Born: 23 April 1858
Died: 4 October 1947
Birthplace: Kiel, Germany
Best known as: The German physicist who originated quantum theory
Max Karl Ernst Ludwig Planck was a German physicist who provided the watershed between classical and modern physics. Around 1900 Planck came up with a mathematical solution to explain the nature of black-body radiation. He showed that energy is emitted and absorbed in discreet packets of what he called "quanta," and that these had a definite size -- an absolute constant now called Planck's constant (symbol h). Planck's finding didn't get much attention until the idea was furthered by Albert Einstein in 1905 and Niels Bohr in 1913. Planck won the Nobel Prize in 1918, and, together with Einstein's theory of relativity, his quantum theory changed the field of physics. He spent most of his career at the University of Berlin. After his retirement in 1926 he was the president of the Kaiser Wilhelm Society for the Promotion of Science until 1937, when he clashed with Adolf Hitler's Nazi party. Planck stayed in Germany during World War II, but Allied bombing destroyed his house toward the end of the war. He was rescued by American forces while trying to flee Germany and spent his last years in Göttingen.
Extra credit: Planck's first wife died in 1909, his two daughters died while in childbirth in 1917 and 1919, one son was killed in World War I in 1916 and his other son was executed in 1944 for plotting against Hitler.
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