28

I think you are on the right track and this is a really fun question. I think the issues you mentioned with things like generating heat are much larger obstacles than doing chemistry in a fluid medium would be. For an aquatic-native race, anyway. I'm going to focus mostly on the last part of your question, "What would their developmental path look like?" ...


21

Possibly. Push water or high-pressure air in from the bottom of the container. Essentially what you're doing is making artifical quicksand*. See also fluidized beds: https://en.wikipedia.org/wiki/Fluidized_bed I've no idea whether it would actually work with coins, though, given their shape. *If you happen to walk into quicksand, the recommended action ...


18

There's actually a (beyond minuscule) loss of mass when fuel is burned. Your figures aren't much off for gasoline -- the extra mass comes from oxygen in the air. To oversimplify, let's assume gasoline is pure octane, C8H18 (molecular weight 114). To fully combust, it'll need 25 oxygen atoms (two for each carbon, and one for each pair of hydrogen), ...


14

Aerate the aggregate Forcing air (or water, or both) up through a container of sand makes quick sand. Each sand grain is suspended in fluid, and free to flow. I propose this same approach could work for any aggregate material, including metal coins. Problems: A mechanism to move that much air Noise from air and clanking coins Drowning I'm imagining ...


12

I find the answers that suggest to mix the coins with another fluid (air or water) unsatisfactory. Swimming works for 2x reasons: the thing swimming is neutrally bouyant in the medium the medium behaves like a fluid So to swim in coins you need to approximate those 2x conditions. assuming a human swimmer 1) reduce the density of the coins to that of ...


11

During my PhD years I had to work with some materials which were quite reactive: as soon as they were exposed to oxygen or water they reacted very vigorously with them, leaving the poor student with a damaged sample or, even worse, with a sample which spontaneously took fire. A solution for handling these materials and keep the students alive was to use ...


10

No. Very unlikely. With heavy objects like coins a person would just lie on the surface and thrash about with a few coins being thrown around. Should the coins be made lighter and smaller the situation would perhaps approach what happens in grain silos which are very dangerous. Dozens of people fall into grain silos every year and a lot of those are engulfed ...


8

You have a few issues that the planet and its residents need to confront Size of ant: average 10mm Size of human: average 1650mm Ratio: 1:165 For your giant to be same ratio from a human, your giant's size: 272.5m high Due to the Square Cube Law (volume / weight and surface area increase at different rates as size enlarges) you run into issues when you ...


8

Use LEGO coins and water: They're plastic, so they'll float in water, it's just a matter of determining the ideal ratio of coins to water. It's better than using normal currency-sized coins because the smaller coins will impede your movement far less. Might be a bit pricey to get enough of these to fill a swimming pool to the appropriate density, but hey, ...


7

balistic gel or something like jelly is out of the question, i want proper liquid. That leave all non-liquids out of the question. In fact, you are leaving all newtonian liquids out of the question, because they would fill the container in which they are in... and therfore not remain stuck to the person/object. Now out of the non-newtonians... I bet you ...


6

Take assorted hydrocarbons from the gasoline. As the name suggests, they consist mostly of carbon and hydrogen, and by weight they are mostly carbon. Burn it, and one $C$ (carbon) atom bonds with two $O$ (oxygen) atoms from the air, forming $CO_2$. Each $O$ atom is about 1.33 times the weight of a $C$ atom, which means each $CO_2$ is only 27% carbon by ...


6

Formamide can be formed by the condensation of carbon monoxide and ammonia. https://en.wikipedia.org/wiki/Formamide A reducing planet with an ammonia / methane atmosphere is plausible. If there is also some water, one could imagine atmospheric water undergoing photolysis to generate a small percentage of free hydrogen and oxygen. Hydrogen will head up and ...


6

Zippered Sword This will not be an easy feat in smithing, but: The sword consists of two chain-link sides that are flexible when apart, but zipper together to become inflexible. The scabbard top would function as the 'runner' of the zipper, zipping the sword togetherwhen drawn and unzipping it when it is sheathed (maybe part of the top comes off with the ...


6

Modern "gunpowder" isn't really a powder, it's only people call it that because it replaced black powder. Honestly, as long as you can make black powder, you can also make it, all you need is know-how. All you have to do is convert sulfur into sulfuric acid, saltpeter into nitric acid, and instead of charcoal, get cellulose. Usually, cellulose used for this ...


