Something I find deeply unsatisfying in my reading of fantasy fiction is that magic is invariably treated as a means to cheat real physics. The fantasy world is built to operate according to the way modern science says our world does, and then a self-contained set of magic rules is tacked on to allow magic-users to arbitrarily cheat the laws of physics transplanted from our world. If technology is introduced then it operates according to real physics and thus separately from magic; in some cases technology and magic may be actively opposed (conversely, magic-users relying on real physics for their biology are not poisoned by using magic).

In contrast, when what is more or less physics cheating magic appears in science fiction settings it is usually treated as advanced technology, a quirk of physics or simply left unexplained. Star Wars has magic powered by mitochondria, Farscape has alien wizards, Andromeda gives stars intelligence and humanoid avatars, etc.

How could one devise a magic system that isn't just a shortcut to cheat physics whenever the user desires? Replace magic with sufficiently advanced technology? Make all physics work according to magic rules?

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    $\begingroup$ In Hamilton's Void Trilogy sorts of magic are built into an engineered area of spacetime allowing sentient beings within to intuitively access a control layer of their pocket universe by thought. Is that what you were thinking? you might want to go into more detail of what you'll accept. $\endgroup$
    – Murphy
    Jul 14, 2016 at 13:03
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    $\begingroup$ This seems like a dup of this question: worldbuilding.stackexchange.com/questions/40949/… $\endgroup$
    – spacetyper
    Jul 14, 2016 at 15:24
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    $\begingroup$ Also seems similar to this recent question: worldbuilding.stackexchange.com/questions/46279/… $\endgroup$
    – Mwr247
    Jul 14, 2016 at 16:11
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    $\begingroup$ In Star Wars, it's not mitochondria, it's midi-chlorians, which are intelligent microscopic organisms that live symbiotically within a person's cells. $\endgroup$
    – Tophandour
    Jul 14, 2016 at 16:43
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    $\begingroup$ It's not clear what constitutes a "cheat" to physics in your question. If something is left unexplained, does that constitute a "cheat"? How explained does it have to be? Does it have to actually have detailed physical laws, or is a quick bit of technobabble sufficient? Does it have to have well-defined interactions with General Relativity, Quantum Mechanics, and Thermodynamics, or is a human-level sketch enough? $\endgroup$ Jul 14, 2016 at 17:55

12 Answers 12


We need to define what magic is.

I like the definition that arises from Clarke's Third Law. Any technology sufficiently advanced is indistinguishable from magic.

Radio waves are a good, nearly contemporary example of this. Everything from AM/FM to Wi-Fi is taken for granted by everyone nowadays - these things just exist and work. But imagine explaining a pair of walkie talkies to the ancient greek or egyptians, for example. Telepathy in a contraption!

I also know of an anedoctal case, of a man that impressed the indigenous populations of the new world some four hundred years ago by setting fire to alcohol. The indigenous people didn't know alcohol and thought it was water. Fire on water... Magic!

So when someone is tapping into the arcane to do something that would seem impossible otherwise, perhaps they are just making use of the laws of nature in ways which we do not understand YET.

A few examples of stuff that would be mind-boggling to our ancestors from, say, the 17th century, and which we can carry/conceal in our hands/bodies:

  • Radio, as mentioned above
  • Computers (cell phones and smaller electronics). Thinking machines!
  • Laser pointers that can lit a cigar or set a carpet on fire
  • Antibiotics. The Panacea in a potion!

Some things that may boggle OUR minds within a few years, decades, or centuries, and will probably be portable at some point:

  • Brain-to-machine interface implants;
  • Quantum entanglement for FTL communication;
  • Either the above or radio + brain-to-machine interface implants for an even more direct form of telepathy (as seen in the book Dancing With Eternity, writen by TF2's Sniper)
  • Stem cells in a packet that you can place over a wound to cause it to heal nearly instantly
  • Tazers in a more compact format, such as rings or gloves (for a shocking hands spell)
  • Hoverboards that do hover (a prototype was released this year)

And so on...

