway.
* How the machine functions is open to speculation, but ***not*** part of the question.
[Answer]
The volume of the moon is $2.1958\*10^{10} \,\rm km^3$ (0.020 Earths), and its mass is $7.3477\*10^{22} \,\rm kg$ (0.012 Earths).
As is to be expected, we know more about the surface and the atmosphere (yes, there is one) than we do about the mantle or the core.
**[The Core](http://en.wikipedia.org/wiki/Internal_structure_of_the_Moon)**
>
> The composition of the lunar core is not well constrained, but most believe that it is composed of metallic iron alloyed with a small amount of sulfur and nickel.
>
>
>
**[Mantle](http://chemistry.about.com/od/chemicalcomposition/f/What-Is-The-Moon-Made-Of.htm)**
>
> The largest portion of the Moon is the mantle. This is the layer between the crust (the part we see) and the inner core. The composition of the mantle is similar to that of the Earth, but the Moon may contain a higher percentage of iron.
>
>
>
**[Surface Crust Composition](http://chemistry.about.com/od/chemicalcomposition/f/What-Is-The-Moon-Made-Of.htm)**
>
> Scientists have samples of the lunar crust and take measurements of properties of the Moon's surface. The crust consists of 43% oxygen, 20% silicon, 19% magnesium, 10% iron, 3% calcium, 3% aluminum, and trace amounts of other elements including 0.42% chromium, 0.18% titanium, 0.12% manganese, and smaller amounts of uranium, thorium, potassium, hydrogen and other elements.
>
>
>
**[Lunar Atmosphere](http://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html)**
>
> Total mass of atmosphere: ~25,000 kg
> Abundance at surface: 2 x 105 particles/cm3
>
>
> Estimated Composition (particles per cubic cm):
>
>
> * Helium 4 (4He) - 40,000
> * Neon 20 (20Ne) - 40,000
> * Hydrogen (H2) - 35,000
> * Argon 40 (40Ar) - 30,000
> * Neon 22 (22Ne) - 5,000
> * Argon 36 (36Ar) - 2,000
> * Methane - 1000
> * Ammonia - 1000
> * Carbon Dioxide (CO2) - 1000
> * Trace Oxygen (O+), Aluminum (Al+), Silicon (Si+) Possible Phosphorus (P+), Sodium (Na+), Magnesium (Mg+)
>
>
> Composition of the tenuous lunar atmosphere is poorly known and variable,
> these are estimates of the upper limits of the nighttime ambient atmosphere
> composition. Daytime levels were difficult to measure due to heating and
> outgassing of Apollo surface experiments.
>
>
>
From [Wikipedia Commons](http://en.wikipedia.org/wiki/File:Moon_Schematic_Cross_Section.svg)
Note: Thanks to Kromey for the MathJaX.
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[Question]
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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 8 years ago.
[Improve this question](/posts/352/edit)
Sometimes when someone says a map is "small scale", it seems to mean a map shows a small area, but the things are drawn large as a result, and other times it means the things in the map are shown much smaller, allowing for a large area to be shown.
[Answer]
It's the difference between **scale** and **scope**.
In cartography jargon, **"scale"** is the ratio between the actual size of something, and how it appears on the map.
If a road is 10 km long in real life, and is 10 cm long on the map, then the scale map is 1/100,000 times the size of the real world. The scale is 1:100,000.
If the road is 20 cm long, then it is 1/50,000 times the size of real life, and the scale is 1:50,000.
1/50,000 is a larger number than 1/100,000 (it's twice as big) and so we say it's a larger scale.
In everyday speech, however, we tend to use "scale" to refer to the **scope** of something. And in this sense, a map that covers a larger area has a larger "scale". This is where the confusion comes in. To those unfamiliar with cartography or geometry, the "scope" meaning seems more natural but for those trained in the field, the more precise use of scale to mean the scale ratio is normal.
Cartographers do have another term, "extent" which means how big the area covered is, along with where it is. This is closer to what non-cartographers usually mean by "scale".
] |
[Question]
[
A large ring gate appears on Earth that leads to other planetary bodies that vary between being able to sustain human life and just barely allowing humans to exist on the planet for a while.
Another sentient lifeform exists on the planets. The quick and dirty is that they are only capable of moving and living on a sludge-like liquid. If the sludge is in high enough concentrations, the local atmosphere is saturated with particles that are toxic to humans but beneficial to these organisms.
Most importantly, advanced digital computers simply do not work. Either bringing a computer from Earth or building one natively on a planet yields a machine that either doesn't turn on or is inconsistent in operation at all times. Note that this is in reference to advanced digital computers that explicitly use a lot of software. Something like a smartphone isn't going to work. Things like calculators, and some digital computers that use lower-level software work (think pre-2000/late 90s). Analog computers work planet-wide. However, machines that make use of heavy/high level software (ie. levels above say assembly or C) don't work. Note that not "working" in this case doesn't have to mean that the machine is frying itself. It could mean something as simple as a computer is always giving wrong or erroneous output.
**What is causing my advanced digital computers that rely on advanced software from working planet wide when simpler analog and digital computers work?**
The goal here is to stop advanced software-based machines and solutions from ever working on such planets. Things like AI based drones or automated machine learning based factories are impossible on such planets. A planet wide internet network that mirrors ours today is impossible. The cost of human labor in settling the planet, economic, and military sectors is a major point for the setting. Computer technology resembles that of the pre 2000s ideally due to the effects.
**Somethings that might help form an answer:**
1. There is significant radio interference due to properties of the atmosphere and clouds. Long range communication is done through wires. Short range communication can be handled through radios.
2. The organism on the planet that utilizes the sludge releases a particle that can interfere with radio waves. Killing off massive portions of the organism and sludge throw up particles into the atmosphere that impact weather. But they're manageable for humans. An answer can utilize or even add effects to the particle if need be.
3. There are minerals, particles, biological compounds and elements that are completely alien to Earth.
[Answer]
**Your sludge emits radio noise**
Computers are compliant with FCC 15 that states "accepts all interference, including those that may cause undesired operation". So in order to make a modern computer unstable, you only need to provide interference on its data lanes strong enough to cause random bit flips. It can be done in numerous ways, one of them is actual communication in radio by the alien lifeforms, which could require them to produce quite a power in order to be heard at a distance. This alone could cause enough interference for computers to fail. Calculators would still work to a degree, because they process data faster (in fewer steps) thus less possibility for a data corruption, yet the calculations should be verified anyway.
**The particles in the air are fissile/unstable**
Another way to cause random bit flips is high radiation, this works due to modern RAM chips having a very small area designated for a single bit, thus a collision of a random high energy particle with a chip will either break that storage cell or randomly set the value (0 or 1) inside, probably leading to "bit sticking" problem known to aerospace engineers. Either way, simple computers could plain break from the amount of charged particles that are the result of alien particles' fission.
**The magnetic field on the planet is absent or too weak**
Kind of self-explanatory, without Earth's magnetic field whatever solar flares would cause massive radio bombardment; there were even events, historically, that penetrated Earth's magnetic field disrupting communications, inducing voltage peaks on power lines, up to destroying some weaker parts of telecommunication systems of that time, though not exactly "modern computers". Calculators survive due to not requiring an external power supply and also being small enough to not have enough current induced by particle flux.
**The planet's core emits heavy radiation, and sludge is just a protection layer**
This one is harder to implement IMHO as constant or semi-constant high energy radiation originating from below won't allow high-organized life to evolve, at least the life as we know it, yet you can assume that sludge appeared first as some pseudo-living substrate that feeds on radiation converting it into usable energy gradient, so life could emerge within while being protected from too much extra damage. Eventually that life should cover the entire core with this sludge, though, and humans discovering a planet full of sludge might have to plain retreat due to its overall toxicity and depth. (In fact water is sort of this kind of protective layer, both from below and above high energy radiation, but you depict sludge as non-liquid)
**Yet, all these things can be overcome**
Ye olde Faraday cage with an air lock could allow bunkered PCs to still work, any data coming to and from them could use optical media to be passed through the cage, as well as providing galvanic protection to internal communication lines, in the field various protection systems could be employed like for example ECC-based memory with fine-grained control over what cells still are working reliably and what are stuck/damaged, together with analog computers that control navigation by radio emitters, analog data channels being used similar to say PAL TV system to transmit image data, additional telecommunication protocol design to implement error control over L1, maybe more. So while initially Earth-based PCs will NOT work, eventually the humanity could overcome any difficulties and design computers that WILL work in alien planetary conditions.
[Answer]
Almost every problem can be solved by placing a computer inside a box that shields it from various things. But you could disrupt things for a short while with one simple trick.
**The entire digital infrastructure has one critical dependency.**
See this relevant [XKCD #2347](https://xkcd.com/2347/):
[](https://i.stack.imgur.com/0kuQG.png)
In building the advanced software infrastructure, your world's software developers got very complacent and built everything on top of some unnecessary dependency. You can come up with any fun dependency you want and increasingly silly reasons why it stopped working.
But here's one example:
For some reason, all software is built on a dependency that determines the time accurately (which seems reasonable because knowing the time can be very helpful). Unfortunately, it tries to ping the GPS network around Earth to do so. How could this possibly go wrong? There's always a GPS satellite in range. Especially for software applications that operate over a long range, you would always want to be able to determine the time correctly (perhaps to manage time zones). Why would anyone need advanced software infrastructure where there are no GPS satellites available anyway. So buried under mountains of critical code is a tiny dependency that requires a GPS satellite to respond, and perhaps has a very long timeout.
Now, if the GPS satellites around Earth can't be reached for any one of a number of interesting reasons (such as being on a different planet), most software probably just hangs. Depending on how poor the software engineering practices are in your world, this could take quite a while to disentangle!
[Answer]
# Non Newtonian Sludge
[](https://i.stack.imgur.com/TORT2.gif)
The planet is bombarded by radiation from its sun. The shower of high energy particles and high frequency photons damages the delicate circuits in complex computers. Simple computers work for a while because the have fewer circuits, made chunky and less delicate.
The radiation also damages living creatures:
>
> . . . just barley allowing humans to exist on the planet for a while.
>
>
>
This is why the natives live in the sludge baths. The sludge absorbs the radiation. Arnold had the right idea:
[](https://i.stack.imgur.com/mdqdt.gif)
Not only does a layer of nutritious slurry make you invisible to the Predator. It protects you from radiation so you do not get horribly scalded or mutated.
But try to put a computer in the sludge and it will overheat. There is no way to suck in cool air like a normal Earth computer. Even specially designed sludge-cooled computers fail because the sludge is like cornstarch slurry. It hardens when put under stress. To cool properly we must pump the sludge through thin tubes. But pumping it too hard makes the sludge solidify and crack the tubes in half.
[Answer]
## Angry microorganism
Your planet hosts metal-eating air-born microorganism, which specifically targets high frequency wires. On the planet, fast switching electrical field is a sign of it's natural predator, so this microorganism evolved to destroy it on sight, digging if necessary. Such microorganism would be very light, to travel far into the atmosphere and would be able to produce an extremely corrosive or hot oils, to degrade the shielding of any machine housing the sweet high GHz CPU. Any calculators with low enough frequency would not be sensed by those microorganisms.
Perhaps this planet was colonized in the past by machines and this organism evolved as a defense mechanism. Perhaps the planet is otherwise very rich in air-born nutrients as the organism can focus only on electronics destruction. Perhaps this microorganism lives in a hive-mind kind of state and the hive mind really doesn't like machines.
[Answer]
## Zones of Thought
Sci-fi titan Vernor Vinge invented something called the "Zones of Thought":
[](https://i.stack.imgur.com/V5Pu5.png)
From [the TV Tropes summary](https://tvtropes.org/pmwiki/pmwiki.php/Literature/ZonesOfThought):
>
> In the Unthinking Depths near the core of the galaxy, no intelligence is possible; in the Slow Zone, where Earth is, Mundane Dogmatic rules apply; the Beyond allows soft SF tropes such as Faster-Than-Light Travel or Antigravity; and in the Transcend, everyone is Sufficiently Advanced. Thus, as you head out of the galaxy, you see the same progression of advancing technologies as you'd expect to see over time if our technology went through a Singularity. In the Slow Zone, Vinge posits that human technological advance reached an apex with the "Age of Failed Dreams", during which it was discovered that faster than light travel, immortality, strong AI, and a few other things are impossible.
>
>
>
My point is not that you ought to explicitly copy Vinge. My point is that this kind of wildly imaginative thing, which has zero basis in our real-world science, is entirely workable. The Zones are the backdrop in three novels, at least two of which are utter masterpieces of engaging science fiction. (I haven't yet read one of them, so can't say whether it's a masterpiece.)
If Vinge can just make up a galaxy-spanning gimmick to impose narratively useful limits on technology, so can you.
[Answer]
I'm not sure how to get 90's computers, they are basically like modern computers but slower. But an idea for something that is "more like calculators:"
It isn't *just* radio interference. Good news: the planet actually has a fantastic global network! Bad news: it is inhabited by extremely advanced computer viruses which aggressively attack (Perhaps draw inspiration from Battlestar Galactica, and also Maelstrom by Peter Watts). It looks like radio interference, but it is actually [fuzzing](https://en.wikipedia.org/wiki/Fuzzing) in some sense -- it doesn't know what kind of network interfaces you have, so it is just trying everything. Assume the Virus will find and exploit any possible gaps in your defenses.
Some examples:
* All the obvious things that people find all the time; stuff like bugs in encryption schemes
* Slightly less obvious stuff like attacking your wifi and bluetooth radio, which probably have bugs in their drivers.
* Your computer probably has a microphone and/or camera, and that's probably got some software, that software probably has bugs, which the Virus will try to exploit.
* The Virus will play [Rhythm Nation](https://www.bleepingcomputer.com/news/security/janet-jacksons-music-video-is-now-a-vulnerability-for-crashing-hard-disks/) at your hard drive.
* A long trace on a PCB can be an antenna, surely we can get up to all sorts of mischief by inducing some current here and there, maybe flip some bits.
Essentially, anything which can be reprogrammed will be reprogrammed in the most malicious way possible.
The Virus doesn't have the ability to emit an infinite amount of power, so simple communication schemes like a sufficiently powerful radio with some kind of truly random frequency hopping (coordinated beforehand on Earth) should still work.
Your humans might develop simplified computers which store their programs in read only memory (programmed on Earth) and don't have any network interfaces. Minimal data will be stored; any state which accumulated over more than a couple cycles will be regarded with suspicion as bits may have been flipped.
Likely your humans will also want to take sensor readings and process them. These sensors are an opening through which the Virus will attack, so whatever the sensors feed into will be scrutinized. Maybe they will feed directly into hardware combinatorial logic (no memory to corrupt or general purpose computers to try and infect). Or if they must feed into a computer, it will be as simple as possible, the computer and any programs run on it will need to be [formally verified](https://en.wikipedia.org/wiki/Formal_verification) and robust against flipped bits.
[Answer]
**Toy around with the quantum realm**
What if some quantum rules/parameters are slightly different on those planets?
Modern CPUs and other chips are made with high component and trace density, so compact that quantum rules definitely have a say in whether the chip works or not.
One obstacle that has plagued chip manufacturing for a long time now, is the fact that electrons can jump from trace to trace prvided the right (or rather, wrong) conditions are present.
Slightly different (possibly localized) quantum rules can easily throw something as complex as a modern CPU out of whack - either producing different results or disabling/frying it outright.
Earth could be in a "sweet spot" concerning these quantum rules, but other planets - including "Sludgeworld" has some twisted parameter that doesn't allow for working computers if, say the CPU, is produced with a fine enough manufacturing process.
Result: On "Sludgeworld", anything more advanced or recent than around a Pentium III (late 90's CPU) wouldn't work. That will affect pretty much any computer technology after that era, including smartphones.
Older or simpler technology (including cheap calculators) would work fine, however.
This could be extended to other worlds in the "ring gate" network as well. On planet A, nothing more advanced than a C64 would work, while on planet B, they could have the ability to make even more advanced electronic CPUs than on Earth.
It can positively or negatively affect the inherent tech level of the different civilizations, or produce effects/non-computing tech that seems almost like magic.
Some things, humanity may be able to overcome (eg. by developing photonic computer technology), and various aliens (including the "gate builders") have overcome or exploited these quantum effects in different ways...
[Answer]
>
> What is causing my advanced digital computers that rely on advanced software from working planet wide when simpler analog and digital computers work?
>
>
>
You want PCs from 90s to work while modern ones should not.
The main architectural difference that you may use for your purpose is the different process size of the CPUs.
For instance an [i486DX2-66](https://en.wikichip.org/wiki/intel/80486), production started in 1992 (my first PC by the way) has a process of 800nm.
A modern [I7](https://en.wikichip.org/wiki/intel/core_i7) has a process of 14nm.
The huge difference is relative to the size of the transistors of the CPU. Of course the smaller the transistors the more of them you can fit in a square centimeter.
There are many advantages in the miniaturization of transistors, less power drain, less heat but most of all more transistors in a chip means faster computing.
Unfortunately the smaller the transistors the more prone they get to be switched by ionising radiation, causing the CPU to be set in an inconsistent state by
**COSMIC RAYS**
This is not an Ed Wood's story, it's real.
[BBC - The computer errors from outer space](https://www.bbc.com/future/article/20221011-how-space-weather-causes-computer-errors)
>
> What causes this variation? Two factors are important. The first, as already mentioned, is altitude. The higher a location is above sea level, the less atmosphere exists above it to shield it from cosmic-ray showers.
>
>
> Why, then, does Leadville experience more cosmic rays than La Paz, which is higher? This is where the second factor comes into play. This is something called 'geomagnetic rigidity', the minimum energy a cosmic-ray particle needs to have to penetrate to sea level at a given location. This depends on the geometry of the Earth's magnetic field which, apart from the atmosphere, is the principal determinant of cosmic-ray impact at ground level.
>
>
>
[Nature - Cosmic rays and computers](https://www.nature.com/articles/news980730-7)
So, you see, you have three elements you can play with that could fit in your story: the intensity of the cosmic rays reaching the planet, atmosphere of the planet and its magnetic field.
So unless the PC is duly protected (underground, under tens of meters of rock) modern hardware is not going to function.
Computers like the 486, 386, Amigas, ZX Spectrum, Commodore 64, Arduinos are going to work.
I think I would like your world.
[Answer]
# Vespene Chlorine gas
The particles in the air that interfere with humans and computers is chlorine. Pure chlorine is a gas that is extremely lethal to humans and will damage anything made of silicon and many metals really fast.
Even if the concentration is low, it will be a pain. It will react with moisture in the air to form hydrochloridic acid, a.k.a. muriatic acid. It is a common household item that you can use to clean stuff. It can also burn your eyes, make it very hard for you to breath and in large enough concentrations some of it may become chlorine gas again. It can also damage computers.
By the way, mix one part muriatic with three parts sulfuric acid to make something that can damage even gold alloys. Fun stuff, but your chemistry teacher might hold a grudge for years, so don't do it in your school lab. So maybe thw monsters secret a lot of sulfur.
Say humans try to clean up the chlorine by throwing a lot of sodium compounds around. Now you got a very strong brine. Brine is usually healthy for humans, but the amount of sodium you will need probably means you will damage the ecossystem and your own gear in other ways, possibly explosively. Electronics also hate brine with a passion as it is a matter of time until something shorts. My cell phone is water resistant but in some beaches I've been to it kept complaining about moisture being detected in the USB port, even though it never touched any water.
You can make a device that resists brine by making it water **proof** (not just resistant), but even a scratch may be enough to undo that.
Brine also greatly accelerates natural rusting. In my home city home appliances don't last as long as mostly everywhere else. So it may be that not only computers have a hard time working, it is also hard having a infrastructure to support them there (facilities and power stations, for example).
You might say that this is just an engineering problem. It may be that the problem is implementing a server structure in place when venomous aliens want to kill you. Take a page from Starcraft Terrans, who could never build on Creep (a substrate used by, you guessed, venomous aliens).
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[Question]
[
I'm working on creating a pre-industrial culture of tundra-nomads that herd large, yak-like beasts with large bodies and thick wool, but I'm having trouble figuring out what their clothing would look like. They would definentially have to be warm enough to allow them to survive through the cold temperatures of the long winter, probably by implementing the wool provided from their creatures, but I'm not sure how it would look or even function for a people who have to do a large amount of physical activity. Any answer helps!
[Answer]
**Herd Beast Hide Coat**
[](https://i.stack.imgur.com/gmWi2.jpg)
The above is a Sami Reindeer hide coat. The Sami are a nomadic people who traditionally herd reindeer in Northern Scandinavia.
[](https://i.stack.imgur.com/Ae8kF.png)
Of course there are also less rugged traditional wear. Perhaps something like this was worn under the parka and around the house.
[](https://i.stack.imgur.com/NWzp5.png)
I cannot tell you how much of the above is actually traditional and how much is "for the tourists". But it is a starting point to start researching for yourself.
Certainly a reindeer hide coat sounds like good weather protection. But it is stiff and waterproof since you have the reindeer skin and not just the fur coat. So you need something less hairy to wear underneath.
Also check out the Karelians, the Native Americans/Canadians, and the Nenets people in North Mongolia.
[Answer]
A useful technique is layered clothing. Basically, several thin layers of clothing can keep a person much warmer and be much more flexible than one big layer of equal thickness. You can have them wear soft down shirts, or vests under knitted sweaters, or doublets under hide coats, or ponchos, or what have you. Use whatever fits your culture.
[Answer]
**Model your clothes on the Tarim mummies.**
Here is Cherchen man in the clothes he was buried in, 3000 years ago.
[](https://i.stack.imgur.com/UyeV4.jpg)
<https://thisbelongsinamuseum.com/mummified-cherchen-man-xinjiang-regional-museum-urumqi-china/>
But Science News has a fine description of what he actually was wearing.
<https://www.sciencenews.org/article/pants-oldest-ancient-horseman-asia-culture-origin>
>
> He sported an outfit that consisted of the trousers, a poncho belted
> at the waist, one pair of braided bands to fasten the trouser legs
> below the knees, another pair to fasten soft leather boots at the
> ankles and a wool headband with four bronze disks and two seashells
> sewn on it.
>
>
>
Let me show you those serious hard rocking pants!
[](https://i.stack.imgur.com/30BZC.jpg)
So: belted poncho, belted boots, pants with multicolor accent bands and braids to hold the legs. And headband. I am not sure why he did not have on the headband for his picture but the 4 bronze discs and shells sounds cool. I hope you are making a graphic novel!
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[Question]
[
There is a species of animal in my world with a potent venom that can cause paralysis at a specific dosage. This renders a given target unable to move for 24 hours. This venom "locks" a victim's muscles in place; after injection, the target cannot move a muscle until the venom wears off. For instance, if a target was running when injected, after the venom takes effect their muscles would "lock" in whatever position their legs/arms were when running and would stay this way for a full day.
While I am aware of neurotoxins being able to cause paralysis by affecting nerve impulses, as far as I know these neurotoxins cause [flaccid or spastic paralysis](https://www.differencebetween.com/difference-between-flaccid-and-vs-spastic-paralysis/), such as the scorpion toxin described [here](https://www.sciencedirect.com/science/article/abs/pii/B9780121852665500336). So could a "muscle-locking" toxin such as the one described above realistically exist?
[Answer]
# No
Muscles want to be in one of two states - lengthened or contracted. As you say, certain toxins or bacteria can cause spastic paralysis, where the muscles move to "contracted" in an uncontrollable fashion (see tetanus as a longer-term example), and others can cause flaccid paralysis (eg. curare), but if you're in motion, your muscles are in transition, and that state cannot be made to persist, because "in transition" is not a state which your muscles can "understand".
(Scare quotes because muscles cannot understand anything, but it is a useful descriptor.)
Muscle tension is activated/deactivated by the presence of neurotransmitters at sites in a muscle cell. While certain muscle groups are capable of isometric tension (and therefore static paralysis), the vast majority are not.
It would also go without saying that even if it were possible, this would cause death in its victims very quickly, as even if cardiac muscle were excluded from systemic muscle paralysis, the diaphragm would not be, and the victim would asphyxiate *well before* a day had passed.
[Answer]
jdunlop's answer above is a pretty solid no, but a venom produced by the body and spread via stinger that locks the muscles in either the spastic or flaccid position depending on which state the muscle is closer to could work if the venom hijacked the dragon's nervous system. This could result in an eerie effect where the muscles spasm at the moment of injection before locking in place as they go to their spastic/flaccid position.
The poison would also not affect them instantly, instead starting at the limb the venom was injected into and spreading through the body via the bloodstream. This would result in the victim doing a creepy involuntary imitation of a 'turn to stone/gold' effect as the venom spread through the bloodstream, paralyzing one body part at a time over the course of a dozen seconds or so.
The 24-hour thing is a stretch of the imagination though, as the venom would have different durations depending on the size of the victim. It would last longer on smaller victims and shorter on larger victims.
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[Question]
[
The Greek Sphinx is a mythological creature with a woman's head and the feet of a lion, which kills its victims by strangulation
While this is all well and good for a written myth, it has some glaring issues that won't do for any sphinx I add to my world
To explain, though both humans and lions are capable of strangulation/suffocation, they do it in different ways. A human will use their hands, either directly or using some sort of tool; the leonine feet of a sphinx are inelegant tools of running and slashing, with no capacity to do the fine work of human strangulation. A lion will use their powerful jaws to clamp their prey's throat; the sphinx's mouth is tiny and weak, and could not withstand constant use in strangulation
The sphinxes for my world would be smaller than lions, close to humans in size. The head is human-like, as is the neck, which is short and curved. The rest of the anatomy is leonine. Like the sphinx of mythology (and lions to some degree), they would strangle/suffocation all of their prey and victims. They would have a similar set of prey to leopards, but with a significant number of humans mixed in. I could make small tweaks to details of the body, if it is required for this strangulation
Is there some way that these sphinxes could realistically strangle or suffocate their victims?
[Answer]
**Snake for a Tail**
[](https://i.stack.imgur.com/rYeYZm.png)
Much like the Mythical Chimera, the Sphinx has one or more long scaly tails. These tails are in fact live constrictor snakes that are used to strangle the victim.
