Max Planck presented the quantum theory of radiation
On this day · 14 December 1900
On December 14, 1900, a reluctant physicist told a Berlin meeting that energy comes in lumps — and quantum physics was born.
On December 14, 1900, Max Planck presented a new derivation to the German Physical Society in Berlin. To explain how hot objects glow, he made a radical assumption: electromagnetic energy is emitted not in a smooth flow but in discrete packets, or quanta, each a multiple of an elementary unit.
This Planck postulate solved the stubborn “blackbody radiation” problem that had defeated classical physics. The date is now widely cited as the birth of quantum theory.
Planck later called the step “an act of desperation” — he had simply run out of other options.
Ironically, the revolution went largely unnoticed. Physicists admired the mathematics but treated the quantum as a convenient trick rather than a description of reality, and Planck himself doubted its deeper meaning. Only over the following decades — through Einstein, Bohr, and others — did the quantum idea reshape our entire picture of matter, light, and energy.
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