- Historians have debated ad nauseum whether Einstein himself was aware of the Michelson-Morley experiment in 1905. Pais seems to believe that he wasn't. However, even if Einstein himself wasn't, it was very much "in the air" that no sound experiment had ever found direct evidence of the ether, and Einstein was certainly aware of that fact. Moreover, regardless of whether Einstein himself knew of Michelson and Morley, many of the prominent physicists of that era were definitely aware of it, and directly cited it. To the extent that Einstein's work on relativity was guided by concerns that we well-known among scientists of that era, he was influenced by Michelson and Morley, irrespective of whether he was directly aware of their experimental result.
- Poincare, Lorentz, Fitzgerald, and others had all worked on ways to modify physics to account for the non-observation of ether effects. The Lorentz transformations and length contraction formula had been written down, and Poincare openly pondered a possible need for modifying the laws of motion. However, everybody was positing these things as either ad hoc fixes or as mere observations on the symmetry of the Maxwell equations. Nobody prior to Einstein posed these ideas as being derivable from the equivalence of all inertial reference frames. That's Einstein's real contribution: To see that these equations that address all of the deficits in the ether model are in fact consequences of the laws of physics being the same to all observers.
- I learned about the post of privatdozent in German-language universities, which seems quite similar to the modern phenomenon of the adjunct professor. Apparently a privatdozent could teach classes and receive a very modest fee for it, but did not have the status, institutional role, salary, or research support that a professor would enjoy. Many people back then said that academic careers were only suitable for the independently wealthy. All of this has happened before and will happen again.
Sunday, September 18, 2016
Next reading project: Subtle is the Lord by Abraham Pais
I'm currently reading Subtle is the Lord: The Science and the Life of Albert Einstein by Abraham Pais. It's a biography of Einstein, heavy on scientific detail. I'm about half-way through. Some key observations: