QUOTE : The theory also showed that superconductivity is not a mere extension of ordinary conductivity. Previously it had always seemed paradoxical that the best normal conductors, copper and silver, are feeble superconductors; they do not superconduct even when the temperature is a thousandth of a degree above absolute zero. Seen in the light of the new theory, however, that finding began to make sense. Good conductors are good precisely because their conduction electrons ignore the lattice. But by encouraging the electrons and the lattice to go their separate ways, these materials never give Cooper pairs a chance to form. Remember, the pairing mechanism relies crucially on an electron’s ability to deform the lattice (like the bowling ball rolling on the waterbed) so that a second one can follow in its tracks. If the waterbed is so stiff that the first bowling ball can’t make a groove in it, there’s no chance that a second one will follow. So good conductors are lousy superconductors, because they can’t form the necessary Cooper pairs.