Max Karl Ernst Ludwig Planck

Planck, Max Karl Ernst Ludwig (1858–1947), German physicist whose quantum theory, with Albert Einstein's theory of relativity, ushered physics into the modern era. Initially influenced by Rudolf Clausius, he made fundamental researches in thermodynamics before turning to investigate blackbody radiation. To describe the electromagnetic radiation emitted from a blackbody, he evolved the Planck radiation formula, which implied that energy, like matter, can exist only as quanta (discrete amounts).Planck himself was unconvinced of this, even after Einstein had applied the theory to the photoelectric effect and Bohr in his model of the atom, but Planck received the 1918 Nobel Prize for physics for his achievement.

See also: Quantum mechanics; Radiation.