Physicist — Josef Stefan (Sankt Peter, near Klagenfurt, 1835 – Vienna 1893) was an Austrian physicist of Slovene origin, professor at the University of Vienna. He is best known for deducing, in 1879 on an experimental basis, the law describing how the power radiated by a black body grows with the fourth power of the absolute temperature; a few years later his pupil Ludwig Boltzmann derived it theoretically, so the relation is known as the Stefan-Boltzmann law. With it Stefan managed, for the first time, to reasonably estimate the Sun’s surface temperature. He also worked on heat conduction in gases, diffusion and the solidification problem (Stefan problem), leaving a lasting mark on thermal physics.
Trivia
Applying his law to the available measurements, Stefan estimated the Sun’s surface temperature at around 5700 °C, a value remarkably close to the one accepted today.
Theories and contributions
- Stefan-Boltzmann law — The power radiated per unit surface by a black body is proportional to the fourth power of the temperature: .
- Stefan problem — Mathematical description of a phase change with a moving boundary (e.g. ice formation), fundamental in the physics of heat conduction.
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Linked atoms
3 linked atoms.