Abstract

It is a commonplace for historians to write that physicists came out of their World War II radar service with microwave engineering superadded to their knowledge of quantum physics. But what exactly was the content of this new amalgam? How fully was it achieved and by what processes? I suggest that one approach to these questions is via a study of noise and coherence in the 1950s. In these years, novel instruments were proposed and/or operated that were of interest for both engineering and physics; among them various forms of the maser. These instruments required the deployment of both engineering and quantum physics concepts. At the same time, they raised problems for both physics and engineering notions of noise.