BOLTZMANN, LUDWIG Austrian physicist, was born on Feb. 14, 1844. He was educated at Linz and then at Vienna, where he obtained his doctorate in 1867 and was appointed assistant in the Physical Institute of the university. In 1876 Boltzmann was appointed professor at Graz where he stayed until 1891, when he went to Munich. He held the appointment of Professor of Physics at Vienna with the exception of a short period in 1904 when he went to Leipzig, from 1895 until Sept. 5, 1906 when he committed suicide at Duino.
Boltzmann's most important work was on molecular mathemati cal physics ; he was one of the most important contributors to the development of the kinetic theory of gases (see KINETIC THEORY OF MATTER). His first paper, published in the Wiener Berichte (1866), was on the second law of thermodynamics (q.v.) ; this was followed by three papers (1868, 1872 and 1892) on the partition of energy. These papers attempted to put on a more satisfactory basis the work already started by Maxwell; the ,second paper contained what is now known as Boltzmann's H-theorem; and in 1877 he began to apply the theory of probabil ity to the above problem. Boltzmann wrote a number of papers on the integration of the equations of molecular motion, on viscosity and diffusion of gases, on Maxwell's electromagnetic theory (q.v.) and on Hertz's experiments. He also gave a theo retical proof of Stefan's law for the energy radiated by a black body (see RADIATION) . These papers were published in the Viennese, German and English scientific periodicals.