One of the explanations I use a lot here in Worldbuilding for supernatural stuff is that we exist in more than three dimensions. IMO, in fictional worlds which make use of magic, magical energies may be linked to structures, natural or artifical, that we cannot see because they exist beyond the three dimensions we perceive. All magic is natural, we just call it magic because we cannot explain it given our understanding of nature... So when a wizardry school fails to explain how magic works, they are either:

  • Hiding a secret;
  • Using magic through cargo cult means (i.e.: I don't know how it works, I just know that it does if I do it this way);
  • Going through a phase in the development of a science, just like we had to go from nothing to alchemy in order to develop chemistry.
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    $\begingroup$ I think this hits at a key idea: If magic is just another part of the physical world and falls under the study of the physical world, it is no more unique than electromagnetic forces, or vibration, or the various traits that make electronics work; they all work together and to the ordinary man they're just "part of reality" when he becomes used to them. If the asker goes down this path magic won't be something of particular specific and individual note any more than radio waves are. $\endgroup$
    – Ranger
    Jul 14, 2016 at 14:38
  • $\begingroup$ I would even be impressed by you setting fire to alcohol if I knew you would be doing that. $\endgroup$ Jul 14, 2016 at 16:01
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    $\begingroup$ The Cargo Cult idea works pretty well, especially if the Sufficiently Advanced people who invented it offed themselves catastrophically with it. See Ra, Worm, Harry Potter and the Methods of Rationality, and the Mistborn series for various shades of this idea. $\endgroup$
    – Ketura
    Jul 14, 2016 at 16:40
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    $\begingroup$ Actually, taking one walkie-talkie to a primitive civilization probably won't impress them nearly as much as taking two. $\endgroup$ Jul 14, 2016 at 17:50
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    $\begingroup$ "Quantum entanglement for FTL communication" - nope, provably not possible. I'd be willing to buy subspace micro-wormhole photon channels, though, as long as they promptly destroy themselves as soon as you try to make a closed time-like curve (tech-talk for a potential for time paradoxes) $\endgroup$ Jul 15, 2016 at 4:51

Well, to give an answer that is going the complete opposite direction as the others...there is another option. Build out your world in such a way that 'Magic' is the core of how the world works.

A good example of this is some chunks of the lore around the tabletop RPG Exalted. In that world, things fall to the ground not because of the natural attraction between large masses, but because the beings who designed reality decided it should work that way, and the pattern spiders operating the Loom of Fate make sure it continues to be the case. If something happened to the Loom...or even just to the local Weave, "physics" would start to malfunction. A few examples they give of what might happen if the weave is messed up...doors may stop opening to the right location. A construction worker may fall to his death...and simultaneously be standing safely on the scaffolding, having watched himself plummet to the ground. And in extreme cases the color orange might start tasting like the number fish.

Another pretty good example is the Stormlight Archives and the way Spren act and interact with the world ('washing the hands wards off rotspren')

In this case...things that look like 'Physics' are actually just a manifestation of the natural magic of the world. Fire is not a rapid oxidation reaction, it is a magical phenomenon that consumes certain materials as reagents to maintain itself...but is difficult to control and will run rampant if given more of the reagent it can consume. The river doesn't flood because it rained too much, it flooded because the local river spirit is angry. A thrown object doesn't sail through the air because of Newtonian Physics, it does so because the magical forces that make up the world declare that it should move that way. Smelting iron isn't a matter of refining existing materials from its raw form by heating the ore to a point that the iron melts while the stone does not--it's a matter of a formalized ritual for fusing together Earth and Fire to create a strong material. Iron doesn't rust because of oxidation, it rusts because the bond between the Earth and Fire was imperfect and interaction with Water and Air can cause the bond to start to break down. Washing your hands isn't removing germs, it is a cleansing ritual to clear them of malignant magical forces.

A world like this can look just like our world, functionally. Smelting can look the same, fire can act the same...but the underlying mechanic could be magical in nature, rather than physical. And this could result in some things being very, very different from how they are in our world. For example, in Exalted...gunpowder doesn't exist and cannot be created, because the world doesn't actually operate with regard to the periodic table. Sulfur, Saltpeter, and Charcoal may exist, but they are all varying combinations of Elemental Earth with other things, and don't combine to create an explosive.

In such a world, Magic is simply making use of a deeper understanding with, and connection to, the way the world actually works. In some worlds it could be a science that can be researched, studied, and understood by anyone who put forth the effort. Alternately, the world may have special requirements to break away from the 'standard' rituals (like striking flint and steel together to call Fire)...again to bring the example of Exalted: the world functions atop a force/energy/matter called Essence, and unless you have the ability to channel it, you can't do anything 'supernatural.'

