Explaining the laser’s light: classical versus quantum electrodynamics in the 1960s

Abstract

The laser, first operated in 1960, produced light with coherence properties that demanded explanation. While some attempted a treatment within the framework of classical coherence theory, others insisted that only quantum electrodynamics could give adequate insight and generality. The result was a sharp and rather bitter controversy, conducted over the physics and mathematics that were being deployed, but also over the criteria for doing good science. Three physicists were at the center of this dispute, Emil Wolf, Max Born's collaborator on a canonical text on optics as a branch of classical electromagnetism, Roy J. Glauber, a student of Julian Schwinger and a high-energy particle theorist, and Leonard Mandel, both experimentalist and theorist and versed in the physics of photodetection. The story told here is thus one of three distinct research trajectories and of the explosion that occurred when, pushed into the well-financed field of laser studies, these trajectories collided.

What Have the Historians of Quantum Physics Ever Done for Us?

“…Although we are accustomed to read narratives on the theoretical development of quantum physics, several authors have recently highlighted the role of applications and experiments not only in backing up theories, but also in keeping disciplinary unity, fostering new questions, refining old concepts and setting new research agendas. This revamping of the interest for material culture has not been limited to classical experiments of old quantum physics (see, for instance, Gearhart, , ), but has also reached the history of solid state physics and quantum optics (Bromberg, , ; Silva and Freire Jr, ; James and Joas, ).…”