# is Cryomancy scientifically possible?

Like in video games where characters are able to control the temperature around them by simply removing the heat.

Is it possible for a machine or biological creature to have the power of absorbing heat from the outside causing things to freeze? Or does it go against the laws of thermodynamics?

Would such a super-power be too much, in the sense, would something able to fully control this power be also capable of controlling the universe?

• It is not only possible, it has already been done. – Hackworth Jun 14 '16 at 13:13
• When I read the title, I assumed this was about reading the minds of people who have been cryogenically frozen. It's a shame -mancy is so misused. – Mystagogue Jun 14 '16 at 18:40
• @Mystagogue: actually, "cryomancy" should properly refer to cold-divination, whatever that would look like (seeing visions of the future in ice?). – zeta Jun 14 '16 at 19:00
• Is (insert any kind of magic here) scientifically possible? According to Arthur C. Clarke, one of the greatest story writers ever: "any sufficiently advanced technology is indistinguishable from magic" (Clarke's Third Law). – Renan Jun 14 '16 at 21:36
• @Mystagogue: Yes, I also expected something like Greg Bear's "Heads". – David Cary Jun 15 '16 at 0:56

Yes, this is possible without violating the laws of thermodynamics. If it wasn't, refrigerators wouldn't work. You're essentially making a heat pump spell.

There are two rules you have to keep to if you don't want to break physics as we know it. First, the heat has to go somewhere. Energy can't be destroyed or created, so whenever you cool something down something else must heat up. Note that it must be the same total heat energy, but not the same temperature if you release it into something of different size/heat capacity. If you freeze a small object and release the heat into the ground or a large body of water it might not even be noticeable.

Second, the process itself must use some external energy to make it work that is converted into heat - and no, you can't use the heat you move as a source. This is to not violate the law about entropy. The source of this energy is probably the same as the source of magic in general - chemical energy from the casters own body perhaps, or maybe he needs to drain a battery to do it.

As for controlling the universe, not any more than we already do. As long as you keep the power within the bound of thermodynamics, it would be useful (especially if it is efficient or has an easy-to-get energy source) but not game-breaking. It doesn't do much we don't already have machines to do. If you could ignore thermodynamics, that would be a different question altogether.

• Out of interest. Why can't you use the heat you're moving as a source? – Space Ostrich Jun 15 '16 at 3:08
• @SpaceOstrich: Because you can't use heat to do anything without allowing it to flow from a hot environment to a cold environment, which is the opposite of what you're trying to do. That's a direct consequence of the second law of thermodynamics. – Kevin Jun 15 '16 at 5:09
• Simplified, heat is no source of energy, just like a water level in a lake can not be used to drive a power plant. in both cases, you need two different levels ("potentials") - the water must go to a lower level to drive a water wheel or turbine. – Volker Siegel Jun 15 '16 at 7:03
• Note that it must be the same total heat energy. Should it be the same amount of heat energy or just the same amount of energy? In other words, is there anything that prevents you from converting the heat into some other form of energy instead of simply moving it? – Jasper Jun 15 '16 at 9:24

In a word?

YES

Let's explain a bit more in-detail.

• Endothermic reactions exist in real life and photosynthesis is a good example of this (Wikipedia link if you want to read more), while I'm not sure about the logistics of getting things to actually freeze (as freezing is actually an Exothermic reaction (gives off heat.))

• Next, the law of thermodynamics means that the energy that used to be heat has to be converted into something else (energy never is added to or taken away, only changed form.) The exception here, being entropy, which will eventually, render all energy useless to thermodynamic laws. (Not pleasant)

• The part about some super-powered being with full control of this ability being able to control the universe is questionable if you're taking into account thermodynamics (again, because the energy has to be converted into something else you could easily argue that there's another being whose power is the exact reverse, adding heat.)

I'm surprised no one has mentioned that this can be done with lasers.

https://en.wikipedia.org/wiki/Laser_cooling

All laser cooling techniques rely on the fact that when an object (usually an atom) absorbs and re-emits a photon (a particle of light) its momentum changes.

When you slow down the particles with this technique, you are effectively cooling any matter.

This video explains it quite well: How does laser cooling work?

• Now for the real question: why can't we redirect the blueshifted laser to a solar cell and extract all of the energy spent to lase and then some back? – John Dvorak Jun 12 at 19:18

You couldn't control the universe with this super power.

The only way to absorb heat from the surroundings is to be colder than the surroundings via heat transfer (conduction, convection, and radiation). A hypothetical creature that could magically lower its exterior temperature would still only be able to absorb heat at a rate governed by those heat transfer mechanisms.

For example, suppose that a being in the room with you suddenly lowered its temperature to zero degrees Celsius. No big deal, just leave the room. Suppose it lowered its temperature to zero degrees Kelvin. No big deal, you would feel a big chill from their direction (like the opposite of a fireplace). Don't stick your tongue to it.

