Gravity before Einstein and Schwinger before gravity

Julian Schwinger was a child prodigy, and Albert Einstein distinctly not; Schwinger had something like 73 graduate students, and Einstein very few. But both thought that gravity was important. They were not, of course, the first, nor is the disagreement on how one should think about gravity, which was highlighted at the June 2012 meeting of the American Astronomical Society, the first such dispute. Explored here are several views of what gravity is supposed to do: action at a distance versus luminiferous ether, universal gravitation versus action only on solids, finite versus infinite propagation speed, and whether the exponent in the 1/r2 law is precisely two, or two plus a smidgeon (a suggestion by Simon Newcomb among others). Second, an attempt is made to describe Julian Schwinger’s early work and how it might have prefigured his “source theory,” beginning with his unpublished 1934 paper “on the interaction of several electrons,” through his days at Berkeley with Oppenheimer, Gerjuoy, and others, to the application of nuclear physics ideas to radar, and of radar engineering techniques to nuclear physics. Those who believe that good jobs are difficult to come by now might want to contemplate the couple of years Schwinger spent teaching introductory physics at Purdue before moving on to the Radiation Laboratory in 1942.