- Invitation Status
- Posting Speed
- One post per week
- Slow As Molasses
- Writing Levels
- Adept
- Advanced
- Prestige
- Douche
- Adaptable
- Preferred Character Gender
- Male
- Female
- Genres
- Fantasy is my #1; I will give almost anything a chance if it has strong fantasy elements. Post apocalyptic, superhero, alternate history, science fantasy, some supernatural, romance, and a few fandoms (especially Game of Thrones) are also likely to catch my eye.
"But Jorick," I'm sure some of you thought upon reading the title, "magic can't be realistic, it's MAGIC~!"
"But reader," I say in response to my fabricated hypothetical objection, "shut up and read the thing."
Man, I'm a rhetorical genius.
On a more serious note, what I mean by "realistic" is not that it matches reality, because a magic system matching reality would be a non-existent magic system. Instead I am talking about magic that operates via rules as close to the rules that govern how things work in reality (AKA physics). This may sound daunting, but it's simply a different framework for magic than you're probably used to. You can have a realistic magic system and still have wizards throwing massive fireballs and dragons flying around and necromancy all over the place and so on, because there are some easy workarounds to the potential limiting factors of realistic magic that don't violate the realism aspect, and I'll explain some of those as they become relevant. First though, there's an obvious question that must be addressed:
Why Should You Use Realistic Magic?
Because reasons. Aw yeah, still got that rhetorical skill on my side.
If you're creating a magic system for a roleplay, realistic magic does a few things that you as a GM might enjoy. The big thing is that it will lay out some simple rules to regulate magic so that you don't have to worry over borderline cases of godmoding nonsense with magic; instead it'll be a simple matter of "Did this follow the realistic magic rules? If yes, great, if not, DIE GODMODER DIE!" For players who like having actual limitations on their power level, realistic magic provides a nice balance of fantastical shenanigans and logic to dictate what is possible or not. Another good reason for it is that realistic magic is uncommon, thus it's a novelty that might draw in extra interest from people who haven't really experienced what it's like. Bowling enemies over with a blast of wind is fun and all, but when you add in realistic physical laws that make the mage also get flung back, well, that just adds a whole extra level of fun to things, doesn't it?
If you're creating a magic system for something else that will be read/viewed rather than played, realistic rules will help turn magic from deus ex machina silliness to a satisfying plot device. Very generally speaking, audience satisfaction with magic being used to solve problems is closely correlated to how well they can understand the rules of the system. A sorceress winning a magic battle by outwitting her opponent with a clever use of magic is great; a wizard pulling out a clutch super duper hardcore badass magic spell in his time of dire need despite being supposedly exhausted is just silly and horribly overdone. Realistic magic is rather easy to understand since you've got to lay out the rules for it up front at some point, so that makes magic a plain old useful plot device all the time, so long as you stick to the rules you set up.
If none of the above appeals to you, that's alright, it's not for everyone. You could always use some of these concepts and disregard others to have a fantastical magic system with some elements of realism, so reading this may not be a complete waste of your time if you choose to keep going. For those who do like the idea of realistic magic, now comes thetedious fun part: the laws of physics that will govern such magic systems.
Conservation of Energy
The law of conservation of energy states that energy is neither created nor destroyed, it is simply moved around or transformed. A campfire is a great way to explain how this works. Starting a fire may seem like the creation of energy, but it is in fact just change and movement of energy. All methods of starting a fire that I can think of (everything from the low tech method of rubbing wood against wood really fast to get a spark to the modern method of using a lighter) are ways of transforming the physical energy of movement into thermal energy to get enough heat going to set the wood on fire. Fire is the product of a chemical process called oxidation, which shoves oxygen into existing chemical bonds; this releases a lot of energy in the form of fire, which is energy spreading out and dissipating. Once the fire burns out there is still energy left in the burnt wood and ashes, just far less than there was in the wood to start with. No energy is created or destroyed, just changed or moved around.
