Max Planck (1858–1947)

Born on 23 April 1858 in Kiel, Germany, theoretical physicist Max Planck was a founder of quantum theory. Planck studied physics at the Universities of Berlin and Munich, earning his doctorate in 1879 at the age of 21. After teaching at the Universities of Munich and Kiel, he accepted a teaching appointment in 1889 at the University of Berlin, where he would remain until retiring with emeritus status in 1926. His research into blackbody radiation and the first and second laws of thermodynamics led to his discovery in 1900 that radiation is absorbed and emitted in discrete packets, called quanta, whose energy is proportional to frequency. Planck’s insight not only accurately explained experimental data but also provided impetus to the new quantum theory. In recognition of his discovery of energy quanta, Planck was awarded the 1918 Nobel Prize in Physics. A strong proponent of the German physical community, he was one of the first prominent physicists to support Einstein’s theory of special relativity and helped bring Einstein and others, such as Max von Laue, to Berlin. Planck also served as permanent secretary of the Prussian Academy of Sciences and as president of the Kaiser Wilhelm Society (now the Max Planck Society). In 1929 he received the Royal Society’s Copley Medal. With the rise of Adolf Hitler in the 1930s, Planck struggled to preserve German physics and was a vocal opponent of Hitler’s racial policies. In 1944 Planck’s house in Berlin was destroyed by bombs, and one of his sons was implicated in a conspiracy to assassinate Hitler and executed the following year. Planck died at age 89 in 1947. Eleven years later, Physics Today reported on a celebration of Planck’s 100th birthday. Notably the event was held in both East and West Berlin, marking “the first time scientists from the two sectors of Germany had collaborated on a common project.”

Date in History: 23 April 1858