As far as controlling the universe... heat transfer across space is accomplished only by radiation. Space is already very cold on average (about 3 degrees Kelvin), so the existence of a being at zero Kelvin is not going to be noticeable to anybody on another planet, solar system, galaxy, etc.

• 0 Kelvin is -273 celsius, I think that would be quite a big deal unless you were prepared for it. The rest of your answer I agree with though – Mr.Burns Jun 14 '16 at 14:24
• @Mr.Burns: You might be right. I assumed it would be similar to an astronaut looking out into space through their visor. Of course the creature in your room would quickly frost over as the air begins to freeze onto its skin. You would want to open the windows to avoid a very cold room. – James Jun 14 '16 at 14:34
• @James it's a misconception that outer space itself is cold. Temperature is a collective property of matter and space has, by definition, negligible matter. In fact, because the near-vacuum is such a good insulator, overheating is a big problem in space. – Travis Christian Jun 14 '16 at 14:48
• @TravisChristian: Yes, good catch. I should have said that the effective average temperature of space for radiation heat transfer is about 3 degrees Kelvin. (helios.gsfc.nasa.gov/qa_sp_ht.html) Matter is so diffuse in space that the temperature of the matter itself is not a factor in heat transfer. – James Jun 14 '16 at 15:11

This could occur within the laws of physics, albeit a corner case of them which is typically not given much credibility because it offers fantastical possibilities for which we have little to no evidence for.

The laws of entropy really only take hold when you forget information. Many constructs built around reversible computing specifically avoid erasing bits of information so that they can be returned to their previous state after the calculation is done. This construct legally sidesteps entropic losses, if you could actually build one.

The reason entropy always "wins" at our level is that we very rapidly "forget" the result of collisions between molecules. We treat them as "random events," which means we lose a little information every time they occur simply because we're not tracking them 100%.

What if something was tracking them?

If you had an entity which could track the results of those collisions, it could do some pretty amazing things. It could be thought of as a ghost, or it could be thought of as some exotic field, but the result would be the same. Every "random" collision we think we observe may actually be carefully planned, and thus not random at all. We just don't know the key to unlock the "randomness" and realize that there's a pattern to it.

All of science would be justified in believing that these collisions are random and that the entropy of the system has increased with each collision, but they'd be wrong. All that information would be retained by this entity, usable for exotic things like suddenly making all the air molecules in the room move to one side of the room. Statistically, it is highly improbable that it will occur, if the air molecule movements are "random." However, if we know a-priori that there is a structure to their "randomness," it becomes a lot more plausable.

It would be hard for any entity to merely "remember" those trillions of collisions every moment; however, if it were to interact with the system to encourage those collisions to occur in a way which is highly compressable, in the data sense, it may be able to keep track of far less information (so long as it can keep the whole system coherent).

For such a system, crypmancy would be easy. You would merely beseech this entity to freeze something for you, and it would kindly take away all that "heat" that is actually particle motion between particles whose positions are know to it (but not to science). It would appear that entropy would be decreasing when you do so, but in reality all that would be happening is you would be having to update your estimate of how much entropy is in the system in the first place. Entropy would still be increasing, you'd just see the illusion of it decreasing.

There would be a lower bound to this if there is any actual indeterminism in the world. If the classical observations of quantum mechanics are truly random as they are in the Copenhagen interpretation, this entity would be in a constant fight with QM to maintain that detailed structure of the universe while making sure the structure is too advanced for us humans to recognize. However, some of the other interpretations may suggest that entity could step beyond our universe, and be in a position to manipulate the quantum waveforms directly.

Not impossible by the laws of physics. Improbable, but then again, what do we know about the probabilities of our own existence?

• As that entity would observe the system, it would be part of it. It seems to me that the entity would need more and more computational power to remember the collisions. The entity could not track itself and its entropy would rise until... until... hrm. Collapse? Explosion? – PatJ Jun 14 '16 at 15:58
• Would this be theoretically possible from a distance? It's hard to see how a single machine or creature could control the universe in this way. – James Jun 14 '16 at 15:59
• @patj, you are right. However, it's surprisingly difficult to differentiate what the entity would have to do and what we do as living creatures. We shape our surroundings such that it is easier for us to understand. The only real difference is sclae – Cort Ammon Jun 14 '16 at 16:55
• Well, your entity would have to be outside of the universe to monitor all of it. – PatJ Jun 14 '16 at 16:57
• @James, it most likely would have to be an up close and personal distributed system. In theory you could use principles like the holographic principle to do it from afar, but I think the question of having enough computation becomes a lot nastier from afar – Cort Ammon Jun 14 '16 at 16:57