This is a major factor in determining whether a magic system is realistic or not. In your classic fantastical magic system, magic users create energy all the time by making giant fireballs poof into existence out of nothing. There may be something that makes it look like there's a transformation of energy going on, such as the mage getting tired after throwing a lot of fireballs, but there's a problem with this that can be expressed by a very simple inequality formula: energy in >= energy out, or energy in is greater than or equal to energy out. This means that to achieve a desired energy output you must put in an equal or greater (because energy transfer usually isn't 100% efficient) amount of energy to achieve it. In fantastical magic systems you're often given no explanation about how mages recoup their magical energy, or if you are given information on it it tends to be something simple like the mage needing a rest and a meal to be fine. How the hell does one get dozens of fireballs worth of energy from a nap and a sandwich? By breaking the law of conservation of energy, of course.
In a realistic magic system you'll want to avoid that sort of thing. Does that mean you'll need to have mages gorge themselves on food to store tons of energy in order to cast fireballs when needed? Well, no, but the idea of using body fat as energy storage for magic is a pretty amusing one, so feel free to take it and use it with my blessing if you so desire. All you need to do to keep things realistic is to pull some shenanigans with the energy input side of things. Remember those workarounds I mentioned in the introductory section? This is where those come into play. I'll give you a few examples of ways to rig the energy in >= energy out system so you can have all the crazy magic fun you want while remaining in the realm of realistic magic, but it's by no mean an exhaustive list.
Conservation of Matter
The law of conservation of matter states that matter is neither created nor destroyed, it is simply moved around or transformed. Sounds familiar, right? That's because it's very closely related to conservation of energy. This one is very simple though, so it'll be short. In a realistic magic system, things cannot just be created out of nothing. Fireballs can slide by since those can be viewed (incorrectly, but that's fine) as just balls of thermal energy. However, something like poofing a piece of wood into existence would not work. Manipulating things that exist would be totally fine, even to the point of taking something like sand and manipulating it to transform it into a piece of wood somehow, but flat out creation is just not viable if you want magic to be at all realistic. This also goes for totally making things magically stop existing: smashing, burning, or disintegrating it is fine, but you can't have things completely disappear from existence or else that's matter being destroyed.
The only real workaround here is to bullshit the system with gods. Gods are overpowered and can hypothetically do anything, physics be damned, so they can create matter and not really break your realistic magic system.
Newton's Laws of Motion
There are three of these here laws courtesy of Newton, but the first two come down to super simple common sense things that won't require a lot of thought or effort.
The first law is commonly defined as "objects at rest tend to stay at rest, objects in motion tend to stay in motion." This is just inertia at work, and it's not likely to matter much for your magic system. Basically what this is saying is that something will stay still if no outside force acts upon it, and something will stay moving in the same direction and at the same speed so long as no outside force acts upon it. Gravity and wind resistance are outside forces that can affect moving objects, so you can maybe try to take those into account for spells being thrown long distance, maybe by having mages throw spells in an upward arc to hit a long distance target for the same reasons that archers don't just point the arrow at the target and fire, but it's not a big deal if you don't worry about this law of motion at all.
The second law is commonly defined by its simplest equation: "force equals mass times acceleration." In layman's terms, this means that the force required to move an object depends on its mass and how fast you want it to go. The heavier something is, the more force is required to move it; the faster you want something to move, the more force required to move it at that speed. This is why firing a 9mm bullet requires only a tiny amount of gunpowder and such to be shot at very fast speeds, whereas a six pound cannon ball takes literally pounds of gunpowder to fire at almost the same speed... at least until these first two laws of motion come into play and the greater mass of the cannon ball plus the more powerful wind resistance it would face make it slow down much faster and travel a lesser distance than the bullet. The practical application of this law in a realistic magic system is simple: more magical force should be required to lift heavier things, and more magical force should be required to make something move faster.