Most depictions of the Sphinx have a normal lion tail. The Sphinx likes to keep the snake tail secret as they don't want to be associated with the more beastly Chimera. So they sit (often for years straight without moving) with their tail underneath them, and only reveal it when it is time to strangle.
[Answer]
**Why the Great Sphynx lost her nose**
In 1378 CE, Muhammad Sa'im al-Dahr destroyed the Great Sphynx' face, and most modern scholars always assumed only her nose was cut off. But if you look at the damage closely, the eyes as well as the nose are gone. This was because Muhammad Sa'im al-Dahr, upon discovery, was captured by her seductive talents. As a pious muslim, Muhammad regarded the statue as *haram* for that reason. He cut the face, destroying the eyes and the nose.
**She's absolutely fatal**
When you encounter a sphynx, or a well-crafted statue of a sphynx, she will hypnotize you. The face is so beautiful, you'll get hypnotized, you'll keep looking at her.
The life sphynxes that existed in the age of pharao Khafre used this talent to approach a prey closely, and *freeze* it. While the prey is hypnotized, it will keep staring at the sphynx, into her beautiful eyes, exposing its throat, without any defense.. The sphynx would strangle the victim, by leaning on the throat, or slash the throat with her claws.
<https://www.history.com/topics/ancient-egypt/the-sphinx>
<https://www.smithsonianjourneys.org/blog/photo-what-happened-to-the-sphinxs-nose-180950757/>
[Answer]
This problem is solved by ART:
| [enter image description here](https://i.stack.imgur.com/KoWfF.jpg) | [enter image description here](https://i.stack.imgur.com/lieqZ.jpg)[enter image description here](https://i.stack.imgur.com/T0r6g.jpg) |
| --- | --- |
The depiction to the left is that of a sphinx (Gustave Moreau's *Oedipus and the Sphinx*), those to the right are symbolic representations of nightmares (Daumier's *Horse Meat is Healthy and Digestible* & Füssli's *The Nightmare*, resp.) (I thought I remembered seeing a combination of the two, but I might be mistaken).
**The sphinx suffocates by burdening her victims.** This can be done both physically and psychologically.
This is not at all surprising, given the [etymology](https://www.etymonline.com/word/sphinx) of the word '*sphinx*':
>
> "*In English from early 15c., from Latin Sphinx, from Greek Sphinx, **said to mean literally "the strangler,"** a back-formation from sphingein "to squeeze, bind" ([ref.] 'sphincter')*"
>
>
>
[Answer]
A big cat like a lion or leopard could easily suffocate a human with only its paws. It could pounce on a person’s back and pin them to the ground as it put all of its weight into the back of the neck, which would quickly lead to unconsciousness and death
[Answer]
**Claw power**
It can give a powerful blow with its claw on neck or spine of the victim, which will make the victim unconscious. Then it can drink the blood from the neck.
**Jump from height**
It can jump on the victim from a tree or stone with nails piercing the body of the victim.
**Strong hit**
It can run fast and hit the victim with great force.
[Answer]
I think the key here is in your use of the term "human-like", in your description of the "sphinxes for [your] world".
Compared to real-world big cats, yes, human mouths and jaws are both tiny and weak. But jaw strength is not a significant issue here. A normal human jaw can produce something like 125 pounds of pressure, but it takes only about 11 pounds of pressure to stop blood flow in the carotid artery. (I accept my numbers might be somewhat off, but not enough to change the results)
So the strength is there. What about size? Here's where the "human-like" comment pays off. You're obviously already mixing and matching biology here, so why not make one last tweak, that doesn't have to have any outwardly visible indicators? Just make the Sphinx' jaw have a wider range of motion than a real human jaw. Slightly stretchy-er skin around the sides of the mouth (need not be noticeable when not actively being stretched), and similarly unnoticeable small subsurface adjustments to jaw muscles and bone connections, and you have the appearance of a human, but a gaping maw when needed.
Finally, what about holding on long enough? With a lion body (and presumably at least somewhat comparable, at least proportionally, muscle strength), I'd think the strength and claws would be more than enough immobilize prey long enough for them to lose consciousness.
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Lets say that you have a wormhole where both ends are attractive. Here an object starts far away from rest, accelerates towards the wormholes mouth, travels through the throat at a small fraction of light, then come out the other end and decelerates as you travel away. Now lets say someone "clogs" the wormhole by dumping lots of matter into the wormhole through both ends at once, resulting in the matter staying inside. This would make safely travelling through the wormhole impossible as any ship that passed thorugh would burn up like a sattelite falling from orbit. How would someone "unclog" the wormhole and make it safe to travel through?
[Answer]
**Dump antimatter "cleansing agent"**
Provided you can accurately measure how much matter is clogging your wormhole, you just need to add the same amount of antimatter. The two will annihilate, and the resultant gamma radiation will escape the wormhole leaving it nice and clean.
**Flush it out**
Alternatively just giving it a good relativistic hosing down with regular matter may do the trick too: part of the momentum of the additional material will be transferred to the matter clogging the wormhole and bring it out to a distance where it can be captured. Repeat the process until the wormhole is sufficiently clean.
[Answer]
Using extremely high powered lasers to vaporize the materials and blow the gas into space. Or using some kinetic projectile to push or scoop out the material, pushing it to over the wormholes escape velocity.
[Answer]
## A shovel
Assuming the matter itself is just space rocks and dust, you can just shovel it into space. You just need to fling it at at least the escape velocity of the wormhole. (This should be done by robots, obviously.)
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In the SF/post-Apocalyptic world that I'm building, the Earth is struck by interplanetary EMP bombardments that destroy most electronics. The year is around 2040~50, and the tech level is bumped back to late 19th c. and wars ravage and crumble civilizations due to lack of resources.
I initially considered the possibility where the Sun undergoes a strange plasmic transformation, emitting series of X-class EMP bursts much more frequently, but I'd like to ask if there could be more **likely space events** (e.g. EM ray from distant galaxy striking either the Sun or Earth, Earth's magnetosphere depletion causing ordinary solar flares to cause greater havoc, severe CME storms etc.) **that can** **cause regular EMP bombardments that permanently make the production/maintenance of electronics severely more difficult on the Earth's surface.**
In the world, biotech had developed before this global EMP event, allowing production of artificial organisms in shielded locations. So I'm trying to build a plausible world where biopunk tech replaces the current-world electronics tech due to EMP bombardments. Machines/electronics do function in shielded environments (e.g. Faraday cages, underground/water facilities), but can't function on the surface unprotected, necessitating biotech.
(I've looked into the Revolution TV series in which nanites cause a permanent blackout, but I'm not considering that tech or any artificial EMP strikes)
Thank you in advance
[Answer]
Handwavium, right? Like, lotsa handwavium, but with a plausible mechanism.
[IK Pegasi](https://en.wikipedia.org/wiki/IK_Pegasi) is a binary with a secondary 1.15 M☉ white dwarf and A-type main-sequence star primary. They circle each other in a close enough orbit with only 21.72168 days as period.
Moreover, the primary is a [Delta-Scuti variable](https://en.wikipedia.org/wiki/Delta_Scuti_variable), with an actual metallicity ratio of 1.17, about 17% richer in metallic elements than the Sun (so, maybe a tad older than the Sun)
Handwaving it accordingly, if you make the primary going a red giant, the system can become a [cataclismic variable binary](https://en.wikipedia.org/wiki/Cataclysmic_variable_star) - in which the progenitor's mass form an accretion disk and falls into the white dwarf until the later bursts in a [recurrent nova](https://en.wikipedia.org/wiki/Nova#Recurrent_novae). It is plausible to happen in the near future, Wikipedia lists them among [near Earth future supernovae](https://en.wikipedia.org/wiki/Near-Earth_supernova) ("as little as 1000 years" they say).
Because the two Pegasi are pretty close one to another, it just (handwave) happens that the periodicity is exactly 1 year and the effects happen on Earth just when the Sun, Earth and the two Pegasi are aligned. Periods that short aren't common in Milky Way, but it happened in the yard of our neighbor, Andromeda, with [M31N 2008-12a](http://www.sci-news.com/astronomy/nova-super-remnant-andromeda-galaxy-06810.html), which went for millions of years and created a super-remnant of size in 100pc range (300+ ly).
So, Ok, the radiation of the nova explosion is not felt so intense at the IK Pegasi distance (154 ly and its a nova explosion, not a supernova, with an intense shock rich in gamma rays), however the super-remnant is made of highly ionized gas and it will (handwave) increase the amount of ionization in Earth ionosphere by quite a lot. Even without the Sun being "angry" and [throwing its crown](https://en.wikipedia.org/wiki/Coronal_mass_ejection) everywhere at that moment, but an influx of charged particles in ionosphere will create new [radiation belts](https://en.wikipedia.org/wiki/List_of_artificial_radiation_belts). Nukes with just [a couple of kilotons exploding in near-space during the Argus operation](https://en.wikipedia.org/wiki/Operation_Argus) established a radiation belt lasting for weeks and "damage or destroy arming and fusing mechanisms of intercontinental ballistic missile warheads, and endanger crews of orbiting space vehicles... degrade the reception and transmission of radar signals".
Scale up, with a new front from the super-remnant arriving each year, lasting over times spanning of few weeks, and *impacting the whole Earth surface*.
If you still don't think that's enough for the "yearly EMP", handwave some side effects on the [Solar activity cycle](https://en.wikipedia.org/wiki/Solar_cycle), with the coronal ejection more probable in the direction of incoming ionized super-remnant, due to the [magnetic lines reconnection](https://en.wikipedia.org/wiki/Magnetic_reconnection) being enhanced by the "interstellar current" flowing in. One decadal [Carrington event](https://en.wikipedia.org/wiki/Carrington_Event) should keep the things at bay in regards with the use of electricity and electronics.
Bonus point if, during the yearly "global ionization fest", the super-remnant delivers to Earth a trace dose of extra radioactive elements, sprinkled over the entire surface of Earth and [flipping memory bits](https://www.johndcook.com/blog/2019/05/20/cosmic-rays-flipping-bits/) 1000 times [more frequent than today](https://en.wikipedia.org/wiki/Soft_error#Causes_of_soft_errors) ("Internet's DNS system... up to 3,434 incorrect requests per day due to bit-flip changes for various common domains.") *all year around and increasingly so every year*.
[Answer]
Q: *"regular EMP bombardments that permanently make the production/maintenance of electronics severely more difficult"*
A yearly EMP needs not be so big, to make production difficult.. some black hole far away, wagging its plasma jet\*\* tail in a certain direction.. Earth travels through it every year.. refer to Adrian's answer for the options.
For me and my fellow computer programmers, these small, yearly EMP's pose an issue ! we will get the blame, when *our* bits start flipping. Bet it does not take that much cosmic energy, to organize subtle, annual ionizing events, resulting in *slightly more* say order 10e3 more flipping bits than usual. Everyday humanity will hardly notice these EMP's, computer users will.
It could already be happening.
Usually, the bugs pop up in September and computer programmers get fired in the first week of October. Most of the "bug fixing" is done in India, because India is not affected by the EMP's ?
==========================
\*\* ref. ChristopherJamesHuff comment below, indeed Hawking has nothing to do with it, the "tail" I referred to is the jet of plasma emerging from the rotational center of the black hole <https://en.wikipedia.org/wiki/Astrophysical_jet>
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In the distant past, Water was a world much like Earth--but all of its continents have been eroded away, such that its surface is entirely covered in, well... water.
While many of Water's ancient inhabitants went off and colonized the stars, two technologically-regressed groups still live there: the People of the Water, who live on top of the water and breathe air, and the People of the Land, who live on the land; that is to say, *under* the water. Millions of years ago, the progenitors of the People of the Land genetically engineered themselves to be able to survive in their changing world as *dry* land became more and more scarce. They are regionally endothermic, keeping their central nervous systems and core muscle groups warm but not wasting energy regulating the rest of the body; they have bioluminescent patches to produce their own light to see by in the deep regions; and they can survive on fermentative metabolism, ultimately producing CO2 and methane waste, for a long time.
(The People of the Water are partially designed as well, just in different ways from their land-dwelling cousins.)
But, oxygen is still really nice to have, and anoxia, while survivable, is not pleasant! They live full time *on wet land*, rather than *in the water column*, so regularly surfacing to breathe air like the People of the Water do is not an option. So, given that they have a basically-humanoid head and upper torso (so not a lot of room for gill slits in the neck), with tool-using arms and hands, and that, while evolution has had time to change them, they were initially *engineered*, what would be the most effective way for them to get oxygen underwater?
[Answer]
**External gill hair.**
[](https://i.stack.imgur.com/Gzvnk.jpg)
[image source](https://marvel.fandom.com/wiki/Medusalith_Amaquelin_(Earth-616))
The external gills have the entire length of the body to hang down, and minimally encumber the humanoid. Augmenting blood flow to the head is no huge ask - the head has 4 big arteries supplying it already and gravity can help with the venous return of oxygenated blood.
Plus all that red gillage is a rocking look. But be careful with the comb now. That red is blood, and it is close to the surface.
[Answer]
Body hair can be used as exchange surface for breathing.
Considering that on average a human body has a surface of 1.8 $m^2$, or 18000 $cm^2$, with an average hair density of 100 $cm^{-2}$, assuming a hair diameter of 1 micron with just 20 cm long hair one could get an exchange surface of about 110 $m^2$, as compared with the 70 $m^2$ of a land human.
This would reduce the risk of suffocation, since it's more difficult to have the whole body not exposed to fresh water or accidentally hair trimmed.
[Answer]
**Through the lungs**
I see no reason why we need to change the full body plan. We can make due with what us there and adapt it.
If we try to just submerge us and use gills in the lungs, we'll suffocate. Water hold much less oxigen than air, so we would need to take in more water for the same oxigen. That alone is already enough to kill us, but it isn't all. As water is much more difficult to 'breathe', you'll also exert much more energy for each breath. It would be like doing a full marathon of effort, just to breathe normally.
To improve this, we can start with making the lungs more fish like. Fish gulp a mouthful of water and force it along the gills. I didn't find exactly why they force it, but I suspect good gas exchange between the blood and water only happens well if water flows past fast, as it'll be saturated quickly. If we gulp down water, we can force it out at gills at the lower end of our ribcage. This both increases the throughput of water, as the exit is close to the surface, and decreases the amount of energy wasted by forcing it through a long tube twice. If we follow this further we can decide to have gill 'inputs' closer to the lungs on the ribcage. This does pose difficulties for how the ribcage is constructed. In addition, biology normally reduces the amounts of orifices, as each orifice is an extra area susceptible to infection and such. We can still see that where needed more holes are available, like gills with fish.
If we're already upgrading the ribcage, you could look at a way to breathe separately with each lung. That way you always have a flow of water, letting your beings be oxygenated more equally at all times.
**Advantages and disadvantages**
Compared to lets say gill hair you have many advantages. The active process makes sure you don't suffocate. Gill hair on the head or body is passive, making it possible that the person will draw the oxigen out of the oxigen in touch with hair and then it isn't replenished, making them suffocate. This can happen during sleep or when doing stationary (heavy) tasks. Even some movement isn't going to help. If this was the case, fish would do it.
The energy needed isn't too high, as you have many gill slits close to the lungs make sure the flow is as easy as possible. This resembles fish breathing more closely as well, which have had many millenia of evolution to come up with good breathing methods under water.
The ribcage needs an overhaul. The gill slits will make the workings of a ribcage or similar more difficult. Possibly they can be installed front and back just under the ribcage. This requires a much smaller amount if work, doesn't interfere with the muscles used for breathing and only marginally increases the length of the tubes to the lungs as well as decrease the total draw in size of the holes.
The lungs can possibly be more flat, allowing for better musculature. This is as volume is less important than flow over the gills.
If the adapted lungs are asynchronous, the oxygenation of the blood can happen more homogeneous. Compared to spikes in oxygenation of the blood this can have many small health benefits over long times.
The fish people do require no clothing at the gill holes, but as they are regionally endothermic this isn't too much of an issue. In addition, the temperature at a certain ocean layer is also very stable, so they are likely evolved to withstand such temperatures.
[Answer]
# Farming
While getting air from the surface is not an option, the surface is far from the only place with air
Regular humans need around 0.84kg of oxygen every day. Water can have at most 20 mg/L on Earth, and gills can extract up to 75% of the oxygen in the water. This means that, based on what real data we have, your humans will need to extract oxygen from 56000L of water each day, or about half a litre per second. While this seems like a lot, they don't have to do it themselves
This figure we have extracted seems rather reasonable when spread across several sea-creatures. A fish, with a properly designed swim-bladder system, could extract enough oxygen to create a rather good oxygen mix, which they could then put out into some sort of collector in which the humans could go to breathe
The humans would still need adaptations for holding their breath like whales and manatees, if this system is to work. They would also benefit from some sort of gill. Such a gill would best be fish-like, on the 5 pharyngeal arch in the neck, and would have the form of a gill pouch in the neck that opens somewhere in the pharynx and empties out of the sides of the throat.
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In death a new beginning is certain, for the jaws that bit my flesh will suffer a tragic end and no amount of laments or tears will ease the pain.
My blood will flower and fruit inside their bodies, growing a new me inside of them.
My killer, who violated my body and soul will also be the nest of my children, so they my avenge me as they ironically burst out leaving a carcass of what was once my violator.
I can also reproduce sexually if my social fitness allows and if the opportunity arises, yet my blood is capable of producing new offsprings when I'm being eaten by another creature. How is this possible?
[Answer]
Within your bloodstream flow several thousand dormant pluripotent pseudo-morulas. They can't stay dormant forever, of course, but the original produces more periodically as the older ones perish. Low-doses of some suppressant hormone keeps them in check.
However, when eaten by some wild animal, your flesh is present within their mouths, where any number of ulcers and lacerations are present... enough for one of these to enter their bloodstream. These migrate to some part of the body (abdomen, most likely) where it uses that same blood vessel to supply itself with nutrients.
In addition to using the same tricks that most parasites use to trick the host immune system, it also induces various pregnancy-like hormones to cause the host body to be a more amenable environment. Unlike pregnancy though, the developing clone doesn't gestate in a way that will preserve the viability of the host... in fact, since this organism is a confirmed predator of the species, if the gestation kills the host that's just good strategy. The host eventually withers away, unable to move, hunt, or care for itself... just about the time the clone is ready for rebirth.
[Answer]
Covid has made the knowledge about RNA viruses prolific.
So far, however, the viral mRNA process seems only to spur the host infected cell to make copies of just the virus proteins itself, or of specific proteins. They are single-strand RNA.
Should a 'virus' system evolve such that the entire genome of the original creature be encapsulated in a multi-strand RNA virus package, this virus could conjecturally result in the virus causing the infected host cells to produce entire stem cells. These stem cells would then be fully functioning 'clone' cells that would grow in the petri dish of the new host, surrounded by nutrients, resulting in clones of the original creature.
The cells of the original creature, of course, would have evolved defence mechanisms that prevent the viral RNA from hijacking the cells in their own body.
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In my fantasy setting there is a species of merfolk who live in the ocean. They have hands with human level of dexterity and can live completely underwater.
I would want to ask a question about what kind of houses merfolk would be able to build, and how they would be constructed and kept in place.
The merfolk have contact and trade with a nearby human civilization who are technologically as advanced as mediterranean civilizations during classical antiquity, the 500s B.C., however most materials traded from humans are available to the merfolk "upper classes" while the lower class merfolk for the most part have to use materials gained from their natural environment. Finding suitable building materials underwater is difficult but I've decided that rocks and mats woven from seaweed and kelp would be one of the few suitable ones that can be made naturally. However, I'm not sure about the shape of the houses nor how such a building could be kept in place, since on land most dwellings made of rock uses cement/some kind of glue for keeping the bricks together, and that doesnt work underwater.
Something the shape of an igloo but composed of stacked rocks would make the most sense, but unlike snow, stone isnt malleable and I'm not sure if it would be structurally sound without some adesive holding the "bricks" together.
As for the roof, i'm imagining it as a mat of woven or thatched kelp laid over the walls, but it has to be tied to something so it doesnt float away.
[Answer]
## What do you use a house for?
The biggest question is: what do you need a house for? what are the social, environmental or psychological reasons for having a house? Humans have houses for many reasons, and your merfolk may have different ones. You may come to find merfolk need NO houses, or live in dorms, or use individual pods. Form follows function, so ask why they have houses.
* **Humans have houses to protect from the environment**, but anyone dealing with depths is likely to be more temperature-tolerant. But merfolk may need temperature-controlled environments for special functions like reproduction or child-rearing. Places may need to be sheltered from currents, or create still areas where debris can settle out of the water for whatever reason. The nature of water makes temperature control tricky if water can circulate. I don't know what heat sources merfolk might have, but keeping spaces warm might involve considerable complex engineering.
* **People want houses to protect from violence**. That might mean saltwater piranhas, giant octopi, or rival warring merfolk. the shape of the dwelling will be defined by what it is you are trying to keep OUT. Fine woven mesh protects from small things, while huge stone spikes might be needed to keep out a Kraken.
* **Humans use housing for privacy**. They live close to other people, but don't want others to watch them all the time. For visual privacy, simple woven mats might suffice. Sound travels oddly in water, so soundproofing might look very different for merfolk. The bigger the community, the more merfolk might not want strangers staring at them. If merfolk evolved as nomads and live now in cities, pretending your neighbors AREN'T next door might be crucial. Or, maybe they have no privacy in families but keep out strangers. Do your merfolk value secrecy? Do they commit crimes, defy the government, or live in communal utopia? Do the rich merfolk want to conceal their wealth so as not to anger others?
* **Humans use houses to store stuff they don't want lost/eaten/stolen.** Keeping resources contained is an undervalued thing. Do your merfolk steal? Do fishes sneak around trying to eat their food? What kind of threats do you need to deal with for your stuff?
* **People want houses to show off.** Perhaps rich merfolk build houses out of stone because it's difficult, not because of practicality. Keeping up with the Joneses is a big deal, and if you're from a rich family, you might be more reproductively successful. Or merfolk may desire to impress humans, despite not caring for houses themselves. They may want houses because they imitate humans whom the perceive to be rich, successful, or influential.
* **Houses are places to interact in controlled environments**. Do your merfolk mate publicly? privacy for mating could be important. Do they need someplace to contain sperm so it doesn't randomly impregnate strangers? Do they invite humans over? If so, dry or semidry parts of a home are crucial. A half-flooded top floor could be a hosting place. Do they have special work functions (like smelting on the surface, while sitting protected from heat in the water)? This will radically affect how these places are shaped.
**Materials**:
People build first with what they have, then with what serves the function. Chipping stone in an aquatic environment might be a high-resistance task, but saws would have continuous cooling. Metal tools could be expensive or tricky. Wood often rots more slowly in the water, but could be expensive and vulnerable to parasites. Growing corals and plants to fit needs would be an elegant solution to many problems, but your merfolk would need a fair amount of biological technology to do so. However, given an understanding of selective breeding, they could guide various types of mangroves, corals, kelps, and the like to do their bidding.
Shells might function as direct components of walls, OR the calcium carbonate could be used for some type of cement. Perhaps the glues used by some kinds of clams and barnacles could allow walls to be grown from these organisms, or use these organisms to bind together other hard materials into solid structures. A barnacle bred to glue things on multiple sides could be the binder for hard material in the environment, from shells to loose stones. Then the irregular parts get filled in with whatever is available.
**Design:**
Your merfolk might extend home up to the surface, and then have no roof. homes might even be hanging down into the water from floats, like curtains weighted with stones or shells. A home then becomes mobile or even migratory like a ship, as needed. Such houses would need an anchor when staying put. If moving against the current but with the wind, sails could be used to guide the house. You could even use them to alternate direction, 'sailing' your town back and forth to keep it in place or following harvests.
I'm guessing due to buoyancy, a lot of the structures would be made of seemingly flimsy materials like kelp. Flexibility might be more important than strength. Solid structures make more sense to keep out predators like sharks and sea monsters, but a lot of big things aren't going to push through barriers they can't see through.
[Answer]
**Wood.**
[](https://i.stack.imgur.com/bFL8J.jpg)
<https://brightside.me/wonder-curiosities/20-unbelievable-sunken-ships-people-completely-forgot-about-128505/>
Wood is great stuff to build a house with, on land or in the sea. Maybe even better in the sea because it wont catch fire, although there are shipworms to worry about. Once wood is waterlogged it sinks. The wood of this ship is 500 years old and I think I could make a fine little shack with it. There is a lot of wood on the bottom of the sea. There is even a vogue lately for [bringing up those huge old trees that have been underwater for centuries](https://brunerlumber.com/sinker-cypress) and building with them.
You would need to anchor the wood. That is true on land too! Anchor it with stones, as one does.
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Given the following graph: ,
Relations exist among the escape velocities, molar masses of gases and the masses of natural planets and satellites. Is there a general math formula where inserting a molar mass of a gas, mass of the celestial body and generating the boolean whether the gas can stay inbound of the body?
For what it worth, the graph shows a xenon atmosphere would have retained on top of Lunar. Even if radioactive Xenon poison from nuclear fission reactor gives away their neutrons to become stable isotope and is released at the moon or an intrinsic Xenon atmosphere would be possible, humans would have mined such precious Xenon resource.
How about Krypton?
[Answer]
In general, you want to compare some characteristic [thermal velocity](https://en.wikipedia.org/wiki/Thermal_velocity) $v\_{\mathrm{th}}$ of a gas molecule with the escape velocity of the planet. There are different choices you can make, all within a factor of 2 or so of each other. I tend to take
$$v\_{\mathrm{th}}=\sqrt{\frac{3k\_BT}{m}}$$
where $k\_B$ is Boltzmann's constant, $T$ is the atmospheric temperature$^{\dagger}$ and $m$ is the mass of a single molecule. If $v\_{\mathrm{th}}\gg v\_e$, where $v\_e$ is the escape velocity, then most of that particular gas will be lost to space. If $v\_{\mathrm{th}}\ll v\_e$, then most of that gas will be retained. In the regime in between, where $v\_{\mathrm{th}}\approx v\_e$, you'll get a result somewhere in the middle; I believe a rule of thumb is that [if $v\_{\mathrm{tm}}\gtrsim v\_e/6$](https://www.sfu.ca/%7Eboal/390lecs/390lec9.pdf), most of that gas will be lost over several billion years.