5

This is the kind of question for which an axe-cut approximation is well worth it. Let's take a human, and observe how he/she is made by various things: muscles, bones, hair... well, let's approximate all of this with water. And, since we want to generalize, let's take 1 liter of water, which conveniently weights 1 kg. The heat of vaporization of water is ...


5

Are supercritical oceans of CO2 possible? That depends on how you define "ocean", but yes. Making them more liquid-like just requires a cooler environment, easily achieved with a Venus-like world that happens to be somewhat farther from its sun than Venus is. How would it behave? That depends on just exactly how liquid-like it gets. There are two not-very-...


5

Humans exist at a certain size because of the structure of their bones, muscles and their metabolism. Humans cannot exist too far beyond their normal size for many reasons. One issue is the fact that bone strength increases with the square of the bone size whereas weight increases with the cube of size, another issue is the ability to retain heat. Too large ...


5

Well, Stephen L. Gillett thought so.... It's not really possible to give a definite yes-or-no answer to this, but it seems reasonably plausible. I haven't been able to find any data on the use of iron pentacarbonyl as a solvent itself, but it is soluble in most organic solvents (like ether and acetone) and slightly soluble in alcohols... so it seems ...


4

The problem with supercriticality is that due to the circumstances under which it arises, you lose any clear distinction like "liquid/gas" as you might get at the surface of a conventional ocean. Instead, you get a smooth increase in density and viscosity from the gas phase bits of the atmosphere into the supercritical bits, like a fog that just gets thicker ...


4

Two factors could make it possible (if extremely unlikely): 1: The planet has very low gravity. The weight of the giant is so small that its muscles can hold it up and move it around, even with a very small muscle cross section to mass ratio (square-cube law). The mass itself, however, will be a major issue, since intertia will be great. The giant would ...


4

OK, slightly left field answer to this one. Assuming you are in an equivalent ocean to Earth's, you're never going to need to do your chemistry purely underwater. You have a water surface, you have underwater vents, fish have swim bladders etc. If you are careful you can "harvest" these, with anything waterproof (intestines, etc). You may even be able to ...


4

The ease with which information could be obtained would depend on the details of the environment and might be seriously limited. The “easiest” situation would be a civilization based in a shallow sea with access to the materials of the coast and access to the surface. Harder would be a civilization based in a deep sea far from land. And the hardest would be ...


4

Origami rapier and ballon shield. The simplest way would be a flat, thin piece of triangular metal or plastic that folds several times along its length (along pre-machined lines), to form a somewhat stiff skewer. It will be more of a thrust than a cut-and thrust sword, think small sword or even rapier. The actual tip is manufactured from a hardened steel. ...


3

Two possibilities: 1) You want a dust explosion. There are lots of materials that, if you have a pile of them or if they are at all wet, then they won't burn very well at all. Consider ordinary wheat flour, for example. A pile of flour will work quite well to extinguish small flames. And you don't need to be concerned about having many 10's of kg of flour ...


3

There is a bit of research on this in regards to robotics Here is an article on materials research into structural rigidity, deformation and flexibility in materials that can be controlled using various methods to allow on-demand or controlled use. The typical application in a modern context is in actuators, devices that allow controllable movement, in ...


3

With the large amount of CO2 generated by the burning gas, there could be a multitude of uses. 1.A) Terraforming, specifically on planets with little/no atmosphere, could use the quick greenhouse gases(though not practical) 1.B) The military could use it to gas-out areas that are crucial to capture or to kill/capture the opposing forces.


3

You requirements all together make the thing almost impossible to do. While curable polymers seems a good material choice for making a bubble, and I remember as a kid to having been exposed to the ads of a product doing exactly this, it will not fly to any significant height. Reason for this is that bubbles float because of the buoyancy, and they are ...


3

Possibly... when sand is stimulated with sonic vibrations, it behaves a lot like a liquid. I'm not sure if coins are small enough to experience this phenomenon, but if they were, they may become swimmable. [edit] This effect is significantly amplified and paired with blasting air up through it which I did not include in my original answer since the OP ...


3

Make them highly ionized. For example, if each coin has a very high negative charge, they will repulse each other and act like a gas. Then you need to wear an highly ionized swimsuit that will cover all part of your body. The swimsuit should have 3 substrates: 1) external substrate with same charge of coins, it will repulse them and allow you to swim. 2) ...


3

The goal is, as others have said, to reduce the friction between coins... or rather, to allow them to slide past each other smoothly: that coins don't do this is not completely because of friction. But we want to do this by the intrinsic properties of the coins, not through adding a gas or liquid. Orientation Normally, coins poured into a container will ...


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