The third law of motion is commonly defined as "for every action there is an equal and opposite reaction." Explaining this one in simpler terms isn't really going to happen, because that definition is pretty basic already, but it should be clarified that the action and reaction are forces acting upon physical objects. Consider the simple example of sitting on a bench. You exert a force (that of gravity pulling your mass toward the center of the Earth) upon it, but it doesn't just collapse or break due to that force (unless it's a pretty crappy bench, I guess). The reason for this is that it exerts an equal and opposite force against the force of your weight, thus balance is achieved and it doesn't break and you don't get shoved upward off the bench. However, if too much force is applied to one of the objects, then it can indeed break. For example, let's say a guy punches two walls. The first wall is plain old drywall with nothing behind it where he punches, and he exerts enough force to break the drywall without really noticing the opposing force. The second wall is concrete, and he punches it with more force than his bones can handle, so the equal and opposite force from the wall breaks his puny bones whilst the wall remains unmarred (except for some blood probably). Explaining why exactly this stuff happens would require a whole lecture about how atoms work and how they bond with one another and the forces involved there and so on. If you want that kind of info, go look up lectures on Newton's laws of motion, preferably ones with experimental examples because those are always fun.
Anyway, this third law is the big one that ought to impact a realistic magic system. Taking the example I teased in the section where I extolled the virtues of realistic magic, let's say we've got a wind mage who wants to give someone a very personalized flight to the other side of the country. In a magic system that ignores physics this mage would just dramatically point their hand at the target in a menacing way, shoot a blast of wind at the target, and bye bye goes the target with nothing happening to the mage other than a sense of great satisfaction and maybe some dramatic robe flapping in the wind action. In a realistic magic system, that mage just exerted HUGE force from their hand, so there should be an equal and opposite reaction. Y'know how there's a lot of recoil when firing a gun? A similar principle should apply here, and our smug wind mage should be sent flying back in the opposite direction of the hapless target. The same ought to go for any magic used that generates large forces from the caster toward a target, from throwing fireballs to hurling rocks to whatever else you can think of.
There isn't exactly a comprehensive workaround for this one other than ignoring that it exists. Mages aren't always going to be knocked around by their own spells if you do choose to make use of Newton's third law though. They could cast some kind of encasing shield around them to dispel the force over a greater area and maybe only push them back a bit, or they could make themselves much heavier for a few moments (perhaps by encasing themselves in rock or making gravity much stronger in the area right around them, whatever works) to prevent it. If they use a staff to case magic, they could plant the butt of it in the ground so that the force just shoves the staff hard into the ground. You can also simply limit magic users to only casting kinda smaller spells, like no throwing thousands of pounds of rock or summoning personal hurricane winds, meaning they'd only get pushed back a little for throwing stuff with less force. However you want to make it work, honestly this one comes down more to being a flavor thing than being intrinsically required for your magic to operate realistically.
Miscellaneous Other Bits of Realism
There are things that you can add in for a greater sense of realism that don't require laws of physics to explain. For example, when casting fire magic, why is it that the caster and their clothes and such never get burned by it in most magic systems? The heat of the fire should cause some damage before it gets tossed away at an opponent. Or how about earth mages opening up chasms in the earth that drop enemies into the abyss but they are not affected by that at all? That should cause some localized earthquake action at the very least. How come magical plagues never seem to affect the one who created or released them? Why is it that summoning a lightning storm does bad stuff to enemies and unsuspecting trees but never gets out of control and zaps the mage or their pals? Why is it that someone with superhuman speed never runs into things that they're rushing toward faster than they ought to able to process? How come someone teleporting to another place never randomly gets stuck in a wall or other people?
Basically anything about magic that has ever made you think "wait, why doesn't it work like in real life?" or "why doesn't this ever go wrong?" can fall under this nice little catch all section. All you've got to do is think of them and then decide that those bits of reality and failure can happen in your system and you're all set.