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    $\begingroup$ I like this because it also applies to simulation worlds as well. In the Matrix doors open to where they open because the computer code that runs them says so. But they can be hacked as seen in Reloaded. In this way magic is still inherent to the way the world works, it's just our model of reality that is innacurate. $\endgroup$ Jul 14, 2016 at 16:46
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    $\begingroup$ While I like the concept of this answer a lot because it's one of the only ones that actually preserves any sort of magic, the specific examples are mostly flaky in that they don't seem like they would give rise to sufficiently consistent physics to develop any practical (predictive) physical models. @Renan's comment takes it in a much better direction where physical laws have some sort of reality but are built upon a more "magical" underlying reality (albeit with a real physical reality underneath that, in the particular example of the Matrix). $\endgroup$ Jul 15, 2016 at 2:27

@Renan provides an excellent answer, but if you don't want to be that drastic, consider holding steadfast to the following rules of thermodynamics (edited slightly to make them more generic):

  • Zeroth law: If two systems are in equilibrium with a third system, they are in equilibrium with each other. Magical energies and sources of magical energies (which, can be the same energies as for physical energy, such as heat) should abide by this
  • First law: When energy passes, as work, as heat, or with matter, into or out from a system, the system's internal energy changes in accord with the law of conservation of energy. Equivalently, perpetual motion machines of the first kind are impossible.
  • Second law: In a natural energy process, the sum of the entropies (unordered, unorganized randomness) of the interacting systems increases. Equivalently, perpetual motion machines of the second kind are impossible.
  • Third law: (I don't see how this would apply, so it has been removed)

Further, magic always accomplishes "work." It might not be useful work, but magic does something, and cannot cheat and do the something for nothing. If an object is moved (teleported, pushed, etc), it takes at a absolute minimum the same energy as it would with a perfectly efficient physical equivalent; I would expect teleporting myself from point A to point B to take the same effort as sprinting the distance, if not more.

So the energy has to come from somewhere. Although you could have the mages gain power from atomic bonds and not cheat physics, this still seems like a cheat as easily gaining such energy is extremely difficult to do in the real world. Instead I imagine magic has to be powered from a far less efficient mechanism, in which there's a lot of heat and loss of potential useful energy.

The gaining and expenditure of energy should be your main concern with not cheating magic. Also note that control fights entropy, so anything that requires finite control uses more energy. It should be much harder to cast a fireball that looks like a horse than just a fireball of the same size. It should be incredibly difficult to metamorphosis oneself, as the adjustment of individual cells would be an extreme battle with entropy.

In summary: the respect of both energy and entropy is a major step in making sure magic doesn't cheat physics.

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    $\begingroup$ I like this answers because it matches every single literature I've ever read where there are proper methods and approaches to magic, rather than having a "it just works like that" take on it. $\endgroup$ Jul 14, 2016 at 15:02

Clearly you've never read Terry Pratchett! One of the key points in the Discworld canon is that magic always comes at a price. In one particularly memorable scene, a witch grabs a sword in her bare hands. Later on, back home, she prepares bandages, hot water and a needle and thread, and says (to no-one in particular), "I reckon I'm ready now". The point being that magic can push against the world, but the world will push back too, and a magic-user stands at the balance-point. Get it right, and the power flows through you. Get it wrong, and the power destroys you.

Tad Williams's "War of the Flowers" envisages a society built on magic in a thoroughly technological way. What we achieve with science is generally available in the fairy world too, but with a completely different implementation.

Charles Stross's "Merchant Princes" series takes another turn. The ability to step between worlds looks deeply magical, and is considered that way by the world-walkers. However when the other world commits an act of war on the USA, various US government departments investigate this by "persuading" captured world-walkers to do their thing under laboratory conditions, resulting in them developing a technological version. I'll avoid spoilers, but it doesn't end well for the world-walkers.

Or for a more unified version, consider Scott Lynch's "Gentleman Bastards" series. Alchemy is a standard part of that world, which has many implications in a world which is basically in the Enlightenment stages of technology. Magic as you'd define it is also a part of the world, but only within a tightly-knit group of mages. As far as the world knows, their powers are infinite - and they've put a lot of effort into making sure the world thinks that, so they have more weaknesses than they'd like people to know.


If you don't want your magic to cheat physics, have your magic work with physics instead.

One of the best examples I've seen is sympathy, in Pat Rothfuss's The Kingkiller Chronicle books. The most general idea of sympathy is that what you do to one thing can be made to affect another thing in the same way. For example, if you have two coins and you establish the proper sympathetic binding between them, you can pick one up and the other will also be raised into the air.

Sympathy is described as working by very specific rules:

  1. Conservation: Energy is neither created nor destroyed; sympathy can only move it around.
  2. Correspondence: The more two things are alike, the easier and more efficiently you can form a binding between them. (It's much easier to do the trick described above with two coins than with one coin and one block of wood, for example.)
  3. Consanguinity: A piece of a thing represents the whole thing. (A sympathist can form a binding against a person's entire body with a small bit of their hair, skin, or blood.)

