Another question (and others in this line) got me thinking. In a magical universe we often try to make sense of it with similar physical laws but extended into another realm: nuclear power is "magic" chemistry, as it provides another place energy can be stored so conservation laws and thermodynamics still work. Magic might cause things to happen essentially by providing a place/state where additional energy can come from and enter our normal world.

But here's a twist on that idea. What if it's not a source but a sink. There is power in normal room air if there is an absolute-zero sink to drive a potential difference. Calm level water can drive a mighty water wheel if it suddenly drained into a black hole.

But the real twist isn't to have a sink of energy directly; rather, have a sink where entropy may be dumped. In chemical reactions like exothermic reactions we know that entropy trumps energy and the 2nd law of thermodynamics is really just entropy applied in the simplest way to heat.

Now look at other things we expect of magic besides raw power: intelligence. Organization of matter comes from nowhere, and high-level understanding needs to guide the various effects.

Now we know that information is intimately related to thermodynamic entropy, as revealed by the final solution to the puzzle of Maxwell's demon and Hawking's black hole temperature.

So, how can we formulate a magical universe based on communicating with a place which has the effect of changing the information content of the system?

  • $\begingroup$ But entropy is a result of the chemical/physical reactions. You cannot increase entropy without accelerating the chemical reaction rate, which would be bad enough by itself (after all, an explosion is little more than an uncontrolled oxidation). $\endgroup$
    – SJuan76
    Commented Dec 31, 2015 at 13:31
  • 2
    $\begingroup$ Entropy is any hidden information. It's not limited to chemical reactions, and increasing entropy can decrease temperature; both of which I mentioned in the OP. In any case, as a sink it is used to locally decrease entropy of the local world around the magician, by providing another place where it can be increased. $\endgroup$
    – JDługosz
    Commented Dec 31, 2015 at 13:58
  • $\begingroup$ So basically, this magic could create particles whose state is indistinguishable from a statistical random variable? $\endgroup$
    – Cort Ammon
    Commented Dec 31, 2015 at 17:38
  • $\begingroup$ I think it could serve as a sink of high entropy to be disposed of, and used another way provides creation of information from "nothing". Reading a random number generator is not something we need this realm to accomplish. $\endgroup$
    – JDługosz
    Commented Dec 31, 2015 at 18:41
  • $\begingroup$ Not long enough to be a post, but riffing on JDlugosz's mention that entropy is hidden information - could magic be powered by forgetting? (As in, you're spending information to power magic.) $\endgroup$ Commented Jan 4, 2016 at 22:05

4 Answers 4


The best entropy-sink based magical device I've ever seen is Galaxy Quest and the Omega-13 device. Per the Second Law, Entropy must increase. The device will remove the last 13 seconds of entropy. It requires enormous power to operate - enough that it will (out of necessity) destroy the universe. It just leaves a 13 second younger one in its place.

Similar thoughts can go for smaller things. Let's try a fireball:

  1. Swap out inert gas in the local area for flammable materials. Pollen works really well. It's just Maxwell's Demon. With a long enough casting time to allow the pollen to drift into the immediate area and not allowing it to leave.
  2. Light up a spell component (say a match, or the traditional sulfur). Using rearrangement, get enough of the oxygen radicals in the air.
  3. Using the Demon again, bombard several of those pollen grains with the oxygen radicals. Order and arrange them to go towards other grains until the reaction is self sustaining.

Other thoughts can go further. Cone of cold is simpler - only allow the really slow molecules in the imminent area of the cold.


Regarding intelligence as a powering device for the entropy, this is seen with the Demon analogy as well. While information will have to be erased per the physics involved, the more intelligent, the less erasing, and the more efficient and less energy draining the magic is. Hence, why you "get more" out of it - you use the same entropy draining mechanism, but you get more damage / more power / more skill out of it with a higher intellect.


So, powering magic by taking energy from our reality through entropy is cool and makes a kind of sense. Even if it was just moving energy around instead of losing it forever (Take heat energy from a rock to boil water. The rock gets ice cold and cracks from the thermal contraction, and the water gets really hot).

The intelligence is kind of the easy part, as that's where the caster comes in. Say you want to create something. You cause entropy in your power source, take the raw magic energy and push it through your spell which gives it direction and substance.
It would be like hooking the output from a water tower into a cities water grid. The pipes tell the water where to go and what to do.
In the same way, the rules and structure of the spell tell the magic where to go, what to create, what to destroy.

The only other source of intelligence would be something outside our universe.
The eaters in the dark, gods, demons, or other extra dimensional entities drawn out by the magic and put into service.
This has the potential of going pear shaped really really fast though.
It would be a way to create a kind of AI, as beings are drawn forth, bound and harnessed into service, forced to serve by the bindings and wards that hold it.
Just don't make a mistake when drawing them...


Dumping entropy somewhere that will have no effect on the rest of reality, is like extracting potential order from somewhere else. That would be magic, if not magical.

Fully realized magic of course involves more than just the disappearance of entropy, but includes the creation of anti-entropy and the application of it to macroscopic phenomena at will.

  • $\begingroup$ I was thinking it could provide information to power the intellegence behind magic, where order is needed. So the flow is in either direction, perhaps using 2 different effects. $\endgroup$
    – JDługosz
    Commented Jan 4, 2016 at 22:40

To make entropy control into magic... What about a universe made of ternary pieces of information?

