Interlude: The BKS Proposal

Abstract In January 1924, Niels Bohr, Hendrik Anton Kramers, and John Clarke Slater submitted to the Philosophical Magazine an article [Bl] that contained drastic theoretical proposals concerning the interaction of light and matter. It was written after Compton’s discovery, yet it rejected the photon. It was also written after Einstein and Bohr had met. This chapter on the BKS proposal serves a twofold purpose. It is a postscript to the story of the photon and a prelude to the Bohr Einstein dialogue which will occupy us more fully later on. I have already mentioned that Einstein was immediately and strongly impressed by Bohr’s work of 1913. The two men did not yet know each other at that time. A number of years were to pass before their first encounter; meanwhile, they followed each other’s published work.