Hans Albrecht Bethe

Hans Albrecht Bethe was born on July 2, 1906, in Strasbourg, then in German Alsace-Lorraine and now in France.⁠[1][2]

His father, Albrecht Julius Bethe (1872–1954), was a Privatdozent in physiology at the University of Strasbourg; his mother, Anna Bethe, née Kuhn (1876–1966), was a talented musician and a writer of children’s stories.⁠[3]

From 1915 to 1924 Bethe attended the Gymnasium in Frankfurt.⁠[2]

In 1924 Bethe entered the University of Frankfurt, first studying chemistry before turning to physics and theory; after two years in Frankfurt he applied, on a recommendation, to join Arnold Sommerfeld’s seminar in Munich, and spent two and a half years at the University of Munich.⁠[3][2]

In July 1928 he received his PhD in theoretical physics under Sommerfeld, with a thesis on electron diffraction that built on the work of Paul Ewald.⁠[2][3]

After his doctorate Bethe was an instructor in physics for one semester each in Frankfurt and Stuttgart; from 1928 he was Ewald’s assistant at the Technical University of Stuttgart.⁠[2][3][4]

From 1929 to 1933 Bethe was based in Munich, becoming a Privatdozent at the University of Munich in May 1930.⁠[2]

A travel fellowship from the International Education Board took Bethe to Cambridge in the fall of 1930 and to Rome for the spring terms of 1931 and 1932, where he worked with Enrico Fermi.⁠[2][4]

In the summer of 1932 Bethe was offered an assistant professorship at the University of Tübingen, serving as acting assistant professor in the winter of 1932–1933. Because his mother was Jewish, he was dismissed under the racial laws in April 1933 after the Nazis came to power.⁠[3][2][4]

After leaving Germany Bethe went to England, where he was a temporary lecturer at the University of ManchesterUniversity of ManchesterThe University of Manchester is a research university in Manchester, England, formed in 2004 by combining the Victoria University of Manchester and the University of Manchester Institute of Science and Technology (UMIST). It traces its origins to 1824 and is a member of the Russell Group.Open the full entry in 1933–1934 and a fellow at the University of BristolUniversity of BristolThe University of Bristol is a research university in Bristol, England, United Kingdom. It began as University College, Bristol, which opened in 1876, became a university under a royal charter in 1909 and is a member of the Russell Group.Open the full entry in the fall of 1934.⁠[2][5]

In 1934 he and Rudolf Peierls developed a theory of the deuteron, which he extended in 1949. That summer he received a cable from Cornell University offering him an acting assistant professorship.⁠[2][3]

In February 1935 Bethe became an assistant professor at Cornell University and was promoted to professor in the summer of 1937. He remained at Cornell for the rest of his career.⁠[2][1]

In March 1938 the fourth Washington Conference was devoted to problems of stellar energy. That year Bethe showed that fusion powers the stars and proposed two processes by which hydrogen nuclei are fused into helium: the carbon–nitrogen cycle in brighter stars and the proton–proton reaction in the Sun and fainter stars.⁠[3][1][2]

The resulting paper, “Energy Production in Stars,” appeared in Physical Review in 1939 (vol. 55, pp. 434–456) and formed the basis of much work in astrophysics for decades.⁠[3]

In September 1939 Bethe married Rose Ewald, daughter of Paul Ewald; they had a son, Henry, and a daughter, Monica.⁠[3][2]

Bethe became a U.S. citizen in February 1941 and received security clearance that December. During the war he first worked on microwave radar at the MIT Radiation Laboratory and then moved to Los Alamos.⁠[3][2]

A study group at BerkeleyUniversity of California, BerkeleyThe University of California, Berkeley (UC Berkeley) is a campus of the University of California system; the University of California was founded in 1868 through a merger of two institutions and moved to Berkeley, California, in 1873.Open the full entry in the summer of 1942 led to the creation of the Los Alamos laboratory in 1943. As head of its theoretical division, Bethe led the effort to assess theoretically the performance of the designs that became the Hiroshima and Nagasaki bombs.⁠[3]

On July 16, 1945, he witnessed the Trinity test. In January 1946 he returned to Cornell.⁠[4][3]

After the Shelter Island Conference of June 1947, Bethe became the first to explain the Lamb shift in the hydrogen spectrum, laying the groundwork for modern quantum electrodynamics.⁠[3][2]

In 1952 Bethe returned to Los Alamos for half a year. He later opposed nuclear weapons.⁠[2][1]