As gases follow [Maxwell-Boltzmann distributions](https://en.wikipedia.org/wiki/Maxwell%E2%80%93Boltzmann_distribution), obviously not all particles move with $v=v\_{\mathrm{th}}$, so you'd expect some amounts of each gas to escape and some amounts to retain. It's impossible to say that all molecules of a particular gas will escape, but you *can* determine whether the *majority* of the gas will escape or be retained.
I should note that the above assumes the planet loses gases due to non-thermal escape mechanisms, such as the pathways by which [Earth loses $\mathrm{O}^+$ near the poles](https://science.sciencemag.org/content/291/5510/1939.full). However, thermal escape is usually the dominant mechanism, and as a rule of thumb, you'll want to follow the above recipe and just compare
$$v\_{\mathrm{th}}=\sqrt{\frac{3k\_BT}{m}},\quad v\_e=\sqrt{\frac{2GM}{R}}$$
where $M$ and $R$ are the mass and radius of the planet and $G$ is the gravitational constant.
---
$^{\dagger}$Stricly speaking, I believe that this should be the temperature in the upper atmosphere, given that the temperature varies dramatically with altitude.
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[Question]
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I have some intelligent dragons that can discharge electricity.(Lets assume they can somehow release this electricity through contact with an object/animal when outside the water, as air is of course not a suitable conductor.) My question is: **Being that they they have this readily handy energy, what kind of technology could they develop that exclusively uses their discharge as the main power source?** (Or if not a power source, a main component in achieving a desired effect. We can hand wave and make it so they can produce a steady current, and realism for necessary power output isn't hugely concerning to me, as long as it isn't extremely outlandish, especially considering they are social and therefore could utilize several dragons at once to achieve something, much in the way electric eels utilize [social predation](https://www.biorxiv.org/content/10.1101/2020.08.10.244129v1.full).) Some things I was immediately curious about were induction heating, chemical reactions, and inverse piezoelectricity via [this answer](https://worldbuilding.stackexchange.com/a/201069/84593) to another of my questions on this site.
Edit: Here is some additional info that may be useful. These creatures typically live in areas with access to the sea. (Islands, costal, tropics, or even other areas with large bodies of fresh water.)They are big on ocean travel, so ship and water related technology would be heavily utilized. (They are capable of sensing electrical fields while in the water, similar to how electric eels hunt.) They would be highly motivated to harvest metals for their conductive properties, I would imagine, so mining would also be important. As for how advanced they are, I would like them to be around renaissance level technology maybe a little further. (though the change in available electricity will change progress, so things being invented sooner is fine too.) most things are still made by hand (or, claw?) but new technologies make the work for these individuals more efficient. However, because they would have access to electricity before fire, I would think they'd be more likely to make discoveries about electrical properties, meaning the progress on that front would be accelerated.
[Answer]
**Basic DC** is what they can use.
Sensing electrical potentials would make it easier to develop knowledge of half-cell galvanic reactions, especially if they used metallic rods as hunting aids. A copper and a zinc rod left in a puddle, and someone leaning against them, could be enough. That immediately leads to thoughts of **electroplating**. Coating copper hunting-rods with gold would vastly reduce corrosion.
It's also possible that (available power permitting) someone tinkering might come up with an **electromagnet**. Perhaps they're making jewellery at the time. That could be used as a **compass**, or to open a **latch**. It's unlikely that they could create practical ballistic weapons using it, although if they can sustain electric-eel power for a quarter-second, then these are surprisingly close to reachable [(calculation for lower-limit)](https://www.wolframalpha.com/input/?i=10g%20%28100m%2Fs%29%5E2%20%2F%20400W). Some capacitors might let them use railgun principles. (**Ed**: More plausible than I thought, see below.)
Recharging chemical batteries would be a **draining** process using one's own biochemical energy, though. It seems plausible that it might be developed further as a mystical process. Using **non-rechargeable batteries** could be a stop-gap until someone found a way to store the energy in the longer-term.
Electrolysis can be used for **aluminium refining** once you have certain prerequisite infrastructure, allowing for about [25g per one-second pulse](https://en.wikipedia.org/wiki/Hall%E2%80%93H%C3%A9roult_process) in an industrial setting. Difficult enough to keep aluminium worth more than gold, but you might be able to produce practical quantities with a large crew and some time. You'd probably gold-plate it to reduce corrosion. And so by accident, we've discovered why dragons have shiny hoards of gold-lookalike which is still light enough to carry off and ridiculously valuable if you do. (Other metal extractions might also benefit, Al-refining is just one I'm familiar with.)
This baseline of electrical technology also paves the way for the discovery of other effects, and a generally easier path to using electricity for motors, solar panels, and production.
---
**Edit**, having mentioned this to an engineer:
**Basic AC** is also on the table. While the mathematics which underlie transformers may not be easily accessible, an **inverter** can be made with an electromagnet which opens its own control switch. This allows **low-frequency AC** to be discovered by accident. While the AC transformer was invented in the 1880s based on the 1830s discovery of induction. But the required calculus was invented by the 1680s, and mathematical understanding isn't necessary if you can do trial-and-error, but you're stretching a bit to get it to happen.
Why is this important? With a diode (relatively easily discovered), a **rectifier** can be built, allowing you to get high-current or extra-voltage DC too.
A **capacitor** is also relatively simple to make with metal foil and paper, and allows **handheld railgun-weapons** to become practical. Or a coordinated team can fire a **cannon-sized version**, once the small-scale principle has been established.
---
Assumptions about power output:
400W, 600V, so a raw current of 0.66A per individual. Let's assume that they can sustain this for 1s. (An electric eel can do 0.002s, but these creatures are far larger and can train.)
[Answer]
**Musketeers and welders**
First, a bit of analysis. This question really boils down to "Given an anachronistic power source, what uses are there for electricity before the rest of the material sciences catch up?" So, let's look at what electricity was used for in the days of yore.
Light: This is crucial to enabling widespread industrialisation and sleep deprivation. It is great to be able to flick a switch and illuminate an area without fiddling around with igniting a substance that gives off a bit of light and a lot of noxious fumes and soot. For dragons who are mining underground for conductive metals this is an even greater advantage. However, I am slightly dubious that electric light would be easily invented by a small community of dragons - while there were light bulbs before [Edison](https://en.wikipedia.org/wiki/Thomas_Edison) invented the carbon filament bulb, it took a dedicated industrial effort and late nineteenth century manufacturing to make them economically feasible. Definitely not feasible for Renaissance technology.
Firearms. Early firearms were, frankly, rubbish. Looking at a flintlock firearm it was necessary to pour powder down the barrel, ram a ball and patch down the barrel, prime the pan with more powder, cock the hammer, aim at the target and squeeze the trigger. At this point the rifle had to be kept pointing steadily at the target for a slightly uncertain time while the spark from the striker hopefully ignited the powder in the pan (misfires were common) and the flame made its way through the flash hole to the charge in the barrel. Closing one's eyes was a good idea to avoid burns from the powder in the pan (where the saying "flash in the pan" comes from).
Now let's look at a black powder musket / rifle / pistol made for dragons. Instead of a flash hole that flame travels down, there is an insulated wire inserted and tightly sealed, with one end exposed to the powder in the chamber and the other end exposed where the trigger would normally be (but insulated from the barrel). The dragon still has to pour in the powder and ram down the ball and patch, but then they calmly aim at the target and create an arc between the trigger wire and the barrel, resulting in a spark that reliably ignites the powder. There is no need for an unreliable spark mechanism (flintlock, matchlock etc), no need for messing around with loose powder near the face that will fall out if the firearm is tipped on its side, no need for a separate percussion cap once they are invented.
As a result, until the invention of cartridges that include a primer, dragon-used firearms will reign supreme on the battlefield for reload speed, accuracy and reliability, with the same principle used for cannons on land and sea. The dragons have no concerns about anyone capturing their weapons, as they cannot be used by inferior species that cannot generate sparks from their bodies.
Welding: Welding was really difficult back in the old days, basically blacksmiths had to melt metal and bash it together. Dragons, however, can introduce [arc welding](https://en.wikipedia.org/wiki/Welding#Arc) centuries before it appeared in the real world. This will make dragon-powered welding crews a highly valued resource for constructing metal structures and for early factories. Not an especially glamorous role, but very economically valuable.
[Answer]
**Electromagnetic projectiles and simple remote communication**
By charging coils of insulated wire wrapped around long hollow tubes (e.g. rubber- and gold-dipped fiber ropes wrapped around hollow tree trunks) they could build solenoids powered by their own bodies which could shoot large iron slugs with deadly force. Teams of dragons working together could scale up the results to rival the largest cannons produced by man.
By sparking their energy they could produce simple electromagnetic signals that could be received using extremely simple radio detector technology (<https://en.wikipedia.org/wiki/Wireless_telegraphy>). Detection of such signals may even be an inbred result of evolution similar to how electric eels and knifefish communicate using electric discharges.
[Answer]
More like a comment than an answer
Will there be a difference? Not really, by definition of your constraint, at that time mechanical energy and mechanical devices were the king, and conversion of one into another is an extra step and simpler to use body or animals or water gradient or wind - the way it was done.
Maybe in everyday life, it will have some use like sex toys or medical applications as electricity is native to them, so we may expect to see some strange little quirky things. And if you like just fashion it, add some different colors to known picture it can be enough, things like that mentioned in the existing answers.
Your problem is that you try to put a square object in a round hole.
The change u introduced is so fundamentally humongous, and despite its fundamental difference in starting position, u try/expect to find some subtle changes taking the state of things at 1300-1600ac.
The difference starts, if we try to put a triangle object in a square hole, and take parallels with humankind evolution and consider the first fire to be around 1.5 million years ago, the difference in development starts before that 1.5 million years, as electricity is their native secondary power thing. (By secondary I mean humans had one - muscles, those guys have 2 forces to use and explore muscles and electricity and related things)
They sensitive to magnetic fields, it was quite a problem for humans to navigate, Columbus missed by a continent, eh. But those guys are like birds, built-in compass. Do you think it won't have a difference loooong loong before the roman empire project?
Those guys of yours out of the box capable to do magic of electrolysis, out of the box eh, thus few million years before humans even recognized the existence of electricity.
The only bottleneck for them is their intellectual capacities, if they are smart enough and under the right conditions/pressure they can develop like a rocket in conditions where humans would fail, but if they fail to use brains there is no saving for them.
All we do with electricity, this tech tree unlocked for them from the start, and the electricity drives basically everything here.
As they get on the technological road, soon after the first stone knife and discovery of conductivity there is no stopping for them, after they discover conductivity in metals it is a snowball. But at the end of the day, a 1GW nuclear reactor is a much better energy source for electricity generation than making it on a bicycle, than "handcrafted" electricity. So it more like they have a research tool from the start, than something which actually drives things.
Such a native ability means probably a different tech tree from the get-go if conditions are right. And u try to take a magnifying glass to see the difference in a speck of dust of a completely different picture.
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My world has Eusocial Wyverns that live in groups of a thousand or so. They are about the size of rats. They have several castes, similar to ants or naked mole rats. All members of the same cast are the same size. They have a strong bite, sharp teeth, and an stinger at the end of their tail with a breath weapon as a possibility.
The dragons they have to deal with every once in a while are about the size of elephants when they're adults and are assumed to have a breath weapon. The dragons attack the Wyvern nests to eat the equivalent of their larva and possibly a honey-like substance they produce to feed them during the winter.
The eusocial wyvern's goal is to chase off the dragon at the very least regardless of their breath weapon, how would they do so?
[Answer]
**They cook the dragon.**
[](https://i.stack.imgur.com/ctxuW.jpg)
<https://www.smithsonianmag.com/science-nature/bizarre-bee-havior-in-the-battle-against-the-giant-hornet-129395782/>
Your wyverns are bee analogues. Your dragon is a killer hornet. As the hornet is immune to any sting or bite a bee might have, so too the dragon is immune to the weaponry of the wyvern. The hornet is not vulnerable to individual bees. Together, the bees have an emergent property.
>
> With a two-inch-long body and a 3-inch wingspan, the hornet is
> enormous – many times larger than the bees. But the honeybees have
> evolved a unique defense mechanism: When a hornet invades a honeybee
> hive, as many as 500 bees gang up and form a tight ball around the
> attacker. The heat from the bees’ vibrating wings and the carbon
> dioxide they respire proves a deadly combination. In less than an
> hour, the hornet is dead.
>
>
>
Your wyverns do the same. They cluster around the dragon and shortcircuit their breath weapons to heat up their entire bodies and keep them hot. The dragon is cooked alive. Most of the wyverns involved die too, either in the ball or later.
The hive survives.
[Answer]
## What is the relationship?
[Eusociality](https://en.wikipedia.org/wiki/Eusociality) almost by definition involves a caste system, so I'm not sure if your wyverns meet the technical definition, but that's semantics. However, without a caste system, every individual represents a reproductive unit and has an evolutionary incentive to avoid self destruction unless it is clearly to the benefit of their own gene group. Consider a caste system, or possibly rethink what the relationship between the dragons and the wyverns and humans looks like.
* Bury their hive underground, with the desirable parts in areas dragons can't reach.
* Evolve toxins that poison dragons but not wyverns, then exude those into their honey and the eggs(?)/larvae by adding them to the food used to produce honey or the food fed to larvae. This can be the same poison they have in their stingers.
* Have hostility behaviors where the wyverns constantly snipe at dragons within their territories, poisoning them slowly to discourage the dragon from even being in the general area. Wyverns might seek out dragon nests and kill their young or steal/break eggs to eliminate threats. If dragons are intelligent or organized, this may eventually cause them to develop strategies to get rid of wyverns.
* Pick climates that are less friendly to dragons. If dragons are in mountains to avoid pesky knights in shining armor, then wyverns live close to people and at low altitudes. This can even be a symbiotic relationship if wyverns help human crops, and the two groups may eventually learn to accommodate each other like humans and bees. Humans might even build wyvern nests to attract wyverns, with secret tunnels into them to allow surreptitious 'honey' collection.
* If dragons and wyverns are closely related, there may be some exotic relationships that evolve. The larvae may be captured by dragons who want wyvern pets/servants. If so, the wyverns may find themselves domesticated and in a symbiotic relationship with dragons who value their use against humans as well as the 'honey' supply, while the wyverns start treating the dragon like a queen. Conversely, wyverns may steal dragon eggs to raise as protectors, possibly even somehow pithing the dragon to make it less likely to destroy the hive. Perhaps dragons constantly exposed to wyvern toxin develop differently and behave like a different species.
[Answer]
## Predators Don't Go After High Risk Prey
Even if these wyverns do produce a honey like substance, the dragon would not bother attacking a hive unless it was sure that the risk is minimal. Most animals do not even prey on animals with a high chance of causing minor injury which means that the wyverns CAN'T significantly harm the dragon if you want dragons attacking wyverns over food.
When a dragon attacks a wyvern nest, his scales are too thick for the wyverns to sting through in most places, and those few spots they can get through don't matter much because dragons have evolved alongside wyverns to have a high resistance to wyvern venom. So at most, the wyverns would be a minor irritation to the dragon. Not enough to really drive it off until the dragon is full enough to outweigh the discomfort of being stung.
The good news is that it does not matter that the wyvrens can't beat a dragon BECAUSE they are Eusocial. Eusocial creatures follow [r-selection](https://en.wikipedia.org/wiki/R/K_selection_theory) meaning that Wyvern colonies can get decimated by dragons on a regular basis and still recover quickly enough to do well as a species. Instead of victory, the wyverns need only to focus on not getting wiped out. To do this, the wyverns put thier "honey" near the outside of the hive and keep the queen and eggs near the inside. This way when a dragon attacks, it just rips open the outer walls, eats its fill of honey and leaves. It has no interest in eating the Queen or her eggs; so, the wyverns simply rebuild and go on about thier existence.
I would personally revisit your ideas for your other two eusocial creatures and really ask yourself if it make since for them to be dragon killers either. Things the size of elephants tend to follow K-selection meaning that they would not survive as a species if swarms of other creatures keep killing them off. When dealing with r-selection, you also need to ask yourself what is keeping these swarms of creatures from overpopulating. IE: if dragons aren't keeping their numbers in check, what is?
[Answer]
If the Wyverns are intelligent then you can use human ways of dealing with birds and big animals. One possibility is:
1. Throw a net on the dragon (Nets can be produced like humans do it. There are some fire resistant materials) and the dragon falls to the ground.
2. Hit spears from above when the dragon is grounded. Gravity helps with penetration even if the scales of the dragon are tough.
I would generally say that intelligence is the weapon for hunting bigger animals. During stone age humans likely managed to hunt to extiction all mammoths and cave bears.
And it is even more pronounced in mordern time. Just look around. Do you know about any bears in your nearby park/forest? They are (or almost) extinct in Europe. Wolves are forbidden to hunt. Alligators usually do not survive eating human children. And this is not even including modern technology. A dragon appearing in the sky? Will be hit immidiately by an anti-aircraft rocket. A dragon is too tough for an anti-aircraft rocket? Add an anti-tank shell that penetrates 1m of steel.
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I have a system in which the main habitable planets are on the many moons of a super-neptune. The ice giant has not migrated inwards, but rather the habitable zone has expanded outwards due to the red giant phase. However I need this red giant phase last long enough that life can form, evolve into an intelligent form, and colonize neighboring stars, all starting from that super-neptune system. Red giants are unfortunately not particularly known for their longevity, and 1 billion years (as our sun would last) simply isn't long enough.
There is the potential for life having a head start here if it formed in a tidally-heated subsurface ocean like that of Europa, so the red giant doesn't need to last 4 billion years+, as life would only need time to colonize land and then land life develop intelligence and technology. However the longer it lasts, the better.
My first guess was that a lower mass star would also have a longer lasting red giant phase, However I found out it was impossible for low mass stars to even become red giants; so the problem remains that its too short-lived.
Magic and aliens are not allowed as this is the source system in which the first life developed. At least in this galaxy.
I have also considered a couple options for older universes, such as making the central star a red dwarf that evolves into its hotter phases (Helium dwarves and blue dwarves for example) and thats how its habitable zone expands, however that necessitates a very old universe to accomodate the time for a red dwarf to evolve that far, which is inconvenient considering I want really massive stars to still be present and dominating the color of galaxies.
or by having a high metallicity star. However I haven't been able to find much information on how stellar metallicity effects the lifetime of stars and their red giant phases, so I don't even know if this would lengthen the phase.
Edit: High metallicity stars last shorter according to the answer by HDE 226868, so that option is out of the question
[Answer]
This is a good question, and you actually might be able to achieve your goal naturally. The lower cutoff for helium fusion is $\sim0.5M\_{\odot}$; given the main sequence lifetime relation $\tau\_{\text{MS}}\propto M^{-2.5}$, we can estimate that such a star would stay on the main sequence for approximately 56 billion years. A good rule of thumb for red giant lifetimes is approximately 10% of the main sequence lifetime$^{\dagger}$, so a star just above this fusion cutoff would spend $\tau\_{\text{RG}}\approx$ 5.6 billion years on the red giant branch, which should be adequate for your purposes.
Increasing the metallicity may shake this up a bit. Metals do [aid in the cooling of molecular clouds](https://astronomy.stackexchange.com/a/40217/2153) as protostellar cores begin to collapse, which means that it's much easier to form lower-mass stars now than in the beginning of the universe. It also may lower the maximum mass of stars (see [Adams & Laughlin 1997](https://arxiv.org/abs/astro-ph/9701131)), but in the distant future this limit is expected to be no lower than $\sim30M\_{\odot}$, which should only affect the most massive of stars - nothing like the ones we care about.
Effects on stellar populations *en masse* aside, will increasing the mean metallicity decrease the lifetime of a star of a given mass? In the extreme case, yes. Adams & Laughlin estimate a metallicity dependence of
$$\tau\_{\text{MS}}\propto Z(1-4Z)\left(1-\frac{64}{27}Z\right)^{7.5}$$
This leads to a peak lifetime at $Z\sim0.04$. The Sun's metallicity is $Z\_{\odot}\approx0.02$; increasing this to $Z\sim0.10$ would decrease the main sequence lifetime (and, roughly, the red giant lifetime) by roughly 30%. In the expected maximum metallicity case of $Z\sim0.20$, we would see *extremely* short lifetimes. (Whether the extrapolation to that case is truly valid is another question.) The upshot is that even when mean stellar metallicities are five times higher than they are today - still very much in the far future - the decrease in age shouldn't be significant enough for you to cause problems. It's only at the very end of the stelliferous era that you'd run into problems.
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$^{\dagger}$ See *Stellar Interiors* by Hansen, Kawaler and Trimble.
[Answer]
### You need to refuel your star somehow
The best way to do this is probably a [Stellar merger](https://en.wikipedia.org/wiki/Stellar_collision). This needs to be a very lucky collision that gets in the sweet spot where they merge gently, such that it doesn't cause a supernova, or create a black hole, or melt your ice world, or create a gamma ray burst that sterilises the system. This is quite the trick shot.
0.99 billion years into the red giants lifetime, the helium flash just months away, a rogue small yellow dwarf enters the system, gets captured into a tight elliptical orbit, and after a few laps (that luckily stay far away from your planet) it's eventually brushing past the sun at low speed, forming a [contact binary](https://en.wikipedia.org/wiki/KIC_9832227), eventually merging. The yellow dwarf's hydrogen and helium resupply the red drawf, buying it another ~billion years.
This will be quite the heat-wave on your planet, and probably with quite a death toll, but with some careful tuning of the numbers there should be regions that survive.
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In my story, one of the characters essentially possesses something akin to true invulnerability and is essentially immortal due to [redacted]. In this part of the story, a group of terrorists with stolen sci-fi grade technology use it to open a tear in space-time right next to said character, a tear which creates a portal between his current location and a point in space at 10 meters away from an artifical (man-made) black hole's event horizon. This causes the character to be sent into space and sucked into the black hole.
The main scenario is: said character, due to [plot-armor] his composition, manages to not end up reduced to another chunk of compressed matter, and thus he is left trapped inside the black hole until it completely evaporates.
The problem: I'm having trouble stipulating the size and mass of the black hole, since I'm not very knowledgeable and I'm yet to comprehend how to use the black hole calculators I've found. I want this black hole to last a reasonably long time for human standards, but no more than 10000 years. Is there any easy(ier) to understand black hole calculators that I could use to have a better idea of its mass and size? In the scenario in question the black hole would be positioned in a place where, ideally, it wouldn't gain any additional mass other than what it had the moment the tear was open.
(this isn't the last time I plan to use black holes in this story, so I'm in need of a simpler calculator until I can understand more about them. )
[Answer]
According to [this calculator](https://www.vttoth.com/CMS/physics-notes/311-hawking-radiation-calculator), you want a black hole with a mass of 1.55 million metric tons and measuring 0.0000000046 nanometers across (~40 times wider than an atom). Any gas around it may reach a temperature over dozens of trillions of kelvin. At the distance characters and portals will be from the black hole, that means enough luminosity to probably cause a lot of destruction. As per the comments in this answer:
>
> The black hole will emit 150 TW of blackbody radiation at 80 tera-Kelvin. You won't be as much sucked in as literally torn apart by gamma radiation. The black hole will "only" emit 16 grams of photons per second (yup, you read that right), but they'll be moving at the speed of light. For comparison, the Hoover dam produces measly 2GW, and it's much bigger than a 20-meter sphere.
>
>
> * [John Dvorak](https://worldbuilding.stackexchange.com/users/807/john-dvorak)
>
>
>
150 TW means that, [in a little over four hours, the black hole emits as much energy as all nukes ever detonated in history (until 2020), combined](https://en.wikipedia.org/wiki/TNT_equivalent#Examples). That will not bode well for whatever is on the other side of the portal.
Even if you only keep it open for a second, that's still like two Fat Man bombs. Of course the portal won't get all of that energy through it since the black hole would spread energy in all directions. But it would be just like opening a portal next to a big modern nuke detonation.
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Generally speaking, black holes that have a considerable enough size for you to to be able to "see their disc" from afar could outlast practically everything else in the universe. A 2 km (~1.25 miles) wide black hole would have a lifetime of 8.13 $\times$ 1065 years. Read it without scientific notation to let that sink in: 813,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 years. That's almost the expected development time for Half-Life 3. Yet it would have only about a third of a solar mass. Its energy output would also be orders of magnitude greater than the nanometer black hole calculated above.
[Answer]
This seems like an really easy question to answer. The formula by which you can calculate the lifetime of a black hole is given below here.
[](https://i.stack.imgur.com/lz4Kr.png)
The formula on its own seems really frightening to an amateur physicist, but I will try to break this down.
Here, $\hbar$ stands for the Planck's Constant, which is about 6.62607015 × 10-34 m2 kg/s. **G** here is the gravitational constant, about 6.6743 × 10-11 m3 kg-1 s-2. $\pi$ is $\dfrac {22} {7}$. **c** is the speed of light, about 299,792,458 m/s. **M** is what we need, it's the mass.
Therefore plugging in the calculations, [according to Wolfram-Alpha](https://www.wolframalpha.com/input?i=%28%28%2822%2F7%29*5120*%28%286.6743*10%5E-11%29%5E2%29%29%2F%281.8083*6.62607015*10%5E-34*299792458%5E4%29%29*x%3D10000), we find that we need 1.3 quintrillion *(not quintillion)* tons (1.3 sextillion kilograms). That is a lot of mass, and again using the Schwarzschild radius formula
[](https://i.stack.imgur.com/VYSDL.png)
The radius at final is about [1.9308x10-6metres](https://www.wolframalpha.com/input?i=x%3D+%282*%286.6743+%C3%97+10%5E-11%29*%281.3*10%5E21%29%29%2F%28299792458%5E2%29)
across, which is really small.