1, 0, and 0.5 with the middle being entropy and the extremes being inverse information. If you manipulate entropy then you're subtracting or adding 0.5 to your piece of information (but only as long as it stays on the 0 side). To us "1-siders" a 0.5 is representationally a zero since it's the entropy point on our axis. If we assume that 0.5 and 0 appear equal (0 is information that doesn't apply to our "1-sider axis"). Then you can hide magic in the 0 side. If you construct an information blob in 0's and entropy (0.5's) then when you add information evenly to the blob it flips to 1's and entropy (0.5's). Scientific laws stay the same because to the 1's side entropy and "0 information" are identical. You can't read 0 information unless your performing magic. It's always "lost". So now you have the choice of whether you want (real life) entropy to be destroyed information or just shifted to the 0 & 0.5 encoding. If it's lost then you can't push 0.5 to 0 unless you're performing magic. Regardless, you can have another world hiding in the 0-side and you can even constrain yourself to just "producing entropy" and still perform magic: If you only subtract 0.5 from pieces of 1-information/entropy and construct a gradient in potential then when the potential flows it creates energy. Usable energy is information. Anything with structure and direction is information and usable energy definitely has direction. If your 1-side works on 1 and 0.5 values then energy flow is a flow of information that adds 0.5 to whatever it crosses (subtracting 0.5 from 1 wherever the energy was generated (this is your heat production, etc.)). As the energy flows over your special configuration it activates it and makes it real information. You could also have the 0-side act like 1-side information but be indistinguishable and get up to shenanigans that way.

Semi-Clarification (It's still a fuzzy idea): When we're working with binary states entropy isn't a 1 or a 0. Its definition is instead related to the amount of information we can hold versus how much we're actually holding. Same is true for a ternary state. The catch here is that we only have access and effects from two states. We basically have 1 and +0 and -0. With no way to tell if a zero is negative or not. We've altered entropy's definition here. Since no information actually ever becomes entropy in actuality. It appears as if its entropy whenever there's a 0. That's because each "bit" doesn't store 2 pieces of information, it stores 3. But we can only access the 1 and 0 difference so we can only read 2 pieces of information. We "lose" 1 piece whenever it goes to 0. The definition of entropy here has shifted towards defining any 0 as a piece of entropy. This model assumes information is never created or destroyed. Just rearranged, hidden, and unhidden.

How about the standard illustration about 2 gasses in a container that mix after a partition is removed? How is it made of 0,.5,1 values, and how does adding 0.5 make the gas mix or unmix?

I'm going to move to a lattice model of the universe with information describing the system. Let's assume momentum as a primary quantity. Vector is in a 1, +0 representation. Move it into a +0,-0 representation (add entropy). You've killed momentum but saved state. Manipulate as needed. In the example we need an incoming momentum of (0.5,0.5,0.5) (which is physically none) to reverse our process. That momentum is the same physically as (0,0,0) but informationally is different. Can we add that from nowhere? Physically that's creating energy and reducing entropy from adding two pieces of entropy. If that's not acceptable you'd need to set it up so that when the area outside of our manipulation adds in its quantities we have a vector set up so that the result is our inverted vector which also adds in the possibility of nearby magic messing with us.

Example: (1,0.5,1) -> (0.5,0,0.5) -> (0,0.5,0) + (0.5,0.5,0.5) = (0.5,1,0.5)

The example "inverts" the vector after moving it into "entropy land". You could also just subtract (0.5,0,0.5) twice. When added momentum influences that region it will be in the form of 1 and +0 (remember +0 is code for 0.5).

Note that our "vector" isn't truly "inverted" momentum-wise, we have no negative quantities as described. The above is also a toy thought experiment because I'm not sure what happens when a "1.5" would appear (It can't happen because the ternary system doesn't allow it. A 1.5 is really 0 with overflow of 0.5. Does that excess disappear, propagate to the next cell, is it disallowed from happening, or do something else?) That's why this answer was meant to be a comment. The system needs to fleshed out and can be tackled in many different ways, all with unique methods of manipulation to cause certain effects. You also need to state what your primary quanta are and describe them. If its a simulation on a machine that's fairly easy. Just take your bits of RAM and make them tri-state. Your program becomes the description.

  • $\begingroup$ Was trying not to post and make this a comment instead, but it didn't fit. Apologies if it's, well anything really, but especially if it's wrong in the energy flow area (I was trying to fit in the "sink only" requirement and I'm not sure a lattice/machine model of the universe makes a lot of sense even if quanta do make sense...). $\endgroup$
    – Black
    Commented Jan 1, 2016 at 0:05
  • $\begingroup$ Sorry, I don't get it. $\endgroup$
    – JDługosz
    Commented Jan 4, 2016 at 22:31
  • $\begingroup$ @JDługosz That's cool. I sorta winged it and it's confusing from a theoretic information perspective. I'll clarify at the bottom of the post... $\endgroup$
    – Black
    Commented Jan 4, 2016 at 22:44
  • $\begingroup$ Entropy means something... how does "entropy point on the axis" have anything to do with the actual meaning of what entropy is? $\endgroup$
    – JDługosz
    Commented Jan 4, 2016 at 22:58
  • $\begingroup$ @JDługosz Ternary states in binary systems have a lot of interesting effects. Hopefully I clarified it properly... $\endgroup$
    – Black
    Commented Jan 4, 2016 at 22:59

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