You guys have really gone off the deep end with this thread, demons... come on. There is a philosophy that attempts to define the nature of matter, void, and existence. It is called metaphysics. Ancient Greek metaphysics from Thales of Melitus to Leucippus, and then democritis, there is a linear progression of philosophers one after the other who attempted to define the nature of substance. Aristotle, in his metaphysics, took the works of these philosophers and attempted to construct a grand metaphysical scheme that would define the nature of substance.
In his attempt to define the nature of substance he was faced with several contradictions. First, he defined substance as the whatness of a thing. And in that respect it was the body that defined substance more than anything else. He argued that substance was something that was generated, so he proposed that what was generated was the 'body' of substance. The problem is that he argued that matter was the underlying material of the change, that during the change matter did not change. Change was suppose to be between contrary states. From a potential to an actual body. The contradiction was that if matter becomes substance, that substance is matter-and he was never able to make a clear distinction between the two.
The fact that our science incorporates the notion of matter, means that we are left with this same contradiction. So if you look up a definition of matter in a dictionary, it will state that it is substance and visa versa. In the realm preceding Aristotle, there was a theory called 'monism'. Philosophers proposed that all of existence was composed of one material, called the aiperon, intelligence, etc. There was also the schools who proposed contraries, the limited and the unlimited, the body and the void. Monism suggested that the two were the same material.
In modern terms, it has been accepted that a substantial body is composed of matter. The problem being that this leaves the space between substance empty and non-existent. It also leads to certain contradictions concerning the nature of force, in that a force has to act through a distance. Even Newton understood that force at a distance, through a void, was impractical. He simply had no way to solve the puzzle, and was more concerned with the empirical nature of his physics.
The idea of an ether in electromagnetics tried to introduce the concept of nonlocality, by introducing the idea of a prevading material between substance. This worked in a classical sense to explain the nature of how interference and such things, the wave nature of substance might work- but the model was vague and it was disproven by Michaelson and morely. The concept of an ether should not be confused with the ancient greek concept of an 'aether'- the two are completely distinct.
If you are having a hard time understanding the difference between energy and matter, you are not alone. The problem rests with the philosophy of science, the scattered interpretation provided to us by Aristotle. It is important to understand that matter is the foundation of what we perceive as substance, it is the fundamental construct. Consider that adding the concept of energy to that foundation, is philosophically unqualified. You can't just add a new 'eternal' without explaining how it is related...
Yes Einstein argued that matter and energy are interconvertable, but there is no model to show how that occurs. Epsitemologically speaking, Science in its present state is concerned with the knowledge 'that occurs' and has no way of explaining 'how that occurs'. The end result is that we are left with the same contradictions that Aristotle found, in many new and strange ways-the same problem exists now as it did then...
From my perspective, classically speaking, energy is defined as the motion of a body or the potential to move. In that respect, it is created by a force, and is not a force. However, during a collision, the energy of one particle can transfer to another, and that represents a force. Really, the momentum of one is transferred to the other. It may be arguable, that if energy as an incorporeal entity exists, say as a photon, where the particle nature of the photons is obscure and potentially nonexistent, that this represents a motion as well. Given that each photon has a linear propagation that is incorporeal, ie, not particle in nature, but an energy that is related to the wavelength- it may be possible that the photon has another internal motion that we are unable to appreciate.
The question that evolves is what a particle is? Is it a body, with a physical size and is that a constant? Aristotle argued that substance, as a body, is generated. It follows that if there is a process which generates the body, that the process is a constant, whereas the body may be a variable. The question then becomes, what happens if the body is a minimum? Does the process vanish or does it still exist, and do we now treat the virtual state of a particle in terms of energy alone, since the definition of a particle no longer exists.
Well at least I am trying to contribute...