In October 1924, The Physical Review, a relatively minor journal at the time, published a remarkable two-part paper by John H. Van Vleck, working in virtual isolation at the University of Minnesota. Van Vleck used Bohr's correspondence principle and Einstein's quantum theory of radiation to find quantum formulae for the emission, absorption, and dispersion of radiation. The paper is similar but in many ways superior to the well-known paper by Kramers and Heisenberg published the following year that is widely credited (...) to have led directly to Heisenberg's Umdeutung paper. As such, it clearly shows how strongly the discovery of matrix mechanics depended on earlier work on the application of the correspondence principle to the interaction of matter and radiation. (shrink)

The ArgumentThis paper is about the context of Albert Einstein's concerns at the time of a most intense intellectual effort — his own and that of a small group of scientists concerned with classical quantum theory. I describe contemporaneous interactions and differing views about the prospects for and the significance of the First Solvay Congress of 1911 as voiced by major participants. There are two axes around which the paper evolves: the Einstein-Nernst-Lorentz dialogue and the public institutional creation of the (...) “Solvay” stage. In certain ways, this paper is about personal and institutional patronage: the working out of a difficult theoretical impasse requires individual and collective moral support. It is about the forging of the identity of a scientific problem and the personal and institutional setting, the public space, in which this problem was collectively addressed. But I also uncover heuristic playfulness and flexibility which accompanies theoretical change. (shrink)