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77 votes

Is it possible for a substance to be thermally inert?

Hmm ... does your material have to be a crystal? If not, try an aerogel. From wiki (https://en.wikipedia.org/wiki/Aerogel): Aerogel is a synthetic porous ultralight material derived from a gel, ...
akaioi's user avatar
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69 votes
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Superheated bullets and the damage they would deal

The name of the game for weapons is the amount of energy they transfer to the target and how fast and how concentrated it is when it gets there. The kinetic energy of a fast-moving projectile ...
Mark Olson's user avatar
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49 votes
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Why are my caves warm with nobody heating them?

Geothermal heat. It's well established that the more in depth one goes, the higher the temperature is. It It is called geothermal gradient Geothermal gradient is the rate of increasing ...
L.Dutch's user avatar
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49 votes

Why are my caves warm with nobody heating them?

Caves are that way. Caves are well insulated. Cave temperature equals average outside temperature for the year. https://startcaving.com/info/heres-why-caves-stay-the-same-temperature-year-round ...
Willk's user avatar
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49 votes
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Could negative kelvin be achieved?

To use scientifically correct terms: forget about it. The first reason comes from the definition of temperature. In layman's terms, temperature measures how much the molecules of matter vibrate around ...
L.Dutch's user avatar
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47 votes

How to make ice magic work from a scientific point of view?

The measure of a cold magician is not really how low they can bring the temperature. As you say there's a hard limit. They call it "absolute" zero for a reason. The real measure of a cold magician ...
David Johnston's user avatar
42 votes

How can I heat my buildings without fire in a low-fantasy setting?

Frame Challenge: The blind can use fire perfectly well, and should You are searching for a solution that itself is looking for a problem. Respectfully, everything listed is a non-issue. Housing: ...
automaton's user avatar
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40 votes
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Medieval method of measuring temperature

The simplest method of measuring temperature would be to use a bimetallic strip: You put together a layer of copper and a layer of steel, and you get a spring that will change form significantly with ...
cmaster - reinstate monica's user avatar
40 votes
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How can I heat my buildings without fire in a low-fantasy setting?

Housebarn Have you ever slept in a tent? When you wake up, the inside of the tent is warmer than the outside. Steam issues forth when you unzip the panel, and you go "AAaah!" when the chilly ...
Daron's user avatar
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38 votes
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Why might an area of land be so hot that it smokes?

Something underground is burning. https://www.centraliapa.org/about-centralia-pa-mine-fire/ The bones are kind of extra but this is a good photo of the Centralia mine fire. There is a large coal ...
Willk's user avatar
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38 votes

Could negative kelvin be achieved?

The short answer is that it is indeed possible to create systems with negative temperatures. Unfortunately, that doesn't imply that the system in question has a negative energy density. What is ...
HDE 226868's user avatar
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32 votes
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What would be best way to re-melt Mars' mantle and core to revive its magnetosphere

Late answer, just found this article: Nasa Proposes Magnetic Shield For Mars The important bit from the article: Ask scientists why Mars is cold and dead and they'll usually point to the death ...
AndyD273's user avatar
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31 votes

Why are my caves warm with nobody heating them?

A Natural Nuclear Reactor Natural Reactors existed on Earth a few billion years ago, in places such as Oklo. Slightly permeable rock containing uranium ore, when saturated with water, became ...
IronEagle's user avatar
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28 votes

Superheated bullets and the damage they would deal

What Damage Does A Normal Bullet Do? As with any new weapon, we first have to ask whether this is a marked improvement over what we already have. Is it worth the bother? Let's run the energies ...
Schwern's user avatar
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28 votes

At what temperature should the earth be cooked to prevent human infection?

The humans are toast (well, medium rare anyway). Short version : ten degrees Celsius should do it, twenty would be more than enough. Luckily for us, their ovens are really slow and the Earth heats ...
StephenG - Help Ukraine's user avatar
28 votes

Why are my caves warm with nobody heating them?

