Sheldon Lee Glashow

(b. 1932) American theoretical physicist

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(1932– )

US particle physicist, who shared the 1979 Nobel Prize for Physics with Steven Weinberg and Abdus Salam for his discovery of the charmed quark and the unification of the electromagnetic and weak forces.

Glashow was educated at the famous Bronx School for Science, where he was a classmate of Steven Weinberg. He continued his education at Cornell and Harvard, gaining his PhD there in 1959. After short periods at the Bohr Institute in Copenhagen, CERN in Geneva, and the California Institute of Technology, Glashow spent the years 1961–66 teaching at the University of Stanford and the University of California (Berkeley), before returning to Harvard in 1967 as professor of physics. He has been a member of the science policy committee of CERN since 1979.

In 1964 Glashow postulated the existence of a fourth quark. Murray Gell-Mann, who had introduced the quark concept into physics, had initially recognized three quarks. Glashow, however, was struck by the lack of symmetry between quarks and leptons, as the latter group consisted of two pairs, electron and electron neutrino together with the muon and muon neutrino, interacting with each other through the weak force. If a fourth quark were to be added, a lepton–quark symmetry would result. The fourth quark, given by Glashow a quantum number to represent the property he called charm, was ignored by many physicists as speculative. Confirmation of Glashow's proposal came in 1974 with the discovery of the J particle, whose unexpectedly long life is believed to be due to its composition from a charmed quark and a charmed antiquark.

Glashow's charmed quark also had implications for the work of Weinberg and Abdus Salam, in their attempts to unite the electromagnetic and the weak force. In their original formulation the theory only applied to leptons. Glashow's contribution was to show that it could be applied to all elementary particles.

His publications include over 200 scientific papers and the book Charm of Physics (1990).

Subjects: Contemporary History (Post 1945) — Science and Mathematics.

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