Arthur E. Haas (1884-1941) was an Austrian theoretical physicist, one of the last students of Ludwig Boltzmann, and today mainly known for his early contributions to quantum physics. In the 1920s he was a very successful author of several textbooks and popular science books on topics of modern physics. He gave multiple lectures in Vienna and Berlin, and across the entire United States. He was...

Optical spectroscopy was an important field of research at the University Vienna around the year 1900. Several devices are still kept in the historical collection of the Faculty of Physics and some are presented in this talk. Franz Serafin Exner (1849-1926) wanted to use optical spectroscopy to find new chemical elements in meteorites, which were available at the Natural History Museum Vienna....

Boltzmann’s H-theorem has revolutionized the thinking about the evolution of entropy in thermodynamics. It has proved the unidirectional tendency of irreversible processes contradicting the time-reversed laws of physics (Loschmidt’s and Poincaré’s paradox). However, the entropy is quantified as a state variable and defines quasistatic equilibrium in an infinite time limit. The H-theorem...

Ideas of Wilhelm Lenz 1921 and Walter Schottky 1922 how Coulomb energy might induce an interaction which orders the elementary magnetons made possible the formulation of a corresponding model by Ernst Ising 1925 but did not lead to a magnetic phase. Only the development of the new quantum mechanics allowed Pauli to formulated 1930 at the Solvay conference the Ising model as we know it...