Einstein’s witches’ sabbath in Brussels: The legend and the facts

Abstract

This paper is about the first Solvay Council on Physics, its surprising origin and its far reaching consequences. In spite of the various accounts that have been given by several authors — they include historians of science, but also outstanding scientists, such as Leon Rosenfeld, Niels Bohr and Eduardo Amaldi — it appears that only limited attention was paid so far to the more singular aspects of this legendary meeting, and to the peculiar circumstances which led to its convening. This fact may be due to the restricted availability of relevant documents, many of which are located in different archives. It also reflects the rather abstract character of Ernest Solvay’s Institute of Physics — an Institute without a permanent staff, governed by geographically separated bodies: a scientific committee with a chairman in Haarlem, a secretary in Copenhagen and an administrative committee in Brussels.

One of the purposes of the paper is to fill this gap by revisiting the course of events which led to Solvay’s invitation of June 1911. Another aim is to present a brief, yet balanced, account of the deliberations which took place in October–November 1911, by pointing at some elements that may be regarded as highlights of the Council, and by focusing on the contrasting aspects of its main results: the contrast between the Council’s disappointing conclusions on the one hand, and its positive consequences on the other hand. Special attention in this context is given to the unexpected concern about the validity of Planck’s law, expressed by Emil Warburg, and to the apparent contradictions in Einstein’s private reactions to the outcome of the Brussels meeting.

The paper also aims at restoring the truth about some facts regarding the Solvay reports and their discussion, by revealing the discrepancies between the official account — the Gauthier-Villars volume “La théorie du rayonnement et les quanta”, published in 1912, and the actual proceedings of the conference, based on notes taken during the meeting by Maurice de Broglie. A significant point is the removal from the official volume of an important remark made by Planck about the status of the “heat theorem” during the discussion of Nernst’s report.

A last section of the paper is devoted to one of the durable consequences of the Council: Solvay’s decision to create the International Institutes of Physics. This section serves as an introduction to Frits Berends’ paper: “Lorentz, the Solvay Councils and the Physics Institute”.