> Electrons interact with each other. In principle correct, but in the particular case of Cooper pairs (responsible for the super conduction) the el-el interac

> Electrons interact with each other. In principle correct, but in the particular case of Cooper pairs (responsible for the super conduction) the el-el interaction plays a subordinate role. Actually, the Coulomb force is counter-productive to building electron pairs, as electrons repel each other. The effectively attractive el-el coupling of Cooper pairs is mediated by the electron-phonon interaction (Phonons are the quantized lattice vibrations). The following picture might help: When a negatively charged electron moves through the lattice, the positive cores of the lattice ions are attracted and move away from their equilibrium position. This causes a lattice polarization. In metals, the ion movement is much, much slower then that of the electrons. So when the polarization-inducing electron has already moved on, the lattice is still out of its equilibrium position. A second electron that comes into that region, "sees" the lattice polarization and the elongated positive ions and is attracted to it. Thus the lattice vibration has mediated an effectively attractive coupling between the two electrons.