History^13Fig. 1Poincark died not long after the first Solvay Council; Lorentz just a few months
after Solvay-5. Marie Curie wrote for the volume in honor of what “the soul of our
meetings” had meant to the assembled physicists: “The illustrious master teacher
[makre] and physicist, H.-A. Lorentz, was taken from us [4] February 1928 by a
sudden sickness - when we had just admired, one more time, his magnificent in-
tellectual gifts that age had not diminished.” He had, in Curie’s view, brought to
the meetings diplomacy, students, followers, and collaborators - he was in all senses
master of the field. Lorentz was “the real creator of the theoretical edifice that ex-
plained optical and electromagnetic phenomena by the exchange of energy between
electrons and radiation in accordance with Maxwell’s theory. Lorentz retained a
devotion to this classical theory. It was therefore all the more remarkable that his
flexibility of mind was such that he followed the disconcerting evolution of quantum
theory and the new mechanics.” [23]
Langevin took over for Solvay-6 following Lorentz’s death; it was Langevin who
guided discussion in October 1930. By then, the themes we have been discussing
split Einstein ever further from Bohr, and their struggle continued long after they
left the Metropole - through Einstein-Podolsky-Rosen and beyond. Throughout,Einstein famously pressed ahead in his quest to show that the problem with con-
temporary quantum mechanics was that it was incomplete - that our state was one
of ignorance in fact, not in principle: ignoramus not ignorabimus. One Gedankenex-
periment followed another, for which just one, perhaps the most remarkable, must
stand for many.