Memories of electrons in crystals
As a student in Zurich, it was my good fortune to be present at the colloquium in which Schrödinger told the first time about his wave mechanics. When both he and Debye accepted positions in Germany I decided upon the latter’s advice to continue my studies under Heisenberg in Leipzig, where I arrived in the autumn of 1927. Already in Zurich my interests had turned from experimental to theoretical physics, and particularly towards quantum mechanics, and before coming to Leipzig I had started some calculations on the radiation-damping of wave-packets. As the first thing, Heisenberg encouraged me to complete this work, later published in the Physikalische Zeitschrift , whereupon he considered me ready to start on a topic for my Ph.D. thesis.