Josef Stefan 1835-1893

 Austrian Physicist, Josef Stefan was born on March 24, 1835, near Klagenfurt, Austria. During his lifetime, his contributions spanned several important fields, including: the Kinetic Theory of Gases, Hydrodynamics and in particular, Radiation.

 Stefan was educated at the University of Wien, received his Doctor of Philosophy in 1858 and became Privatdozent in Mathematical Physics. In 1863, he became Professor Ordinarius of Physics and in 1866 Director of the Physical Institute. He was a distinguished member of the Academy of Sciences where he was appointed Secretary in 1875. Before Stefan's work, G. R. Kirchhoff had already described the perfect radiator as the "perfect black body," namely, one that absorbed all the radiation that fell on it and reflected none, but emitted radiation of all wave lengths. Stefan showed empirically in 1879 that the radiation of such a body was proportional to the fourth power of its absolute temperatures. This relationship became known as the "Stefan-Boltzmann Law " after it had been deduced by L. Boltzmann in 1884 from thermodynamic considerations.

 In the year 1891, Stefan published his work on the formation of ice in the Polar Seas, giving a special solution of this non-linear conduction problem with phase change (the more general solution being due to F. Neumann). He died January 7, 1893 in Wien.

Grigull, Sandner, Straud, Winkler. Origins of Dimensionless Groups of Heat and Mass Transfer. Lehrstuhl a Fuer Thermodynamik Technische Universitaet Muenchen. IHTC, Muenchen 1982.

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