As someone who tries to find an explanation for the stuff I write, I wanted to make something that explains the nature of mana, magic, universes, souls, auras and whatnot. This is purely a hypothesis and has little basis in reality, but I think it works well as a generally accepted theory in my fiction, as it also connects to physics, chemistry and biology. So if you're ready, here's a wall of text, that may just help you out in magical RP's!
A Guide to Magic, the Soul and the Multiverse
The Lowest Level
Mana is the very basic fabric of everything in existence. It should be clear, from this point forward, that if you go down and down on the scale of particles, and go from molecules to atoms, from atoms to nucleons/electrons, to quarks and so on, you’ll even get to the so-called ‘strings’ that actually pulsate in 10 dimensions. Eventually you'd come across something that you can't really see. But that something is the structure of mana.
The Nature of Mana
There are a number of different ways atoms can be put together make various kinds of molecules. The same counts for mana and everything in reality, like the ten dimensions, the fabric of space-time, the natural forces, like gravity and electromagnetism, and matter and energy. Indeed, this means that wherever there is no mana, that doesn’t exist. Out of existence, not even the concept 'empty' or 'zero' applies, because those are things you can actually know. One more thing about mana is the fact that mana is absolutely analog, rather than digital. There can be incredibly high or near-zero concentrations of mana, because it’s not a collection of particles that take up space; it’s one smooth transition, much like water on a large scale.
So, mana structures make everything else. This means that if a structure would be changed, what was at the place of that structure will become something different. It could be a grass hill turning into an airplane, or the strength of a planet’s gravity becoming a faster flow of time. Moreover, while matter stays at rest (at least in certain reference frames), the mana that is in you now, or that computer you are using, is different at the end of this sentence. Only the structure remained at place, but the mana that makes a structure keeps moving in various directions and will then become part of another structure.
Creation of the Universe
In the space between universes (Yes, I'm using the Bubble-universe theory) is a space, which is often considered infinite (although nobody actually knows for sure), filled with raw mana. It has minimal structure, and just swirls around. Here is where the vast majority of all mana resides, but the significant differences in amount even there makes the mana storm around with significant force. Sometimes, on rare occasions, that mana clashes into other mana in a certain way, resulting in a rather complex and very dense structure, so that a universe can be created. It might be difficult to believe that random interactions of mana have a greater chance of becoming a universe than an atom, but it’s just so. See the next paragraph.
When mana collides, the things that have the most chance of happening are those that are the most basic in reality, and such a thing is the universe. Within that, mana flows in calmer, but more irrationally fixed ways. The only reason universes aren’t created within universes is due to the fact that the structure required to initiate a vast and expanding sphere that consumes more mana as it grows, is very dense and concentrated. Such a thing can only naturally happen in the unformed space outside universes, where the amount of mana is great and flows with incredible force. Something like a star, on the other hand, can only be created inside a universe, where the form of flow is much different than outside the universe and where it’s the higher where of reality that does most of the work (with mana structures forming as a result).
Expansion and Monkeys
From the point where this structure was created, the Big Bang starts, and the universe starts to grow. The edge of the universe already has a structure, and when it grows, its structure becomes larger, taking more mana into itself. Within the universe, the same sorts of things happen, but to things that already have structure (shortly after the universe is created). I’ll go ahead and skip a part of time, to the young Earth. What you will learn here and in the next paragraph will help visualize an analogy for the practice of magic, later on. The Earth started off rocky and was fed the right amount of lightning, lava, water and whatnot to shape itself, and eventually -after billions of years- allow for certain chemical activities to produce a self-replicating molecule. Now, since the moment life was created there was roughly only one way to go, if nothing outside of that system intervened with it. If it just takes it course, and develops only from the inside out, it's 'natural'. If something happens from the outside in, to alter that process, it's 'artificial'. Up until the point the humans were born, everything happened natural. Well, mostly natural. Monkeys learned to use sticks before we existed, which is essentially is a change to the course of nature.
Forces of Artifice
When the humans learned certain things, they could bend their surroundings to their will. A piece of wood wouldn't naturally combine with a piece of rock, to form a spear. We did it ourselves, so it’s artificial. Much later in time: houses didn't just appear with nature flowing its own course. If another system intervenes with the natural flow, to make it different, it has to be artificial. Do note that if that artificial ‘something’ is still close to nature, it is easier to do. Gathering some sticks to build a campfire is easy, and scratching a flint to make fire isn’t all that difficult either. However, if you want to build an airplane from scratch, it's rather far away from nature so it takes much more effort.