Conclusion
That's really all there is to making a magic system realistic. You can have all sorts of crazy fantastical stuff happen, it's just a matter of minimizing how many unrealistic things you dismiss with "it's magic, it just works that way." Picking and choosing which parts of physics apply to your magic system is a good way to customize things, because despite my dismissive tone in the little introductory bit, seriously, it's MAGIC~! You can get away with only using a little bit of realistic magic elements if you feel like it, and I doubt anyone will care unless you implement it poorly. Magic is a pretty flexible tool, use it as you wish. This workshop is just a guideline for some new things you can try, not a mandate for how magic ought to work.
And finally, if you want some examples of more or less realistic magic systems in action, check out the systems used in the Mistborn books by Brandon Sanderson and the Dresden Files series by Jim Butcher; neither of them are great at the conservation of energy bit, but they do follow the laws of motion rather nicely.
"But reader," I say in response to my fabricated hypothetical objection, "shut up and read the thing."
Man, I'm a rhetorical genius.
On a more serious note, what I mean by "realistic" is not that it matches reality, because a magic system matching reality would be a non-existent magic system. Instead I am talking about magic that operates via rules as close to the rules that govern how things work in reality (AKA physics). This may sound daunting, but it's simply a different framework for magic than you're probably used to. You can have a realistic magic system and still have wizards throwing massive fireballs and dragons flying around and necromancy all over the place and so on, because there are some easy workarounds to the potential limiting factors of realistic magic that don't violate the realism aspect, and I'll explain some of those as they become relevant. First though, there's an obvious question that must be addressed:
Why Should You Use Realistic Magic?
Because reasons. Aw yeah, still got that rhetorical skill on my side.
If you're creating a magic system for a roleplay, realistic magic does a few things that you as a GM might enjoy. The big thing is that it will lay out some simple rules to regulate magic so that you don't have to worry over borderline cases of godmoding nonsense with magic; instead it'll be a simple matter of "Did this follow the realistic magic rules? If yes, great, if not, DIE GODMODER DIE!" For players who like having actual limitations on their power level, realistic magic provides a nice balance of fantastical shenanigans and logic to dictate what is possible or not. Another good reason for it is that realistic magic is uncommon, thus it's a novelty that might draw in extra interest from people who haven't really experienced what it's like. Bowling enemies over with a blast of wind is fun and all, but when you add in realistic physical laws that make the mage also get flung back, well, that just adds a whole extra level of fun to things, doesn't it?
If you're creating a magic system for something else that will be read/viewed rather than played, realistic rules will help turn magic from deus ex machina silliness to a satisfying plot device. Very generally speaking, audience satisfaction with magic being used to solve problems is closely correlated to how well they can understand the rules of the system. A sorceress winning a magic battle by outwitting her opponent with a clever use of magic is great; a wizard pulling out a clutch super duper hardcore badass magic spell in his time of dire need despite being supposedly exhausted is just silly and horribly overdone. Realistic magic is rather easy to understand since you've got to lay out the rules for it up front at some point, so that makes magic a plain old useful plot device all the time, so long as you stick to the rules you set up.
If none of the above appeals to you, that's alright, it's not for everyone. You could always use some of these concepts and disregard others to have a fantastical magic system with some elements of realism, so reading this may not be a complete waste of your time if you choose to keep going. For those who do like the idea of realistic magic, now comes the
Conservation of Energy
The law of conservation of energy states that energy is neither created nor destroyed, it is simply moved around or transformed. A campfire is a great way to explain how this works. Starting a fire may seem like the creation of energy, but it is in fact just change and movement of energy. All methods of starting a fire that I can think of (everything from the low tech method of rubbing wood against wood really fast to get a spark to the modern method of using a lighter) are ways of transforming the physical energy of movement into thermal energy to get enough heat going to set the wood on fire. Fire is the product of a chemical process called oxidation, which shoves oxygen into existing chemical bonds; this releases a lot of energy in the form of fire, which is energy spreading out and dissipating. Once the fire burns out there is still energy left in the burnt wood and ashes, just far less than there was in the wood to start with. No energy is created or destroyed, just changed or moved around.
