A/N: Hello, dear readers. Do not be discouraged by the scientific and mathematical babbling that ensues; it is quite plain and very interesting. Please ask me if you have any questions at all, or if you find an error in my mathematical laws. This is not intended to be taken seriously. Enjoy and be amused.

A Brief Study on Energy, Entropy, and Youkai

It occurs to me that youkai hold three basic, yet powerful allures. These are superior senses, superior strength, and immortality. How are these three characteristics possible, and can humans—by undergoing some mysterious change—become youkai as well? This question occurred to me while reading the multitude of fan fiction in which Kagome miraculously becomes a youkai, or through some sort of mark that possibly alters her chemistry she then possesses youkai-like qualities. Is there any theoretical or non-theoretical explanation for the qualities youkai are fabled to possess, and would it indeed be possible for Kagome to turn into a youkai herself? In this very random (and very geeky) one-shot, I shall explore these questions.

First, I shall go into the background of energy and entropy so that the concepts may be more easily understood. Then, once this understanding has been asserted, I will connect the subjects of energy, entropy, and immortality and discuss how youkai and humans relate.

The Law of Energy Conservation according to Clausius states that energy is neither created nor destroyed. It can change manifestations (as in thermal, mechanical, acoustic, etc.), but ultimately the amount of energy in the universe is constant. This expression can be simply and mathematically expressed by the equation:

∆E(universe) = 0

Translated back into Standard English, this equation states that the net change in total energy in the universe is equal to zero, because the total energy in the universe is constant. The fundamental theorem of this equation is also true under Einstein's new Conservation Law of Energy which can be expressed by the equation:

∆ {∑nmc2β} =0

This can be simplified to:

E=mc2β

Or, more famously

E=mc2

The only difference between this formula and the original by Clausius is that Einstein's identifies energy and mass as the same thing. Mass IS energy. The fact remains, however, that energy (and mass) cannot be created or destroyed, only changed.

In theory, then, it should be possible to utilize all possible energy to create 100% productivity. If one were to create an engine that converted 100% of the heat it was given into mechanical work, then 100% of that work was converted back into heat, it could theoretically run itself for eternity. Unfortunately, in real life this does not work. This can be seen in any working "machine", including ourselves as human beings. Take for instance a steam engine. Energy in the form of heat is applied to water, which converts to steam. The energy which was once heat now becomes mechanic as the pressurized steam pushes the pistons down. Steam engines are not very efficient because a lot of the energy generated by the engine and put into the engine is lost through reconversion to heat through friction. The same is seen in our bodies' loss of body heat. This radiating heat, then, is wasted energy and makes a perfect perpetual-motion machine impossible.

As it turns out, there are no perpetual-motion machines in nature whatsoever; all things come to an end, they are mortal. It is the natural state, then, for things to break down or equalize. A steaming soup left in a cold room becomes colder while the room becomes somewhat warmer. Humans live until their energy can no longer maintain them. These natural processes are considered positive entropy. Unnatural processes, such as converting heat into work, or forcing heat to go from a cold place to a warm place (as in refrigerators) are considered negative entropy, or the reversing of the natural breakdown.

All processes are composed of positive and negative entropy. Simplistically, by adding all of the positive and negative entropy produced, one can then see which way the universe is headed. As it turns out, there is more positive entropy in the universe than negative so as to increase the overall entropy, which means that the universe is ultimately breaking down. This led Clausius to the equation:

∆S(universe) [greater than sign]* 0

This means that the net change in the entropy of the universe is always greater than zero.

Surprisingly, life is actually negative entropy, which therefore defies the natural disorder of things. However, because life is imperfect, a lot of energy is wasted and we eventually expire, creating positive entropy in consistence with the universe. If a perpetual motion-machine did exist, its entropy would equal 0 and it would continue on indefinitely.

Let us explore the possibilities of the aforementioned perpetual motion-machine. If such a machine did exist, then it would efficiently use all of the energy provided, and then reconvert it all in order to use it again. In short, it would be self-sustaining, capable of continuing on indefinitely. Because of this its entropy would equal 0. All of this we have already discovered; now we shall look closer into the implications. If this machine used its energy to its fullest potential, then it would be many times more powerful than a regular machine. Also, since it is self-sustaining, this machine would never need to refuel. Finally, whereas normal machines would eventually wear out and break down, this machine would continue on forever.

In lieu of these realizations, I propose that youkai are simply perpetual motion-machines and humans are their imperfect counterparts. Because youkai utilize all their energy to their fullest potential, they are much more powerful than a human in their physical strength and the strength of their senses. They do not need to eat because they endlessly reuse their energy, which is why the more powerful ones "do no eat human food". The youkai seen eating are generally lesser youkai, and this too can be explained. Mass is energy and energy is mechanical power. For a perpetual motion-machine, such as a youkai, eating would only add energy to their store and therefore mechanical power. It stands to reason, then, that powerful youkai do not need to increase their power by eating, and lesser youkai would desire to do so. Finally, youkai live on indefinitely. Unless they are forcibly killed in battle they do not die. This is consistent with the perpetual motion-machine theory.

Hanyou are not a perfect perpetual motion-machine because of their mix of human blood. Nevertheless, they still perform with more power and efficiency than a human, even if it is less than a full-blooded youkai. Hanyou are then proof that hybrids of the two types of machines can then be formed. This gives hope to the idea that Kagome could, through a bio-chemical change, gain characteristics of youkai. What would be taking place would be a change in the way her body functioned, allowing her to utilize her energy more effectively. Unless it was a complete chemical reaction, she would remain only partly converted, so in order to become a full youkai she would need enough of the catalyst to ensure that the change was all encompassing. Serious bio-chemical testing would have to be done to isolate the compound that would create such a reaction, possibly beginning with an analysis of youkai blood to isolate what makes it possible to be energy efficient and self-sustainable. Perhaps from this a catalyst could be derived.

Perhaps, because Kagome is generally bitten before she turns into a youkai, the catalyst already exists in youkai DNA, possibly in the blood or saliva. The property that allows youkai to be perpetual motion-machines might even be the catalyst in itself. Even though the exact cause is not known, however, it remains that it is entirely possible to become a youkai by being genetically converted. As for other ways in which Kagome becomes miraculously a perpetual motion-machine herself, I cannot here sanctify them. Human beings are built imperfectly and as such it is impossible for them to equalize their entropy on their own without cause. Chemical and biological changes must occur, which cannot occur spontaneously. At the very best, if no catalyst is used, this change must be a gradual evolution of the body spanning hundreds of thousands of years (which is most likely how youkai came to be, splitting off from the average human species millions of years ago. This also explains why the two races can interbreed, suggesting that they are closely related, much like dogs and wolves).

In conclusion, energy is mass, which is constant. All energy in the universe is breaking down and equalizing, which is because of increasing entropy. If entropy=0, then the process in question continues on indefinitely. This is called a perpetual motion-machine, and is completely theoretical. Youkai, being theoretical also, can be considered perpetual motion-machines because of three similar characteristics: immortality, 100% efficient use of energy, and self-sustainment. Being human and not a perpetual motion-machine, it is only slightly possible that through a bio-chemical changed caused by a catalyst Kagome could convert into a youkai. But it is possible.

*For some reason the site did not like the greater than symbol that was in there. Also, my sub and superscripts have become normal text...

A/N: I hope this made some of the more scientific and mathematical minded people chuckle. Reviews are always welcome. (Yes, I know youkai are actually created from the spirits of animals)

Theoretically yours,

The Masked Fox