Sometime ago, in my partial state of sleepiness and being awake (you could call it trance - yo!) I had a thought that during perfectly elastic collisions, it's the deformation of the colliding particles which transfer energy from one to the other. But doesn't that assume that there are empty spaces in the composition of the particles? Now, let me say, what if we get down to the smallest particle, that is that particle has no composition but that of itself - it is a complete unity of solidity-, and two such particles collide, would elastic collision occur? I have fair suspicions that this might have something to do with Quantum Physics or something far beyond my scope but it's nevertheless a good thing to be relieved by random, useless, pointless, and mindless wanderings of the mind.