# My final answer
You need 1.3x1018 tonnes of mass to make a black hole that lasts 10,000 years
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Take a modern setting and a character with a good working knowledge of physics and no fear on telling people about whatever supernatural stuff they've found. As the only piece of magic in the setting, suppose that they are given a large branch of wood that burns eternally and produces smokeless but hot fire. Suppose also that this branch's fire can't start other eternal fires, but can start normal ones.
Clearly, this is a source of infinite energy. However, the power is very low. Leaving aside the social implications of discovering what appears to be magic, can something as small as this have world-changing consequences? On one hand, "infinite energy" is setting off alarm bells for me, but on the other, I have no idea how to change the world with something that would take an hour to heat up my bathtub. Am I overestimating the dangers of including such an object?
[Answer]
### Your log has prevented the heat death of the universe.
That's... kinda a big deal.
Short term, it's a boring form of infinite energy. I see:
* an increase in thefts and murder as people want the magic log for themselves
* a town burning down, getting rebuilt, and then burning down over and over,
* some physicists throwing out their good work
A good steam turbine is 40% efficient at turning heat into energy, and a good seasoned wood log can put out 4kw of heat energy. That's 1.6kw of power for life, I have solar panels on my roof giving me more free power than that.
However in the lifespan of a human, of even the planet, that small amount of power adds so little energy that it can be basically ignored.
Over extreme long term, the universal implications are paradigm breaking.
[Answer]
The main limitation in usefulness would by that you only have your puny human lifespan to make use of it.
It would tell us a lot more about how the universe works than be useful in its own right...at least until we figure out how to make people live forever with extremely long periods of hibernation for the power to be accumulated somehow. If people lived forever but had no hibernation it still would not be very useful.
And it would not just tell you stuff about energy either. Fact is that all matter decays into iron eventually and if something lasts forever then it must not decay which makes it a research piece about more than just energy.
[Answer]
If this ever burning branch is useless at large power levels required by human activities, it can become really interesting when powering one small thing, such as a space probe.
Combined with a thermocouple it can produce electricity (like radioisotope thermoelectric generators do) for communications, cameras, sensors and everything else requiring electricity.
Mostly it produces photons, that can be directed in one direction, becoming an everlasting photonic thruster. This (very low thrust) would allow the small probe to visit the entire solar system, and thrusting for decades could also allow it to reach ridiculous speed, so that a mission to one of our nearest neighboring star system becomes possible.
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I am wondering if habitable planets could form around stars in super dense dwarf galaxies. There are some super dense galaxies such as M60-UCD1 and M85-HCC1 which can have a typical distance between stars of 1/20th of a light-year, compared to the Milky Way's average of 4 light-years between stars.
It is believed the reason for the density is their outer stars were stripped of by a larger galaxy neighbour. Due to the close proximity of stars, solar systems would have to be smaller than ours without the further out icy planets, and any planets that do form could be sent out of orbit from their home solar system from the pull of nearby stars.
I wondered if it is possible at all that habitable Earth-like planets could form? Due to the extremely short interstellar distances, an advanced civilization could explore their area of the galaxy, searching for life, terraforming or even harvesting energy from many stars, with far more ease than in larger galaxies.
Is it possible at all that rocky Earth-like planets could form around stars in such a densely packed galaxy and remain in a stable orbit for long timescales?
[Answer]
Sure. Not a whole lot, but you'll get a decent number.
[Beer et al. 2004](https://academic.oup.com/mnras/article/355/4/1244/992851) present a formula for calculating the mean time before a star passes within a distance $b\_{\text{min}}$ of another star:
$$\tau=7\times10^8\left(\frac{n}{10^5\text{ pc}^{-3}}\right)^{-1}\left(\frac{b\_{\text{min}}}{\text{AU}}\right)^{-1}\left(\frac{M}{M\_{\odot}}\right)^{-1}\frac{v\_{\infty}}{10\text{ km s}^{-1}}\text{ years}$$
where $n$ is the local stellar number density, $M$ is the combined mass of the stars and planet, and $v\_{\infty}$ is the velocity of the intruding star when it is far away.
It looks like M60-UCD1 has a number density of $n\sim3.4\times10^3$ per cubic parsec. Let's say the star and the perturber are both red dwarfs (hence the orbiting planet can be tightly bound and still remain in the parent star's habitable zone). Say the planet will be severely perturbed if $b\_{\text{min}}=100\text{ AU}$. A decent estimate of $M$ is $M\approx0.4M\_{\odot}$. We then get $\tau\approx5\times10^8$ years. This may be a bit conservative - I suspect that $b\_{\text{min}}$ could be smaller by a factor of a few - so we'll maybe increase this to about 1 billion years.
(I should add that I used a number density from Wikipedia, if we use yours (the number density can be found from the mean separation as roughly $n\sim l^{-3}$), we can a timescale lower by a factor of about 2. That's not terrible. Factors of 2 are often ignorable in astronomy. An order of magnitude difference - well, *that* would be problematic.)
A billion years or so isn't bad. Not a significantly short time. Life took a couple billion years to develop on Earth, but that's not necessarily representative of all planets. Besides, this is merely an average timescale. Plenty of planets in the galaxy will be disrupted sooner, and plenty will be disrupted later, if at all. Yes, they could form, and yes, a number would survive long enough for life to develop, if it had the chance to begin.
## How many planets?
M60-UCD1 has a stellar mass of [about 200 million stellar masses](https://ui.adsabs.harvard.edu/abs/2013ApJ...775L...6S/abstract). Let's say that translates into 300 million stars. Maybe 10% of those form planets. You now have about 30 million planets. Now, the majority of these stars will be red dwarfs; you'll see comparatively few Sun-like stars - low-mass stars are simply much more likely to form. If even 1% of those have planets that survive a couple times longer than expected, you should have a few hundred thousands of planets, most around red dwarfs. If even 1% of *these* are habitable, you still have thousands of systems that may develop life.
I'll definitely need to update this section with some literature-supported numbers, but I'll note that I was very conservative, I think, with some of these numbers.
## Supernovae may not be a problem
Now, we still have one question to answer, which [DWKrauss pointed out earlier](https://worldbuilding.stackexchange.com/questions/174710/could-habitable-planets-form-in-an-ultracompact-galaxy#comment543444_174710): What about nearby supernovae? The minimum distance for a typical supernova to have severe impacts is in the vicinity of 8 parsecs. Given the above number density, there should be about 1.78 million stars within that distance. For [a Milky Way-like present-day mass function](https://physics.stackexchange.com/a/123438/56299), that should produce about 7-8 stars which will become supernovae - not great!
That said, *that's an overestimate*. Recent work ([Dabringhausen et al. 2008](https://ui.adsabs.harvard.edu/abs/2008MNRAS.386..864D/abstract), [Mieske & Kroupa 2008](https://ui.adsabs.harvard.edu/abs/2008ApJ...677..276M/abstract)) indicates that ultracompact dwarfs have an extremely high mass-to-light ratio. Unless there's a high proportion of nonluminous matter (possibly dark matter - that hypothesis for the $M/L$ ratio hasn't been ruled out), that means that our stellar population models are wrong. Now, this in turn has two explanations. The first is that there are plenty of dim stellar remnants - neutron stars, black holes, etc. - floating around. After all, many of these galaxies are old, and unless something triggers a new round of star formation, many massive stars exploded long ago. If there's little star formation, then our estimate of the supernova threat was an overestimate.
The other possibility is also enticing. It holds that the mass function is what's called *bottom-heavy* - in other words, there's an extreme number of low-mass stars. One big reason that's possible is that ultracompact dwarfs are nothing like the Milky Way, and it's quite likely that their mass functions are quite different from ours. A bottom-heavy mass function would explain the observed $M/L$ ratios well - and would indicate that our estimate for nearby supernova-producing stars is *way* too large.
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1/20th of a lightyear is within the [extension of the Oort cloud](https://en.wikipedia.org/wiki/Oort_cloud#Structure_and_composition).
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> The Oort cloud is thought to occupy a vast space from somewhere between 2,000 and 5,000 au (0.03 and 0.08 ly)
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Quite surely planets might form in such a closely packed galaxy, but due to the close proximity with other stars I highly doubt they would be
* on stable orbit
and
* not subject to constant bombardment by space rocks
for a time long enough to allow life as we know it to develop.
This without even taking into account the lethal shower of radiation occurring when a neighbor star goes supernova and flashfries the closeby systems.
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So, due to reasons magical, civilization has aversion towards metals which are above antimony in [reactivity series](https://en.wikipedia.org/wiki/Reactivity_series). Yet, that doesn't stop them from developing gunpowder and wooden cannons. But while wooden cannons made of hardened wood with a copper tube inside is cool, one wishes for more than just that, even if these special cannons would be rare.
**So my question is, among the metals and alloys consisting solely of these metals, is there any that would compare to bronze in terms of both simplicity of making guns of**(that is, it doesn't have too high a melting point), **and does have qualities of cannon metal comparable to the gun bronze?** *Rarity of the material is not an issue, only the simplicity of working with and quality of the final product.*
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[Monel](https://en.wikipedia.org/wiki/Monel) or its naturally occurring counterpart [Cupronickel](https://en.wikipedia.org/wiki/Cupronickel) is probably your best bet. They are nickel-copper alloys that melts at 1300–1385C (hotter than bronze, but doable by your standard medieval blacksmith) and it's highly resistant to corrosion from acids, salt water, and high oxygen environments; so, it should be at least on par with antimony for corrosion resistance and fairly easy to to cast like bronze.
[Monel 500-k](https://elginfasteners.com/resources/materials/material-specifications/monel-k-500/) vs [Bronze 510](https://elginfasteners.com/resources/materials/material-specifications/phosphorous-bronze-510/) shows us that Monel has about 50% more yield strength than bronze; however, this is a comparison of high-end modern alloys that include trace amounts of aluminum, titanium, phosphorus, etc. which you would not expect to find in a fantasy setting.
If you are looking at possibilities for earlier firearms, you may be more interested in the relationship between Tin Bronze and Cupronickel as seen on [this chart](https://www.nationalbronze.com/pdfs/spec_reference.pdf). At these values, the naturally occurring Cupronickel is still about 50-80% better than your basic non-modernized bronze. Both of these alloys were already in use by the time gunpowder was invented.
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How about using silver? It has a similar melting point and would be subject to a degree of corrosion from sulphurous compounds as bronze is. Might need to be a little thicker as silver is not particularly strong but then again bronze isn't that strong itslef and at least silver is a very good conductor of heat.
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The copper/silver eutectic alloy (28% copper and 72% silver) has a yield strength of about 40k psi. Compare this with eg the 60k psi yield strength of 4140, the most common modern barrel steel, and the eutectic would be very suitable, especially if we are talking about comparatively low pressure black powder weapons.
It's not great at dealing with heat, so rates of fire should be kept slow but not painfully so - three or four rounds a minute for a rifle or musket would be OK, but no sustained fully automatic fire.
I don't know enough about cannon to give a rate of fire, but it is 8 times as thermally conductive as steel and five times as conductive as bronze, so if cooled with water I'd guess the sustained rate of fire would probably be as fast as you can muzzle-load it. That's a guess, I'd do tests first if I had to fire it, but it should be ballpark.
Barrel wear could be an issue.
There are other silver/copper alloys which would be usable, like coin silver (90% silver, 10% copper) or even sterling silver, and some with less silver (eg 55%), but the eutectic would be best if cost was not an issue.
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Tungsten would be a good choice, but it is rare. Other metals like copper, silver and gold would be too soft. There are alloys, but they require metals that are more reactive.
Instead of guns, they might use more rockets instead. Not as efficient, but you don't get the high pressures you do with a gun.
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So, as far as science fiction is concerned, **Strangelets** are very potent.
They are so stable that they convert normal matter into strangelets as well, 100% conversion, emitting gamma radiation in the process. Because of that, they are likely to cause an “Ice-9” scenario, [where the whole world becomes strangelets](https://i.stack.imgur.com/xRjqh.jpg).
However, assuming the world is advanced enough to store and produce it in the first place, maybe some world only wants to destroy, say, a mountain, a country, an asteroid, but never the entire planet. Is there a way to reduce the effects of the ‘strangelet bomb’, such that their area of effect is much reduced, i.e. like a reduced half-life or only being reactive to solids?
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**If one existed, it'd be better than the strangelet device**
Strangelets, for all intents and purposes, are just gray goo, except they function on a sub-molecular level. That means that you'd need a device capable of destruction on that level to stop the spread. And if you have such a device, capable of destroying the strangelet spread, than just use that instead.
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The long-term stability of strangelets has been hypothesised, but it might not be true. A strangelet suitable for use as a weapon needs to be stable *enough* to ingest and convert a useful volume of matter in the target before it decays. A gun capable of shooting a strangelet would be able to penetrate any armour within its range, and wherever the strangelet passed through matter intense amounts of gamma rays would be released but in a fairly short period of time the strangelet would decay into a bunch of other particles in a final shower of gamma rays.
Given that it isn't clear they're even possible in real life, you can handwave this as you see fit.
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There exists a concept called [point zero energy](https://en.wikipedia.org/wiki/Zero-point_energy) which is similar to what you describe. The idea being that the universe as-is is not at it's lowest energy state. This comes from the concept that even in a vacuum we can find phantom particles and consequently energy.
With enough energy, if you could convert spacetime to zero point energy (so a true vacuum with nothing inside), it would eliminate everything at that point outwards at the speed of light. If you died to this type of explosion, you wouldn't even have time to react. There are some theories that this is why we can't find life in the universe. It is because they reach a point where they can generate the necessary energy and it destroys them completely (sobering thought, isn't it?). The only reason we're still around is because the speed of light is a relatively slow thing in our universe.
That tangent aside, I think such a device would act like ice-9, but for literally any kind of matter. Many things contain water, but at least with ice-9, you can prevent it from spreading by simply not letting it spread to a body of water.
This sounds like it would be very deadly indeed. I have to agree with @Halfthawed on this one. Gray goo at least would have an aspect of it that you could control, say, it can be disactivated on command. These strangelets, even if you could slow or halt the conversion if say the temperature were really low, well you may be able to halt it on the surface like a spreading fire, but below the surface it would continue to convert rapidly making it uncontrollable just the same.
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So, in my story, there's a guy that can produce electricity, and functions as pretty much an endless power supply of electrical energy. With that, I was wondering, what would be required to make it so that he can function as a railgun?
For example, what would be the minimum necessary materials for him to build a railgun arm cannon, and what amount of voltage would that need?
Sidenote: Assume that this guy can't get access to state-of-the-art materials, and can only get relatively basic stuff like alloys.
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Power *supply* currently isn't the reason we're not all running around with railguns - it's an engineering problem.
Lets make a few assumptions about our power user first:
1. Newton's 3rd law doesn't apply (no reaction force)
2. Our super can make closed currents outside of his own body, which behave much like lightning (lightning makes a plasma, which allows for much higher current than anything we know excepting superconductors)
3. Our super can think really fast, or can "pre-program" his power (for example, do X, 3 nanoseconds later do Y)
The reason railguns don't work are because we can't accelerate them hard enough. Doing so requires a really high current in our electro magnets.
The superpower is required to fix that issue. So you'll make a series of really powerful magnets, use them to accelerate the bullet (or iron rod, or whatever you shoot). The fast switching requirement is because you need to switch off any magnetic field behind the bullet, or you'll slow it down.
It'll look like you make rings of lightning, then pull a bullet/whatever through it, cancelling the rings as it moves through them.
The reason we'll want to have no Newton's 3rd law is because we have our lightning rings free-floating. If we did have a reaction force, it'd push them out of alignment and disrupt them by pushing all the plasma's charged particles out of it.
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Kinda obvious problem: we can't actually do a very good job of making a rail gun *right now*, even with access to plenty of money, power, engineering talent and high quality, high precision manufacuring. Unless your dude has super machinist powers too, any weapon he makes will likely be a less effective projectile thrower than a gun that he could probably just buy.
Lets see what we can do, though.
Lets say that to start with, we want something that is at least as capable as a regular handgun. Our theoretical handgun fires a 10g projectile at about 400m/s (compare with a 9mm parabellum, which is more like 8g and 380m/s). You want an "arm cannon", I'm not sure how big that is, but lets say it has a 25cm barrel (so, a forearm cannon, really). To reach the desired speed, you need an acceleration of 3.2x105m/s2 (about 2/3rds of the acceleration the 9mm bullet gets). On a 10g bullet, this needs a force of 3.2kN.
A railgun works by having a magnetic field pointing in one direction, an electric field at rightangles to that, and there interaction producing a force in the projectile at rightangles to them both. The pair of rails point at the target, the projectile sits between them, and you whack a massive current across the two (note that I said *current*, not *voltage*). You also need a load of magnets above and below the rails to provide the magnetic field. These will probably be electomagnets, and you'll need to feed them with a generous amount of current, too.
The simplest (and wrong, but it'll do here) model of a railgun says that $F = I\ell \times B$, or force is current multiplied by the length of the barrel multiplied by the strength of the magnetic field. An iron core electromagnet can have a maximum field strength of 1.6 tesla, though alternative materials can push thus up a bit. A real world example of a suitable magnet would perhaps be [GMW 3470](https://gmw.com/wp-content/uploads/2019/11/GMW-Specifications-3470-10.25.2019.pdf), which is about 38\*28\*23cm, and weighs over 30 kilos. It can develop over 1.6T and only costs a few thousand dollars. It is a very high grade bit of scientific kit, so maybe a more industrial one will be a bit cheaper and lighter, but I bet the figures are in the right ballpark. I'm not sure if you'll be able to run it at a high enough power level for a railgun magnet. It also says it needs water cooling if operated at high power. It isn't entirely adequate, as you'd be hard pressed to fit enough of them into your barrel space to provide a uniform magnetic field of high enough strength. You can of course use lighter, more compact, less powerful magnets, but you'll need to increase the current to compensate. Really, you need some room-temperature superconductors, and that's a whole new set of superpowers.
To provide the required force over the given length, we need a current of 8kA (more than 20-40 times more current than a powerful portable MIG welding rig). The projectile comes out with 800 joules of kinetic energy. It takes 1/800th of a second to leave the barrel, meaning that your gun must develop a power of 640kW whilst operating, if it is 100% efficient, which it won't be. Wastage will appear as heat, though I won't work out how much right now.
Even with this teeny tiny toy railgun, you can see that the power requirements are Quite Demanding. Sure, all those kilowatts and kiloamps only have to be supplied for a very brief length of time, but switching all that on and off precisely and avoiding nasty ringing effects (the magnets discharging might shock your dude, which could be embarassing) is quite challenging, which is why we don't have any railguns right now. Your rails need to be machined to very high tolerances, because they must contact the projectile perfectly, without airgaps because that will result in arcing which will waste power and damage the railgun. Your bullet will wear down the rails a little anyway, which will result in arcing soon enough. If the bullet gets stuck, it risks being welded to the rails immediately ruining the gun. The rails must be very firmly braced to prevent reaction forces bending them, which will cause rail-bullet wear or separation, resulting in more arcing. An 8kA arc is going to toast stuff pretty quickly, which is why current real-world railgun designs need to regularly swap out the rails (which is why you need super-machinist powers, to make lots of high quality replacements).
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Note that the *average* power required for the railgun (again, at an implausible 100% efficiency) is 800W, assuming a rate of fire of one round per second (it'll scale linearly with the fire rate). That's a simliar power output to a serious aerobic athlete. I don't know how you plan to power your powers, but if you want to tend towards realism, he'll need to eat well and he'll get tired quickly in combat, *especially* he's doing anything more than just standing there shooting.
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Lets look at the alternative. Use a common-or-garden, off the shelf handgun, if available, otherwise a rifle or a shotgun should be slightly more easily obtained. Just shoot people. Cheap, easy, all the machining issues are solved for you and mass production means costs are low. They don't weigh tens of kilograms and need no water cooling. If it breaks or you lose it you can always buy or steal another. You want to use electrical weapons? make like a taser and use your hands, and perhaps some weighed throwing wires.
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He would be able to make one, and he could fire it, but there would be problems.
You see, even though he *could* shoot it, it would be a one-shot emergency weapon, as the recoil would be truly tremendous. As in "firing while standing equals broken wrist / shoulder" stupendous. It would be like an eight-year-old firing a 12 gauge shotgun (trust me, it's not pretty).
Also, it's worth mentioning that even if the recoil doesn't knock him into next week the gun would still be a 1 (possibly 2) shot weapon; one of the main reasons why railguns aren't in use today is because the conductive rails wear out *extremely* quickly.
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I'm writing a novel in which an isolationist republic has to open its borders following a series of volcanic eruptions in its territory that destroyed most of the crops and coal mines (the republic is currently in the industrial era). This nation can no longer feed its population because of the bad harvests and is in serious need for more coal to power its industries, so it has to open up trade with its neighbours.
I'd like to ask how would this republic go about it? Send messengers to every nation close to it, invite representatives and ambassadors to the capital, etc., or simply open the borders and let the traders in without involving foreign politics?
This is a big plot point in the story. Until now, I assumed diplomats and ambassadors would be invited into the capital for a tour and establishment of diplomatic relations.
Is this how nations in our world opened up after a long period of isolation? If not, what is? Or is it hard to say and up to my judgement?
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**They will come to you**
If your world is full of other cultures, especially in an industrial era, there are probably thousands of companies / people / merchants itching to take advantage of a new market and wanting to trade with your isolationist nation.
As soon as official channels send a signal indicating they are now 'open for business', then many nations would likely send trade envoys to meet, greet and gather knowledge of how to do business. I was a part of such a trade envoy to China in a relatively new industry, funded by our government (the Department of State Development), to take advantage of potential export markets.
So your nation would, in sequence:
* Indicate it is ready to do business with, and perhaps create a new 'envoy' visa or similar that allows business owners and other foreign officials to enter
* Create envoys of it's own to discuss it's importing requirements, protocols (to do with shipping, currency exchange etc.), tax implications and also to indicate export opportunities
* Enable its own citizens to trade with other foreign companies. You could do this in many ways, however it is generally seen that a floating currency, a local stock exchange that interfaces with foreign ones, a common shipping protocol or infrastructure agreement, are starting points.
* The government may also provide incentives for trade to 'get things going'. Your countries need is not new, in fact all current economies have 'needs', sometimes even needs that are vital or life-saving. Governments usually have trade agreements to get these, with incentives to trade such as lower tariffs, lower tax and stamp duties, or government spending in infrastructure specifically for that product (such as iron ore rail lines etc.) to fast track the receiving of these goods.
It would be an exciting time for your nation in question. A lot will change.
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**Open formal diplomatic relations**
One thing your country should do if it hasn't done so yet is open embassies in and exchange ambassadors with every country it wants to deal with. This is how formal diplomatic communication is conducted between governments. Once established, your country will now have a way to make arrangements for trade or anything else with these other countries. There is no substitute for having your own representative keeping an eye on things happening in foreign capitals.
Assuming your country has resources that others are interested in, there will be traders showing up, legally or illegally. But if you want to regulate trade, then formal relations will be necessary to secure agreements with nations on the other side.
**Note**: Leveraging trade power and monopolies was the favored tactic of 19th century colonial powers to innocuously insert their influence into much of the rest of the world. For example, the British East India Company. Something to think about before flinging open those doors of trade.
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It won't be done. It could be done, certainly, but it absolutely will not be.
Scenarios much like you describe are explained in the book [The Dictator's Handbook](https://rads.stackoverflow.com/amzn/click/com/1610391845). And the main thesis is, the dictator would massively prefer that most of the people in his country die horribly than to open the borders.
Example: After the 2004 [Christmas Tsunami](https://en.wikipedia.org/wiki/2004_Indian_Ocean_earthquake_and_tsunami), many people tried to bring assistance to the affected countries. One group brought several trucks to Sri Lanka to assist in distributing aid. The government impounded the trucks and required that import duty be paid on them, duty amounting to much more than the purchase price of the trucks. Said duty supposedly being charged to protect the truck manufacturing industry in Sri Lanka. The result was that these trucks languished in an import yard for most of a year after the tsunami because the aid agency had blown all their cash on buying food and medicine and emergency shelters. Which aid sat in the warehouses at the airport, waiting for some way to move it.
In case after case, dictatorial leaders would far rather have their people die than let foreigners move about freely and give them ideas. Earthquake, flood, volcano, war, famine, plague, nothing persuaded them that it was time to let the foreigners in.
And there's a very strong (though evil) reason for that. If they let the foreigners in, then their own people can move around freely and talk to the foreigners, and each other. And that way leads to revolution pretty damn quick. Which the dictators absolutely will not allow if they can possibly avoid it.
So those trucks had to be kept out because they could not only move food and medicine. They could be used to move disgruntled people trying to organize a coup. They could move weapons to arm revolutionaries. They could move communication equipment, from radios to photocopy machines, that would inform a revolution. Nope. That absolutely will not be allowed.
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Based on one of the comments in my previous question about [What is the max size for underground creatures before the square-cube law takes a toll?](https://worldbuilding.stackexchange.com/questions/160651/what-are-the-max-size-for-underground-creature-before-squarecube-law-take-the-to)
Makes me want to know the limit size for a long creature like a snake/worm before their own body crushes them or their organs don't function properly.
And I know there's a prehistoric snake like titanoboa that is very huge, but I still want to know: Is that the limit a snake/worm can be, or theoretically can it be even longer and bigger than that and still function?
Feel free to edit the tag to be more appropriate.
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The main problem with snake would be not size and weight, but interchange with external media: feeding, breathing, etc. Snake is cheating with square-cube, making it square-square or even square-linear (if it is does not increase its width).
There theoretically can be a kilometers-length snake of several centimeters wide in terms of structural stability. It even will be able to move! (Each "section" of a snake is self-propellant)
But then comes a problem - how to keep tail nutrient? Almost anything this snake eats would digest in several first meters! And then next several meters of tissue would take all nutrition to itself.
So the snake is just an envelope around digestive tract. And the length of digesting tract is determined by the size of its pray and the length of digestions.