Rest of the Multiverse
Back onto mana and the universe. All mana is the same – certain quantities only differ in structure. Now, since it all should follow the same natural flow, only changed by artificial influence, most universes should end up somewhat like ours. The species are never exactly the same, and the color of things may vary, and the strength of the four powers of the universe, one of which is gravity. But because they all follow a similar natural way, the universes are actually comparable to ours, within, say, a difference of 0.3 to 3 times the magnitude of something. That’s why you will be able to understand -although study may be required- what's going on, and what is in other planes of existence. You won't be completely surprised by the weird things of another nature, because the mana structure began the same way, and ended up not ridiculously different. Assuming the ratio I just set, the size of Earthlike planets may be one third of ours and have a double gravity, or they may be five times larger, with slightly less powerful gravity.
Magic: the Analogy
Now let’s move onto the actual magic. Notice I talked about 'the natural flow of mana', rather than 'magic'. That is because magic is only to bend mana to your will, and create your own structures. Magic is artificial and not natural. If a person casts a spell, it’s something that wouldn’t just happen out of nothing. It was an unnatural change to the natural structure of mana. This way you can create lightning, fire, wind and earthquakes, where they normally wouldn’t just appear. Do note, however, that these kinds of spells are still relatively close to nature. Such events do happen all the time on their own, so it’s not too difficult to replicate a natural event. However, the spells that are further away from nature are typically stronger, as shown by another analogy. All it takes to create an abacus is some wood, maybe some metal, put them together in a simple form, and maybe even paint it. A calculator, or a computer is much –much- stronger, but they are also much harder to make. All it takes to make a torch, to see in the dark, is to take a piece of wood, put something in it that can burn, and set it on fire. A light bulb, or something like that, lasts much longer. Though, it’s harder to make. The same counts for magic and its spells.
Cooking and Breathing
Luckily, we don’t have to think about complicated structures too much to make more artificial-like spells. In Fable, you can create flying swords. In Magic: the Gathering, you can set up a wall of glowing, rune-like hands. In many other games, you can summon your own minions. They make it look as easy as natural things like fireballs. How do they do this? The spells are premade. Some wizard I guess, a long time ago, has already designed that spell for you, like a recipe for pie or an instruction manual to those darned Ikea closets. When you learn a spell, either from a teacher or a book, you won’t get it right away and will need some guidance until you know it by memory. However, in magic it’s less obvious how one puts the spell together. You can’t very well comprehend something that moves through ten-dimensions, let stand something that makes the ten dimensions. You are bending the mana into certain structures, but you don’t notice it. You can’t actually see mana. It’s comparable to how you are not aware of the fact that you are breathing, but the level at which you do become more aware of how you use mana is very, very high. Once you are able to control your breath, you can consciously breathe faster, slower or in an irrational rhythm. However, you still don’t notice the various muscles you contract or extend in order to do so. This analogy explains how you are able to create spells, yet don’t comprehend the very basis of everything, in its ten-dimension generating, space-time initiating, matter and energy creating glory. Of course, a spell’s creation does not have to be assigned to just one person. Two people could come up with the idea of roasting a fish, just like two people could come up with throwing a fireball. A spell that casts seven blades with intricate runes and covered in purple flames could be analogous to a five-course dinner at the most expensive restaurant in town. Still, two separate people could, in theory, come up with the same idea.
Brain and the Soul
‘’So what’s the deal with souls?’’ I’m not sure where that question came from, but I’m glad you asked! Well, as you know, mana makes the structure of everything. However, this does not mean that all that is created is a direct result from mana flowing in order to become that structure. Actually, most things we see around us flow in a higher level of reality, with the structure of mana coming as a result. Our brains are part of that; at the moment of conception, a child is but a blob of cells. These cells have an underlying mana structure. As the child develops, it grows certain body parts, one of which is the brain. All parts of the body have an underlying mana structure, but the mana structure in the brain –being as complex as it is- is much more intricate. And even as we grow up, after being born, our brain is vastly more complex than the rest of our body, it being the place where our thoughts and memories reside. As a direct result, the underlying mana structure is also very complicated. This ‘knot’ of mana is what’s called the soul. It’s not an entity that’s separate from the body; it’s directly connected to the body.
Aura as a Medium
Now, the brain is where our thoughts take place. If we think of something, certain pulses move through our brain, and it is reflected in the mana structure. If you visualize this mana structure as a physical thing, you can see a complex knot, with threads on the outside connected to it. That part just outside the soul is not part of it, but still under its influence, as the mana around the soul is very much connected. Thus, if something in the knot is stirred, this ripple will pulsate through the outer laying web, where it eventually dies out. It does work both ways; if something is able to stir the web outside the soul, it may just make its way into the soul, granting us a thought through other means than our senses. This thing that is not part of our soul, but still close to our minds is the aura. The aura is the medium that will let us turn our soul’s thoughts into actual movement in mana, in order to create spells. It does take either a born gift, or great meditation, in order for us to be aware of that part of our soul. That which extends to the outside world, like fingers waving an air current. Those who master the processes in the soul and the rippling of the aura can become true magicians, sorcerers, planeswalkers or whatever.