This is a major factor in determining whether a magic system is realistic or not. In your classic fantastical magic system, magic users create energy all the time by making giant fireballs poof into existence out of nothing. There may be something that makes it look like there's a transformation of energy going on, such as the mage getting tired after throwing a lot of fireballs, but there's a problem with this that can be expressed by a very simple inequality formula: energy in >= energy out, or energy in is greater than or equal to energy out. This means that to achieve a desired energy output you must put in an equal or greater (because energy transfer usually isn't 100% efficient) amount of energy to achieve it. In fantastical magic systems you're often given no explanation about how mages recoup their magical energy, or if you are given information on it it tends to be something simple like the mage needing a rest and a meal to be fine. How the hell does one get dozens of fireballs worth of energy from a nap and a sandwich? By breaking the law of conservation of energy, of course.
In a realistic magic system you'll want to avoid that sort of thing. Does that mean you'll need to have mages gorge themselves on food to store tons of energy in order to cast fireballs when needed? Well, no, but the idea of using body fat as energy storage for magic is a pretty amusing one, so feel free to take it and use it with my blessing if you so desire. All you need to do to keep things realistic is to pull some shenanigans with the energy input side of things. Remember those workarounds I mentioned in the introductory section? This is where those come into play. I'll give you a few examples of ways to rig the energy in >= energy out system so you can have all the crazy magic fun you want while remaining in the realm of realistic magic, but it's by no mean an exhaustive list.
The God(s) Did It method, as I like to call it, is a simple one. Gods are beings that exist outside of the bounds of physics, which is totally fine in a work of fantasy even if you're striving for realistic magic, so they can totally break energy rules. If a mage's power is derived from a divine source, you could say they're tapping into the divine energy pool and that's effectively infinite so all is well. However, this will effectively make the energy portion of your magic system work the same way as a fantastical one, because to regulate power level and power usage you'll probably have to say a character gets tired after a while of acting as an energy conduit for god powers. Alternatively you could set an arbitrary limit on how many spells a character can perform each day with the god-granted energy, or just randomly make the god annoyed at the pesky mortal for being so demanding and just cut them off from the holy mojo tap for a while. Whichever way you choose to go, this workaround will make your realistic magic system appear to be quite a lot less realistic on a surface level.
The Fantasy Material method is also pretty simple. Essentially what you do with this workaround is you create some fantasy material that is the source of magic power in your world. You could use something like crystals that are just the solidified form of magic power itself, of you could have some kind of metal mined from deep in the earth, or you could even have something like super special fruits that grant magic power. Whatever form it takes, this fantasy material is just chock full of magical energy and a mage just needs to touch it or consume it to take in its power and recharge their own storage of magical energy. This works just fine because it's fantasy, you're totally allowed to make up random things that exist, and if mithril and such can exist without question then so too can magical uranium. With this workaround the method of regulating magic power will be to regulate the supply of the fantasy material and place some guidelines on how much of that material equals a certain amount of magical energy. You can be a bit vague here, but keep things as close to realistic as you can manage; if 1 unit of magic material can create a single fireball, then it should definitely not be enough to open a chasm the size of the Grand Canyon under an enemy's army, for instance.
The Vampire method might appeal to some. There's a lot of mysticism and superstitious thought about there being some mysterious power inherent in life itself, so you could take advantage of that and use the generally acknowledged concept as the basis for your magical power. Call it the soul, the spirit, whatever, have your mages devour them to gain their power. Alternatively you could go with a slightly more tame version of generic life energy and have that gained by just consuming blood (thus the method's name), because people also generally accept the idea of supernatural powers inherent in blood. The regulating methods here would be similar to the Fantasy Material ones of determining how much of the source of power is worth how much actual magical output, plus you've got the ability to decide which life forms provide this power in what amounts, how exactly it has to be gathered, and how available the supply will be.
