Developments of concepts in superconductivity

In this talk, I would like to trace the origins of some of the major theoretical and experimental advances which have led to the development of a successful microscopic theory of superconductivity and then to indicate briefly some of the current problems. Fritz London made extremely important contributions to the theory and laid the groundwork for our present understanding. He showed how the Meissner effect and other superconducting properties could be understood as a consequence of quantum effects operating on a macroscopic scale. A striking prediction of his, which only recently has been verified experimentally, is the quantization of flux in a superconducting ring. My own work on superconductivity theory has been influenced greatly by that of Fritz London.