Bethe was an original member of the President’s Science Advisory Committee and served under Presidents Eisenhower, Kennedy and Johnson; he chaired an interagency panel on detecting Soviet nuclear tests and took part in the 1958 Geneva talks.⁠[3][4]

He championed nuclear arms control, helping to persuade the White House to ban atmospheric nuclear tests in 1963 and antiballistic missile systems in 1972, and later opposed the Reagan administration’s Strategic Defense Initiative.⁠[4]

In 1967 Bethe, of Cornell University, received the full Nobel Prize in Physics “for his contributions to the theory of nuclear reactions, especially his discoveries concerning the energy production in stars.”⁠[1]

On December 11, 1967, Bethe delivered his Nobel Lecture, “Energy Production in Stars.”⁠[6]

Bethe trained graduate students from 1945 until he retired from active teaching in 1975, after which he spent another 30 years at Cornell in retirement.⁠[4][3]

In 1978 Bethe began collaborating with Gerald E. Brown on supernovae in Copenhagen, and the two worked together every January for about 19 years. He also worked with John Bahcall on the solar neutrino deficit, and at 83 apprenticed himself to BrownBrown UniversityBrown University is a private nonprofit research university in Providence, Rhode Island, and a member of the Ivy League. Chartered by Rhode Island's colonial legislature in 1764, it is known for its undergraduate Open Curriculum, which has no common required core. Christina H. Paxson, president since July 2012, announced on August 3, 2026, that the 2026–27 academic year would be her last in office. As of October 1, 2026, the search for Brown's 20th president remained underway.Open the full entry to learn lattice gauge theory.⁠[3][4]

Bethe died at his home in Ithaca, New York, on the evening of March 6, 2005, at the age of 98. At his death he was the J. W. Anderson Professor Emeritus of Physics at Cornell University. He was survived by his wife, Rose, his children, Henry and Monica, and three grandchildren.⁠[1][4]

In 1935 Bethe resolved contradictions in the nuclear mass scale; from 1935 to 1938 he studied the theory of nuclear reactions, predicting many reaction cross sections and developing Niels Bohr’s compound-nucleus theory quantitatively. In the late 1930s he published three review articles in Reviews of Modern Physics that nuclear physicists long used as a textbook.⁠[2]

In atomic and collision physics he wrote a review of atomic physics for the Handbuch der Physik, developed a theory of inelastic collisions used to determine stopping power, and with Walter Heitler calculated bremsstrahlung from relativistic electrons and electron-pair production by high-energy gamma rays.⁠[2]

In solid-state physics he worked on the splitting of energy levels in crystals, the theory of metals and a theory of order and disorder in alloys. From 1955 he returned to nuclear theory, focusing on nuclear matter and on explaining the properties of atomic nuclei in terms of the forces between nucleons. He also worked with many collaborators on the scattering of pi mesons and their production by electromagnetic radiation.⁠[2]

Bethe recruited Richard FeynmanRichard FeynmanRichard Feynman (Richard Phillips Feynman, 1918–1988) was an American theoretical physicist who rebuilt quantum electrodynamics with the path-integral formulation and Feynman diagrams, for which he shared the 1965 Nobel Prize in Physics with Julian Schwinger and Sin-Itiro Tomonaga. He took part in the Manhattan Project during World War II and then taught for decades at the California Institute of Technology, where his introductory physics course became The Feynman Lectures on Physics; in 1986, as a member of the presidential commission investigating the space shuttle Challenger accident, he used ice water to demonstrate that the O-ring lost its resilience at low temperature.Open the full entry and Robert Wilson to Cornell; he and Feynman played a central role in the development of quantum electrodynamics, for which Feynman shared the 1965 Nobel Prize in Physics.⁠[4]

Bethe was elected to the US National Academy of Sciences in 1944 and received the Henry Draper Medal in 1947, the Max Planck Medal in 1955, the Ben Franklin Medal in 1959, the Enrico Fermi Award and the Eddington Medal in 1961, and the Rumford Prize in 1963.⁠[3]

He received the German government’s Order Pour le Mérite for Arts and Sciences in 1984, the Los Alamos National Laboratory Medal and the Bruce Medal in 2001, and, posthumously, the Benjamin Franklin Medal in 2005.⁠[3]

The University of Bristol lists Bethe on its “Nobel Prizes and Fellowships” page among the Nobel laureates connected with the university, recording that he held a fellowship there.⁠[5]