The Mr. Freeze method, AKA Exploiting Thermodynamics For Fun And Profit, is a method I just came up with off the top of my head, and if I can think of weird things that work for realistic magic then so can you. Heat is a form of energy, and this method would be a mage simply stealing that energy from his or her surroundings (thus making it very cold around them) in order to fuel their magic. It would require a bit of shenanigans, specifically by way of saying mages can somehow steal thermal energy in their vicinity because reasons, but that's not really a big stretch for a world where people can do magic in the first place and the lack of rock solid logic has never been a problem for fantasy before so that's fine. The issue with this method would be regulating how much magical juice the thermal energy would give them, but it comes with the fun side effect of mages being able to give themselves hypothermia and frostbite and even the chance to freeze to death if they try to use too much magic in a short period of time.
The Pseudoscience method, AKA Mages Are Actually Organic Nuclear Power Plants, is another one I've just come up with, this one as I was writing up the Fantasy Material method. I've never seen anything like it actually used before, but it could totally work in a realistic magic system. Basically the idea here is that what makes mages special and able to do magic is that their body possesses some abnormal organ or process that does nuclear fission or fusion reactions in the body and transforms the released nuclear energy into magical energy. This would suffer the same regulatory problems as the God(s) Did It method, but instead of the divine intervention to keep things sane you could instead say that a mage that pushes too hard too fast ends up with radiation poisoning or parts of their insides exploded due to destructive nuclear reactions. Science is fun.
The Fantasy Material method is also pretty simple. Essentially what you do with this workaround is you create some fantasy material that is the source of magic power in your world. You could use something like crystals that are just the solidified form of magic power itself, of you could have some kind of metal mined from deep in the earth, or you could even have something like super special fruits that grant magic power. Whatever form it takes, this fantasy material is just chock full of magical energy and a mage just needs to touch it or consume it to take in its power and recharge their own storage of magical energy. This works just fine because it's fantasy, you're totally allowed to make up random things that exist, and if mithril and such can exist without question then so too can magical uranium. With this workaround the method of regulating magic power will be to regulate the supply of the fantasy material and place some guidelines on how much of that material equals a certain amount of magical energy. You can be a bit vague here, but keep things as close to realistic as you can manage; if 1 unit of magic material can create a single fireball, then it should definitely not be enough to open a chasm the size of the Grand Canyon under an enemy's army, for instance.
The Vampire method might appeal to some. There's a lot of mysticism and superstitious thought about there being some mysterious power inherent in life itself, so you could take advantage of that and use the generally acknowledged concept as the basis for your magical power. Call it the soul, the spirit, whatever, have your mages devour them to gain their power. Alternatively you could go with a slightly more tame version of generic life energy and have that gained by just consuming blood (thus the method's name), because people also generally accept the idea of supernatural powers inherent in blood. The regulating methods here would be similar to the Fantasy Material ones of determining how much of the source of power is worth how much actual magical output, plus you've got the ability to decide which life forms provide this power in what amounts, how exactly it has to be gathered, and how available the supply will be.
The Mr. Freeze method, AKA Exploiting Thermodynamics For Fun And Profit, is a method I just came up with off the top of my head, and if I can think of weird things that work for realistic magic then so can you. Heat is a form of energy, and this method would be a mage simply stealing that energy from his or her surroundings (thus making it very cold around them) in order to fuel their magic. It would require a bit of shenanigans, specifically by way of saying mages can somehow steal thermal energy in their vicinity because reasons, but that's not really a big stretch for a world where people can do magic in the first place and the lack of rock solid logic has never been a problem for fantasy before so that's fine. The issue with this method would be regulating how much magical juice the thermal energy would give them, but it comes with the fun side effect of mages being able to give themselves hypothermia and frostbite and even the chance to freeze to death if they try to use too much magic in a short period of time.
