The Emergence of BCS

Major contributions in theoretical physics do not emerge in a vacuum. They usually are inspired by experiment, require near total immersion in the relevant theoretical and experimental literature, and are often preceded by years of preliminary work, including the publication of failed or incomplete attempts at producing a theory, while recognition of their success does not always come instantly. The 1957 theory of John Bardeen, Leon Cooper, and Robert Schrieffer, known as BCS, which provided, forty-six years after the discovery of superconductivity, a highly successful microscopic theory of its emergent quantum behavior, fits well into this general paradigm. In this highly personal perspective on their work I address these issues, writing not as a historian, but as a colleague and sometime participant in the events that led up to the theory, and some that followed.