 In 1920 Reichenbach became an instructor in physics, and eventually associate professor, at the Technische Hochschule in Stuttgart. The Theory of Relativity and A Priori Knowledge (1920f) was accepted as his habilitation in physics. In this period Reichenbach married Elizabeth Lingener and they had two children, Hans Galama in 1922 and Jutta in 1924. While in Stuttgart he developed contacts with Moritz Schlick, Rudolf Carnap and Erwin Schroedinger. In 1926, after much back and forth, he assumed a teaching position in “natural philosophy” at the University of Berlin, where he remained until Hitler came to power in 1933. During this time Reichenbach organized discussion groups on scientific philosophy, similar to those of the Vienna Circle (see entry on  Vienna Circle).  The group around Reichenbach that developed out of the Society for Empirical Philosophy and became known as the Berlin Group included Kurt Grelling, Kurt Lewin, Richard von Mises and later Carl Hempel, Reichenbach’s student. Together with members of the Vienna Circle, Reichenbach initiated the publication of the journal Erkenntnis in 1930 as a forum for scientific philosophy. Reichenbach and Carnap were the only editors after Schlick resigned in reaction to Reichenbach’s opening article (see  Section 4.4  below). In addition (and also for financial reasons), Reichenbach was a frequent contributor of popular essays and a regular radio lecturer on scientific topics. 