The Pseudoscience method, AKA Mages Are Actually Organic Nuclear Power Plants, is another one I've just come up with, this one as I was writing up the Fantasy Material method. I've never seen anything like it actually used before, but it could totally work in a realistic magic system. Basically the idea here is that what makes mages special and able to do magic is that their body possesses some abnormal organ or process that does nuclear fission or fusion reactions in the body and transforms the released nuclear energy into magical energy. This would suffer the same regulatory problems as the God(s) Did It method, but instead of the divine intervention to keep things sane you could instead say that a mage that pushes too hard too fast ends up with radiation poisoning or parts of their insides exploded due to destructive nuclear reactions. Science is fun.
Conservation of Matter
The law of conservation of matter states that matter is neither created nor destroyed, it is simply moved around or transformed. Sounds familiar, right? That's because it's very closely related to conservation of energy. This one is very simple though, so it'll be short. In a realistic magic system, things cannot just be created out of nothing. Fireballs can slide by since those can be viewed (incorrectly, but that's fine) as just balls of thermal energy. However, something like poofing a piece of wood into existence would not work. Manipulating things that exist would be totally fine, even to the point of taking something like sand and manipulating it to transform it into a piece of wood somehow, but flat out creation is just not viable if you want magic to be at all realistic. This also goes for totally making things magically stop existing: smashing, burning, or disintegrating it is fine, but you can't have things completely disappear from existence or else that's matter being destroyed.
The only real workaround here is to bullshit the system with gods. Gods are overpowered and can hypothetically do anything, physics be damned, so they can create matter and not really break your realistic magic system.
Newton's Laws of Motion
There are three of these here laws courtesy of Newton, but the first two come down to super simple common sense things that won't require a lot of thought or effort.
The first law is commonly defined as "objects at rest tend to stay at rest, objects in motion tend to stay in motion." This is just inertia at work, and it's not likely to matter much for your magic system. Basically what this is saying is that something will stay still if no outside force acts upon it, and something will stay moving in the same direction and at the same speed so long as no outside force acts upon it. Gravity and wind resistance are outside forces that can affect moving objects, so you can maybe try to take those into account for spells being thrown long distance, maybe by having mages throw spells in an upward arc to hit a long distance target for the same reasons that archers don't just point the arrow at the target and fire, but it's not a big deal if you don't worry about this law of motion at all.
The second law is commonly defined by its simplest equation: "force equals mass times acceleration." In layman's terms, this means that the force required to move an object depends on its mass and how fast you want it to go. The heavier something is, the more force is required to move it; the faster you want something to move, the more force required to move it at that speed. This is why firing a 9mm bullet requires only a tiny amount of gunpowder and such to be shot at very fast speeds, whereas a six pound cannon ball takes literally pounds of gunpowder to fire at almost the same speed... at least until these first two laws of motion come into play and the greater mass of the cannon ball plus the more powerful wind resistance it would face make it slow down much faster and travel a lesser distance than the bullet. The practical application of this law in a realistic magic system is simple: more magical force should be required to lift heavier things, and more magical force should be required to make something move faster.
The third law of motion is commonly defined as "for every action there is an equal and opposite reaction." Explaining this one in simpler terms isn't really going to happen, because that definition is pretty basic already, but it should be clarified that the action and reaction are forces acting upon physical objects. Consider the simple example of sitting on a bench. You exert a force (that of gravity pulling your mass toward the center of the Earth) upon it, but it doesn't just collapse or break due to that force (unless it's a pretty crappy bench, I guess). The reason for this is that it exerts an equal and opposite force against the force of your weight, thus balance is achieved and it doesn't break and you don't get shoved upward off the bench. However, if too much force is applied to one of the objects, then it can indeed break. For example, let's say a guy punches two walls. The first wall is plain old drywall with nothing behind it where he punches, and he exerts enough force to break the drywall without really noticing the opposing force. The second wall is concrete, and he punches it with more force than his bones can handle, so the equal and opposite force from the wall breaks his puny bones whilst the wall remains unmarred (except for some blood probably). Explaining why exactly this stuff happens would require a whole lecture about how atoms work and how they bond with one another and the forces involved there and so on. If you want that kind of info, go look up lectures on Newton's laws of motion, preferably ones with experimental examples because those are always fun.
