Josef Stefan

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Josef Stefan

1835-1893

Austrian physicist who, with his lab assistant Ludwig Boltzmann (1844-1906), showed the relationship between the temperature of a body and the amount of radiation it emitted. The Stefan-Boltzmann law, established in 1879, also describes the primary color emitted by a hot body. This law is used today by astronomers to determine the temperature of stars, the interstellar medium, and gases swirling into black holes based solely on the wavelength of light emitted by these objects.