OK, I would really appreciate it if somebody could explain to me as simply as possible why entanglement happens (between electrons), what a Cooper pair is, and what causes superconductivity. I have read that if two electrons are entangled and something happens to one of them, it will affect the other, no matter what the separation distance is. First off, is this true? If so then that's confusing because the only forces that one can exert on the other are a tiny gravitational force, an electrostatic repulsive force and a weak nuclear force, and the effects of these rapidly decreases as distance increases (inverse square law). I do not know what Cooper pairs are at all, I only know that they occur when Aluminium is super-cooled and becomes a superconductor. In a ground state atom all of the electrons are in the lowest possible energy level's. Yet this does not mean that a ground state atom has no energy, I know that elctrons have spin (I don't get spin either, maybe that will be the subject of another thread) and angular momentum etc. so to lose even more energy, an atom could lose the angular momentum and spin that the electrons have. And eventually after losing enough energy it may even reach absolute zero. Sometimes though, once the temperature of a particular group (albeit a very large group) of atoms has dropped below a certain temperature, it can becomes a superconductor and an electric current can be passed through it without experiencing any resistance. This is really befuddling. I thought that when an electron travelled down a wire, it might "bump" into an atom and lose some energy to an electron which would be promoted to a higher energy level, then when it dropped back down again it emitted a photon (usually infra-red). So how does a superconductor work and why? It would be really nice of someone to answer just one of these questions, although please don't bury me in mathematical equations that I won't know, I only want to know the theory behind why these things work. An analogy may also help if you can dream one up, for instance I like to think of Higgs particles as treacle that slows stuff down.