Hey, I know I'm wrong, but I don't know where. I've read several textbooks and searched the web, I would appreciate if you could explain my mistake: When two atoms collide with each other, they would do work on each other. By the second law of thermodynamics, some of this work would turn to heat, which will dissipate. Eventually, all of the atom's energy would convert to heat, and the atoms would stop moving. This is clearly not happening, so what's wrong?