77

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, in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density and low thermal conductivity. Nicknames ...


69

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 transfers energy very effectively: It slows down a lot (leaving the kinetic energy behind to damage tissues). The heat energy of a hot projectile? Not so much. It ...


49

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 temperature with respect to increasing depth in Earth's interior. Away from tectonic plate boundaries, it is about 25–30 °C/km (72–87 °F/mi) of depth near the surface in ...


49

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 Why do caves stay at the same temperature year-round? Caves stay at the same temperature year-round because they are thermally insulated from the external ...


46

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 is "how much heat can they absorb?". If they can absorb more calories of heat than Fire-guy can generate then they win a magical arm wrestling competition ...


39

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 temperature. The two layers have different thermal expansion coefficients, so when you heat the strip, one layer will expand a little more than the other, ...


32

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 critical for about 30 minutes, heating the water and driving it to steam. After that 30 minutes there wasn't enough water to sustain the reaction, and it stopped ...


29

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 of its magnetic field some 4.2 billion years ago. Without that protection, solar winds gradually stripped it of most of its atmosphere. A NASA-led team, ...


28

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 involved, because bullets wound by transferring energy to the target. Let's assume a standard M855 5.56 NATO rifle bullet fired from an M16 with a 20" barrel, ...


28

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 geothermal spring is a spring produced by the emergence of geothermally heated groundwater that rises from the Earth's crust. While some of these springs contain ...


28

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 seconds in, mild hypothermia sets in. Normally the person would be shivering at that point, but things are so local and so quick, this won't have a chance to ...


27

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 food. The average human consumes around 8700Kj to maintain a body temperature of around 37oC, in environments that average around the 25oC mark. Note, this is ...


26

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 up really slowly (a few degrees celcius every year) Which, I assume would give use enough time to react to the change in temperature and allow us to start ...


23

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 touching object. Something similar happens for example with the ceramic tiles used in the thermal shield of the Space Shuttle: few seconds after being taken out of ...


23

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-idUSN2530000020080626 Your world was hit by a large impactor. On resolidifying, the iron core of the planet was no longer in the center of mass. A large lobe of silicaeous ...


23

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 a full half circle with a one mile radius, so basically 3.14 miles. How long does a beat take? 1 minute? 1 second? 10 seconds? Lets go with 10 seconds. The ...


22

It would be so close to absolute hot that you probably couldn't tell the difference. The two concepts are not really on opposite ends of a spectrum from what we consider "normal" (~300 Kelvin). In the cold direction, there is 300 Kelvin, in the hot direction there is 1.416785(71)×1032 Kelvin. If you mix two equal amounts of substances at the temperatures ...


22

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 to make sense of this: Temperature is proportional to the (square mean absolute value of) relative motion of atoms. You might get in trouble choosing your ...


20

Electromagnets are far more powerful, pound per pound, than planetary magnetic fields. You can overcome the Earth's field with a little bar magnet. So why bother trying to resculpt the planet at all? Park huge electromagnets in a system of orbital stations in such a manner to generate a similar magnetic field as a planet would. Add the zillions of solar ...


18

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 finely ground metallic fuel, oxidizer, and a small amount of organic fuel. It burns at several thousand degrees. If fired into dry brush or grass, it will ...


18

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 comparison part and following, it's a more accurate formula) This simply is an expansion to Binary Worriers answer. (Math to display the true scale) This is ...


17

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 of tea is, but I know it's hotter than my hand and cooler than the kettle. This means that if we have a range of objects whose temperatures we know, we can tell ...


16

Option 1: Move it to orbit Jupiter: https://web.archive.org/web/20150703090935/http://www.planetaryexploration.net/jupiter/io/tidal_heating.html Tidal forces will heat the interior, restarting the core and presumably your magnetic field. Might take a while but is probably faster than some of the other listed options if you get it close enough. You'll ...


16

There are two types of planets which are likely to exhibit small temperature ranges that I can think of: planets exhibiting a significant greenhouse effect and those with rapid rotation rates. Greenhouse gases Small temperature variations are found on planets with thick atmospheres. On these planets, the thickness of the atmosphere provides sufficient ...


16

We can live in this temperature. We would have to adapt to it but we will get used to it soon. The limit for living on a planet is the point that proteins denature (~40 degrees Celsius). Because at this point we (our body) could no longer survive.


16

The average temperature of Earth is ~15 degrees Celsius. So, your planet is about 19 degrees warmer than Earth. I suppose Dakkar would be uninhabitable if it were 19 degrees warmer, but Helsinki would have a temperature similar to Miami. Seems livable to me, though if its life forms were autochtonous, life in each hemisphere would probably differ a lot from ...


16

The higher the temperature of the metal, the more easy it is to deform it. So you can end in a situation where your bullet doesn't pierce the target, but rather splash on it if the impact surface is sturdy enough. You have basically achieved the same result of an arresting rubber bullet with a more complicated and expensive implementation. A normal ...


15

A global average temperature of 34°C would be very uncomfortable and have expanses of areas uninhabitable by humans, but it would not preclude human life in some areas. The bigger problem would be understanding wet-bulb temperature. In a civilization with advanced technology, interior areas could be made habitable, but there is a limit where it becomes ...


15

There are a lot of such organisms right here on Earth. Undersea volcanic activity produces hydro-thermal vents. These are places where water is heated and then rises out of the sea floor. Typically this also brings with it a wide variety of chemicals that are ordinarily not available in such quantity in the ocean water. And there are organisms that find ...


14

If you want to stick with science, then first you need to correct a misconception or two. You seem to be thinking of heat or temperature as an intrinsic property of a material, but it's not. Whatever the apparent temperature you measure by e.g. touch, then that's the temperature. A material can have temperature gradients in it : one part hotter or colder ...


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