Max Karl Ernst Ludwig Planck was born on April 23, 1858, in
Kiel.
When Planck was nine years old, his father received an appointment
at the University of Munich, and Planck entered the city's renowned
Maximilian Gymnasium. He started to study physics at the University
of Munich in the fall of 1874, and received his doctoral degree in
July 1878 at the unusually young age of 21. The following year he
completed his Habilitationsschrift (qualifying dissertation) at
Munich and became a Privatdozent (lecturer).
In 1885 he was appointed ausserordentlicher Professor (associate
professor) at the University of Kiel. In 1889, Planck received an
appointment to the University of Berlin, where he came to venerate
Helmholtz as mentor and colleague. In 1892 he was promoted to
ordentlicher Professor (full professor).
Max Planck made many contributions to theoretical physics, but his
fame rests primarily on his role as originator of the quantum
theory. Planck was 42 years old in 1900 when he made the famous
discovery that in 1918 won him the Nobel Prize for Physics: The
quantum of action, now known as Planck's constant h, relates the
energy of radiation to its frequency. He also evaluated the
Boltzmann constant, Avogadro's number, and the charge of the
electron. Planck became permanent secretary of the mathematics and
physics sections of the Prussian Academy of Sciences in 1912 and
held that position until 1938; he was also president of the Kaiser
Wilhelm Society (now the Max Planck Society) from 1930 to
1937.
In 1909, his first wife Marie Merck died, leaving Planck with two
sons and twin daughters. The elder son, Karl, was killed in action
in 1916. The following year, Margarete, one of his daughters, died
in childbirth, and in 1919 the same fate befell Emma, his other
daughter. The younger son, Erwin, was implicated in the attempt
made on Hitler's life on July 20, 1944, and in early 1945 he was
killed by the Gestapo. At war's end, Planck and his second wife,
Marga von Hoesslin, moved to Göttingen. There, on October 4, 1947,
in his 89th year, he died.