# How to determine power or limits of magic if it's bound by laws of physics? [closed]

I'm a fan of plausible superpowers and believable magic.

I want to come up with several magic discpiplines and superpowers (or abilities), that are rather impossible in real world, but are still believable and give authentic vibe. I want to make as little assumptions and make as little SF/F "laws" as possible.

For example. Let's assume, that in created world, there are people that can somehow act on electricity. Other than that, all real life science applies. How can I use science, math and physics laws to determine what would be possible to do, how powerful would it be and what drawbacks would it have? For example, would it be plausible to generate enough electricity to kill someone? Power a smartphone? Make pin magnetic?

I watched Youtube channel called "Because Science" and they tackle several superpowers from science perspective and that what inspired me.

Is there a way for me — a non-physicist — to have some universal method to determine powers and limits of such magic and abilities?

I don't really want answer limited to the electricity example I've made, because I would have to come back with every magic/ability I design. I'm interested in a methods for me to work on my own.

PS. One of things I've considered so far is law of conservation of energy, but I'm simply not enough confident to be sure if that's enough to make magic and super-powers feel authentic and believable.

PPS. I've stumbled upon this question, and what describes my goal almost perfectly is MichaelK's answer:

You make the effects of magic be observable, predictable, and repeatable.

In short: your magic is simply new physics that is waiting to be explored.

• If you haven't read them, you could check out most of Brandon Sanderson's work, or the Grimnoir books. Those have pretty good limited magic systems that are somewhat physics consistent. – Brizzy Sep 15 '18 at 3:54
• @Brizzy I keep postponing reading him. Maybe I will give him a try at last. Thanks for the tip! – Forien Sep 15 '18 at 3:56
• This is too broad. You have to ask about a specific power set. How to limit all forms of magic has too many possible answers. – kingledion Sep 15 '18 at 4:58
• Is it widely known that "there are people that can somehow act on electricity"? – RonJohn Sep 15 '18 at 5:28
• @kingledion bewcause you haven't understood my question, doesn't mean it is too broad. I never asked how to limit all forms of magic. I asked for tools and methods for me to be able to find all the answers myself. Look at accepted answer, it is exactly what I wanted and what I asked for. – Forien Sep 16 '18 at 14:17

First off, I highly recommend reading my answer to What is the smallest change to physics to allow magic. It is the dual to your question. You ask how to limit magic to be physical, and they ask how to change physical to be magical. They're a good pair of questions.

The reality is that we can't tell you what is bound by the laws of physics, because we don't know them. We talk about "laws of physics" like "nothing can travel faster than the speed of light in a vacuum," but really that's just our own hubris. We humans wrote that law... what's to say the universe really follows it.

That being said, Sanderson's First Law of Magick is:

Sanderson’s First Law of Magics: An author’s ability to solve conflict with magic is DIRECTLY PROPORTIONAL to how well the reader understands said magic.

If you are trying to make your magic "realistic," then you are assuming that the reader's understanding of your magic will be based on the physics they know. If you try to write some magic engaging string theory, you'll probably get away with it... unless your target audience is string theorists. Then they'll criticize your lack of knowhow.

The list of checks I would make on a physics-based magic system for an average reader would be:

• Conservation of Energy -- This is a very important fundamental law that we've written. Much of what we understand in physics has underpinnings in this. In any reasonable Lagrangian system (fancy word for "the systems you typically might think of"), conservation of energy is tied via Nother's theorem to time invariance. If your system creates or destroys energy, it requires the laws of physics to change over time. Fun to write about, if you have the mathematical background for it.
• Speed of Light -- Don't go faster than it unless you're willing to write your own physics. So many things break down if you permit faster than light travel that you are almost forced to bring in the handwavium if you do.
• Conservation of momentum -- This is a funny one, but a big deal for speedsters (superheros who travel faster than humans can, like The Flash). These speedsters almost universally break this law. Like the conservation of energy, this one has a symmetry tied to it via Nother's theorem. Conservation of momentum is tied to translational invariance. If you break it, it means the rules of physics are different for different places. If you have a "center of the universe" where a ruler rules the universe from their throne, your story may support breaking conservation of momentum. Otherwise, make sure it works.
• Conservation of angular momentum -- Almost nobody thinks of this one, other than perhaps ballet dancers and ice skaters. You can probably write a story that forgets about angular momentum and get away with it. However, I like to include it on my list because its Nother's theorem symmetry is orientation invariance. If you break this law, the laws of physics are different based on which direction you are facing. This one is fascinating to me for plot purposes because there is some preferred direction almost egging the hero on towards the book's conclusion. This lends itself to breaking the rules, but it can be hard to see how.
• Don't play Quantum Mechanics mumbo-jubmo unless you actually understand the theory. It's so easy to write bad QM science fiction magic. If you know what you're doing, by all means, go for it, but it's trivial to accidentally do something atrociously forbidden in QM, like transmit classical information via entanglement. Leaves a bad taste in my mouth.

There are two powerful entwined concepts which I highly recommend for magic magic out of physics. The first is information. Knowledge is power. I may not be able to violate the conservation of momentum to stop a bullet coming my way, but if I know where it's going, I can simply choose not to be there. It's really hard to distinguish between a wizard and someone who simply knows a secret law of nature. I played with this in an answer to one of the Alynn the Scientific Mage questions a few years ago. Indeed, if you want some prior art to work from, just search this site for Alynn!