If we imagine snake capable to swallow and digest brachiosaurus (up to 20m long), then it need to have times more length - say about 100m but not that much - less then 200m. Snakes can stretch a lot (tenths of times) so "empty" snake width would be less then a meter - about 30-50 cm in common and 1m in widest parts. This snake would eat one brachiosaurus in couple of years and then lay still for most of the time digesting. It is hard to imagine conditions were this snake would not be eaten by other predators, but lets say it has perfect adaptive camouflage (chameleon-like), and, say, spread some predator-repelling smell. (but I still hardly imagine how this thing can evolve!)
So we can have 150m length, 0.5-1m thick, about 10-15 t snake, which is almost invisible, can swallow brachiosaurus and then lay for years digesting it (and spreading terrible odor in process).
There can be more than that - but then you need a bigger prey to feed it.
In current conditions largest snake would be an elephant or giraffe (largest length)-eating snake with size about 20-30 m length, 10-30 cm thick, with weight about 1-2t. A "Doubletitanoboa".
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My answer to this question: [Can a land-based organism get to be at least 100 ft. in length and still be plausible?](https://worldbuilding.stackexchange.com/questions/128114/can-a-land-based-organism-get-to-be-at-least-100-ft-in-length-and-still-be-plau)[1](https://worldbuilding.stackexchange.com/questions/128114/can-a-land-based-organism-get-to-be-at-least-100-ft-in-length-and-still-be-plau) may be useful.
The Longest known land animals, sauropodmorph dinosaurs, had thick bodies, but their long slender necks and tails were a bit snakelike.
The longest known sauropodmorph dinosaurs were estimated to have maximum lengths over 100 feet. And the legendary lost fossils of the possibly largest dinosaurs of all indicate a maximum length of up to 190 feet for the single specimen of one species.
So a snake like creature 100 feet long, 150 feet long, or even 200 feet long would have a lower body mass than the largest known land animals. But it wouldn't have legs to support its body above the ground, and so it's body would have to be strong enough to slither along the ground, and to avoid being crushed by gravity.
Some large snakes, like anacondas, actually live in mud and fresh water, and it might be theoretically possible for fresh water snakes to be much larger than anacondas and titanaboas.
I note that earthworms are snake or worm like creatures that burrow in the ground.
Crytozoolologist Ivan T. Sanderson once speculated that some northern European water monsters might be gigantic cacelians. Caecelians are limbless amphibians who live underground and underwater and look like earthworms or snakes. This theory was mentioned in David Drake's fantasy Arthurian novel *The King's dragon* 1979, revised as *The dragon Lord* 1982.
There are many snake like and worm like creatures in the oceans, with a big range in size.
Sea snakes are rather ordinary sized and are very venomous.
Many reported sea monsters or "sea serpents" were described as being serpentine. Many whales are rather slender, so a sea creature as wide as a whale but two or more times as long would probably seem serpentine.
Here is a link to a question about the size and anatomy of giant sea "serpents":
[How large could my sea serpents be?](https://worldbuilding.stackexchange.com/questions/114545/how-large-could-my-sea-serpents-be/114678#114678)[2](https://worldbuilding.stackexchange.com/questions/114545/how-large-could-my-sea-serpents-be/114678#114678)
There are many types of marine "worms".
The bootlace worm, *Lineus longissimus* has a very narrow and very long body.
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> Bootlace worms may grow very long but are usually only 5 to 10 millimetres (0.20 to 0.39 in) in width
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> In 1864 a specimen washed ashore in the aftermath of a severe storm by St Andrews, Scotland, which was more than 55 m (180 ft) long,[6] longer than the longest known Lion's mane jellyfish, the animal which is often considered to be the longest in the world. However, records of extreme length should be taken with caution, because the bodies of nemerteans are flexible and can easily stretch to much more than their usual length.
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<https://en.wikipedia.org/wiki/Lineus_longissimus>[3](https://en.wikipedia.org/wiki/Lineus_longissimus)
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> The lion's mane jellyfish, also known as the giant jellyfish or the hair jelly,[3](https://en.wikipedia.org/wiki/Lineus_longissimus) is the largest known species of jellyfish. Its range is confined to cold, boreal waters of the Arctic, northern Atlantic, and northern Pacific Oceans. It is common in the English Channel, Irish Sea, North Sea, and in western Scandinavian waters south to Kattegat and Øresund. It may also drift into the southwestern part of the Baltic Sea (where it cannot breed due to the low salinity). Similar jellyfish – which may be the same species – are known to inhabit seas near Australia and New Zealand. The largest recorded specimen was measured by Alexander Agassiz off the coast of Massachusetts in 1865 and had a bell with a diameter of 7 feet (2.1 m) and tentacles around 112 feet (34 m) long,[4](https://en.wikipedia.org/wiki/Lion%27s_mane_jellyfish) although it was incorrectly reported by the Guinness Book of World Records that the sighting occurred in 1870 and that the jellyfish measured 120 feet long. Lion's mane jellyfish have been observed below 42°N latitude for some time in the larger bays of the east coast of the United States.
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<https://en.wikipedia.org/wiki/Lion%27s_mane_jellyfish>[4](https://en.wikipedia.org/wiki/Lion%27s_mane_jellyfish)
If a jellyfish with tentacles 112 feet long had two pointed straight apart, their tips would be 224 feet apart.
I find it easy to believe in the theoretical possibility of snake like or worm like sea creatures hundreds of feet long.
Added 11-15-19. And also see this question:
[What kind of planet could have giant sand worms?](https://worldbuilding.stackexchange.com/questions/161034/what-kind-of-planet-could-have-giant-sand-worms/161088#161088)[5](https://worldbuilding.stackexchange.com/questions/161034/what-kind-of-planet-could-have-giant-sand-worms/161088#161088)
It asks about sand worms, like in *Dune*. And maybe some of the answers will discuss the possible size range of hypothetical sandworms on an alien planet.
[Answer]
ksbes makes a good point that the limit on length is likely to be logistical rather than structural. It's a bit like how the height of skyscrapers is limited by the need to devote more and more space to elevator shafts.
You can get around this by having all the relevant systems distributed along the worm's length – e.g. hearts, brains, and mouths spaced every few meters – but that raises the question of why such an arrangement would be advantageous over a bunch of smaller independent worms.
Another issue with being very long compared to your width is that, like a skein of yarn, you have the possibility (indeed, the likelihood) of ending up irreversibly tangled as you move around. I suspect the processing power required to either avoid that, or to undo a large tangle, would very quickly become infeasible for a free-roaming worm whose length was more than a few hundred times its width.
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A squid-like organism uses gravity powered flight but relies on jet propulsion for launch, pouncing, and evasive tactics.
It’s aerodynamically based on the way a true squid flies however it has evolved atmospheric jet propulsion to replace the constricting hydraulic jets.
It’s tentacles and fins have become much larger for sustained flight, but it’s arms remain articulate for grappling and marine locomotion.
The jet deflagration chamber is the scavenged nearly perfectly flared cylindrical exoskeleton of another mollusk, with a diameter acoustically tuned to an OH deflagration cycle. This squid binds it to its body, having an intake on the nose and exhaust from the posterior of the animal. The material is unlikely keratin or calcium carbonate, it needs to have good thermal insulating properties and structural integrity.
The jet fuel is twofold: H gas is a natural fermentation byproduct stored in bladders; a symbiotic algae lives in a layer under its translucent skin, consuming its respiratory exhaust and producing O$\_2$ which collects in another bladder. The two gasses are injected into the unvalved deflagration chamber for propulsion.
The jet only needs to run for 2-second bursts of possibly 8 - 12 pulses. It’s purpose is to simply gain enough momentum to get airborne, or evade a predator while in flight.
Assume the animal’s total gross weight is 5kg, and it can accelerate at 8 ms$^{-2}$ for two seconds.
Given the heat generated by this reaction,
# What lightweight cooling method can be used to prevent heat damage to the combustion chamber and O$\_2$ & H fuel jets?
The cooling method of course should include materials suited for heat transfer and possibly heat removal.
I don’t know how much fuel this activity would consume however assume it has evolved 40% efficiency in producing thrust, so 60% is converted to heat, but 80% of that heat is exhausted.
If H$\_2$ doesn’t have sufficient energy density to generate the required thrust, I’m open to other organically derived fuel options.
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So, ignoring drag (too much like hard work), a 5kg mass accelerated from stationary at 8m/s2 for 2s has a kinetic energy of 640J. With your 40% efficiency, that means it needs a 1.6kJ burn producing 960J of heat of which 192J needs to be disposed of by active cooling.
The specific heat capacity of water is about 4.2kJ/l. 10ml of water would be heated by slightly less than 23K if it fully absorbed that heat energy. The simple solution therefore, is to use a small water bladder to force seawater through cooling ducts around the rocket chamber.
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The issue of what sort of rocket you should be using is complicated enough that you should ask about it in a separate question. Oxygen is a perfectly reasonable oxidiser, but storing hydrogen is sufficiently awkward that you may as well use some lightweight volatile hydrocarbon instead. You do lose out on Isp, but your fuel density goes through the roof (comparatively) and your chamber temperature is likely to go down which will help with materials engineering (you'll also get a nifty orange rocket flame, rather than an invisible one).
You have not addressed the problem of how your rocket is actually ignited. The fuel/oxidiser combination you've suggested is obviously not hypergolic, so you'll need something else (perhaps taking a leaf out of the bombardier beetle's chemistry book).
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The squid has access to all the water it can use. It uses it in 2 ways.
1. **Water cooled.**
The squid has access to much water. In addition to the H2 and O2 mixed in the chamber the squid adds water. The H2 and O2 reaction produces hot gaseous H2O, and once the phase change is accomplished, every degree over 100C is wasted. The squid adds H2O to absorb that extra heat. The squid adds just enough that much of the added water is itself converted to 100C gas (steam!) and so contributes to propulsion.
The nozzle itself rests within the internal reservoir used to supply the water - possibly the same one the squid uses for aquatic propulsion. Heat escaping through the outside of the shell is captured to preheat the water which will shortly be injected.
This halfbakery idea lays out the scheme as applied to an engine.
<https://www.halfbakery.com/idea/internal_20combustion_20steam_20engine#964198800>
>
> The heat lost by internal combustion engines is pure waste. If a
> deisel-type injector were programmed to inject just after ignition the
> exactly right amount of water to maintain a temperature of, say, 150C
> at the exhaust valve, the latent heat of evaporation would keep the
> engine at the right temperature, and the expansion ot the water
> droplets into steam would triple the work obtained from the fuel. The
> cylinders are insulated to conserve the heat, not cooled as currently
> done.
>
>
>
2. **Water for thrust.**
The propulsion conferred by the expanding gas is measured a F = mv2. The m here is the mass of the gas itself, thrown behind the squid. But the squid has additional cheap reaction mass - water. As it prepares to launch it takes in a quantity of water and uses the expansion of the gas to throw this water behind it. It is a water rocket - reaction mass of water propelled by pressurized gas, which here is the hot H2O from the reaction.
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**Home grown shells?**
I like the idea of a salvaged shell from another mollusk but that means evolutionary pressure on the squid cannot work on the shell, which in the flying squid serves a much different purpose than was the case for its original maker. Mollusks are very capable of making shells - an example being the doughty nautilus with an excellent shell. The shell would be specialized as a rocket nozzle because the squids which fly better live to reproduce. I am not sure cephalopods compete for mates but I like the idea of male squids showing off their flying prowess in a lek.
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In my somewhat hard sci-fi setting I'm thinking of using a high powered microwave weapon as the secondary armament of my ship to supplement the missiles it would carry.
I was thinking it would be a pretty massive active electronically scanned phased array <https://en.wikipedia.org/wiki/Active_electronically_scanned_array> that would also double as a radar, comm unit, and electronic warfare suite, but is also capable of focusing it's energy into tight beams to act as a long range directed energy weapon to perform against multiple targets.
I was thinking it could be used to either fry the electronics or burn through critical components of incoming missiles or other projectiles, possiblly vaporize them if small enough, or it could be used at longer ranges to burn through critical components or fry electronics of other starships.
However, I am wondering is a device of this kind of power feasible for a somewhat realistic low end torchship, and what disadvantages keep microwave weapons from being deployed in space as I notice they are quite uncommon compared to other devices such as lasers?
[Answer]
The principle problem with your idea is one of focus, I'd say.
The smallest spot size your microwave weapon could be focussed on is limited by diffraction. The size of that spot is defined as
$$R\_T \approx \frac{0.305 D \lambda}{R\_L}$$
where $R\_T$ is the radius of the spot at the target, $D$ is the distance to the target, $\lambda$ is the wavelength of the emitted radiation and $R\_L$ is the radius of the emitting element. Size of the spot scales linearly with wavelength. If your device spits out millimetre waves (~1mm wavelength) then at the same range it will have a thousand times larger spot than a 1μm IR laser. Alternatively, to get the same power density at the target, the target either needs to be a thousand times closer, or the emitting element needs to be a thousand times bigger. That's why most people go for lasers as weapons. Also they're more awesome, because *lasers*. Pew pew!
Now, that's not *entirely* the end of the world. One thing we can do with microwaves that we can't do with visible light (right now) is make a [phased array](https://en.wikipedia.org/wiki/Phased_array) of emitters, which is of course exactly what your [AESA](https://en.wikipedia.org/wiki/Active_electronically_scanned_array) is. This means that if you can build each emitting element cheaply enough, you can just plate your entire hull with the damn things. Omnidirectional beam, biggest possible aperture, no mucking about with turrets or mirrors or waveguides or any of that nonsense. Sure, you might lose some of the emitters to micrometeors or enemy weapon fire, but that doesn't matter because they have to scour your hull clean to fully turn the damn thing off. With a bit of cunning you can fire your microwave beams in phase with one or more friendly ships, a trick somewhat harder to manage with lasers.
Secondly, if you're using this as an electronic warfare device rather than trying to blast or burn the enemy, you can get away with an order of magnitude lower power density at the target. Electronics frazzle easily. Refractory armour does not. Scifi with space battles isn't that interested in weapons that don't make people go *foom* (brief honourable mention for Banks' effectors) so such things are unlikely to ever get centre stage.
Thirdly, microwave generation tends to be higher efficiency than laser generation. Stuff like [gyrotrons](https://en.wikipedia.org/wiki/Gyrotron) have been around for years, and have already hit >60% efficiency at quite serious sustained power levels approaching megawatts. We still don't really have laser technology that can claim the same thing. Low efficiency means lots of heat and requires silly big power plants, which means more heat. Microwave ships need smaller heatsinks.
>
> However, I am wondering is a device of this kind of power feasible for a somewhat realistic low end torchship
>
>
>
Even the smallest, weediest torchship requires a monstrously powerful nuclear engine and significantly higher spacefaring technology that we have now. Quite frankly, using microwaves instead of a laser burn death kill beam is weirdly restrained. I wouldn't sweat it.
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Yes it's feasible, but microwave weapons have some serious drawbacks. This is why they are only now being deployed with extreme caution on the real world.
One, they only work against electronics (and even those can be hardened. If your target is entirely optronic, photonic or whatever - ie not using electricity -- you have no effect.
Two, the effects are highly unpredictable, even against fairly well-known targets.
Three, fratricide is an issue, as they may do some damage to targets other than intended which are a lot further away.
Four, no visible effect, so you don't know whether you've destroyed that missile's brain, caused it to reboot briefly, or done no damage at all as it continues to hurtle towards you.
[Answer]
**What you are describing is a MASER** - <https://en.wikipedia.org/wiki/Maser>
The microwave variant of a LASER. Similar to a laser the power could be varied drastically to allow for utility, weaponisation and communication.
[](https://i.stack.imgur.com/JjFLm.jpg)
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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.
I've read all the related questions on here and as far as I can tell this should be breathable on my planet Liskuel, which has 1.5 bars of pressure. However, I'm really bad at maths and don't really know how to scale it up with atmospheric pressure, so I would really appreciate a fact check.
***Edit: I've updated the stats to match some feedback I got, but just so the original answers make sense, here are the original stats:***
[](https://i.stack.imgur.com/ejZIU.jpg)
***...And here are the updated stats (more oxygen and water vapour):***
[](https://i.stack.imgur.com/BPuX5.jpg)
*Additional query:* I've included a fair amount of Xenon - do you think there is enough to accumulate in the lowest valleys and knock out your average human?
[Answer]
What matters for breathability is the partial pressure of the gas.
According to [Dalton law](https://en.wikipedia.org/wiki/Dalton%27s_law)
$Partial\ Pressure = Total \ Pressure \cdot volume \ fraction$
For Earth
$P\_{O\_2}=1 [bar]\cdot 0.21=0.21 \ bar$
On your planet
$P\_{O\_2}=1.5 [bar] \cdot 0.055=0.08 \ bar$
That's a tad more than the partial pressure in the [Death Zone on Mount Everest](https://simple.wikipedia.org/wiki/Death_zone)
>
> at the top of Mount Everest the average person takes in about 30% of the oxygen in the air that they would take in at sea level; a normal human person used to breathing air at sea level could only be there for a few minutes before they became unconscious.
>
>
>
Therefore the atmosphere of your planet is at the limit of breathability, and would require proper acclimation to not be lethal.
That apart, it is also pretty dry, which is an additional issue, though not impacting breathability.
After your edit:
$P\_{O\_2}=1.5 [bar] \cdot 0.105=0.16 \ bar$
which is breathable, comparable to what we breathe when we are on a mountain.
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Probably breathable but almost certainly dangerous:
* The [recommended 8 hour Ozone exposure](https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners) is at most 0.1ppm, that's a thousandth of your atmospheric concentration. Given that [studies](https://www.ncbi.nlm.nih.gov/books/NBK430751/) have shown that tiny increases of just 0.001ppm cause notable increases in fatalities this is almost certainly a sizeable problem in a continuous exposure scenario.
* The other thing that makes this situation dangerous is the fact that breathing that much Nitrogen under that much pressure is the equivalent (1.245bar post edit) of being in a constant [SCUBA dive](https://en.wikipedia.org/wiki/Scuba_diving) at a depth of roughly 6 metres, while many people will notice little to no effect from this, [at least initially](https://en.wikipedia.org/wiki/Dysbaric_osteonecrosis), many others will be immediately, if lightly, impaired (approximately the equivalent of drinking two thirds of a martini an hour). As the long term build up, over days or weeks instead of hours, of dissolved Nitrogen in the blood is not a well understood phenomena the effects of this may lessen or worsen over time.
To address the Xenon issue, no probably not, [Xenon anesthesia](https://anesthesiology.pubs.asahq.org/article.aspx?articleid=1945725) is only effective in a 70/30 mix of Xenon to pure Oxygen there's simply not enough of it to concentrate to that degree. Having said that in combination with the mild narcotic effects of the Nitrogen and its oxides lower concentrations may prove to have some effect.
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As for the breathability of the atmosphere. I encountered this list in a [video by worldbuilding YouTuber Artifexian](https://www.youtube.com/watch?v=9-j_JOWPLj8) and have added to it since. I did check several values and found them to be correct. Going down the list it became increasingly difficult to verify the values, so take everything without a link with a grain of salt.
* N2 < [3 atm](https://en.wikipedia.org/wiki/Nitrogen_narcosis)
1.25 atm, o.k
* CO2 < [0.02 atm](https://en.wikipedia.org/wiki/Carbon_dioxide#Toxicity)
0.015, o.k
* CO < [0.0001 atm](https://www.uptodate.com/contents/carbon-monoxide-poisoning)
not found
* CH4 < 0.05 atm (not toxic, but [explodes at this point](http://aetinc.biz/newsletters/2010-insights/october-2010))
0.00045 atm, o.k
* SO2 < 0.000005 atm
not found
* O3 < [0.0000001 atm](https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners) i.e. 0.1ppm
0.000165 atm, exceeded by 3 orders of magnitude
* O2 < 0,16 – 0,5 atm ([0.3 - 0.35 atm wildfire limit](https://www.earthmagazine.org/article/flammable-planet-fire-finds-its-place-earth-history)) [For the maximum](https://en.wikipedia.org/wiki/Oxygen_toxicity) [and this](https://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Pulmonary_toxicity_tolerance_curves.svg/1024px-Pulmonary_toxicity_tolerance_curves.svg.png) and [for the miniumum](http://www.geography.hunter.cuny.edu/tbw/wc.notes/1.atmosphere/oxygen_and_human_requirements.htm).
0.1725 atm, low but o.k
* Ar < 1.6 atm
0.00006 atm, o.k but very low, see below
* NH3 < [0.0001 atm](https://www.ucl.ac.uk/~ucbcdab/urea/amtox.htm)
not found
* Xe < 0.21 atm
0.00135 atm, o.k I would be surprised if anyone would even notice, nevermind get knocked out.
There is surprising little Argon in the atmosphere.
>
> Nearly all of the argon in the Earth's atmosphere is radiogenic argon-40, derived from the decay of potassium-40 in the Earth's crust. In the universe, argon-36 is by far the most common argon isotope, as it is the most easily produced by stellar nucleosynthesis in supernovas. - [Wikipedia](https://en.m.wikipedia.org/wiki/Argon)
>
>
>
Argon isn't in the atmosphere by chance but as a result of the alpha decay of potassium-40. This means that the planet is either very young (not older than maybe 0.5 byr at most), in a low metallicity system (meaning it would most likely be a planet dominated by water), lost its original atmosphere in a geographically speaking recent event, is an artificial world around a gas giant or black hole or is so small (moon-sized) that it had little radioactive material, to begin with. If none of these assumptions are correct, I suggest adding argon.
And you are going to have one hell of a [greenhouse effect](https://www.science.org.au/curious/earth-environment/enhanced-greenhouse-effect) CO2(factor of 4.5), H2O (factor of 24), CH4 (factor of 3), NO3 (factor of 4.5), O3 (factor of 41.25) and H2 (no direct effect, yet it increases the lifetime of other gases) are relevant for the greenhouse effect. Ignoring anything but H2O and CO2, which are responsible for most of Earths greenhouse effect (this is not really a clean approach as you added even more of the minor and stronger greenhouses gases) we see that you increased those by a combined factor of 66. Now calculating greenhouse effects is really hard and [requires simulation programs](https://en.m.wikipedia.org/wiki/Climate_model), but it is save to say that it will be way higher than Earths 33 K. Maybe 150 K? Now you are either dealing with a planet with a [runaway greenhouse effect](https://en.m.wikipedia.org/wiki/Runaway_greenhouse_effect), which is on the way to become an exo-Venus or one still habitable but near the outer edge of the habitable zone. In Solar system terms, this means out beyond Mars or even in the asteroid belt.
Where does this leave us? Ozone is way too common but it might still be fine because ozone is usually found in the [ozone layer](https://en.wikipedia.org/wiki/Ozone_layer) and not in the troposphere. The greenhouse effect might turn the planet into a cooking-pot. Then the air won't be breathable because it will boil you alive. Avoid getting the planet hotter than 47 °C to avoid the greenhouse effect. So apart from this, the fact that there is an odd lack of argon and that your greenhouse effect will be enormous compared to Earth the atmosphere is breathable.
[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 have not done the maths, but using common sense and some research I have got you an answer. At 5% oxygen concentration on earth, with one bar of pressure, you start to die, although with 1.5 bars of pressure you would definitely survive. It seems (at least with my understanding) that with a 5.5% percent concentration of oxygen would act like 8.5% concentration of oxygen. This concentration is normally not enough for a human to survive, although it is likely that we would be able to adapt by increasing the amount of hemoglobin in their blood.
There also doesn't seem to be enough water, which could lead to a lot of deserts.
hopefully, my math is correct and I have helped you with this.
edit: I actually did the math, and didn't plan to at the start so I wrote it wrong. sorry.
<https://www.thenakedscientists.com/forum/index.php?topic=44734.0> source for the amount of oxygen needed
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**This question asks for hard science.** All answers to this question should be backed up by equations, empirical evidence, scientific papers, other citations, etc. Answers that do not satisfy this requirement might be removed. See [the tag description](/tags/hard-science/info) for more information.
In the far future the posthuman successors of mankind have disassembled the stars and live on ultra slow and ultra efficient solar system sized computers, [Matrioshka Brains](https://en.m.wikipedia.org/wiki/Matrioshka_brain). The last enemy of intelligent life is entropy, the harbinger of the universes inevitable heat death. Once there is no energy gradiant left to exploit entropys final order will purge the universe of all life.
For obvious reasons this fate should be delayed as long as possible, so the most efficient use of resources usable for energy generation is imperative. Leaving fission and the harvesting of the Hawking radiation and rotational energy of black holes of the table; **I'm interested in how much energy can be generated out of one kilogram of hydrogen using the following process.**
The hydrogen is fused into helium using the [CNO-cycle](https://en.m.wikipedia.org/wiki/CNO_cycle) as efficiently as plausible followed by helium, carbon, neon, oxygen and silicon fusion. The iron produced by this process can't produce net energy in a fusion process anymore, so it is fed to a black hole to harvest the frictional energy it will produce in the accretion disk. As I understand it this should be the most efficient way to generate energy from matter if I didn't miss anything.
[Answer]
### [CNO Cycle](https://en.wikipedia.org/wiki/CNO_cycle): 4H $\rightarrow$ He
4 protons (i.e. Hydrogen nuclei) combine to form a Helium molecule while releasing 26.7 MeV energy. This is the net result of any of the various fusion pathways for hydrogen to helium.
### [Triple-$\alpha$ process](https://en.wikipedia.org/wiki/Triple-alpha_process): 3He $\rightarrow$ C
Three Helium molecules combine to form a Carbon molecule, while releasing 7.4 MeV of energy. Since it takes three CNO reactors (and 12 protons) to make a Carbon molecule, we now have a net gain of 87.5 MeV.
### [$\alpha$ process](https://en.wikipedia.org/wiki/Alpha_process): C + 11He $\rightarrow$ Fe
See the link, this is a long chain of reactions, each successively adding a Helium to get to a bigger element, until we get to Fe-52. The total energy released by this chain is 80.6 MeV. Taking into account the 87.5 MeV to form the initial carbon and 11 $\times$ 26.7 MeV to form all of the Helium, the net energy gain from fusion is 462 MeV, divided by 52 initial protons.
