Black body radiation
Generic depiction of black body radiation of radiation emitted from a cavity resonator or black body. [1]
In radiation thermodynamics, black body radiation is electromagnetic radiation emitted by a black body when heated.

History
In 1860, German physicist Gustav Kirchhoff introduced the term “black body” and formulated radiation equations that gave a partial solution to the phenomenon of radiation emitted by such bodies.

In 1894, German physicist Max Planck began to work on the thermodynamical understanding of black body radiation and in 1900 solved the then plaguing problems, e.g. ultraviolet catastrophe, and in doing so reformulated Kirchhoff's equations on black body radiation, using Ludwig Boltzmann’s postulate that the energy of bodies could be divided up into discreet quantities or portions, and on this basis introduced the idea of the “energy element” and thus launched the quantum revolution.

References
1. Gribben, John. (2002). Quantum Physics: a Beginner’s Guide to the Subatomic World (pg. 13). DK Publishing.

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