Planck, Max Karl Ernst Ludwig (1858–1947)
Max Planck was a German theoretical physicist whose revolutionary quantum theory (see Planck and the origins of quantum theory), along with Einstein's theory of relativity, brought physics into the modern era. He served as professor (1889–1928) at the University of Berlin.
Initially influenced by 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 (1900) which implied that energy, like matter, is not infinitely indivisible – that it can exist only as quanta (see Planck constant). Planck himself was not convinced of this, even after Einstein had applied the theory to the photoelectric effect and Bohr in his model of the atom (see Bohr atom); but for his achievement he received the 1918 Nobel Prize in Physics.
Planck remained in Germany during the Nazi era, but spoke out against the persecution of Jews In 1944, his son Erwin was executed for taking part in the unsuccessful plot to assassinate Hitler. He served as president of the Kaiser Wilhelm Society for the Advancement of Science, Berlin, which after World War II became part of the Max Planck Institute.