Now, Fe-52 is not the most stable element, and you could theoretically get more energy by reacting up to Fe-56 or Ni-62 or something. But, I wasn't able to find a clear path for fusion up to that point. In the real world, creation of these elements is a result of an equilibrium between various fusion reactions and photodisintegration and such. I think this energy estimate is the best for your purposes.
### Energy released by accretion
This is much more difficult to estimate, because there are a lot of factors here, and it depends strongly on the size of your black hole and shape of the accretion disk. However, reworking an [estimate of luminosity](http://www.astro.utu.fi/~cflynn/astroII/l6.html) based on mass transfer rate into a black hole gives:
$$E = \frac{\mu m}{R},$$ where $\mu$ is the standard gravitational parameter for the black hole, $m$ is the mass of the object falling into it, and $R$ is the radius of the accretion disk.
Lets take the [black hole at the center of our galaxy](https://en.wikipedia.org/wiki/Sagittarius_A*) as an example. I calculate $\mu$ to be about $5.7\times10^{26}$ and $r$ about $7.5\times10^{12}$ meters (~ 50 AU). Therefore, each [AMU](https://en.wikipedia.org/wiki/Atomic_mass_unit) generates about 0.8 MeV as it falls into the accretion disk. Consider this a pretty rough estimate. The problem here is that much of this kinetic energy is either a. carried into the event horizon by the falling particle or b. radiated into the event horizon by the accretion disk. Either way, much of the released energy is unusable.
### Conclusion
You get about 9 MeV from fusion per AMU of protons that you throw into this process, and less than 0.8 MeV from accretion per AMU of protons. Converting to J and kg, we get 870 TJ per kg from fusion, and less than 77 TJ per kg from accretion. So, you are looking at something in the range of **900 TJ per kg of hydrogen**.
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[
This is for a medium/high fantasy magic setting with a medieval flavor (a D&D campaign setting) and am trying to get a grasp on expected long term effects/reaction by repeated worldwide devastation that happens on a cycle and a mechanism that would allow nearly in its entirety that it was just a legend or never really happened. Or that it is known by some people ( sages, researchers, secret organization) but nothing is ever done to prepare.
The idea is that dragons return to the world briefly for a few months or years and spend the entire time destroying anything and everything they can. These dragons are exceptionally powerful.
For the first cycle the world is not prepared and already in a form of dark ages dealing with other problems. Dragons were thought to be extinct and have little in their way then mysteriously vanish and the world is left on its own to recover naturally. New cities, new kingdoms, nature reclaims the waste.
Then roughly 1000 years later (timescale flexible) for a second cycle the world is taken by surprise and it happens again. The first 2 occurrences can be explained well enough but after that (by 3 or 4) someone is bound to see a connection.
Like a perpetual cycle of apocalypse through post-post-apocalypse. I hate to tie a parallel here but similar to the Matrix without the concept of "The One".
Main Question: When knowledge of the events would be recorded or passed down in a legitimate way that would be recoverable and actionable by a world population, by what mechanism might I be able to avoid or ignore the usefulness of this information?
I would prefer to avoid civilizations developing dragon fighting weapons and dragon dooms day bunkers or perhaps they wanted to but were somehow prevented from being able to, every time.
[Answer]
**Predictability**.
Regardless of exactly how close the cycle is to 1000 years, it is more important to know how exact the intervals actually are. A cycle that is *"exactly 1174 years, 8 months, 19 days, at high noon on that day, EVERY cycle"*, is much more likely to cause world population to prepare in advance for the next cycle than a cycle that is *"every 600 years give or take 150 years"*. Accuracy of predictability will be the single deciding factor.
Regardless of what information is recorded, it is only useful if the world population can put it to good use at the correct time. If a cycle comes early, the population will not have prepared in time (never underestimate procrastination). If the cycle comes late, the populace could start to believe that it will not come at all (belief that it has turned out to be a false prophecy, or equivalent) then any preparations they might have made could become dilapited from lack of maintenance, abandoned, or forgotten entirely, so when the cycle does come, they are, again, unprepared but for a very different reason.
[Answer]
If the destruction is thorough enough, then the survivors won't be able to tell what happened. I'm talking complete destruction of all buildings. Individuals might survive, but groups would have to be small and avoid buildings. Over 99% of everyone dead. Since destruction is concentrated on buildings, the death toll would be highest in cities--where the most educated generally live.
Rumors might survive, but by the time that a thousand years is up, they'd be disbelieved by most. And in terms of the repeat occurrences, they'd be forgotten. That kind of destruction would destroy the written records in which the previous rumors were posted.
A century or two after the destruction, people would be wondering how long ago it happened. Why? Because all the calendars were destroyed. People having to live a hunter/gatherer lifestyle while trying to rebuild agriculture don't have time to keep track of the days and years. So when the next time is approaching, they won't know. Because they didn't track the length of the last period. The kind of people who would have done that died in the destruction.
The survivors would be trappers, travelers, and the occasional hermit.
[Answer]
Maintenance costs.
All of those dragon fighting weapons cost money. All of those dragon doomsday bunkers need upkeep. Even if they just sit around, someone has to watch them sit around and keep them useable. Or replace them if they become unusable.
It's easy to justify those costs for the first few decades after the dragon attack, because people will still remember it first hand. Then it'll get slightly harder, as people who remember it first hand start dying. Eventually, people will only read about it in books, at which point it will seem like a distant threat that is unlikely to occur again.
When that starts happening, some enterprising young prince or duke will say "Yeah, we don't need to be spending all of this gold on dragon survival bunkers. Let's take that money and spend it on Necromancy For All instead!" And so, 1000 years later, there will be necromancers giving out free healing spells on every street corner and no way to repel the next dragon invasion.
[Answer]
You could look at the first Pern books for inspiration. They have exactly this situation where the threadfall comes on a periodic cycle every 250 years....but sometimes it misses. They had it miss twice in a row and as a result people became complacent and started thinking it would never come again.
[Answer]
### Upkeep Cost
It's a waste of money, all those weapons, catapults, soldiers, barracks, bunkers, oracles, etc, used to determine when the dragon will attack and defend ourselves is very expensive. Only during the first years after the attack will people want to pay for it, but, after some time, like a generation, the dragon attack will only be a story, not an immediate threat. Politics will use all that money from taxes to other stuff, like [bread and circuses](https://en.wikipedia.org/wiki/Bread_and_circuses) or anything better.
### Random Cycle
Dragons aren't machines, they didn't attack every 1,000 years. Maybe the second attack was 900 years later, and the third was 1,120 years later. These differences reduce the credibility of the cycle.
For example, 5 years before the 1,000th year, the king spends a huge amount of money to build an army of dragon-hunters to protect the kingdom. 5 years later, nothing... 10 years later... nothing, 50 years later... still nothing. The king can't pay any longer an army who isn't used and so he dissolves it, 60 years later the dragon comes and kills everybody. Unless you can magically predict when the dragon will come, maintain an army is difficult, more if you promise to people work hard to prepare for the attack, and nothing happens, people won't believe you next time, and obviously, people always forget.
### Memory
1,000 years is a lot of time, plenty of time to forget. With that amount of time, something like a war with a dragon may become a story, a legend, or just a past event that won't occur again.
### Preparation
Okay, you just was attacked by a dragon and all is destroyed. A few years later the kingdom starts recovering from the damages. You know you have 1,000 years to prepare until the next attack. What would you do?
99% percent of people will say nothing since they will be dead by that time. Then, after some time, when people start having a chance of still being alive to the event (like 50 years) will say it's plenty of time, and they will wait. People are [procratinators](https://en.wikipedia.org/wiki/Procrastination) by nature, even more, politics. Any politic will leave the preparation (and its costs) to the next, and this the next, and then the other to the next, until it's too late are you are on fire, literally.
[Answer]
A classic case of "We have the knowledge but not the will to use it." The political expedience where the cure is more disagreeable then the disease. How badly do you want the bearer of bad news to suffer in order to save the population?
One likely scenario is that a minor nobleman/knight's kingdom/village/area of influence was devastated in the distant past and a blood pact/family curse compels the descendants to look for signs and portents of a "reawakening" of the dragons. Now that the crisis is eminent, the "hero" has to inform/warn the public. Of course the family name is in disgrace so nobody will listen to their warnings of coming danger. This is made worse by the fact the protagonist is a drunk or hears voices or did some sort of faux pas so is totally discredited by the powers that be. One thing he can't be is a beggar on the streets as he would zero standing in the community bases on class/social standing. Another typical scenario is that a young monk is tasked with spreading the warning the masters have discovered/saved of the impending disaster but is socially awkward or that sect is currently in disfavor by the religious hierarchy so he falls in with a group of travelling actors/performers and disseminates his message in the form of a morality play to the masses after escaping from some harrowing adventures. The last scenario is where the powers that be are in denial and attempt to kill the messenger because it would disrupt or inconvenience the rulers and their decadent lifestyle.
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In the story I'm currently working on an alien race holds the monopoly on FTL travel. They're using a modified Alcubierre drive system, powered by Negative Mass. Humanity stumbles on a source of Negative Mass, and with assistance manages to bootstrap an FTL drive for themselves.
The aliens have always jealously guarded their monopoly (picture a society based on similar lines to the British East India Company), so inevitably there will be a battle. The aliens have traditionally relied on their speed to take them out of harms way, as they're merchants at heart rather than warriors. They have always relied on *Economic* warfare, as opposed to combat, though when the need arises they have no problem hiring mercenaries to do their dirty work.
At the end of the tale we have a human FTL ship chasing down the alien vessels. My question is this...exactly how would they *do* that? What kind of weapons and tactics actually work at FTL speeds? Lasers and other energy weapons are limited to light speed, and the Alcubierre drive is too massive for missiles. Not only that, their supply of Negative Mass is limited, so what are their options? Outside of ramming the other ship, that is, I'd like to avoid a kamikaze approach. Boarding actions are possible, but a suboptimal choice.
[Answer]
My understanding of the Alcubierre Drive is that it maintains a "warp bubble" of real space that our ship safely sits in whilst it contracts space-time in front, and expands space-time behind.
Assuming two separate Alcubierre warp bubbles don't catastrophically interfere with each other (I have no idea if they do, and I don't know if anyone does have any idea either way), then that would allow two FTL ships to move side by side and merge their warp bubbles to make a peanut-shaped zone of real-space, surrounded by expanding/contracting space time.
In this bubble, standard ship weapons could be employed, be they missiles, lasers or kinetics and they would be carried in this warp bubble along with the ships. Naturally the defending ship will want to split the peanut back into two bubbles so as to prevent getting shot, so you'll be able to have plenty of mind games between the pilots as they try and predict one another's actions as they use their ship's FTL manoeuvrability to best effect.
Projectiles hitting the edge of a warp bubble will also have a really bad day, possibly ranging from instant vaporisation as their atoms are sprinkled across Light Years of space, to (if they're lucky) being shunted into the empty void between stars. I would thus not recommend launching manned fighters or boarding parties when in FTL combat, unless you want to then write the story of some lone snubfighter pilot stuck in the expanse.
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# Tachyonic beam
[Tachyons](https://en.wikipedia.org/wiki/Tachyon) are ( so far sci-fi only) particles that travel faster than light. You can weaponize them.
Messing with FTL involves time travel, so you may end up hitting someone in the past. Don't shoot anywhere close to Earth or you may suffer from the grandpa paradox.
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# There's not much.
It partially depends on how quickly they are going. For instance, suppose they are expected to travel 1 minute at 2c. It might be reasonable to aim at their projected location with a laser and wait a minute (though modern lasers spread out too quickly for that to be reasonable). If they are immobile, you can warp to them and then fire.
But that's more or less moot without a way of detecting where they actually are. At superluminal speeds, ship leave echoes wherever they go (both light and gravitational). It's imperative that ships first have the capability of detecting ships moving FTL more quickly than light can travel, or the only way to fight a ship in FTL is to follow it and shoot it when it stops.
So assuming that your ships are equipped with a tachyon detector or the like, you have two options that I can see:
1. Superluminal weapons (which you say you prefer not to use)
2. Getting in front of your target
To get in front you need to be faster or smarter. Take the kessel run in 12 parsecs or something. Once you're in front, anything works - you just need to aim at where they're going to be. I will also note that superluminal weapons don't actually solve the problem. In order for them to work, you have to have a faster drive than your target anyway.
# In space, you can't force someone to fight
In the rules for the board game *Federation and Empire*, there's a section on the decisions they made when designing it. They make the following point (paraphrased):
>
> In space, you can't force your enemy to fight. There are no coastlines where you can pin them against. Most of the time, they'll fight a little and then just leave. If you want them to fight, you have to threaten something important to them.
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I'll add that because the ship in front doesn't have to have superluminal weapons to hit, they have the advantage.
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If the human ship chasing them is capable of overtaking the chased alien scums ship all they really need to do is to open an airlock and drop a bucket full of bolts\nuts\etc outside and let the alien scum ship run into it, the FTL speed they are going will mean that even the smallest of mass will be enough to blow holes clean through the ship and destroy it.
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would you not be able to fire a weapon in front of them attempting to predict their location at time of impact?
Because they also wouldn't be able to see what is in front of them unless they have FTL sensors too but then a laser is undetectable until impact
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## Some background you may or may not skip
I was daydreaming the other day about how tamed dragons whose magic was somehow harnessed as an energy source by humans could be used as a metaphor for nuclear power in modern societies. While considering this, I surprised myself thinking "*of course they would need to cut the tongue out of tamed dragons so that dragons can't orient their fire anymore*".
Don't ask me where I got the notion that dragons need their tongue for that. Still, this got me wondering about what conditions were needed for this thought to be true.
## Background you should not skip
In my world, dragons ...
* ... fit the stereotypes defined in this [somewhat related question](https://worldbuilding.stackexchange.com/q/313/52315)
* ... breathe fire in the way described [there](https://worldbuilding.stackexchange.com/a/345/52315) except they use magic to conjure the initial flame, inside their mouth. The rest is similar:
the liquid fuel is "sprayed" from a reservoir towards the flame, ignites and finally breathing is used to expel the burning fuel. It so happens that this is more efficient than using pure magic to conjure a full stream of fire.(1)
* ... use their tongue to control the direction of the fire they breathe. This constitutes a competitive advantage over their ancestors who had to rotate their heads to do so: (1) the breathing direction can be adjusted to a moving target more rapidly(2) and unpredictably, (2) the head can remain parallel to flight direction for better aerodynamics.
## Question
If this is possible, what sort of motion / positioning of their tongue could my dragons use to control the direction of their breathing so that the flame is directed? This might be used in combination with other actions that control breathing, much like whistling. All I need is that the tongue be important enough that if the tongue is cut, dragons loose this ability and fall back on the original approach of turning their heads all the way.
An ideal positive answer would
* explain the mechanism,
* if possible back up its claim with examples in real-world fauna achieving similar purposes,
* not make use of any more magic.
An ideal negative answer would either demonstrate that this is not possible or that a significantly simpler mechanism allows dragons to orient their fire and would lead to the same competitive advantages.
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(1): magic consumes mana, which is hard to store and fluctuating. Fuel is a more secure way of storing energy for dragons.
(2): please consider that tongue motion of reptiles is faster that that of humans, [and snakes can flick their tongue back and forth at around 15 Hz](https://academic.oup.com/chemse/article/37/9/883/327681)
[Answer]
I recognise that this is based upon human rather than reptilian tongues, so may not be what you’re looking for, but perhaps your dragons could use their tongues as funnels to direct their flame. Not all humans can roll their tongues (though it’s not actually a genetic predisposition, apparently), but if your dragons are able to gain mastery of their tongues to curl the outer edges into a tube, they could theoretically use that to direct a focused jet of flame, rather than needing to swing their heads to blow a more dispersed cloud of flame.
Also, less of a directional thing than a variation in fire breathing style: musicians who play wind instruments are sometimes directed to make use of a technique called [flutter-tonguing](https://en.m.wikipedia.org/wiki/Flutter-tonguing). Given that reptiles can move their tongues at a greater speed than humans, I wonder if your dragons can make use of this technique to more precisely control the flow of air, peppering their enemies with a barrage of fiery ‘bullets’, rather than just a barrage of flame. (And at the very least, it might just make them awesome clarinet players.)
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They don't have to direct the fire, they just have to direct the spray of the fuel. Assuming the fuel is ejected out of glands beneath their tongues; moving their tongue will twist, compress, and distort their fuel glands to direct their flames. Not entirely unlike the process of [gleeking](https://en.wikipedia.org/wiki/Spitting#Gleeking) that we humans are capable of.
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What if their tongues got hot?
They wave their tongues to keep the gas stream ignited. Gotta mix it right for further reach, higher heat, sustained, fireball, etc.
You can use this as flair, with very well trained dragons able to fully burn the gas, and novices may leave behind small pocket that just smell foul when unburned
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If the ignition happens outside of the mouth, you can establish that the spray from the glands is somewhat irregular and that the tongue is necessary to channel it outside. It would be similar to spitting. Without the tongue the dragons would splash themselfs and set on fire.
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>
> a significantly simpler mechanism allows dragons to orient their fire
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Searching online, it seems that many dragons have side-facing nostrils.
[](https://i.stack.imgur.com/Goos4.png)
In the same way that dogs can direct their ears independently, <https://youtu.be/fsZK4yvKt-o?t=35> , it is reasonable to suppose that dragons could move their nostrils. <https://youtu.be/zACUtVjcLBc?t=7>
I suggest that they can selectively blow fire through their mouth or either nostril at will.
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**Muscle Directing**
If you want dragons to control their aim with their tongues, then you would simply need them to use the muscles in their tongues to shape the route of the fires fuel to be whatever they need it to be.
Its kind of like dumping a bucket of water versus using a hose. the dragon could shape ts tongue to be flat and simply bathe it opponents in loose flames, or it could narrow it to a narrow tunnel, like forming your own tongue into one, and using that to shoot a powerful jet of condensed flames at a smaller target.
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One of the planets I am working on is supposed to have a day of about 6 earth hours long & I’m wondering what effects this will have on its surface and climate. Also, I don’t know if this is relevant, but my world is a terrestrial planet that is a little larger then Earth with rings & an axial tilt of 41.3 degrees.
EDIT: 3 hours of day & night each.
[Answer]
I won't address the almost doubled obliquity (axial tilt) since you didn't ask that specifically, but it will have huge effects and probably deserves its own question. If the radius is going to change by more than 500-1000km or so, that probably deserves its own question as well. In thinking about quadrupling the angular velocity of an Earthlike planet, there are a few areas I can think of right away:
**Gravity:**
The planet will be more oblate (squished at the poles and fatter at the equator). I don't think it's worth the calculation since the effect is so slight, but this will lead to a slightly higher gravity at the poles and lower at the equator. However, there is a larger effect that is not really gravitational but belongs in this section. For a rotating planet, there is a centrifugal "force" acting outward which is strongest at the equator and nonexistent at the poles. This will make the perceived gravitational force at the equator ~5% less than at the poles, with the difference decreasing as one moves toward the poles. This would be barely noticeable for a person day-to-day, if at all, but this would have major effects on the world ocean. The sea level near the poles would drop, and near the equator it would increase. I don't think I know how to make this calculation right now, nor do I have the time to learn, but I would love to hear from someone who has a guess about what the effect would be at the equator in terms of sea level. I guess I am also thinking about this as if it suddenly happened on Earth, but if it were a planet that had always been that way it probably wouldn't be a huge deal.
**Spacecraft:**
The altitude of a geostationary orbit would decrease by over half, from ~42,000km to ~17,000km (EDIT: the numbers I gave are orbital radius - the altitude would decrease from ~36,000km to ~11,000km). This would have lots of implications for how these satellites would operate (close means easier imaging but also narrower field of view). Also, rockets are normally launched (at least partially) eastward and nearer to the equator to take advantage of the Earth's rotation. With increased angular velocity this would still be the case but it would be much easier to get into space, whether for low orbit, geostationary orbit, or interplanetary travel.
**Coriolis:**
The Coriolis force acts at a right angle to the motion of an object not attached to the surface (rightward in northern hemisphere, leftward in southern hemisphere). This doesn't have many implications for day-to-day life, but if you are e.g. a pilot or an on an artillery crew it is pretty important. The Coriolis force has a magnitude of the multiplication of the object's velocity and the angular velocity of the planet, so quadrupling the angular velocity would quadruple the Coriolis force.
More important than ballistic trajectories and powered flight, the Coriolis force has a major impact on climate. At the large scale in the oceans and atmosphere, the dominant currents are [geostrophic](https://en.wikipedia.org/wiki/Geostrophic_current). This means there is a balance between pressure gradients and the Coriolis force, so winds/currents move parallel to pressure gradients. Not to be too complex here, but the point is the Coriolis force is a huge part of how the atmosphere and oceans circulate, and I can't say exactly how this would change. I can say that geostrophy would still dominate, and large storms like hurricanes would spin faster.
**Insolation:**
The total insolation would stay the same, but with a much faster day/night cycle. So while the climate may not actually change drastically with this one, there might be some large local effects. I can think of things like shoreline winds and precipitation in dry areas.
**Tides:**
Does your planet have a moon/moons? Does it specifically have an abnormally large (compared to its size) moon like Earth does? If so, the tides will change pretty drastically. The periods of the tides on Earth are all combinations of aspects of the Earth's rotation and the orbits of the sun and moon. So the periods of tides on your planet will be quite different. The magnitude of tidal variations is very dependent on bathymetry, but I can say any [tidal bore](https://en.wikipedia.org/wiki/Tidal_bore) would be more intense than it otherwise would be.
Currently the moon also "steals" some angular momentum from the Earth via tidal friction, and if the angular velocity were quadrupled this effect would increase. This would still be negligible in the course of day-to-day life or at the scale of human lifetimes.
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A shorter day would have the effect of a more even heathing and therefore an smaller difference between day and night. Daily sea brezes would likely be a lot less noticeable. A faster spin would also increment Coriolis forces, and therefore winds would tend to follow more curved paths and twist more than in real Earth, but that wouldn't be a big deal.
However, what do make a big change in some areas is tilting the planet by 41.3 degrees. That would put the latitudes of London and Berlin North of the Polar Circle, and even in middle latitudes there will be sunlight for most of the day in summer and very short days in winter, therefore making seasonal alternance stronger. Even in the Equator seasons would appear, while in real Earth equatorial climate is nearly seasonless.
In summary: temperature of day and night would be less different than in our Earth, but climate in winter and summer will be very different. If your year were to be larger than ours it would be even worse.
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Expect near constant hurricane-force winds & tidal waves, due to massive coriolis effect. Hard to see that such an environment would be in any way habitable.
*"the first evidence of life, 3.5 billion years ago, happened when the day lasted 12 hours. The emergence of photosynthesis, 2.5 billion years ago, happened when the day lasted 18 hours. 1.7 billion years ago the day was 21 hours long and the eukaryotic cells emerged. The multicellular life began when the day lasted 23 hours, 1.2 billion years ago. The first human ancestors arose 4 million years ago, when the day was already very close to 24 hours long."*
<http://www.iea.usp.br/en/news/when-a-day-lasted-only-four-hours>
EDIT: this effect would be most pronounced in the equatorial region - in the temperate region, things might not be as bad. but the equatorial region would be a permanent no-go zone, other than via air travel.
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I'm trying to auto-generate random solar systems, and I'm basically just allocating 2% of the total system mass to planets (and moons). It provides interesting results, I always have a few gas giants, I often have many Mars-and-Mercury-massed planets.
But to calculate surface gravity, I need a radius.
This largely depends on the planet's composition... which can be quite varied (and depends quite a bit on where it formed, how it formed, etc).
But if I have a planet with 0.7 Earth mass, and 35% of that is iron/nickel (or siderophile), and 50% lithophile, and so on, can a decent estimate of radius be determined?
Do I need the breakdown on composition to be per atomic element, or can this give decent ballpark numbers if I have the mass as the ratio of [lithophile/siderophile/chalcophile/volatiles](https://en.wikipedia.org/wiki/Goldschmidt_classification)?
My understanding of physics in this arena is... inadequate. I do not believe it's enough to simply look up the density of these elements on Wikipedia and calculate backwards from volume. Certainly an iron core compresses a bit such that the density is quite higher than that of an iron ingot on the surface?
[Answer]
# Mass, density and radius are related
Let $m$ be the mass of a planet.
For a given a density $\rho$, the relationship between mass and volume is
$$\begin{align}
V &= \frac{4}{3}\pi r^3\\
m &= \rho V = \frac{4}{3}\pi\rho r^3
\end{align}$$
The bottom equation gives you your relations. Of the two variables you are interested in, mass ($m$) and radius ($r$), the solutions in terms of one another are:
$$\begin{align}
m&=\frac{4}{3}\pi\rho r^3\\
r&=\sqrt[3]{\frac{3m}{4\pi\rho}}
\end{align}$$
Be careful with units! Always convert mass to kg, radius to m, and density to kg/m$^3$ to be safe.
# What should density be?
Since you need density in both these equations, what are some reasonable densities for a planet?
```
Object/Planet Density (kg/m^3)
Earth's Inner Core 12800
Earth's Outer Core 9900
Earth 5510
Mercury 5430
Venus 5240
Mars 3930
Vesta (densest asteroid) 3420
Luna 3340
Ceres (largest asteroid) 2080
Ganymede 1940
Titan 1880
Neptune 1640
Jupiter 1330
Uranus 1270
A small chunk of water ice 934
Saturn 690
```
A lot goes into planetary density, and that could totally be its own question. Mass drives density; the bigger a planet the more gravity will compress it. Mercury has more iron (relatively) than Earth, but is less dense because Earth's gravity compresses its core more. But these values are some guidelines for solving the above equations.
