Sidney Dancoff

Sidney Michael Dancoff (born September 27, 1913 in Philadelphia , † August 15, 1951 in Urbana (Illinois) ) was an American theoretical physicist.

Dancoff received his doctorate in 1939 with Robert Oppenheimer in Berkeley . When calculating the radiation corrections for the scattering of a relativistic electron in an external Coulomb field in quantum electrodynamics , which he carried out under Oppenheimer based on the work of this and Felix Bloch , he “almost” developed the renormalization method . He was missing a term, which Tomonaga added in Japan in 1948, inspired by Dancoff's work. Together with Richard Feynman and Julian Schwinger , who developed the renormalization theory at the same time (though not directly influenced by Dancoff's work), Tomonaga received the Nobel Prize for it. From 1940 he was an instructor at the University of Illinois at Urbana-Champaign , where he worked with Robert Serber on the theory of nuclear forces. During the Second World War, he worked on the theory of nuclear reactors in the Metallurgical Laboratory of the University of Chicago from 1943 to 1945 , where Enrico Fermi had previously got the first nuclear reactor up and running. The "Dancoff factor", which indicates the geometric effect of the shielding of fuel rods from one another, is named after him. In 1941/2 he was a National Research Fellow and 1950/1 as a Guggenheim Fellow at the Institute for Advanced Study , where he worked with Wolfgang Pauli on the field theory of mesons . After the war he was back at the University of Illinois at Urbana-Champaign, where his best-known work was written in 1950, the introduction of the Tamm-Dancoff approximation in the quantum field theory of mesons independently of Igor Tamm in Russia, who introduced it in 1945.

In the late 1940s he also worked with the biologist and radiologist Henry Quastler (1908–1963) in the cybernetic field. Dancoff's law is named after him: in biological systems the greatest growth occurs with the greatest possible error rate in reproduction that is compatible with survival.

Dancoff, considered one of the most gifted theoretical physicists of his generation, died of cancer at the age of only 37. He was married and had two daughters.

Sidney Drell is one of his PhD students .

References

1. ↑ Year and place of birth according to the membership register of the Institute for Advanced Study. Sometimes 1914 is also given as the year of birth. Exact dates of birth and death according to the tombstone index of Mount Hope Cemetery in Urbana-Champaign, Jewish section. His grave is reburied in Los Angeles.
2. ↑ Biographical information based on the short biography in Enz No time to be brief , Oxford UP 2002, p. 373
3. ^ Dancoff, Physical Review, Vol. 55, 1939, p. 959. According to Silvan Schweber QED and the Men who made it , 1994 and Pais Inward Bound , 1986, p. 455.
4. ↑ In the calculation of the mass renormalization, so that there was no finite result after the renormalization.
5. ↑ Tomonaga said in Mehra (editor) The physicists concept of nature , 1973, p. 404, that without this mistake by Dancoff the history of quantum electrodynamics would have been different
6. ^ Dancoff, Serber Strong coupling mesotron theory of nuclear forces , Physical Review, Volume 63, 1943, p. 143
7. ↑ Dancoff, M. Gainsburg "Surface Resonance Absorption in Closely Packed Lattice" USAEC Report CP-2157, 1944
8. ↑ Physical Review, Vol. 78, 1950, p. 382.
9. ↑ Dancoff, Quastler The information content and error rate of living things , in: Quastler (Editor) Essays on the use of information theory in biology , University of Illinois Press, 1953
10. ↑ Enz, loc. cit.