> The Physics of Magic (As explained by the Doctor)
>  by erlenmeyer
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> The Physics of Magic
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        HELLO EVERYPONY. This is a brief explanation of magic in the Equestrian Universe. This will be just concepts only, no equations or any of that. Now this is just a theory postulated by Dr. Strange Quark, a colleague of mine, and it has its holes and flaws. Nevertheless, let us start on our wonderful journey through the magical sciences, shall we?
First we must talk about entropy. What is entropy? Well, it’s a law of thermodynamics (science dealing with the transfer and flow of energy) that states that nature tends to go from a state of order to chaos in a closed system. Radioactive material decay. Living things age. Stars die. That is all entropy at work. A closed system that is as organized as Twilight Sparkle is said to have low entropy. A closed system that more... Discordian, has high entropy. A good example of this is ice. Let’s say you have an ice cube. The water molecules in that ice cube are arranged in a crystalline manner, giving it its shape and rigidity. That means it has low entropy. What happens to the molecules when the ice melts? The molecules have more energy and start bouncing all over, like a certain pink pony I know. The particles' positions are more random. It becomes water. So water has higher entropy than ice.
The universe in which you inhabit started out with extremely low entropy. That state was known as the singularity. Everything was compacted into an extremely tiny point. Then as time got moving, the entropy increased. The universe began to expand exponentially. So it seems that as time goes on for everything in the universe, entropy increases. You are born with relatively low entropy, as you get older, your entropy increases. Because of this, entropy can't be decreased in a closed system. That brings up a little problem: How are stars, computers, life, and ponies possible? If the universe started with low entropy and is getting higher, how can such low entropy phenomena exist? Good question. The fact is that none of those are closed systems. They all have external influences reducing their entropy. Life has energy. Stars have gravity. Computers, people. Think of it this way: You have 9 fillies. The fillies are separated into groups of three based on their coat color. One group is red; another is green; and another is blue. Being fillies, they like to bounce around and play with each other. So they get disorganized over time, entropy increases. When the time comes, you have to put them back into their groups. You are that external factor decreasing their entropy.
So we have learned that entropy in your universe increases over time. This is where it gets interesting. I, Doctor Whooves, have observed a pattern in the Multiverse. Universes balance entropy! It seems to be contradictory, trying to organize chaos. I don't know how this happens but it does! Your universe balances entropy over the arrow of time. One end, the beginning, has extremely low entropy. The other end has extremely high entropy. So they end up canceling each other out. Other universes balance entropy through space. One end of that universe is chaotic and random; the other end is organized and compact. There are even universes that distribute entropy on two dimensions (like time and altitude, or altitude and depth). Our universe, the Equestrian universe, distributes entropy through both space and time.
How? You may ask. Well, for that we have to get into a bit of quantum theory. Don't be intimidated, it’s not that hard to understand (at least for a time lord it isn’t…). You may or may not have heard of elementary particles. These particles are modicums of energy and vibration that are even smaller than atoms. Some of these particles you already know: electrons and photons. Others are more exotic. For example, there are quarks, taus, neutrinos, bosons, muons, gluons, and various other -ons that have strange names. Well, some of these particles, like the Higgs boson (difficult little bugger), control fundamental properties of a universe's contents.
Well, the Equestrian universe balances entropy using one of these little particles. I call them PIPs (Probability Inducing Particles) and you'll see why. PIPs float about in the equestrian universe and attach to particles. These little guys are the incarnations of probability itself. They control the chance of an event happening to that particle. PIPs are attracted to low entropy phenomena. When they attach to a particle, they increase the chances of something happening. It’s random, however it becomes less random when there are other PIPs around. They begin form “connections”, so that a specific event (or evental property) may happen if they are arranged properly. Another contradiction. However, this organization is counteracted by the fact that there are so many combinations of PIPs and there are so many PIPs flying around in the universe, that it is by mere chance that two events have the same evental property. The more PIPs are in that specific constellation, the higher the chance of something happening to that object. So sometimes, suns dismantle unexpectedly. Diamonds mysteriously change into coal.
That also begs the same question, how did the first life form that formed on Equestria not disappear. Well, it probably did or it probably didn't. But, by chance, some little bug got lucky and didn't spontaneously change back into a mix of chemicals. The fact is that the chances of dramatic entropic change happening to a particle, object, or phenomenon are quite small. Usually its small change, like a particle moving somewhere randomly or a piece of a molecule disappears. Maybe the chance of a star evaporating away one day is... about 1 x 10^18. But small enough to be a far off threat to any organisms that may happen to be on a planet orbiting said star. It’s still higher than the chances of that happening in your universe.
