Right, so. A couple years ago, before I learnt about electron orbitals etc. I sorta figured out that energy was quantized. I always thought that my logic was right, but you never know. So I'll outline my argument below and could someone tell me if its logically and physically sound? And if it isn't, why not? So, I had just learnt about 0 K being the lowest possible temperature and that matter was at its lowest energy at 0K. I also learnt that things cant go below this temperature because they cant have 0 energy. Ergo, if something were to go even an infinitesimal bit below 0K, it would have zero energy. But an infinitesimal temperature change would lead to an infinitesimal energy change. Since this is not allowed, temperature must change in some multiple of some number, call it T. Obviously, at 0K matter must have some energy, call it E. So, the only allowed temperature change will be that which would result in an energy change of magnitude E. So, if temperature were to drop below 0K, the first allowed temperature change would result in an energy decrease of E. Which is why temperature would never fall below 0K. So any energy change must be an integral multiple of E and any temperature change an integral multiple of T.