236 votes
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Are there logical gaps in the periodic table in which you could insert a new mystery element for use as a fuel?

No As we currently understand physical chemistry, all possible elements are known below whatever the state of the art number is now (Oganesson - Element 118). The atomic number of an element (the ...
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162 votes

Is it possible to make an alloy that melts at low temperatures and solidifies at high temperatures?

I'm sure this is outside of the range of temperatures you were interested in, but in the spirit of "truth is stranger than fiction," Helium-3 actually does this: The temperatures we are talking about ...
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  • 129k
151 votes

How Long Could an "Eternal" Fire Last?

Yes. Wikipedia has a good article on eternal flames which are fed by underground natural gas deposits. Those deposits can be immense, as we now know because we suck the gas out and use it for our hot ...
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  • 276k
126 votes
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Lembas bread (2000 Calories per bite)

It just doesn't add up if you only consider real world nutritional chemistry. The most calorie-dense food available is fat at 9 calories/gram. That's 220 grams to hit 2000 calories, nearly a quarter ...
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112 votes

What could cause sugary rain?

The rain is actually the blood of billions. A species on a nearby planet is being harvested by a technologically advanced alien civilization and the specimens are drained of all their internal ...
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  • 2,780
106 votes

Is there a real life substance like movie acid?

Liquid Fluorine Vomit yellow in color Cryogenic liquid means it's boiling and smoking at room temperature. Melts/dissolves/burns almost everything "Glows" due to the burning of everything. ...
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  • 6,686
106 votes
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Time Warp: Modern chemist as court alchemist

Why struggling for gold, which any king and even merchant of the medieval world has, when you can go for Aluminum, which no king yet has? Aluminum is shiny, like gold. Aluminum is malleable in thin ...
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  • 241k
103 votes

What could a self-sustaining lunar colony slowly lose that would ultimately prove fatal?

EDIT April 26, 2020 While searching through my answers for research related to another question I came across this answer. The irony that I wrote this one year ahead of the Coronavirus pandemic, which ...
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101 votes

Time Warp: Modern chemist as court alchemist

Gold is one of the densest metals in existence. Only a few metals and alloys are heavier, but they are not much easier to obtain, like iridium, osmium, neptunium and plutonium (!). If you use any ...
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  • 1,568
94 votes
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How to replace a fictional element to the periodic table?

Unfortunately no, you can't replace an element of the periodic table because the ordering of the elements on the periodic table are based on the number protons found in the nucleus of the atom. ...
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88 votes

Lembas bread (2000 Calories per bite)

In the books there is a bit more wiggle room : (Farewell to Lorien; last few pages) 'Cram', he [Gimli] said under his breath, as he broke off a crisp corner and nibbled at it. His expression ...
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  • 3,005
88 votes

A medieval fantasy adventurer lights a torch in a 100% pure oxygen room. What happens?

The torch burns quicker. A lot quicker, but you won't get a violent explosion. Fire requires three things - heat, fuel, and oxygen. You've increased the oxygen, but you haven't increase the fuel, so ...
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83 votes
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Mineral that explodes when cooling down

Use Iron's allotropic forms Iron has a wide variety of allotropes. Two interesting ones are austenite, with atoms aligned face-centered cubic (FCC) and hexaferrum, where the atoms align in a ...
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82 votes

Could Cobalt bind to nitrogen the same way iron would to oxygen in an alien respiratory system?

I think ammonia would be a good gas to breathe in an ammonia world. There is a lot of it handy, I would imagine. As opposed to N2 which is sort of an ice queen and reluctant to mix it up with other ...
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78 votes

Chlorine Trifluoride as a Space Weapon?

No no no no no no no no no. Bad idea. Chlorine trifluoride is one of the most horrifying substances on Earth. Sure, it can kill people and destroy equipment. But it can also kill the people trying to ...
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78 votes
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What elements would be created in a star composed entirely of gold?

Unfortunately, no matter how much pure gold you add to your mass, you will never end up with a star. The reason for this is that fusing gold is an endothermic process, meaning that it requires energy,...
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78 votes

Realistic way to damage bullet proof glass using common substances

Paint. /safely compromise that glass/ so I am within the bounds of the question! The robot is relying on a camera that is looking thru a pane of glass. If you cover the glass with paint, or glue, or ...
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74 votes

How to replace a fictional element to the periodic table?

Option 1: Island of Stability As @AlexP mentioned in a comment, there is a theory called the Island of Stability, that states that there may be a window (or windows) in the super-heavy elements which ...
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71 votes

Chemical weapon to kill a werewolf

Killing the monster with VX nerve gas or an overdose of fentanyl or cyanide muffins seems kind of anticlimactic. You can kill anything with that stuff. The whole thing about werewolves is that ...
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66 votes

How to defeat a pyrokinesis user using tech and science

Shoot Him In The Head You haven’t specified that he has any kind of supernatural senses, so a well placed sniper shot from well out of his visual range, (3km has been done but let’s make it 2km for ...
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64 votes
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How can I create explosions without using oxygen?

Almost all currently used explosives have an oxidant (or it's equivalent) "built-in". They already work in space, under water, etc just as well. Let's look at thermite (which is not an explosive, ...
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  • 3,560
63 votes

How could indestructible materials be used in power generation?

Easy Peasy. Fusion reactors. The primary challenge involved with fusion power is maintaining containment, which is a big challenge given the pressures and temperatures involved. Not only will ...
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63 votes

With what liquid should I fill my dead, intraversable seas?

Acid. Crater lake at El Chichon https://www.usgs.gov/faqs/can-lakes-near-volcanoes-become-acidic-enough-be-dangerous-people-and-animals?qt-news_science_products=0# Crater lakes atop volcanoes are ...
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63 votes
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What happens if King Midas produces gold en-masse

Gold would then be completely unsuitable for use as the basis of any currency. It would just be another material with certain physical properties. Assuming the world society survived the screaming ...
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62 votes

How Long Could an "Eternal" Fire Last?

Yes. They plant a forest of trees ( a renewable resource) to be used only for the holy flame. Faithful can also come and throw offerings (wood, coal, hay, etc) into the fire. They could also carve ...
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  • 4,172
61 votes

Solid material made from human blood

Bloody Paint Why bother turning it into some kind of structural material? Just use it as the paint on literally every surface with this girl's blood. It'll be an awful color when it dries, but if ...
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60 votes

Mineral that explodes when cooling down

Water ok, beer. Watery beer. An explosion occurs when matter changes so as to occupy more volume. We are used to the explosions where a solid or liquid suddenly changes into a gas, which takes up ...
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  • 276k
59 votes
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Is there a real life substance like movie acid?

Dissolving folks quickly is hard work Most acids aren't going to eat through you (or your average door) quickly -- while they denature proteins and dissolve metals, they don't have the oxidizing ...
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57 votes

What would the periodic table of a 4-Dimensional universe look like?

In four dimensions, you don't have a rotation axis (fixed straight line) but a rotation plane (fixed plane). However, not every 4D rotation has a rotation plane; there are rotations which have no ...
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57 votes

Is it possible to make an alloy that melts at low temperatures and solidifies at high temperatures?

Heat drives a compound out of solution Heat can drive moisture out of a substance. If some substance mixed with water is a very viscous fluid, then driving the water out with heat could leave you ...
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