PIPs may not be threats to stars or planets, but it’s BAD NEWS for life. The chances of an organism disappearing is 1 x 10^8. Since our universe balances entropy over 4 dimensions (3 dimensions of space and a dimension of time) instead of one dimension (time) like your universe, organisms live longer. That's more time for the PIPs to make them disappear. For some odd reason, PIPs are excessively attracted to living things. Why aren't ponies disappearing and turning into random things around me? You see living things are capable of evolving ways to mess with quantum mechanics. Plants in your universe manipulate electrons by making them exist in several places at once and making them go the shortest route to the reaction center proteins. That way, almost no energy is lost. All organisms in this universe have evolved a way to deal with PIPs. They can basically channel or even teleport (which is quite possible in the quantum world) PIPs away from their cells so that entropy doesn't get them.
Now what does this have to do with magic? Well, I must digress to another thing to make the connection. Do you remember the infinite improbability drive from a book in your universe called The Hitchhiker's Guide to the Galaxy? It’s a device that increases the chances of the ship to instantly teleport from one place to another by manipulating probability (often with hilarious side-effects). Even though its original purpose was rather funny, yet crude (I doubt Pinkie Pie would need one for her parties), it was a major leap in science. Well, organisms on Equestria evolved not only to remove PIPs, but to manipulate them, turning them into living improbability drives. Organisms manipulating PIPs to make evental properties is how magic is performed! It may have started like this:
The earliest organisms, probably due to an evental property, got a mutation that allowed them to make proteins that manipulate PIPs. Some proteins attract, other repel. The ones that repel PIPs survived longer, due to not spontaneously combusting whilst eating. They passed on that trait to their offspring, the viola! Organisms can repel PIPs and live longer! It’s not perfect. Some PIPs can still find their way in, but the cells have evolved to turn away specific evental properties, like evaporation or transformation. It doesn't stop the occasional mutation or teleportation. Also PIPs can't make the chances of something happening 100%, so there's always a chance to fail (e.g. Twilight Sparkle's fail safe spell).
Some organisms began use PIPs their advantage. Sprites and other faeries can teleport short distances by encouraging PIPs to form a specific evental property in them. Organisms began to evolve ways to freeze PIPs in place and or move them. The clever beasties began to use more advanced magic.
So, what led ponies to be able to use magic by will? Those organisms could only use a spell or two and they can only do it instinctively. How come unicorns can use a variety of enchantments and spells? Well, believe it or not, intelligence and magic go hoof in hoof.
In your universe, predatory organisms are the ones to usually ones to evolve intelligence. There may be an occasional autotroph or herbivore, but that is rare. In the Equestrian universe, intelligence is more common due to the fact that an organism has to be smart to use more spells. The more brain power an organism has, the more abilities it can get. So intelligence is rewarded nicely on our side of void. That catalyzes prey animals to become smarter as well, that way they can outsmart the predator. Ponies evolved as a combination of the two.
Ponies are small, so they can be caught with little struggle. So ponies got faster. Predators got faster, but they also got smarter to outsmart the quicker ponies. Ponies got smarter to outsmart the predators. So on and so forth. Magic played a role in this as well.
Now, enough theory! Let’s talk about the ponies!
Earth ponies are the oldest species of pony. Obviously, Earth Ponies are very good with plants. They have innate enchantment that allows visible light to hit chloroplasts more often. So plants grow faster and higher around Earth Pony herds. Nutrients are also teleported from beneath the ground to the roots to help plants grow. So forests tend to form around resident herds. To navigate the forests and evade predators, they began to grow smarter. Soon, they evolved the ability to help certain species of plant grow and discourage growth from others. To maintain crops, they finally burst into sentience. They also have an enchantment in them to give them massive boosts of strength and stamina by teleporting glucose from the plants around them directly into their muscles. Earth ponies have a symbiotic relationship with the land. The plants give them a home and food, while the ponies them the plants food and water and additional sun.
Pegasi evolved from mountain dwelling Earth Ponies. They got their wings by trying to evade mountain predators by jumping. The ones with proto-wings glided down cliffs safely to evade their enemies. Soon, mammalian feathers came to be and they got their wings. They got cloud walking to evade predators at high altitudes and cloud shaping to live in. They increase the chance of the cloud water becoming a solid, snow like material using an innate enchantment. They can put an eventual property on clouds to make them maintain their shape and repel entropy causing PIPs. They also have an enchantment to make themselves go faster by increasing the chances of their kinetic energy increasing by taking it from the wind itself.
