ABSTRACT
Consider the conduction electrons in a metal, particularly those near the Fermi surface. When an electron e1 near the Fermi surface (high speed) passes near to a positively charged nucleus, the nucleus feels a Coulomb attraction and is set into motion. Another electron e2 near to the Fermi surface may see this nucleus moving away from itself and it will thus experience an attraction. The net effect is that the nucleus has screened the natural Coulomb repulsion between e1 and e2 and indeed, e2 now appears to be attracted to e1. Technically, e1 has emitted a phonon which is absorbed by e2.
