gĕlˈ-män, 1929–, American theoretical physicist, b. New York City, grad. Yale 1948, Ph.D. Massachusetts Institute of Technology, 1951. In 1953, he and the Japanese team of T. Nakano and Kazuhiko Nishijima independently proposed the concept of "strangeness" to account for certain particle-decay patterns; strangeness became the foundation for later symmetry studies. In 1961, Gell-Mann and Israeli physicist Yuval Ne'eman independently introduced the "eightfold way," or SU(3) symmetry, a tablelike ordering of all subatomic particles analogous to the ordering of the elements in the periodic table. The 1964 discovery of the omega-minus particle, which filled a gap in this ordering, brought the theory wide acceptance and led to Gell-Mann's being awarded the 1969 Nobel Prize for Physics. In 1963, Gell-Mann and American physicist George Zweig independently postulated the existence of the quark, an even more fundamental elementary particle with a fractional electric charge; quarks are confined in protons, neutrons, and other particles by forces associated with the exchange of gluons. Gell-Mann and others later constructed the quantum field theory of quarks and gluons called quantum chromodynamics (QCD). Gell-Mann's interests have extended to the study of complexity, and he is the director of physics at the Santa Fe Institute, which he helped found in 1984. He has written The Eightfold Way in collaboration with Ne'eman (1964), Broken Scale Invariance and the Light Cone with Kenneth G. Wilson (1971), and The Quark and the Jaguar: Adventures in the Simple and Complex (1984).

See biography by G. Johnson (1999).

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