Unicorns are the newest addition to the pony genus. They have the ability to freely manipulate eventual properties like no other organism in Equestria. Basically the split from earth ponies and they evolved more in PIP manipulation. They went the route of survival of the most magical. Soon, they gained the ability to manipulate PIPs using special extension of their brain and skull: The horn. They would attract mates by making their horn glow when using magic. The brighter and more decorative the glow, the more powerful in magic that unicorn was. That is why unicorn horns glow and other ponies don't glow when using magic. However, the spells they could use was limited due to this. So unicorns would specialize in different magic.
Now, speaking of specialization, where do cutie marks come from? Well, I'd have to go into less clear realms of science to explain this. You see, for any species of intelligent pony to use magic, they basically have to imagine the event. That's their brain's way of using magic. Imagination in humans probably evolved as a way to help the human predict and plan. Imagination for ponies, evolved as a way to help them use magic in addition to predicting and planning. There is an instinctive enchantment in ponies that makes cutie marks. The cutie mark enchantment evolved as a way of communication between the members of the herd. It signals, “Hey! I can be a big help to the herd!” and tightens social bonds. Cutie marks are actually induced when the pony finds their talent and the enchantment activates when the pony imagines a symbol that represents their talent. It is still unsure on the exact process that happens in the brain to cause this.
What about the Mane Six, Celestia and her dear sister Luna, and that nasty fellow Discord? Where do they fit into this? They are what I refer to as evental anomalies. They are ponies born with several strange enchantments and abilities. Let us begin with our more godlike beings: the royal sisters and Discord.
It seems that alicorns are naturally endowed with extremely powerful evental properties. Celestia’s evental property is tied to the rotation of the planet itself! Though the planet can keep spinning independently of her influence, she can make it so that the planet spins faster or slower, affecting the length of the day. Luna is tied to her namesake, the moon. It works as the planets and other celestial bodies do normally. However she can manipulate its orbit around the planet to make it rise or fall earlier or later. She can even move the moon farther or closer to make it bigger or smaller. Princess Mi Amore Candenza, or simply Princess Cadence, and influence the parts of the brain in ponies responsible for affection and love. I’m not into romance myself since I never stay in one place. 
Discord is an oddity. While he is a living being, or sprit as he refers to himself as, he doesn’t seem to be affected by PIPs at all, though they are highly concentrated in his body. As a matter of fact, he’s the only being I know of that can freely manipulate PIPs as if it was an extension of his body. Hence the chaos that forms when he is out of his stony prison. Though he thinks he’s having nothing but a good time, the reckless manipulation of PIPs is extremely dangerous around living things. Especially if they’re instructed to form very random, drastic evental properties so often. I’m quite glad that he was promptly imprisoned once again. Otherwise many lives may have been lost...
Anyways, lets move from such a grim topic! The evental properties for the Mane Six are much simpler, yet just as fascinating. Our speedster, Rainbow Dash is capable of absorbing more energy from the air than all other pegasi, allowing her to create her signature sonic rainboom! That in itself is another evental property. Fluttershy, the timid animal caretaker, has a property that connects her mind to any non-pony creature. This allows her to have a deep connection with many animals and also enables her to perform the stare. Twilight is capable of much greater PIP control than most unicorns. Her natural genius and memory allows her to memorize many different spells very quickly. Pinkie pie is actually quite similar to Discord. She can freely manipulate PIPs, unlike other earth ponies, but does it on a much smaller and safer scale. Rarity has a natural eye for beauty and has a property that allows her to do math related to aesthetics in her mind much like a savant. She doing complex aesthetic related calculations without even realizing it. Finally, good old Applejack. Her incredible strength comes from the fact that she’s worked hard on the farm all her life. But she also has a property allowing her to absorb more nutrients than other earth ponies can. This allowed her incredible build to be possible.
The Elements of Harmony are the last evental anomalies that I will cover. Very much is unknown about them. Even I am clueless as to what exactly they are and how they work. I do have an idea, though. It seems as if the Elements of Harmony entangle their evental properties with that of a select few ponies. In order to do that, however, the Elements would have to be sentient. How the Elements choose which ponies to bestow their power to is beyond me but it’s quite fascinating!
Well, this has been quite fun (for me anyways)! I hope that those of you who are of like mind enjoyed this little crash course in the physics of magic!