20th-century German physicists

Hans Albrecht Bethe (German pronunciation: [ˈhans ˈbeːtə] ; July 2, 1906 – March 6, 2005) was a German-American theoretical physicist who made major contributions to nuclear physics, astrophysics, quantum electrodynamics, and solid-state physics, and who won the 1967 Nobel Prize in Physics for his work on the theory of stellar nucleosynthesis. For most of his career, Bethe was a professor at Cornell University.During World War II, he was head of the Theoretical Division at the secret Los Alamos laboratory that developed the first atomic bombs. There he played a key role in calculating the critical mass of the weapons and developing the theory behind the implosion method used in both the Trinity test and the "Fat Man" weapon dropped on Nagasaki in August 1945.
After the war, Bethe also played an important role in the development of the hydrogen bomb, although he had originally joined the project with the hope of proving it could not be made. Bethe later campaigned with Albert Einstein and the Emergency Committee of Atomic Scientists against nuclear testing and the nuclear arms race. He helped persuade the Kennedy and Nixon administrations to sign, respectively, the 1963 Partial Nuclear Test Ban Treaty and 1972 Anti-Ballistic Missile Treaty (SALT I).
His scientific research never ceased and he was publishing papers well into his nineties, making him one of the few scientists to have published at least one major paper in his field during every decade of his career, which in Bethe's case spanned nearly seventy years. Freeman Dyson, once his doctoral student, called him the "supreme problem-solver of the 20th century".

Wilhelm Conrad Röntgen (; German pronunciation: [ˈvɪlhɛlm ˈʁœntɡən] ; 27 March 1845 – 10 February 1923) was a German mechanical engineer and physicist, who, on 8 November 1895, produced and detected electromagnetic radiation in a wavelength range known as X-rays or Röntgen rays, an achievement that earned him the inaugural Nobel Prize in Physics in 1901. In honour of Röntgen's accomplishments, in 2004 the International Union of Pure and Applied Chemistry (IUPAC) named element 111, roentgenium, a radioactive element with multiple unstable isotopes, after him. The unit of measurement roentgen was also named after him.

Max Theodor Felix von Laue (German: [maks fɔn ˈlaʊ̯ə] ; 9 October 1879 – 24 April 1960) was a German physicist who received the Nobel Prize in Physics in 1914 for his discovery of the diffraction of X-rays by crystals.In addition to his scientific endeavors with contributions in optics, crystallography, quantum theory, superconductivity, and the theory of relativity, Laue had a number of administrative positions which advanced and guided German scientific research and development during four decades. A strong objector to Nazism, he was instrumental in re-establishing and organizing German science after World War II.

Werner Heinrich Gustav Kolhörster (28 December 1887 – 5 August 1946) was a German physicist and a pioneer of research into cosmic rays.
Kolhörster was born in Schwiebus (Świebodzin), Brandenburg Province of Prussia. While attending the University of Halle, he studied physics under Friedrich Ernst Dorn.Repeating the cosmic ray experiments of Victor Hess, in 1913-14 Kolhörster ascended by balloon to an altitude of 9 km, where he confirmed Hess' result that the ionization rate from cosmic rays was greater at that altitude than at sea level. This was evidence that the source for these ionizing rays came from above the Earth's atmosphere.Kolhörster continued his physics studies at the Physikalisch-Technische Reichsanstalt in Berlin, beginning in 1914. During World War I he made measurements of atmospheric electricity in Turkey. Following the war he became a teacher. He joined the Physikalisch-Technische Reichsanstalt in 1922.In 1928–29, Walter Bothe and Kolhörster used the Geiger-Muller detector to demonstrate that cosmic rays were actually charged particles. The ability of these particles to penetrate the Earth's atmosphere meant that they must be highly energetic.In 1930, Kolhörster started the first institute for the study of cosmic rays in Potsdam, with financial assistance from the Prussian Academy of Sciences. He became director of the Institut für Hohenstrahlungsforschung in Berlin-Dahlem in 1935, where he was appointed an ordinary professor.Kolhörster was killed in a car crash in Munich. The crater Kolhörster on the Moon is named in his memory.

Kurt Alfred Georg Mendelssohn FRS (7 January 1906, Berlin-Schoeneberg – 18 September 1980) was a German-born British medical physicist, elected a Fellow of the Royal Society in 1951.

Friedrich Albert Moritz Schlick (; German: [ʃlɪk] ; 14 April 1882 – 22 June 1936) was a German philosopher, physicist, and the founding father of logical positivism and the Vienna Circle.

Walther Ludwig Julius Kossel (4 January 1888 – 22 May 1956) was a German physicist known for his theory of the chemical bond (ionic bond/octet rule), Sommerfeld–Kossel displacement law of atomic spectra, the Kossel-Stranski model for crystal growth, and the Kossel effect. Walther was the son of Albrecht Kossel who won the Nobel Prize in Physiology or Medicine in 1910.

Eduard August Grüneisen (26 May 1877 – 5 April 1949) was a German physicist. The dimensionless thermodynamic measure known as Grüneisen parameter is named after him.

Wilhelm Lenz (February 8, 1888 in Frankfurt am Main – April 30, 1957 in Hamburg) was a German physicist, most notable for his invention of the Ising model and for his application of the Laplace–Runge–Lenz vector to the old quantum mechanical treatment of hydrogen-like atoms.

Fritz Reiche (July 4, 1883 – January 14, 1969) was a German physicist, a student of Max Planck and a colleague of Albert Einstein, who was active in, and made important contributions to the early development of quantum mechanics including co-authoring the Thomas-Reiche-Kuhn sum rule.Fritz Reiche was born in 1883 in Berlin, Germany. In 1901 and 1902, he attended the University of Munich and he attended the University of Berlin from 1902 to 1907, where he received his PhD. From 1913 to 1920 as privatdozent he worked and taught under Planck in Berlin. Reiche published more than 55 scientific papers and books including The Quantum Theory.He became a professor in 1921 at the University of Breslau and then was dismissed as a Jew from his academic position in 1933. Eventually, with the help of Ladenburg, Einstein, and the Emergency Committee in Aid of Displaced Foreign Scholars, Reiche emigrated with his family to the United States in 1941 and went on to work with NASA and the United States Navy on projects related to supersonic flow.