By setting out these basic rules, the author is able to do all sorts of interesting things and have them make sense.

For example, because sympathy is all about moving energy around, a source of energy is always needed to draw upon. Fire tends to be one of the best sources, but in a pinch a sympathist can draw upon other things. One source that's always available is his own body heat, but this is considered extremely dangerous as reducing their core body temperature by even a small amount of your core can send a person into hypothermia. (One of the most dramatically tense moments in the series comes when Kvothe needs to be able to use magic to protect himself from bandits, then finds out that a well-meaning but inept companion put out the campfire that he was relying on being able to draw from!)

The tricky thing about writing magic that works with physics instead of against it is that you always have to keep actual physics in mind. But if you can do that, you can come up with some really incredible stuff.


Any sufficiently analyzed magic is indistinguishable from science.

Magic obeys the laws of nature and nature obeys the laws of magic because they are the same thing. We would call some aspect of reality "magic" because its roots and practice are steeped in mysticism and we have not yet sufficiently analyzed it.

For example, I believe it would be accurate to label real world alchemy as a branch of magic going through the final stages of being sufficiently analyzed to produce the field of chemistry.

In a story, the reason we would still have magic in a scientific world is because it has somehow resisted analysis. e.g.

  • The mechanics of magic is sufficiently obscure or bewildering enough that scientists haven't hit upon any of the ideas that would let them do much more than just catalog results.
  • Access to magic is rare and magic users have sufficient power and influence to keep its practice rooted in mysticism and tradition and protected from those seeking to study it scientifically.
  • There simply isn't an interest in the scientific study of magic

Alternatively, we have sufficiently analyzed magic, but we still call it magic as an homage to the origins of the field — for example, I believe the term "atom" is a reference to the ancient Democritus's atomic theory of the universe.

Another possibility is that magic is the provenance of supernatural beings; that natural beings cannot perform magic at all, but they can bargain with supernatural beings to perform magic on their behalf. (e.g. an AI in a computer program chatting with the programmer to request that he enact some change in the game world)

Of course, the supernatural world is just the natural world viewed from a greater perspective; this really only applies when there is some meaningful division to be made.

  • $\begingroup$ I. Love. That. Comic! $\endgroup$ Jul 15, 2016 at 4:19

In the Inheritance Cycle by Christopher Paolini, if a person is casting magic to do something, the person must exert an amount of energy no less than the energy required to do it mundanely (and more if it is far away). This way, even the most powerful of wizards are limited in what they can do by their amount of energy (which the story suggests is the caster's supply of ATP).

It is described as magic being manipulation of an energy field that flows through the universe. Most such manipulations are by spellcasters using it to manipulate the world, but some interesting anomalies occur naturally.

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    $\begingroup$ Well, going deeper you have the Eldunarí, and we are left in the dark about their ATP supply and whatnot. But nevertheless great observation $\endgroup$
    – ThreeFx
    Jul 14, 2016 at 14:54
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    $\begingroup$ In the books, it is stated that the Eldunari naturally extract energy from the energy field that magic spells manipulate in order to cast. How Eldunari do it, and if anyone else could, is left a mystery. $\endgroup$ Jul 15, 2016 at 1:10
  • $\begingroup$ the magical system in my world takes heavy inspiration from Inheritance, it's a great system $\endgroup$
    – XenoDwarf
    Jul 19, 2016 at 9:56

@Renan starts with a key point: define what 'magic' is. Alternatively, define what 'physics' is. Accepting Clark's 3rd law is one approach. A different approach is to define magic as physical manifestations that do not obey cause and effect. The impresario who set fire to water (alcohol) still performed an action that had an effect.

The immediate objection is 'isn't performing a cause, regardless of the effect?' and the Socratic answer is what is the effect? If I select the keys 'w','o','r','d' on the keyboard twice in a row, and instead of the (non-magical) expected result of 'word' 'word', I get 'fish' and 'dumb', then 'magic' has happened. There are any number of possible rational explanations for the irrational effect, but to an external observer, none of these are obvious.

However, the OP asks for a deterministic (cause and effect) system that doesn't allow for cheating, but doesn't necessarily follow existing laws of physics. Ok, Change how some physics work. One suggestion: Have the universe allow for local changes to the fundamental constants. Allow the value of 'c', the speed of light, to be altered on a local scale. Or, h-bar, Planck's constant which on a superficial level controls the possible rate of change in energy in a classical system. Make what in this universe are linear relationships non-linear. Add the concept of an manipulable ether, so directional effects are manifest. Combine effects: walking uphill in our universe infinitesmelly decreases gravity. In a different world, gravity is a force that increases with movement. And so forth. For a less deterministic space but still uncheatable, change the properties of the quantum sponge.