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I was reading [this question](https://worldbuilding.stackexchange.com/questions/112038/the-worlds-a-jungle-again-would-doldrums-blow-the-global-air/112254#112254) earlier today. It asks about the characteristics of global winds in a modern-day earth with Eocene-like temperatures. I'm here to ask about other kinds of weather in the Eocene. The only hard estimates of temperature for the Eocene I could find online are [here](https://phys.org/news/2018-01-eocene-fossil-climate-underestimate-future.html). Based on these numbers, let's assume a yearly average of about 24 °C or 75 °F, with averages in the summer being 28 °C (82 °F) and the winter averaging at 20 °C (68 °F). These readings are taken in "the US Gulf Coast," so let's assume these temperatures are representative of 30 °N.
### Based on this data, what weather may have occurred in the Eocene that would affect a human population?
I've researched this a bunch, but I'm not grasping what this data says about the climate of the world as a whole, different areas of the world, or the weather. My main concern here is determining whether severe weather or even mild precipitation would be as common as, less common than, or more common than they are today. My story is about humans living about 50 mya, so I'm trying to establish a setting that's as reflective of real-world conditions at that time as is possible. Hurricanes, wind, and any other significant aspects of the weather are also relevant.
The other thing I've found researching this is that no-one in the scientific community wants to publicly give actual numbers. Given that I'm openly asking for speculation as to what may have been based on a small amount of data, I figured Worldbuilding is the best place for this question. If you think a site that values facts and hard data above all would accept this question better than Worldbuilding, feel free to send me there. If this is too broad, I can easily narrow it.
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You are asking about Palaeoclimatology. Please take everything I say as speculative.
The Eocene Epoch was 56 to 33.9 mya (~22 million year time period). It is typically split into three subdivisions; early, middle, late. It starts off with one of the warmest periods in Earth's History. Then a cooling period begins and Ice slowly starts to reappear at the poles and then finally we have the rapid expansion of the Antarctic Ice Sheet (from [Wikipedia](https://en.wikipedia.org/wiki/Eocene)).
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**TL:DR**
Initially, it was warmer than the present, with a lot more precipitation. Little to no high latitude Polar ice. Little seasonal or latitudinal variation in temperature, hardly any frost. Winds would not have been very strong, as little to no strong pressure gradients.
Later it started getting cooler. More variation in seasonal extremes as well as by latitude. Strong winds, snow, and frost would have been more frequent during Winter. Sea Levels would have dropped and the air would have generally been drier. Larger weather features would start to form as the Atmospheric Hedley/Ferrel cells strengthened and started stabilizing. Distinct climates and biomes would develop.
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**Early Eocene.**
During this time, there is little to no Ice on the planet. There is little difference in temperature between the Equator and Poles. Temperatures are much warmer than today, swamps and forests are spread over most of the landmasses including the higher latitudes.
See this image of one of the [Boundary Condition Models for 55mya (early Eocene)](https://www.earthbyte.org/geoscientific-model-development-a-suite-of-early-eocene-climate-model-boundary-conditions/)
[](https://i.stack.imgur.com/NV0oo.png)
This spread of forests and even palm trees to the higher latitudes is possible due to the fact that there are more greenhouse gases in the atmosphere than present (CO2 and methane). More methane was released from the swamps and wetlands etc creating positive feedback loops. It is also, due to the fact that the Drake and Tasman Passages are closed, allowing the polar waters to mix with the warmer equatorial waters.
[](https://i.stack.imgur.com/txqhP.jpg)
[Eocene ocean sediment paper](https://www.sciencedirect.com/science/article/pii/S0025322714000735)
* A) Global distribution of the marine basin during the Eocene (56–33.9 Ma.), illustrating the closing and opening of the main gateways, which have determined drastic changes in the deep-water circulation. B) Global thermohaline circulation. Red: surface currents; Light blue: deep water; White: bottom water; Orange: main sites of deep-water formation. In the Atlantic, warm and saline waters flow northward from the Southern Ocean into the Labrador and Nordic seas. In contrast, there is no deep-water formation in the North Pacific, whose surface waters are consequently fresher. Deep waters formed in the Southern Ocean become denser than those from the North Atlantic and therefore spread at deeper levels. Note the small, localised deep-water formation areas in comparison to the widespread zones of mixing-driven upwelling. Wind-driven upwelling occurs along the Antarctic Circumpolar Current.
The article you linked to in your question is talking about the discrepancy between the data obtained from various locations and the predictions derived from models. Currently, the models are saying the poles should have been a lot colder than what our records are showing. It's known as the "equable climate problem". There are several competing theories as to how to solve this, but no-one has solved the issue yet. This equable warm temperature in the Arctic allowed a floating aquatic fern (Azolla) to flourish! When the temperatures started to cool, the Azolla fairly rapidly (geologically speaking), sank to the bottom of the sea and sequestered a lot of CO2, allowing for further temperature changes. This is known as the Azolla event, although it's not sure if it was the trigger or just helped with the drawdown of the CO2.
This equable and homogeneous temperature range over the planet would have affected the atmospheric circulation system. One of the [papers](https://academic.oup.com/biolinnean/article/103/2/229/2452613) linked in the accepted answer to the question you linked to (shew, what a mouthful), discussed the effect on the Hadley, Ferrel and Polar atmospheric cells. The paper estimates the winds and precipitation during this time.
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> The ice-free state during LPTM was characterized by a much higher annual-mean temperature and a greatly reduced seasonal cycle along with a lower equator-to-pole surface temperature gradient than is known for any other period in the Cenozoic for which data exist.
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> In the Huber & Sloan (1999) simulation of the LPTM climate conditions, the surface winds for January (Fig. 8A) presented mid-high latitude easterlies centered on 50° to 60°S and a weak westerly wind belt around 30°S. The presence of mid-high latitude easterlies is not the result of an expansion of the tropical easterlies so much as an expansion of the polar easterlies. This wind scenario, characterized by relatively strong easterlies over Patagonia and a weakened wind system over the Pacific Ocean likely generated air mass advection from the Atlantic inducing convection and precipitation over land. Such conditions are consistent with the suggested rich subtropical vegetation that existed over a large portion of Eocene Patagonia with the presence of megathermal families such as palms, other taxa with broader climatic requirements such as conifers, cycads, and Ginkgoales (Wilf et al., 2005; Iglesias, Artabe & Morel, 2011; Quattrocchio et al., 2011), as well as the coals in the east Patagonia (Scotese, 2010).
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> The strong high latitude precipitation in the model scenarios (not shown) was a reflection of the warm high latitude SSTs, as a result of the fact that the removed seasonal sea-ice from the polar seas enhanced local evaporation and precipitation. The reversal of the ‘polar cell’ caused by the deep high latitude convection is a fundamental disruption of the normal atmospheric general circulation. During winter time (Fig. 8B), the winds display the same easterlies pattern over Patagonia but weaker than in summer.
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This marks the change to the cooling **Middle and Late Eocene.**
As the Drake and Tasman Passage started to open up (order still undetermined), the polar waters became isolated from the warm equatorial waters. No more mixing was taking place and the antarctic circumpolar polar was formed. This isolated and unmixed cold water allowed the temperature to drop several degrees and for Ice to slowly start forming at the poles.
There was a brief rewarming of the Earth for about 600 000 years. This reversal from the cooling process that had been started is attributed to India colliding with Asia and forming the Himalayas. So temperatures would have fluctuated at this time, I think while warmer again, there was also a larger seasonal variation. This seasonal fluctuation would have affected those species (plant and animal) that couldn't cope with large temperature and precipitation ranges.
After this brief hiatus, the cooling continued until the end of the Eocene and beginning of the Oligocene. Cooler temperatures, the raising of the Andes Mountains 45mya (which interfered with airflow), the Drake and Tasman Passages starting to open, as well as the lowering of greenhouse gases etc allowed for a rapid expansion of high latitude ice sheets. This would have lowered the sea levels considerably, allowing more land to be exposed which would have further affected the Earth's Albedo. This affected temperatures and precipitation patterns even more, creating feedback loops that reinforced the general cooling trend. Climate and weather patterns were no longer homogeneous and more variation in temperature extremes developed.
>
> The Late Miocene represents a transitional phase between the Eocene greenhouse climate and the Quaternary icehouse situation. Ice had begun accumulating at the South Pole during the Late Eocene (approximately 37.2 to 33.8 Mya) culminating in the Pleistocene ice age. The widespread glaciation of Antarctica and the associated shift toward colder temperatures near the Eocene/Oligocene boundary (approximately 34 Mya) represents one of the most fundamental reorganizations of the global climate system recognized in the geological record (DeConto & Pollard, 2003). Concordantly, the atmospheric circulation pattern also changed (Broccoli & Manabe, 1992) and the climatic conditions in the region of Patagonia were strongly affected.
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> Several mechanisms were connected with Oligocene cooling, including changes in continental distribution (Barron, 1985), plateau uplift (Kutzbach et al., 1989; Hay et al., 2002), oceanic gateways (Sijp, England & Toggweiler, 2009), and the decrease of atmospheric CO2 (DeConto & Pollard, 2003). Scher & Martin (2006) suggest that the Drake Passage opened before the Tasmanian Gateway, implying the late Eocene establishment of a complete circum–Antarctic pathway. However, note that Cavallotto et al. (2011) considered that the Tasman path opened before. The Antarctic Circumpolar Current thermally isolated Antarctica, leading to the growth of the Antarctic Ice Sheet. Toggweiler & Bjornsson (2000) suggest that this opening reduced the poleward heat transport in the high-latitude Southern Hemisphere cooling high-latitude surface temperatures by several degrees (in the range 0.8–4 °C).
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[Question]
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I’m writing a story about someone who is going to be frozen in cryo for about 450 years. He’s frozen in 2120, so the technology is certainly well-developed in his time. I’m thinking maybe the cryo pod he was put in wasn’t built very well, or maybe 450 years is a bit long to be frozen and not the length of time his pod was meant to work for.
I’m wondering what physical and mental side effects he could suffer from, either from being frozen for so many years, or from a not-so-great cryo pod, or both.
I was also wondering if it’s at all possible that he could specifically suffer from some kind of change in his eye color.
I’ve looked at sources online, read about how Fallout and Halo and how some movies handle cryo, but I couldn’t find anything about side effects except confusion and nausea.
Any help would be appreciated :)
[Answer]
Even with really advanced cyro-tech it may still be possible to get "freezer-burn" given the length of time the character is to spend in cold storage. The idea is that in some areas the anti-freeze drugs that are supposed to stop cells bursting due to ice crystal formation either A. didn't take properly or B. the dose was low enough that it wore off before the thaw. Tissue not protected by some form of anti-freeze compound would suffer something like frostbite. The tissue most vulnerable to this form of damage would be that with the worse circulation, fingers, toes, the external ear, and especially the eyeball, this damage even in it's mildest form would manifest as burst vessels that would turn the eyes red with blood.
That's the physical, mental issues would be interesting, it would largely depend, I would think, on how long he *expected* to be out of circulation because after 450 years everyone and every*thing* he'd ever known would be gone so depression and apathy might be expected for a start, the further adrift in time he finds himself the worse I would expect those symptoms to be. Brain damage and associated deficits and psychoses cannot be ignored as logical consequences of extended cyro as well.
[Answer]
First things that comes to mind when thinking about a living organism frozen for so long is: radiation damage.
I am not talking about being exposed to some nuclear incident fallout, but really about constant exposure to natural background radiation. Every living organism has mechanism to immediately repair this damage, but in a frozen organism these mechanisms would be stopped.
When the individual would be awaken all his cells would have to deal with a large damage which is possibly beyond reparable.
[Answer]
**You Die**
If frozen solid the side effect is death and decay. Decay occurs much much slower than normal when a body is frozen but "sleep" it is not. It is death. You are dead and you are rotting, just very very slowly. Additionally ice crystals in the cells pierce the cell membranes causing further degradation to the body at a cellular level. This is a complex way to say that you get freezer burned.
Revival from cryogenic storage is nothing short of a literal resurrection except Jesus would be jealous since he didn't have to reverse the effects of a few centuries of DNA and cellular degradation and freezer burn when he did his. We are talking a full head to toe cellular rebuild from the molecular structure on up. There really is no way of predicting what that level of technology's side effects would be because revival from cryogenic storage is pushing the limit of technology into "seems like magic" territory.
One beneficial and guaranteed side effect of regular applications of this process minus the freezing part is functional immortality though. If you can rebuild the body at such a fundamental level you can essentially apply that treatment every so often and effectively be whatever age you want forever. Again, no idea what the effects would be though. We don't even have a hypothesis how it would work beyond a shrug and "maybe nanites?"
Essentially the potential negative side effects can be whatever you like because you are outside the realm of modern science's present scope of understanding.
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[Question]
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FINAL UPDATE: Thank you for your amazing points and answers, everyone! I mixed up all your ideas and posted the final answer as a community wiki.
So, I'm developing a bacterial infection where the bacterium is slightly magical. This is how the infection develops. Question below.
I know it's a bit of a pain, but please REREAD this list before you comment or answer. I will update it to modify my question and info as questions are asked and comments are made. I'll try to highlight my edits to make them more visible. Thank you.
Bacteria enter through open wound and begin secreting digestive toxin. The body reacts by activating macrophages to absorb the bacteria and producing antibodies to bind to the antigens on the surface of the peptidoglycan cell wall/surface to mark them for destruction by phagocytosis. The bacterium responds by using its first magical defense: magically warping its antigens (surface receptor proteins) and by continuing to divide and secrete digestive toxin. The body responds by adapting to the new antigen and by raising a fever to denature the toxin. The bacteria (all at the same time, magically) switch their antigen over and over again as antibodies are produced.
They can only do this for ten different antigens, though. So once the tides turn in the body's favor, the bacteria switch their antigens one last time and then hide, either near the skin surface or in the reproductive system (to protect themselves from the fever so they can still secrete toxins.)
The toxin causes nausea and headaches at first. The body continues with a higher fever to denature the toxin. Then the bacteria, having multiplied, attach to the insides of blood vessels and manufacture huge quantities of toxin, absorbing sugar from the blood. The body releases a new batch of antibodies. The bacteria can't switch their antigens. Instead, they vanish their non-essential surface proteins entirely. Then they release restriction enzymes (DNA-cutting enzymes.) They release these in lipid vesicles, but they do something genius: they put one of each of the previous ten antigens on the surface of the enzyme package and then release the whole things into lymph vessels, which means the whole immune system and all immune cells will be at risk. Any of the antibodies that are in the blood mark the package for destruction via phagocytosis. But the package fuses with the cell membranes and then slowly (the restriction enzymes) mangle the cell's DNA, killing it over time. Because, though, it's a lipid membrane, it also fuses with B cells and helper T cells. The B cells cannot divide, since their DNA is mangled up. And the T cells die, unable to activate the B cells and macrophages.
The immune system is wrecked now, and the bacteria happily multiply and secrete their toxin, which causes splitting headaches, fever, dizziness, and vomiting. The bacteria start flooding blood vessels with the toxin, reducing the effectiveness of the kidneys (causing dark, dark urine.) Then the bacteria release antigens that bind twice: once to red blood cell receptors, and once that are like the bacterial surface antigens.The immune system begins an auto-immune response, destroying red blood cells, since the killer T cells were left intact. The neurotoxin and loss of oxygen kill the brain. *This bacterium can essentially "vanish" from the immune system's senses and quickly kill off the body's defense.*
**MY QUESTION**: This is all caused by magical mutation and some enzymes. My question is: how would a (1) a vaccine and (2) a cure develop for such a bacterium? Take into account elemental magic (fire, water, earth, air) and nature magic (influencing magical organisms takes huge power, but nature magic includes muscle, skin, and blood cell regeneration, analysis of magical organisms, and toxin/poison resistance).
Approximately 4% of the population can access elemental magic and 1% can access nature magic. Include both types into the vaccine and cure, using medium-light power per dose.
The vaccine and cure should be
1. non-conventional (*antibiotics should only be one component*)
2. easy and inexpensive to manufacture (including the amount of magic required)
3. 90% effective
4. fast.
Assume geneticists have analyzed the protein-coding genes that code for
1. the restriction enzyme
2. the toxin
3. the 10 different antigens.
**Update:** These are the magic systems
Elemental: The usual manipulation of fire (also usable for any type of temperature manipulation) water (ice, water, water vapor) earth (also binding and a little bone/muscle regeneration type of healing) air (wind and latent air.) Also combos: water+fire makes lightning, water+earth=tissue regeneration, water+air+earth=blood magic (focusing mainly on control) (oxygen, iron, plasma) and different crafts. Using a single element is easy, using two is harder, three is difficult, four is very, very complex. Most mages specialize in 2 elements.
Nature: Essentialy witches. Good grasp of how poisons work, tissue regeneration-style healing magic. A little influence over living organisms; more influence (with more snags) over magical ones. Magical ones are more in tune with these nature witches, however, they are more aware and much more able to resist. This includes everything from primates to germs. Nature witches, however, are good at finding out exactly what magical organisms do (not how. But this is how the disease researchers found out about this bacterium anyway. A good witch might be able to not only look at the amino acid sequence for a toxin but also how it's built.)--
**There are limitations here: use your common sense. With a low number like this, using "handwavium" is unreasonable; the magic should take a minor supporting role in the vaccine. And short-term vaccines for bacteria are possible, using surface antibody/antigen solutions. The problem here is the bacteria instantaneously change and/or vanish their antigens, making them immune to normal antibodies, and have an attack system that blocks the immune system, much like HIV/AIDS would. It's okay if an antibiotic is used, but it should only make up a part of the cure/vaccine.**
*This is a bacterial infection, not a viral one. The bacteria can reproduce on their own, they secrete toxins, have double-stranded DNA, they respond to their environment, they evolve naturally. They are composed of cells and have regular metabolisms. They are simply unique in their defense against the immune system.The issue is that after the ten switches, the bacteria vanish their antigens completely. I was hoping for a vaccine that would stop this process somehow. I have no idea how a cure would work.*
[Answer]
So you mention that the bacteria use your worlds version of magic to alter their surface antigens, which seems to be the primary factor making this bacteria more dangerous than the diseases we have in our world. I'm not immediately clear if their shape-changing abilities fall under one of the classifications of magic you mention (does it have a specific elemental affinity, for example?). However, the most obvious cure would be some magic that could freeze their shape, preventing their chameleon ability to fool the immune system. I don't see any "ice" style magics, but surely there are counters and counters to counters in the military applications of magic, so there should be something similar in the medical side.
Alternatively, I note that you said the bacteria ALL change their surface antigens at once, implying some sort of communication. A chemical, biological, or magical interruption of that communication could give the immune system a huge boost in catching up to the disease.
Since you said that the bacteria can only change its antigens 10 times, that seems to imply that it has a fairly set collection of disguises that don't vary from patient to patient, which should allow a vaccine to be prepared that innoculates the immune system to each of the 10 antigen profiles. While that would be time-consuming and quite annoying, it shouldn't be technically difficult. A researcher should just keep some active in a petri dish watching with microscope/colored-chemical-tags/magic and then kill the bacteria with radiation or chemicals when each new stage of antigen presents themselves, and then use those cells as a basis. A world with magical manipulation of blood and similar factors should find the process of developing a vaccine much simpler than our world.
[Answer]
I like the detail and science behind the question, but the premise has a few scientific inconsistencies that you need to work out.
First, antigenic variation is something almost all infectious organisms engage in to fool our immune system. You don't need to invoke magic here. Check out this [article](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3676878/) for examples of real-world, magic-less antigenic variation.
It's also important to fully understand exactly what constitutes an antigen. Any protein on the surface of the bacteria can be treated as an antigen by the body. The bacteria doesn't get to choose what the immune system is going to attack with antibodies. Any protein that is visible to the immune system and is unique to the bacteria is fair game. This means that a bacteria can't simply turn off every antigen. If the bacteria had no surface proteins at all then it would have no way of interacting with the rest of the body. It wouldn't be able to take in nutrients, or adhere to somewhere in the body, or even maintain homeostasis. Perhaps this is somewhere you might use magic to permit a protein-less membrane to function.
Your scheme of using vesicles filled with restriction enzymes also has a couple issues. The first is that antibodies don't just mark antigens, they also adhere to and inactive them by occluding surface proteins. Any proteins that the vesicle is going to use to try to use to fuse to immune cells is likely to be recognized and occluded by an antibody. This is perhaps somewhere antigenic variation or magic might come in handy. Your choice of restriction enzymes as a toxic payload is a strange one. Restriction enzymes would have to get past the nuclear membrane in order to kill the cell. Why not instead use a more traditional bacterial toxin such as a [pore-forming toxin](https://en.wikipedia.org/wiki/Pore-forming_toxin)? These are already designed to kill immune cells. When the vesicle membrane merges with the cell membrane it will kill the cell quickly and easily. There are many other [exotoxins](https://en.wikipedia.org/wiki/Exotoxin) designed to kill cells.
I know the above isn't an answer to your question but I hope you find it helpful regardless.
[Answer]
They don't need to do anything special.
there are already viruses and bacterium that behave like this changing their antigens as they spread nothing magical is needed. Ten varieties is nothing to the immune system, bacteria have dozens of different antibodies on their surface.
also introducing DNA cutting enzymes will have little effect since eukaryotic cells have a double protection against this, the DNA is hidden behind other barriers. worse those lipids can only get added to the membrane with the right signal molecule which is itself an antigen. On top of that by constantly switching strategies the bacteria will actually have very little impact on the cells it is targeting is simply will not reach most of them, if the bacteria is at the stage it can release large quantities of a a substance into the blood stream the fight is already mostly over, and that is the the first step in their "abilities".
If you insist on including magic if bacteria can use magic, multicellular life will have a magical component to their immune system as well, so you are back to handwavium.
[Answer]
There's the obvious answer: every living organism in nature has some other organism that prey on it.
Find it.
Work out how it targets your bacterium.
Replicate the mechanism, or, if it seems relatively benign to humans, deploy it as a cure. Antibiotics started as [mould secretions that attacked bacterial colonies](https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/flemingpenicillin.html).
[Answer]
**Thank you for your feedback, everyone. I decided to combine all of this into a canonical answer as a community post to be fair.**
**Karl Justice said:**
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> "I note that you said the bacteria ALL change their surface antigens at once, implying some sort of communication. A chemical, biological, or magical interruption of that communication could give the immune system a huge boost in catching up to the disease."
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*Good point. I'll use a chemical/magical interruption in their communication.*
**Mike Nichols said:**
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> "[By disappearing its receptors] It wouldn't be able to take in nutrients, or adhere to somewhere in the body, or even maintain homeostasis. Perhaps this is somewhere you might use magic to permit a protein-less membrane to function."
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*Hmm. I'll give the bacterium that superpower, then take it away in the cure I develop. Good idea.*
**Mike Nichols said:**
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> "Any proteins that the vesicle is going to use to try to use to fuse to immune cells is likely to be recognized and occluded by an antibody. This is perhaps somewhere antigenic variation or magic might come in handy. Your choice of restriction enzymes as a toxic payload is a strange one.[It wouldn't work]"
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*Thanks for alerting me. The solution? Simple. Switch the antigens continuously as the vesicle travels. And I'll magic the restriction enzymes to work quickly--my point in using them is to stop the dying cells from dividing.*
# **TL;DR and the conclusion:**
**THE SUPERCURE**: A x5 punch. It uses three separate cures (enhanced with magic), an antibiotic, and an antidote. The antibiotic is just penicillin (or something similar). The antidote (designed by the witches and geneticists) is the perfect shape to lock+block the toxin, effectively stopping it from killing any cells. Over time, the toxin and the toxin inhibitor unfold, and are filtered and excreted through the kidneys. The first cure is a communication inhibitor; best given early on in the infection. It makes each individual bacterium scramble its antigens differently. It also forces all of the surface receptors to rematerialize. This is an advantage because larger amounts of the bacteria are wiped out because they cannot know whether the immune system is targeting them or not. Also, macrophages and antibodies can bind to the bacterium. The second cure is a type of magic-enhanced antibody. It's a really simple water/earth magic. What it does is the antibody binds not to the disease antigens but to the active transport and facilitated transport surface proteins (which have rematerialized due to the first treatment). Now, the bacterium is slightly resistant to penicillin, but its cell walls/cell membrane are still stretched thin from the penicillin inhibiting production of peptidoglycan. Now that the magical antibodies have attached to the mineral-diffusion receptors, they pump minerals using earth magic into the bacterium. Using water magic, they keep the surrounding water out . . . until they detach. Water suddenly rushes into the cell to balance the gradient. The cell membranes are already stretched too thin, and the bacterium lyses (bursts.) The third cure minimizes the damage by stopping the double-antigen cell-mediated autoimmune response and by saturating immune cells to block the restriction enzymes. You're cured!
**THE 2-PART VACCINE:**
The first thing that is done is the ten antibodies, plus the communication inhibitor/protein rematerializor, are combined. This allows the antibodies to fuse to the bacterium's surface. This constitutes the short-term vaccine, since it allows the body to immediately launch an immune response, but is only effective for as long as the antibodies stay in the bloodstream/interstitial fluid/lymph vessels. The long-term part of vaccine utilizes the ten different antigens. This is difficult, since the memory cells cannot work against the magical switching of the bacterium; however, it keeps symptoms high and actual bacterial counts low enough for the body to either (1) eventually fight the disease out or (2) buy time to take the supercure.
### **TL;DR the TL;DR**:
Sorry about that. I was trying to reason through everything. The cure is 100% effective and the vaccine is partially effective in all cases, so it buys time to get the cure.
[Answer]
You don't develop anything.
You cast *Bacterium removium* and the patient is cured.
When you introduce magic into story as a disease the cure will be always magic (or death but that is magic onto itself).
No matter how much science you will have at the end you wrap it in hand waving.
Also vaccines are for viruses not bacteria. Bacteria's are fought with antibiotic that target the bacteria itself not the cause or symptom. Strong antibiotic can destroy every bacteria you have in your body without the need to name it or mark. Ingestions bacteria? You swallow pill. Skin/body bacteria? You take a dip in antibiotic. You're cured, see you next month.
NEXT!
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[Question]
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Some time ago I asked: "[How long would it take until we realise that people stopped dying from natural causes?](https://worldbuilding.stackexchange.com/questions/66614/how-long-would-it-take-until-we-realise-that-people-stopped-dying-from-natural-c)"
I today realized that similar but much more interesting (and more realistic...) question is out there, just waiting for today.
