Quantum physics is born on December 14,…

Quantum physics is born on December 14, 1900, with Max Planck's announcement of the quantum theory.

Having discovered that at long wavelengths blackbody radiation does not conform to the distribution laws set forth by Wilhelm Wien, Planck announces his revolutionary idea that an oscillator can emit energy only in discrete quanta, contrary to classical physical theory. 

Planck had discovered the law of black-body radiation (Planck's law) on October 19, 1900, by introducing the notion of light quanta, which will lead in 1905 to Albert Einstein's explanation of the photoelectric effect and beginning the Quantum Revolution.