THE BROADWAY INTERPRETATION OF QUANTUM MECHANICS "Copenhagen," a play by Michael Frayn about the 1941 encounter between Niels Bohr and Werner Heisenberg, was the subject of a daylong symposium this week at the City University of New York. Physicists, historians, and theater people involved with the production of the play (which opens soon on Broadway after a successful run in London) grappled with the central issue of why Heisenberg, at that time the chief scientist on the German atom-bomb project, should visit his old friend in occupied Copenhagen. Was he trying to learn about the Allies' atomic plans? Did he want to explore with Bohr the ethics of applying physics to the building of this most destructive of weapons? Should we view Heisenberg as a hero for purposely slowing or sabotaging the German bomb effort or an incompetent engineer who didn't know the difference between a reactor and a bomb? The most poignant presentations at the symposium were made by Hans Bethe and John Wheeler, eminent physicists who themselves worked on the Allied bomb project and who knew Bohr and Heisenberg personally. Bethe declared that "Heisenberg had no interest in atomic bombs," citing as evidence the "Farmhall" tapes, the secretly recorded conversations of Heisenberg and the other German atomic scientists while in British custody after the war. News of the Hiroshima bomb was a great shock to the Germans who, while not very far along toward the development of a genuine atomic bomb, had felt they had gone further than the Allies.
Heisenberg's initial attempt to account for the Allied success in an impromptu tutorial for his colleagues seems to indicate that he was very far from understanding how a bomb would work. Wheeler spoke of several meetings with Heisenberg, including one at the University of Michigan in 1939 from which Heisenberg left early in order to return to Germany for military training. The reception of Heisenberg among physicists in the postwar years was often chilly, said Wheeler.
Not surprisingly, Heisenberg tried in later years to defend his honor, and on several occasions hazarded to explain the purpose of his 1941 visit. In one such explanation he maintained that he had come to Bohr to suggest that an atomic bomb would be too unmanageable to produce, that the German effort would not succeed, and that (by implication) the Allies should also give up the attempt. On this crucial point, historian Gerald Holton referred to a recently discovered letter written by Bohr to Heisenberg, but never posted. Holton has read the letter but it is otherwise sealed for another 12 years at the request of the Bohr estate. Without revealing the exact contents of the letter, Holton hinted that Bohr (in this unsent letter) took exception to what Heisenberg had been saying in public about their 1941 meeting.
Will there be any definitive judgment of Heisenberg? Probably not. The metaphorical thrust of Frayn's play is, of course, the extension of quantum uncertainty to the realm of human motivations, and in the course of the play, with its cyclic re-telling of the same event from differing perspectives, we are given to understand that Heisenberg himself was not sure of his own motivations in journeying to Copenhagen. http://inside.gc.cuny.edu/orup/copenhagen/)