**How long would it take until we realise that on the whole world people suddenly stopped being able to conceive a child?** Only regular way to conceive stopped working, artificial insemination and other alternative ways are still possible.
(If you need a reason, let's say it is caused by some alien medicament that they are secretly testing on us, I think the reason shouldn't be important.)
[Answer]
Let's think through what happens in real life (from one perspective... that of my wife and I) and see what happens.
1. A delightful evening ensued (if you need more detail than this, you're on the wrong SE site).
2. And the next morning, we go to work.
This is important. While there may be a few individuals or couples who are so obsessed that they will start using pregnancy tests LONG before they can even detect conception, many (if not most) people simply go on with their lives and let nature take its course. But, just to cover the bases...
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> Even when using the very sensitive pregnancy tests on the market today, you still need to give your body time to start producing the pregnancy hormone. ... The best time to take a pregnancy test will always be after you have missed your period. Even the least sensitive pregnancy tests will be more accurate at this point. By the time your period is due, you will have given your body enough time to produce enough hCG to register as a positive result on the pregnancy test. ([source](https://www.babyhopes.com/articles/conception-pregnancy-test.html))
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That's 2-4 weeks. Let's assume the worst-case of 2 weeks. But, what really happened?
**Here is where the OP needs to make a story decision about how the pregnancies are failing. Are they miscarriages? Are they actual unferilizable eggs? This is REALLY IMPORTANT because there are two possibilities...**
(A) All those excited-to-see-what-happens-next women experience menstration.
(B) Or they don't.
**Let's go with (A) first...**
Our knee-jerk reaction is that sales of pregnancy tests would drop. But, as @Alexander points out, that's actually not true. In fact, the data identifying a problem will be hidden in the wash of real life.
First of all, all those babies concieved the day before "the event" are testing happily positive. The pregnancy test companies need to watch for a trend to develop, because it won't initially be a step function. But, in this case, it won't develop fast enough.
Because those enchanting evenings really haven't stopped (at least one hopes they haven't stopped...). Which means even if the OP's decision is (A), things just keep on rolling untill the next month. Honestly, how many women successfully conceive after a single encounter? According to [this source](https://www.avawomen.com/avaworld/knowing-your-odds/) the odds are only about 20% at best and drop with age very quickly.
So now we're up to 7-8 weeks before a real, detectable trend can be seen. Now the obstetricians mentioned by @RonJohn are starting to see an odd decrease in new-baby patients that can't be explained by a lack of black-outs, a lack of a successful World Series win, or the lack of any of the many other reasons that couples celebrate.
And during all that time women keep buying pregnancy tests in the hopes that this time it'll be positive.
From the perspective of (A), the doctors will identify a detectable trend before the pregnancy test people do because, well... hope springs eternal and the tests are cheaper than a visit with the doc.
***At this point: doctors discover the issue first in 7-8 weeks after "the event."***
But what happens if the OP chooses (B)?
Here's where @StephenG's comment becomes important. If the OP's answer is (B) then sales TANK because all those women think they're pregnant. They tank like New Coke. They tank in a way that makes Fox News and CNN agree on something. However, even this takes a little time. A week, maybe ten days past menstration.
So, the pregnancy test (PT) people in this scenario could see a detectable trend in 3-4 weeks (remember what the quote above tells you about the body needing time...). But, are the PT people really the first?
Maybe not... because the real problem here is when all those happy women visit their doctors and the doctors see (1) an explosion of new-baby visits and (2) those visits all have really bad news... no pregnancy.
This would be a very-fast-to-detect trend, a lot of new pregnancies that aren't really pregnancies (be they miscarriages or any other unannounced reason). The statistics would be blaring.
Which means while the PT people *could* be the first to know, it's still unlikely because they're behind the prenatal care curve. I still believe the doctors would know first.
But the data is still a bit hidden. Remember all those pregnancies that happened in the days before "the event." That will muddy the water for a while. Maybe 1-2 weeks before the doctors really start realizing that more women are coming in with false pregnancy problems than are with successful pregnancy issues.
*You'd think it would be hard to dismiss the "You know, Nurse Chapel, that's the fifth woman this week with a false-positive. That's a bit weird, dontchathink?" reaction, but remember that 20% and less chance to become pregnant at all. Unless "the event" also causes women to conceive at 100%... but this answer is long enough already.*
***So, in this case, 4-5 weeks.***
---
**TL;DR**
The main issue here is that people don't stop living their lives after an attempt to conceive, and nobody knows they're pregnant (or not) at the moment of theoretical conception.
* Many if not most women won't even bother with testing before their next menstral period suggests a reason. But it doesn't matter anyway because...
* Women don't conceive with every encounter. That's life. There's about a 20% chance. That means a guaranteed "there's no doubt anymore" realization is 5 months max. But, for the most part, the happy couple is momentarily disappointed and then renew their dedication to the cause.
* Which means pregnancy tests are being bought long after "the event" that stopped all conception.
* The data will be clouded by all the conceptions that occured during the days (even weeks) before "the event," leading to new-baby and ongoing-baby visits with doctors for quite a while.
* Doctors would eventually realize either (a) the number of new-baby visits have dropped a long, long way (path (A) above) or (b) the number of new-baby-false-pregnancy visits has jumped (path (B) above). But, either way, thanks to the clouded data, this might not actually be detectable for a while.
***Conclusion:***
* If the OP chooses to simply stop fertilization (path (A) above), then it would likely take 7-8 weeks for doctors to realize something was wrong and actively start investigating it because not conceiving children is actually 5X more likely than conceiving them. AKA, it's normal and wouldn't be detected as quickly.
* If the OP chooses to permit fertilization, but the pregnancies are somehow terminated (path (B) above), then it would likely take only 4-5 weeks to realize something was wrong because consistent false-positives are not normal and would be detected more quickly.
*DISCLAIMER: This answer is from the perspective of a happy couple living in the United States. There is a massive amount of variability in fertility, health care, etc. around the world. Absolutely massive. I'm (somewhat arrogantly) assuming that the U.S. has the capacity to detect such a problem first due to the combination of high tech levels and large population bases. Addressing this question beyond this perspective might (and likely does) make the question too broad.*
[Answer]
First you have to realize that unlike your death scenario, there is an inherent delay in this situation -- unless your unknown cause terminates existing pregnacies, it would be almost impossible for it to be recognized for at least a week as the drop in observable pregnacies wouldn't even start until then.
But the delay isn't really that long, it should become noticable within 2 weeks, and would be absolutely conclusive within a month.
There are 2 kinds of pregnancies, accidental and deliberate. Everyday your typical big city OB-GYN has women come in for confirmation of pregnancy for one or the other. This will not stop, but the "deliberate" pregancies will start to tank after a week, and become almost unknown after 4.
While this could theoretically be picked up using pure statistics within a week of your event, that is unlikely, but it will be picked up as a practical matter soon after -- appointment volume for deliberate (want to get pregnant now, around 20%) pregnacies will noticably decline after 10 days and be basically gone after 21 days. That will be noticable. As will the decline in accidental but not unexpected pregnancies.
Basically this will be noticable within 2 weeks, remarkable with 3 and unmistakable with 4.
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[Question]
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Note: Some answers will refer to not just tanks, as previously I asked about military vehicles in general, then edited it because it was too broad.
So, right now I'm working on a project centred around a speculative sapient race that lives on a planet with no landforms larger than Big Island, Hawaii. In terms of anatomy, they are serpentine (Quite similar to Earth's moray eels, superficially.), except for two five-digit claws, which evolved from bony 'fins' and are used as manipulators.
Their technology is about as advanced and capable as human technology, but it progressed without any form of fire, of course. They achieved metallurgy via electroplating and electroforming, pulling metal ions out of the water to a mandrel on the surface with their bioelectricity. So, what I want to know is what you think their equivalent of tanks would look like.
Basically, I'd like you to help me envision a submarine vehicle that is heavily armoured, has a big gun (Firing self-propelled weapons, of course.), and operates on the front line like a modern tank, but also works underwater, is streamlined, and conforms to all the other requirements for aquatic vehicles. It should be big enough to accommodate a small crew (About 3 or so.) of 3-4 metre long serpentine creatures, and would probably need to have some form of defense on all sides, since the ocean is a 3D environment.
As for the military doctrine, I don't really mind - let's say Leopard-style for now, I can adapt it later to other doctrines.
[Answer]
One first needs to know what the purpose of these military vehicles is in order to describe how they will operate. Looking at modern military equipment, we have machines to transport men and equipment, provide direct and indirect fire, send and receive signals, engineer vehicles to breach, cross or create obstacles and so on (and these are just a few of the various categories of vehicles a modern army uses).
Even then the form of these vehicles is determined by the [doctrine](https://infogalactic.com/info/Doctrine) of the using military force. Russian tanks look different from Western tanks because Soviet and now Russian ideas on how to *use* tanks is different from Western ideas. Some of the features considered important on Western tanks, like the ability to depress the main gun @ 10 degrees are not even considered in Russian tanks, since this makes tanks larger, and in any event speed and mass of fire is considered far more important when operating tanks in company and battalion sized manoeuvre units.
[](https://i.stack.imgur.com/G2J5s.jpg)
*The difference in size between an M-1 and a T-90 is largely due to how each side plans to use their tanks*
The only real analogues we could get is the vehicles would operate in a 3D environment like submarines, and weapons would need to be self propelled like torpedoes, as water is 800X denser than air, limiting the ability to shoot or otherwise project weapons with guns, speargun like weapons and so on. Some "nations" might prefer small, fast submarines like the Soviet era "Lira" (NATO code name [ALPHA](https://infogalactic.com/info/Alfa-class_submarine)) if their doctrine involves raiding or similar strategies. Other "nations" might prefer larger submarines with more on board capacity to carry more torpedoes, or remain on station for longer times if the is important to them.
[](https://i.stack.imgur.com/Bx1Sg.jpg)
*Alpha class submarine laid up in dry dock*
Other considerations might have to do with crush depths and the ability to operate in the depths of the ocean. If the creatures have a preferred habitat, there will be military advantage to operating well below the normal depth, including vastly increasing the required search volume and taking advantage of thermal layers in the depths to mask sounds and deflect active sonars.
[](https://i.stack.imgur.com/LMFHX.jpg)
*Bathyscape Trieste II. The crew resides in the tiny sphere under the front of the buoyancy tank. You can see how much different this is from the ALPHA*
Operating on the surface might be problematic, you have not told us if the creatures are amphibious or able to operate out of the water. Even if they cannot, they might be interested in the ability of their technology to operate in a different environment. Water is 800X denser than air, so being able to operate out of water provides a huge advantage in terms of speed and range for the same amount of energy. Rockets or shells fired by surfaced submarines will be abele to cover long distances (in their terms), providing the ability to deliver effects with a high degree of speed and even surprise (sensors, torpedoes and mines could be delivered by these means, just as modern navies do on earth).
[](https://i.stack.imgur.com/zS4HT.jpg)
*[SUBROC](https://infogalactic.com/info/UUM-44_SUBROC) launch. The torpedo will deliver a multi kiloton nuclear warhead 55 km away*
So until you give us an idea of what the creatures intend to do, and how they intend to do it, any answer will be mostly handwaving.
[Answer]
Submarines. Propelled by electric motors.
Moving fast in the liquid really requires streamlines shapes.
In addition, a round cross-section minimizes surface area (and thus armor) given the same internal volume.
If you want different types, the fast fighter craft will the long to minimize water resistance, and slower heavily armored vehicles will be more like balls.
The projectile weapons are a lot less effective in the water since unpowered projectile slows down too fast. Torpedoes will totally be a thing, though, along with acoustic weapons (a ping of modern submarine can kill a diver).
Detecting enemy will be important. You can have all sorts of biological senses or technologies: sonar, water vibrations (<https://en.wikipedia.org/wiki/Lateral_line>), magnetic sensors, even smell.
The only reason to go above the surface would be resources not available underwater. If you are willing to bend the setup a little, maybe they do make metals with fire, and have to go ashore to do that. B/c electricity does not work all that well underwater, and is very dangerous for living things near it.
In fact, I believe for aquatic species, mastery of biology, chemistry and light manipulation is more plausible than metallurgy and electricity. So armor is grown using corals or turtles (fed a diet rich in iron), and computers are quantum ones, not electric. For motors, perhaps they can grow artificial muscles.
] |
[Question]
[
I've come up with an idea of building a fantastical continent inspired by the climates of Scandinavia.
It will be shaped similar to a crescent, and based on two tectonic plates that go over each other (the side of the crescent is basically a mountain range that rose from the interaction between the plates).
As for north and south it will work just like in the real world, colder north and a bit less chilly south.
The farther you move from the mountains the lower the land gets (obviously). There are plenty of fjords as a result of a previous ice-age as well.
So, my questions are:
1. Is this idea realistic? Could such a continent actually form?
2. How would the climate be affected by the given situation? Could it actually be a not!Finland?
Any other tips are very much welcome, I'm very new to world-building and would love some help with this.
[Answer]
How about this crescent shaped land? From Google maps.
[](https://i.stack.imgur.com/VesMT.jpg)
Your tectonic plates, as ordered.
[](https://i.stack.imgur.com/B2IEx.jpg)
<https://volcanohotspot.files.wordpress.com/2015/03/image006.gif>
Very Scandinavian climate looking.
[](https://i.stack.imgur.com/y9yHX.jpg)
[source](https://www.secretcompass.com/expedition/kamchatka-volcano-expedition/)
Well, except for the volcanoes. Finland freaking wishes it had more volcanoes like this.
[](https://i.stack.imgur.com/XzUXf.jpg)
[source](http://misshappyfeet.blogspot.com/2016/03/russia-kamchatka-land-of-fire-and-ice.html)
This is from my favorite terrain generators, Google maps and google image. I hid the sources in hopes someone might think it was fun to figure out where this is. Soft pitch: not even rotated. If you like, post your guesses in comments using [rot13 code](http://www.rot13.com)
In any case Mellow: your idea is very plausible because it exists. Once you figure out where it is you can steal the whole thing and then you will not need to build anything else and you can go to work on the stories. Bonus in case you become enraptured with the idea: you can visit the place and they will be happy to host you.
[Answer]
Stealing Will's idea and moving about 500 miles east...
[](https://i.stack.imgur.com/CmRfD.jpg)
I won't pretend to be hiding what this place is, but it has a downward facing crescent of mountains and volcanic islands along a plate boundary.
To the north, the terrain levels out into taiga and tundra, to the south the mountains drop right into rich polar seas across steep valleys covered with temperate rainforest.
[](https://i.stack.imgur.com/FPFaK.jpg)
To be honest, the climate and wildlife is basically identical to Will's answer: conifer forests, active volcanoes, lots of salmon, brown/grizzly/Kodiak bears, giant fish eagles, etc.
But I figured I'd add it for completeness.
However, I will offer something novel: a climate comparison.
[Anchorage, Alaska](https://en.wikipedia.org/wiki/Anchorage,_Alaska#Climate), and [Helsinki, Finland](https://en.wikipedia.org/wiki/Helsinki#Climate) are at nearly the same latitude. Summer average temps are similar, but Anchorage has much more variation: mid-day highs are 5F hotter and nights are 5F cooler. Alaska'a winter is also much colder: january temps average almost 15F less in Anchorage. Anchorage gets less rain, but that is because of its location relative to the mountains. On the other hand, a city exposed to wet oceanic winds will be much wetter: [Juneau, Alaska](https://en.wikipedia.org/wiki/Juneau,_Alaska#Climate) gets 2.5 times as much rain.
] |
[Question]
[
I am considering setting my next D&D campaign on an earthlike but small planet. By "small," I am imagining a world that still feels vast, yet is circumnavigable over land and/or water with low or no magic, though probably with significant difficulty. I was thinking perhaps 1/6 earth radius, though I'm making that number up. Physical properties would be assumed to be earthlike (probably), due to greater planet density, and there would likely be a diversity of weather phenomena around the planet. As for geography, I am imagining a single large continent, as well as an archipelago of islands covering a large portion of the planet.
For further size context, I imagine that military conquest on the scale of Alexander the Great's campaigns, or maybe the Mongol conquest of Russia, should be able to seize the entire world. The setting is a traditional middle-ages style D&D world, with magic existent but not abundantly used.
Without significant magic, how likely is it that a landlocked city would realize that the planet is spherical and small?
EDIT: Naval technology is high middle ages, around 9th century. The continent is essentially a very large island, so sailing is necessary in order to circumnavigate.
[Answer]
On a planet this size, the roundness of the world will be far, far more obvious than it is on Earth, and it was known on Earth in classical times. It would be pretty obvious to any trading or sailing culture on this world.
The horizon will be only a bit more than a mile away. It's about 3 miles away for a 6-foot-tall observer on Earth; on a planet with 1/6 radius, it will be (square root of 6) or about 2.45 times closer:
<https://en.wikipedia.org/wiki/Horizon#Distance_to_the_horizon>
Therefore, the effect of ships disappearing over the horizon, hull first and mast/sails last (visible even on Earth) will be incredibly obvious here.
Also, the variation in day length and sun angle as one goes from place to place will be tremendously more obvious. One degree of latitude on this planet would be only about 11 1/2 miles, vs. 69 miles on Earth. (Eratosthenes used the variation in sun angle at different latitudes to calculate the size of the Earth in the 3rd century BC.)
[Answer]
As has been stated by @cometaryorbit and several commenters, the roundness can be discovered fairly easily even on land by observing the angle towards the sun.
Since you stated that this planet should be circumnavigable with reasonable effort, i think it is safe to assume that it has been done, adding further backup to the idea of he spherical planet.
But they would never discover that it was small.
Not because they couldn't calculate it's size, which they could feirly easily, but because they would come to a different conclusion: that their planet is perfectly normal in size. Just like we on earth typically think of our planet as normal.
To be more precise, because it feels normal to us, we generally don't think about our planets size at all. After all, none of us have ever been to a bigger planet. And while today we can easily look up the size of earth as compared to the other objects in our solar system, which should lead us to the conclusion that earth is fairly small, it normally doesn't, because neither does comparing a planet to a sun make very much sense, nor does comparing a rocky planet to a gas giant.
I think it is safe to assume that pretty much the same will happen on your world: The people in general don't think about their planets size. They will soon learn that there are other planets, and moons, and that other planets can be bigger, but snce their world is special (it's the one they live on, so it has to be, right?), comparing it to other planets simply doesn't happen.
] |
[Question]
[
The enormous shield volcano that [this question](https://worldbuilding.stackexchange.com/questions/96872/exploration-of-a-50-mile-high-mountain) was based on was held up by magic or God. It presented some very interesting conditions for alternate worlds so I thought I would develop that train of thought to see if something similar could actually exist without the intervention of Gods or magic.
Assume an Earth-like world with standard atmospheric pressure, except with 95% of the water missing (less water arrived when the planet formed). So a desert world, but still inhabited as there is still some water.
Let’s be a little more conservative than the original question was. Can we have volcanoes extending 25 miles up into the stratosphere? If not, why and, if we can, roughly how high might they reasonably be expected to get (rough estimate)?
Edit: assume 25 miles above the mean planetary surface level
[Answer]
Here is my answer from [How would a 30-kilometer tall mountain on an Earthlike planet look?](https://worldbuilding.stackexchange.com/questions/92205/how-would-a-30-kilometer-tall-mountain-on-an-earthlike-planet-look)
This is reminding me of your scheme for islands floating in the mantle because that is pretty much where this one ends - the ginormous diamond mountain would sink down until it displaced its weight in whatever denser material constitutes the mantle.
---
I found this fine math laden site which shows the maximum height for a mountain made of granite.
<https://talkingphysics.wordpress.com/2011/09/08/how-high-can-mountains-be/>
>
> The density of granite is ρ = 3 g/cm3 (actually, the densities of most
> liquids and solids are close to 1. Lead is only about 11 g/cm3 and
> gold is 19.3 g/cm3). The total weight of the mountain is just the
> volume times density times g so:
> Weight W≈ ρgr2h
> To see when the rock
> will start to break, we’ll compare the stress of the weight of the
> mountain to the compressive strength of granite. (Most mountains
> aren’t made out of granite, but it should give us a good upper limit
> on mountain heights). The weight of the mountain is spread out over
> an area of roughly (ignoring constants such as π): A ≈ r2 so the
> stress σ the mountain exerts on the ground underneath it is:
> σ ≈ W/A ≈ (ρ g r2h)/r2 ≈ ρgh
> The compressive strength of a material is the maximum compressive >stress a material can withstand before it starts to deform.
>
> For granite the compressive strength is σC = 200
> megaPascals = 2 × 108 N/m2 so the rock beneath the mountain will start
> to compress when: σ = σC or ρghmax = σC. Rearrange this equation to
> solve for hmax yields: hmax ≈ σC/(ρg) The max height for a mountain
> works out to be:
>
>
> hmax ≈ 2×108 N/m2/(3×103 kg/m3 ˙ 10 m/s2 )≈ 104 m = 10 km
>
>
>
So a granite mountain can only be 10 km. A mountain on earth which was 30 km must be made of material that is less dense, or which has a higher compressive strength.
Less dense is a nonstarter because granite is not that dense at 3, and less dense materials have markedly less compressive strength.
More compressive strength is a tall order because granite is the best among stones at 200. So not stone.
**[Sapphire](http://www.roditi.com/SingleCrystal/Sapphire/Properties.html).**
Sapphire is more dense than granite at 3.98 (we will use 4) instead of 3 g/cc. But the compressive strength is 2 GPa - that is 2000 MPa or an order of magnitude greater than granite.
Plugging in these new values
hmax ≈ **20**×108 N/m2/(**4**×103 kg/m3 ˙ 10 m/s2 )≈ 754 m = maximum of **75 km**
So 30 km is fine. This mountain would not necessarily be a single crystal of sapphire. But that would work.
I was thinking that maybe it is unrealistic to have a giant sapphire crystal. Where would it come from? A mountain of diamond seems so trite, but really it would be better in many respects. Lets get it over with.
[Diamond](https://en.wikipedia.org/wiki/Material_properties_of_diamond): density of 3.5 and compressive strength of 60 GPA; **maximum mountain height is 196 km**
These diamonds would have been [formed in the atmosphere of a ancient gas giant](http://www.bbc.com/news/science-environment-24477667) and then incorporated in the crust of this Earthlike world. I envision this huge, partly fused mountain of diamond extending farther down below the surface than it does above. Despite the huge mass balanced on one point, it does not sink further down because the bottom of the mountain is floating in denser, partly metallic molten materials. The diamond mountain is essentially an iceberg in the crust.
Diamond is one of the best thermal conductors there is. With its big bottom side down into the mantle, the entire thing would be **very hot**.
[Answer]
You need a planet with much less gravity to get that high (if at all possible).
Also a much cooler (deeper fluid part) would help... but that would also make volcanoes impractical.
On "standard Earth" a mountain would collapse under its own weight (or sink into the mantle, to the same effect) before reaching 10miles above sea level.
[Answer]
Water is irrelevant
What drives volcanic formation is the activity of the planets core and tectonics.
Olympus Mons on Mars is 21.9 km
I think the crust would need to be well formed but something needs to keep the planetary core active.
So maybe a gas giant moon that has its own moon which its tidally locked with. Would also be a great explainer for the volcanos size.
] |
[Question]
[
Okay, it's a staple amongst certain fantasy settings where you have different races of creatures and beings co-habiting, which leads to certain off-shoots of different races (the half-elf and half-orc perhaps being the most commonly known).
But how feasible is such a thing? Presumably these different races are all significantly genetically different from each other that a viable mixed race would be biologically impossible? Sure, different races with sexual organs that fit each other would be able to enjoy physical relations (if they were into that kind of thing) but would they be able to biologically produce offspring?
Especially when different races seem to have natural, inherent biological traits: elves are typically very long lived and can see in the dark etc.
And then there is the notion of "half-human/half-demon". Not only are the races separated by their genes but also their planes of existence!
In terms of science, would this be possible?
(yes, I know that asking for a scientific explanation for a trope in a fantasy setting may be somewhat backwards but I am curious to know).
Specifically, this is for a fantasy type of world that I am building. There are three main races: human, alfar (something akin to elves) and floring (a kind of Halfling), with the possible inclusion of a race of infernals that are a line descended from a mixing of human and "demon".
I hope that makes sense.
[Answer]
**It's not impossible, but its not outright possible either**
**Factors:**
* **genetic divergence from a common ancestor** - Its possible they can reproduce if the different 'breeds' are close enough in lineage such that they have the same amount of chromosomes and complimentary genomes. This does not guarantee success it just increases the odds similar to a horse and a donkey. Dogs are a great example of an organism with large differing physical appearances yet still capable of interbreeding.
* **Mechanics** - obviously the mechanics are a factor like a giant cave troll going down on a dwarf might not be physiologically possible. Though sometimes where there's a will [there is a way](https://www.youtube.com/watch?v=ABM8RTVYaVw).
**So is it possible in the same way we have mules yes. Could they end up being sterile yes and no this is dependent on genetic divergence.**
There is another more far fetched possibility of zoonotic reproduction I theorized awhile back.
Basically, one organism is capable of injecting its DNA through a retro-viral like process. Which could both cause pregnancy, pass on traits, and alter the females physiology enough to support the pregnancy. Is this likely, heck no, is it in the realm of possibility; loosely.
[Answer]
Take a look at various [dog breeds](https://en.wikipedia.org/wiki/Dog_breed), or the definition of [race](https://en.wikipedia.org/wiki/Race_(biology)) in taxonomy. Surely a Poodle and a St. Bernhard are at least as different as an Elf and a Dwarf. And in between the Poodle and the St. Bernhard is a great bunch of generic mutts -- or, to extend the analogy, the ordinary humans.
Breed Poodles with Poodles and you get a Poodle, or something much like it. Breed Elves with Elves and you get an Elf. Cross-breed with other races of the same species, and you get **something** that will have recognizable traits of each parent, plus random chance.
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