Hot springs Your caves have geothermal springs in them, which not only keep them warm - they keep the caves expletively hot in the lower places. From the wiki: A hot spring, hydrothermal spring, or ...
The Square-Cube Law's user avatar
28 votes
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How devastating is a weapon that can internally and rapidly cool down a section of a human body?

For an assassin, it's indispensable The Hypothermia datasheet on Wikipedia will be quite useful. 40-50 degrees per second means one degree in 0.02-0.025 seconds. At 35 degrees Celsius, or about 0.05 ...
John Dvorak's user avatar
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27 votes

What problems would a superhuman have whose skin is constantly hot?

The first thing you have to worry about is feeding him. To generate that much heat, he has to be getting the energy from somewhere. Let's assume that he metabolises energy the same way we do; through ...
Tim B   II's user avatar
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27 votes
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Cooling Question: How can I integrate a low tech freezing system into my world?

Desert cultures made and stored ice centuries before the Romans harvested snow from the mountains for their feasts. The key is that the desert environment loses heat rapidly to the sky after dark; ...
Zeiss Ikon's user avatar
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24 votes
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Superheated wing blast!

A one mile long wing is big, I mean, REALLY big. Let's say the "offensive wing beat" starts with the wing pointing backwards and completes 180 degress later pointing forwards. The wing tip completes ...
Binary Worrier's user avatar
24 votes

How can I heat my buildings without fire in a low-fantasy setting?

Your blind civilization has long moved underground, where heating is not an issue. Sight is too big an advantage for surface dwellers. Your civilization would fall to predators or natural disasters. ...
Mindwin Remember Monica's user avatar
23 votes

Is it possible for a substance to be thermally inert?

The best you can have is that the material is so highly insulating that touching it won't give the true feeling of its temperature, and only the thin layer in contact will be thermalized with the ...
L.Dutch's user avatar
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23 votes
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Could a world exist with a distinct line of changing temperatures between the hemispheres?

Tidal locking is a fine method. Here is a different method. Asymmetric magmatic heating. https://www.reuters.com/article/us-mars-crater/giant-crater-explains-strange-shape-of-mars-...
Willk's user avatar
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22 votes
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Is it possible for a substance to be thermally inert?

Temperature is an empirical, macroscopic concept and is not in general equivalent to energy. It breaks down at some point (energy does not), for example at the point you are asking for. But let's try ...
Nobody's user avatar
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22 votes

If a small marble reached Planck temperature, would the heat spread and ignite the atmosphere?

The heat transfer limit wouldn't be what prevents this; it would be the negative energy balance of oxidizing nitrogen that prevents igniting the atmosphere. There was actually a serious concern among ...
Zeiss Ikon's user avatar
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19 votes
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How would merfolk insulate an underwater house?

Ventilation with heat recovery: You just stumbled upon the basic problem home builders are having in the real world. To keep the energy inside the building, buildings are more or less made airtight. ...
Manziel's user avatar
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18 votes

Superheated bullets and the damage they would deal

What you really want exists, it's called a tracer round. A tracer round works like a bullet sized flare. The tracer projectile is filled with a pyrotechnic flare material, made of a mixture of a very ...
gwally's user avatar
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18 votes

Medieval method of measuring temperature

Boiling water, ice cold water and a binary search You did say crude would do... Theory Humans can't do absolute temperature measurement, but they can do relative - I can't tell you how hot my mug ...
walrus's user avatar
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18 votes

Superheated wing blast!

Edit jdunlop has repeatedly pointed out the flaws of my answer so even if you have read the answer please reread it because there have been a few significant changes made. (in the Energy real world ...
Soan's user avatar
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17 votes

Why might an area of land be so hot that it smokes?

You might be looking at a series of fumaroles. These are steam-producing features created by interaction between groundwater and volcanic heat. They are rather flexible: they can appear a few at a ...
Cadence's user avatar
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