Anyway, this third law is the big one that ought to impact a realistic magic system. Taking the example I teased in the section where I extolled the virtues of realistic magic, let's say we've got a wind mage who wants to give someone a very personalized flight to the other side of the country. In a magic system that ignores physics this mage would just dramatically point their hand at the target in a menacing way, shoot a blast of wind at the target, and bye bye goes the target with nothing happening to the mage other than a sense of great satisfaction and maybe some dramatic robe flapping in the wind action. In a realistic magic system, that mage just exerted HUGE force from their hand, so there should be an equal and opposite reaction. Y'know how there's a lot of recoil when firing a gun? A similar principle should apply here, and our smug wind mage should be sent flying back in the opposite direction of the hapless target. The same ought to go for any magic used that generates large forces from the caster toward a target, from throwing fireballs to hurling rocks to whatever else you can think of.
There isn't exactly a comprehensive workaround for this one other than ignoring that it exists. Mages aren't always going to be knocked around by their own spells if you do choose to make use of Newton's third law though. They could cast some kind of encasing shield around them to dispel the force over a greater area and maybe only push them back a bit, or they could make themselves much heavier for a few moments (perhaps by encasing themselves in rock or making gravity much stronger in the area right around them, whatever works) to prevent it. If they use a staff to case magic, they could plant the butt of it in the ground so that the force just shoves the staff hard into the ground. You can also simply limit magic users to only casting kinda smaller spells, like no throwing thousands of pounds of rock or summoning personal hurricane winds, meaning they'd only get pushed back a little for throwing stuff with less force. However you want to make it work, honestly this one comes down more to being a flavor thing than being intrinsically required for your magic to operate realistically.
Miscellaneous Other Bits of Realism
There are things that you can add in for a greater sense of realism that don't require laws of physics to explain. For example, when casting fire magic, why is it that the caster and their clothes and such never get burned by it in most magic systems? The heat of the fire should cause some damage before it gets tossed away at an opponent. Or how about earth mages opening up chasms in the earth that drop enemies into the abyss but they are not affected by that at all? That should cause some localized earthquake action at the very least. How come magical plagues never seem to affect the one who created or released them? Why is it that summoning a lightning storm does bad stuff to enemies and unsuspecting trees but never gets out of control and zaps the mage or their pals? Why is it that someone with superhuman speed never runs into things that they're rushing toward faster than they ought to able to process? How come someone teleporting to another place never randomly gets stuck in a wall or other people?
Basically anything about magic that has ever made you think "wait, why doesn't it work like in real life?" or "why doesn't this ever go wrong?" can fall under this nice little catch all section. All you've got to do is think of them and then decide that those bits of reality and failure can happen in your system and you're all set.
Conclusion
That's really all there is to making a magic system realistic. You can have all sorts of crazy fantastical stuff happen, it's just a matter of minimizing how many unrealistic things you dismiss with "it's magic, it just works that way." Picking and choosing which parts of physics apply to your magic system is a good way to customize things, because despite my dismissive tone in the little introductory bit, seriously, it's MAGIC~! You can get away with only using a little bit of realistic magic elements if you feel like it, and I doubt anyone will care unless you implement it poorly. Magic is a pretty flexible tool, use it as you wish. This workshop is just a guideline for some new things you can try, not a mandate for how magic ought to work.
And finally, if you want some examples of more or less realistic magic systems in action, check out the systems used in the Mistborn books by Brandon Sanderson and the Dresden Files series by Jim Butcher; neither of them are great at the conservation of energy bit, but they do follow the laws of motion rather nicely.
