(1932–2006), American physicist and Nobel laureate who collaborated in the discovery of the muon neutrino.

Born on Nov. 2, 1932, in New York, N.Y., Schwartz entered the Bronx High School Science at the age of 12, and earned his B.A. (1953) and Ph.D. (1958) at Columbia University. He taught at Columbia from 1958 to 1966. During his time at Columbia, he worked in the field of particle physics (see Elementary Particles; Physics) with two colleagues, American physicists Leon Lederman and Jack Steinberger, using the alternating gradient synchrotron at Brookhaven National Laboratory, in Upton, Long Island, N.Y., to investigate the nature of the neutrino. They produced a neutrino beam, with which they proved that a new type of neutrino—the muon neutrino—existed. Another type of neutrino—the electron neutrino—had already been discovered and a third type—the tau neutrino—was discovered in the 1970s. The muon neutrino—classified as a lepton—forms a pair with the muon, an elementary particle that is heavier than an electron and is electrically charged; their work led to a new way of classifying families of subatomic particles.

Schwartz, Lederman, and Steinberger shared the 1988 Nobel Prize in physics “for the neutrino beam method and the demonstration of the doublet structure of the leptons through the discovery of the muon neutrino.”

Meanwhile, in 1966 Schwartz had moved to Stanford University, where a new particle accelerator was just being completed. He was involved in major particle research projects there. In 1983 his career took a new turn when he became full-time chairman and chief executive of California-based Digital Pathways, Inc., a company specializing in the development and manufacture of protective software for computer systems, which he had founded in the 1970s.

Schwartz returned to Brookhaven National Laboratory in 1991 and became associate director for High Energy and Nuclear Physics. He also taught again at Columbia, from 1994 until 1997, when he retired and moved to Ketchum, Idaho. He died on Aug. 28, 2006, in Twin Falls, Idaho.

See also Atom and Atomic Theory; Particle Accelerators; Particle Detectors.