December 14, 1900 (a Friday)

Max Planck

On this date, Max Planck, today considered the inventor of quantum theory, presented his paper Zur Theorie des Gesetzes der Energieverteilung in Normalspektrum (On the Theory of the Law of Energy Distribution in Normal Spectrum) at a meeting of the German Physical Society in Berlin. He shocked the science world by showing that atoms emit or absorb energy in bundles, or quanta, not in a continuous stream. This concept of energy quanta conflicted fundamentally with Newtonian physics, and its importance was not fully appreciated at first, even by Planck himself, who was something of a reluctant revolutionary. However, the evidence for its validity gradually became overwhelming as its application accounted for many discrepancies between observed phenomena and classical theory, among them Einstein’s explanation of the photoelectric effect. In 1918 Planck’s fundamental contribution was recognized with the awarding of the Nobel Prize in Physics, “for the discovery of energy quanta.”

Happy Birthday!

As a result, in view of its significance, today is considered the birthday of quantum mechanics.