spectral-line structures. Like a number of other prominent physicists of the time (including the leading Dutch theoretician H. A. Lorentz) Gehrcke, an experimentalist, was not prepared to give up the concept of the luminiferous aether, and for this and various other reasons had been highly critical of Einstein's theories of relativity at least since 1911. This led to an invitation to an event organized in 1920 by Paul Weyland. Weyland, a radical political activist, professional agitator, small-time criminal, and editor of the vehemently anti-Semitic periodical Völkische Monatshefte, believed that Einstein's theories had been excessively promoted in the Berlin press, which he imagined was dominated by Jews who were sympathetic to Einstein's cause for other than scientific reasons. In response, Weyland organized the Arbeitsgemeinschaft deutscher Naturforscher zur Erhaltung reiner Wissenschaft (Working Group of German Natural Scientists for the Preservation of Pure Science), which was never officially registered. Weyland tried to enlist the support of some prominent conservative scientists, such as the Nobel Laureate Philipp Lenard, to build support for the Society (although Lenard declined to participate in Weyland's meetings). The Society held its first and only event on 24 August 1920, featuring lectures against Albert Einstein’s theory of relativity. Weyland gave the first presentation in which he accused Einstein of being a plagiarizer. Gehrcke gave the second and last talks, in which he presented detailed criticisms of Einstein's theories. Einstein attended the event with Walther Nernst. Max von Laue, Walther Nernst, and Heinrich Rubens published a brief and dignified response to the event, in the leading Berlin daily Tägliche Rundschau, on 26 August. Einstein published his own somewhat lengthy reply on 27 August, which he later came to regret. Rising anti-Semitism and antipathy to recent trends in theoretical physics (especially with respect to the theory of relativity and quantum mechanics) were key motivational factors for the Deutsche Physik movement. Under advice from some of his closest associates, Einstein later publicly challenged his critics to debate him in a more professional environment, and several of his scientific adversaries, including Gehrcke and Lenard, accepted. The ensuing debate took place at the 86th meeting of the German Society of Scientists and Physicians in Bad Nauheim on 20 September, chaired by Friedrich von Müller, with Hendrik Lorentz, Max Planck, and Hermann Weyl present. In this meeting Gehrcke pressed his criticism that Einstein's general theory of relativity now admitted superluminal velocities in rotating frames of reference,