How do these changes happen? Wave your hands. Sacrifice a goat. The point is some actions result in apparently unexpected actions. And the underlying reasons is the laws of physics are allowed to differ either on a local level, or generally.

  • $\begingroup$ In The Colour of Magic, a wizard confirms that his party has entered a magical fallout zone by tossing coins in the air. As they approach ground zero, the following things happen: coins tend to fall on their edges rather than on hear or tails, then a coin reaches escape velocity and never comes back, and then a couple coins turn into grubs. Well done. $\endgroup$ Jul 14, 2016 at 20:30
  • $\begingroup$ Exactly. And thanks. In one Robert Aspirns's MythAdventure books, Maxwell's Demon, the mathematical description of how temperature (or other property such as air pressure) is distributed through a space, is animated, As the animated demon moves through a room, parts become locally hot or cold. Magic, or simply different local physics? $\endgroup$
    – justajoe
    Jul 14, 2016 at 20:56

I see two approaches here: A) Either explain magic so it respects physics.

Example: maybe magic is the handling of a special energy that alters space, time and mass therefore through physical means it changes physical things.

I dont think my example is clear as I am no physicist but i hope you get me.

B) make magic independent of physics. Making it change only things that our outside of physical laws as are ideas, perceptions, feelings, memories even if you are going for a dualism based world in which spiritual and physical realms are exclusive.


One of the big differences with science and the magics I find interesting is how they deal with the unknown. Science has one very straightforward process for dealing with unknowns. They beat it down with more measurements until it fits into one of the nice tidy statistical error terms they are so fond of.

Magics are often comfortable with a very different unknown. Often the true nature of the source of their power is unknown. Sometimes the actual effect of the magic is unknown (especially with wish based magics). It includes unknowns that are not easily sliced into neat tidy random variables using statistics. I find the most interesting magic systems are the ones which give just a glimpse into how these unknowns are being dealt with. While it may look like a shortcut to simply conjure food to eat, the modern day wizard smiles and reaches for a cellphone. "Magic," he says, as he hits the speed dial for pizza. Why did he choose that? Maybe that question sits in your mind for half of the story, until one moment reveals just a bit of the shape of the unknown that he has swirling inside of him. Suddenly you realize that, if he were to rely solely on science, science would tell him he's a dead man. He has to rely on the magic to hold back the tide of what he has created. Now you realize that, while the magic was a shortcut in some places, it came with a cost -- ideally a cost he paid gladly.

An excellent example of this is Gandalf from Lord of the Rings. Throughout the story, it is apparent that there's not very many limits as to what a wizard can do in Middle Earth. But why doesn't he use that ability more often? Tolkien gives us a few chances to see that he is given the opportunity, and chooses not to. We never really understand why. What's inside him is a great unknown to us. However, in a handful of places, we get glimpses of the world the wizards walk in and how impossibly heavy the yoke they must carry. Yes, he cheats physics some times, but it's pretty clear that he treats that as a side effect -- his true calling is much deeper.


The fact that "fantasy fiction uses magic to cheat physics" is a consequence of our understanding: we know physics, not magic, so we think in terms of physics, and adapt magic over that.

One can try the reverse: create an universe with a magic system so complete that physics can be derived from it as a consequence, thought in terms of magic.


Start out by deciding what "cheat physics" actually means. To me, it means violating fundamental principles like conservation "laws", causality (and equivalently, relativity), thermodynamics, purely mathematical laws, etc. and I actually see these violated a lot more often in works that are nominally "sci-fi" than by magic.

Beyond these, magic is free to do a lot without being obviously inconsistent with physics. Want a violent, massively exothermic effect? There's ridiculous amounts of potential energy in ordinary matter all around you that would happily jump to a lower potential given a path; the problem is just the lack of a path. (In some sense this is the "only" obstacle to fusion power). But the existence of some path to lower potential provided by magic does not in any way invalidate or preclude the rest of physics, so hey, go with it.

Regardless of whether magic is "cheating physics", if you don't want it to be "cheating" as a plot device (doing whatever it needs to do to advance the plot), you probably need magic to have its own internal rules for what you can and can't do with it, and concrete costs for using it, but that's a separate issue that deserves a separate question if needed.


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