The second concept is unmesurable quantities. Science works based on measurements. If your world is affected by something that is not measurable, science simply cannot help you. One obvious example is that you can't see if a gun is going to fire if you can't see their finger. In that case, we could argue that you could see the finger, if you were in the right position. But what if something was truly impossible to measure? What if the spirit of a man going to war is actually not physical, but some unmeasurable metaphysical thing? In such a case, those unmeasurables can do curious things which are very convenient for plot.

Remember how I said not to do QM unless you really understand it? Well QM has unmeasurables. The uncertainty principle stems from the fact that it's impossible to simultaneously measure the amplitude of a wave (maximum strength) and its phase (is the wave going up or down) with perfect precision. Some aspect of that wave has to be unknowable, according to the laws of QM. Can you abuse that to make your magic? If you're comfortable with QM, sure. If not, then this is just an example of where the real life scientists start putting out theories that are borderline not "real." The actual scientific concept is called "local realism," and it's a hot topic among people who work on QM. Some of the standing theories don't support this concept of realism at all, and it bugs some people.

So that's some things that you can do, and some you can't, and some you shouldn't. Beyond that, my best recommendation is to be a "red team" of sorts. Take your physics-ish magic rules, and try to break them. Ask yourself "If I was trying to ruin this book, using these laws, could I do it?" Think like Amy from Big Bang Theory, when she demolishes Indiana Jones and the Raiders of the Lost Ark.

I also watch that channel. What I would say you need to do is think about how we with technology or even just how theoretically that concept can be controlled in some manner and then think about what an animal's biology could do to let you give it that power.

For instance, you say you want electricity as an example. Would that be control over charge? If so that is complicated as charge is just the attraction between certain particles. Electromagnetism? That is one of the four fundamental forces in physics. Congrats, assuming you don't put a range on it you just made a deity. Don't believe me? They'd have complete control over chemical bonds so they could effectively be immortal and do anything they want so long as they knew how. And such a power wouldn't be one you "wouldn't want" because well... it only causes problems if you accidentally move something wrong. That's called skill. Professional skill.

But that's probably not what you want.

So what about the ability to produce electric potential energy? Well then they're just a glorified electric eel on steroids. Ok? That's not particularly special other than it does exactly what you'd think it does. They can power circuits by using themselves as a battery. Wooooohoooo. I'm not a physicist either. I think determining the limits of this would be more answerable by reading what eels can do and scaling up the limits of their electrical output.

But now with that example acknowledged the real question was how you can determine the limits of magic or powers. Really what you have to accept is that either the powers are based in technology or real life reality or they are not. If not then physics as we know it is out the door. There's another 5th fundamental force or another fundamental particle or the particles themselves have different scaling factors. Something is different in the universe. That is how you would explain powers, but not magic. Magic I will get to in a bit. Limitations on the other hand have to be determined by you and that might sound silly and maybe even bypassing the question but think of this way. You made the concept of the power and what it does. If you don't explain how it works in terms of underlying physics then that is fine. The limitations are the limitations of the power. Ok so a guy can touch someone and send enough electricity to stop their heart? Well that might be possible and you can do the research but ultimately if you want to know whether or not to do that restriction is up to you.

Now you did ask if bound by physics. Well fair enough. Once again, you kind of have to do research into things that can have that effect and then come up with a way of integrating that into an animal. Animals that breathe fire do not exist yet people speculate on how dragons could biologically work. Do we know if such an animal could structurally exist? Of course not. The only way to truly know would be do an experiment to test that hypothesis and we can't because that would be immoral and we don't have the ability to do any kind of general purpose genetic manipulation in order to attempt such a feat. Could we with a machine? Well of course. Flamethrowers exist. The ability to make such a flying machine technically in theory exists. But I doubt anyone would. The answer is always going to be research.

Magic on the other hand is a different can of worms. By my own personal definition magic is the act of violating the laws of physics in some manner. That is how magic works. That's what it means. Of course magic can create things and then those things follow the laws of physics. However, one cannot claim magic to be consistent with the laws of the universe because that is its concept. The entire idea is to violate the laws of nature. That doesn't mean it cannot be limited. The user can be exhausted by it. The source of the magic could run out or refuse spells at certain times. Spells could be something that have to be carefully produced like something a professional would do. If someone wants a certain spell they have to learn that spells magic words or whatever. Then the limit could be "this is a tense moment and I cannot remember that one spell I need" or "I don't know that spell because I've never learned it" or "someone stole my spellbook and I cannot remember them that easily". So magic can be limited, it's just limited more by the fact they aren't an inherent ability. They have to be learned. Of course this isn't including things that are magical as a lifeform or something. This is magic as in spells. I would classify other things as powers. Spells attempt to rewrite the laws of nature locally to do some effect. Animals that are fantasy creatures or whatever just have an unusual biology.

Really I would say that research is key. It's what I think is necessary to be a proper analysis. Mind you if you just want to write a realistic story, pick a power that you'd expect to see happen in real life. Otherwise, just accept that the realism comes from the consistency of the power's chosen limits and how people choose to use it, not what produces it.

I like to write magic as limited by Calories. You can only do with magic what you can also do with the calories you have on hand. Want to generate electricity? Well how many calories would you need to burn in diesel to create that amount?

This leads to you having a magic system in line with conservation of energy, but leaves you free to manipulate how the calorie exchange works. Can a hero use their powers as much as they want so long as they have body fat? Will doping up on candy be a normal thing? Can some people only use 500 calories an hour but stronger people could use 50,000 calories an hour if left unchecked?

My answer will be short: magic is just transfer of energy. you can supply it with heat or kinetic energy, and it will do same amount of work.