Stefan–Boltzmann law

The Stefan–Boltzmann law states that a black body’s total emitted radiant power per unit area equals the Stefan–Boltzmann constant multiplied by its absolute temperature to the fourth power.

Planck's law: Planck's law gives the spectral radiance of a black body as a function of frequency and temperature. Integrating its spectrum over all frequencies yields the Stefan–Boltzmann law.
Thermodynamic temperature: A measure of temperature on an absolute scale, with zero at absolute zero. The fourth-power relation uses absolute temperature, not a Celsius or Fahrenheit value.
Josef Stefan: Josef Stefan was an Austrian physicist who formulated the temperature-to-the-fourth-power radiation law from experimental evidence. His 1879 analysis identified the empirical fourth-power dependence.
Stefan–Boltzmann equation for stars: The stellar relation connecting luminosity, effective temperature, and radius through black-body emission. It applies the law over a star’s entire spherical surface to estimate luminosity.
Wien's displacement law: Wien's displacement law relates a black body’s peak emission wavelength to its absolute temperature. It tracks where emission peaks, while Stefan–Boltzmann gives the integrated total.
Stefan–Boltzmann constant: The physical constant that relates a black body’s emitted power per unit area to its absolute temperature raised to the fourth power. It sets the proportionality in the law’s quantitative form.
Thermal radiation: Electromagnetic radiation emitted by matter because of its temperature. The law describes the total power carried by this radiation from a black body.
Ludwig Boltzmann: Ludwig Boltzmann was an Austrian physicist who connected thermodynamics with statistical mechanics. In 1884 he derived the law using thermodynamics and electromagnetic theory.
Effective temperature: The temperature of a body that would emit the same total radiation as a black body of a specified size. Astronomical temperatures are often inferred by matching observed flux to the law.
Kirchhoff's law of thermal radiation: Kirchhoff's law states that, at thermal equilibrium, emissivity equals absorptivity at each wavelength and direction. It relates emission to absorption, complementing the total-power relation.

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