This article is about Planck, the German physicist. For the proposed European Space Agency artificial satellite, see "Planck (satellite)".

Max Karl Ernst Ludwig Planck (April 23, 1858 – October 4, 1947) was a German physicist who is considered to be the inventor of quantum theory.

Born in Kiel, Planck started his physics studies at Munich University in 1874, graduating in 1879 in Berlin. He returned to Munich in 1880 to teach at the university, and moved to Kiel in 1885. There he married Marie Mack in 1886. In 1889, he moved to Berlin, where from 1892 on he held the chair of theoretical physics.

In 1899, he discovered a new fundamental constant, which is named Planck's constant, and is, for example, used to calculate the energy of a photon. Also that year, he described his own set of units of measurement based on fundamental physical constants. One year later, he discovered the law of heat radiation, which is named Planck's law of black body radiation. This law became the basis of quantum theory, which emerged ten years later in cooperation with Albert Einstein and Niels Bohr.

From 1905 to 1909, Planck acted as the head of the Deutsche Physikalische Gesellschaft (German Physical Society). His wife died in 1909, and one year later he married Marga von Hoesslin. In 1913, he became head of Berlin University. For the foundation of quantum physics, he was awarded the 1918 Nobel Prize in Physics. From 1930 to 1937, Planck was head of the Kaiser-Wilhelm-Gesellschaft zur F�rderung der Wissenschaften (KWG, Emperor-Wilhelm-Society for the advancement of science).

During World War II, Planck tried to convince Hitler to spare Jewish scientists. Planck's son Erwin was executed on July 20, 1944, for treason in connection with an attempted assassination of Hitler. After Max Planck's death on October 4, 1947 inG�ttingen, the KWG was renamed as the Max-Planck-Gesellschaft zur F�rderung der Wissenschaften (MPG, Max-Planck-Society for the advancement of science).

External links and references

Wikiquote has a collection of quotations related to:

Max Planck

• Timeline of Nobel Prize Winners, "Max Planck (http://www.nobel-winners.com/Physics/max_karl_ernst_ludwig_planck.html)". 3w-hosting.com.
• Planck, Max, "On the Law of Distribution of Energy in the Normal Spectrum (http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Planck-1901/Planck-1901.html)". Annalen der Physik, vol. 4, p. 553 ff (1901).
• Max Planck Winner of the 1918 Nobel Prize in Physics (http://www.nobelprizes.com/nobel/physics/1918a.html)
• Life�work�personality. Exhibition on the 50th anniversary of Max Planck's death (http://www.max-planck.mpg.de)

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