Gregory Breit (Russian: Григорий Альфредович Брейт-Шнайдер, Grigory Alfredovich Breit-Shneider; July 14, 1899, Mykolaiv, Kherson Governorate – September 13, 1981, Salem, Oregon) was a Russian-born American physicist and professor at NYU (1929–1934), U. of Wisconsin–Madison (1934–1947), Yale (1947–1968), and Buffalo (1968–1973). In 1921, he was Paul Ehrenfest's assistant in Leiden.
In 1925, while at the Carnegie Institution of Washington, Breit joined with Merle Tuve in using a pulsed radio transmitter to determine the height of the ionosphere, a technique important later in radar development.
Together with Eugene Wigner, Breit gave a description of particle resonant states with the relativistic Breit–Wigner distribution in 1929, and with Edward Condon, he first described proton-proton dispersion. He is also credited with deriving the Breit equation. The Breit frame of reference is named after him.
In 1934, together with John A. Wheeler, Breit described the Breit–Wheeler process. In 1939 he was elected to the National Academy of Sciences. In April 1940, he proposed to the National Research Council that American scientists observe a policy of self-censorship due to the possibility of their work being used for military purposes by enemy powers in World War II.
During the early stages of the war, Breit was chosen by Arthur Compton to supervise the early design of the first atomic bomb during an early phase in what would later become the Manhattan Project. Breit resigned his position in 1942, feeling that the work was going too slowly and that there had been security breaches on the project; his job went to Robert Oppenheimer, who was later appointed to scientific director of the entire project.
Breit was Associate Editor of the Physical Review four times (1927-1929, 1939-1941, 1954-1956, and 1961-1963).
- Hull, Jr., McAllister H. (October 1983). "Obituary: Gregory Breit". Physics Today. 36 (10): 102–104. Bibcode:1983PhT....36j.102H. doi:10.1063/1.2915289.CS1 maint: Multiple names: authors list (link)[permanent dead link]
- Gregory Breit, nndb biography
- Breit, G., and M. A. Tuve; "A Test of the Existence of the Conducting Layer," Phys. Rev., vol. 28, p. 554, 1926
- Bethe, H. A., and E. E. Salpeter; Quantum Mechanics of One- and Two-Electron Atoms, Plenum Press, 1977, p. 181
- Hughes, Vernon; Iachello, Francesco; Kusnezov, Dimitri (2001). The Gregory Breit Centennial Symposium: Yale University, USA. Singapore River Edge, N.J: World Scientific. p. 9. ISBN 978-981-02-4553-5.
- Weart, Spencer R.; "Scientists with a Secret," Physics Today, vol. 29, 1974, pp. 23-30
- "Press release: Scientists discover how to turn light into matter after 80-year quest". Imperial College London. 19 May 2014.
- National Science Foundation - The President's National Medal of Science