Of course, many people enjoy the idea of the soul living on after we die. If you read what I wrote above, you may think that I find it impossible, as the soul is the mana structure of the brain. However, you may have also interpreted it as the mind, as it reflects the movements of pulses and electrochemical processes. Well, it’s both true, but the true essence of the soul is the latter. The knot is not independent of our brain, but if the mind stirs the soul, after which the brain falls apart, these stirring will hold the knot together. The knot as a whole will have no anchor to material reality and fill start to fall apart, but the impulses of the mind try to hold it together on a deeper, somewhat spiritual level. The conclusion would be that the soul is a knot of mana that results from the complexity of our mind and brain. If the brain –the physical anchor- disintegrates, the soul will start to fall apart, but only over time, as the reflections of the processes that took place insidestill ripple and try to hold it together. If someone were to artificially interact with the mind-part of the soul, they may force it out of the body and into something else, or intercept the soul of a deceased person and use the memories of its appearance to create a new host body for them.
Ways of Magic
At this point I’d like to talk about the different ways of casting magic. As you know, different games and movies use different techniques to tap into the powers of mana. These styles range from simple hand gestures, to spoken incantations, to elaborate witchcraft rituals. So how do actions in these higher levels of reality alter the structure of mana? There are two ways, and not rarely do these two happen to coincide. The first is mental association; the second is the pre-existing framework.
This method takes place inside your own mind. It works by associating certain actions you perform with the spell you wish to perform. Imagine pressing your hand forward, casting a fireball. Simple enough and very familiar, right? Now imagine actually shouting ‘’Fireball!’’ at the same time. Through training, or even before that, you have associated the word with the spell. The moment you say it, your mind will be more focused on the performance of the spell. Another more elaborate example; you can stand completely still and imagine a monster form itself in mid-air, two meters in front of you. You can just stand there and think about the magic you mentally perform. However, you want the spell to be much more powerful, so you’re going to use some form of hand incantation. You put your two hands together and make various shapes with them, one standing for ‘creation’, another one for ‘werewolf’ and the last one for ‘armor’. Now it’s firstly much easier to perform the spell, due to your subconscious’ connection between the gesture and the spell, but also because you added another hand formation which added protection to your furry servant.
This method of casting magic utilizes pre-existing mana structure embedded in the world, or possibly aura. Sometimes wizards get to such a high level that they start to work on an amazing project, often a once in a lifetime accomplishment. They might just decide to set up a framework of structured mana throughout a world, either by enchanting a planet or by creating a new universe. In the case of the pre-existing framework, though, they often have to call upon multiple wizards since this is a significantly large feat. The result is that anyone in that world won’t just bend mana to cast the more obvious arcane magic we’re familiar with, but use the already present structures of mana in vastly different ways. This might result in an essence of the soul being copied, and giving them a kimono, and a fancy sword that matches that part of their soul (Bleach). Or it might lead to a world with a spiritual counterpart where strange creatures live, while the physical world contains special individuals who control the elements, where every so many years someone comes forth to save the world (Avatar). In the case of Avatar, you see that the so-called benders also have to make certain movements in order to perform their skills. This is a part where the pre-existing framework incorporates some form of mental association. Sometimes it’s also possible to use those kinds of magic on other planes of existence, even though the framework isn’t present there. This can be done by recreating that mana structure within one’s aura.
Mana bars? Charging spells?
So it should be pretty obvious what this next paragraph is about. If you have ever played a game that used a form of mana, you know that you can’t just cast the most awesome spells whenever you want. First off, there are games that use mana bars. This represents the availability of mana near you – the amount of mana you can tap into right now, in order to cast a spell. Higher concentrations of mana allow for larger and/or more intricate structures, thus resulting in the more powerful spells. After you send that burning ghost-sword towards your enemy, that structure of mana will move away from you, being represented in a depletion of the mana bar. Eventually, the structure will fall apart and return to its natural state. Much like a wave of water you create, pushing away from yourself, a structure of mana can be shot at the opponent. The amount of water on your side is less, and on the other side it increases, but after some time, the disturbance is gone and you have access to as much water as before. The same applies to mana; eventually, it will be redistributed, providing you with as much mana as before – this is the regeneration of the mana bar. But there’s another mechanic involved in this; charging up. This should be quite obvious, but I shall explain it anyway. You draw the mana to yourself before making the spell. The longer you ‘charge’, as it were, the more mana you can put into a massive and complicated structure that will have a greater chance of bringing you victory. However, in many types of combat time is of the essence, so you can’t stand around all day. Often you’ll have to settle for less, simply because you must make sure you can do something. In pretty much all situations –whether or not it’s a battle- you’ll be using both techniques, as they’re pretty much two halves of the same thing; not a combination of different styles. Admittedly, in a place with a lot of mana you’ll be charging less, while in a place with a low density you’ll have to be careful how much you use.
I hope you were able to understand me and that you think it actually works. Of course there may be questions, and I'd like to think about all the details of what I imagine, so ask away! And lastly, feel free to use it as an excuse of placing magic in actual reality.