In part 2 we closed with the idea that Bohr seemed to be using general relativity against Einstein to save quantum mechanics! A wonderful story. But is it true?

Einstein seems to have thought that they were arguing about something else. We know this from a letter that Paul Ehrenfest wrote to Bohr in July 1931, after a visit with Einstein in Berlin.  Ehrenfest and Einstein seem to have had a long and thorough chat about the debate with Bohr at the previous fall’s Solvay meeting. Ehrenfest reports to Bohr a most surprising comment from Einstein:

Continued from Part 1

Einstein and Bohr – No names loom larger in the history of twentieth-century physics, and rightly so, Albert Einstein and Niels Bohr being the figures most prominently associated with the relativity and quantum revolutions.(1)