Solvay Conferences

Solvay Conferences, conferences on physics and chemistry held in Brussels by the International Solvay Institutes for Physics and Chemistry. Belgian chemist and industrialist Ernest Solvay founded the conferences, with the first in physics occurring in 1911 and the first in chemistry in 1922. They were interrupted by World Wars I and II but since then have kept to a three-year schedule, with a physics conference in the first year, no conference in the second year, and a chemistry conference in the third year. The conferences are usually divided into morning and afternoon sessions that open with one or two reviews of a subject followed by extensive time for discussion. The fifth (1927) physics conference was particularly influential in the development of quantum mechanics.

Chaired by Dutch physicist Hendrik Lorentz and running from October 24 to 29, 1927, the fifth physics conference was devoted to “electrons and photons” but was dominated by disputes about the ideas behind quantum mechanics. Beginning in 1925, Danish physicist Niels Bohr and German physicists Werner Heisenberg and Max Born, among others, had formed what came to be known as the “Copenhagen interpretation” of quantum mechanics, which postulated that the indeterminacy in the theory (i.e., that only the probability of a result could be predicted) was fundamental and should be accepted by scientists. There was no underlying deterministic order to be found. Some physicists, most notably German physicist Albert Einstein, did not accept the Copenhagen interpretation and felt that its reliance on indeterminacy showed that quantum mechanics still was not a complete theory. That dispute was foregrounded at the 1927 conference. Bohr, Heisenberg, and Born were not able to win Einstein over, but the dissemination of the Copenhagen interpretation among physicists was accelerated by the conference, and it eventually became the prevailing view of quantum mechanics.