Jack Steinberger (born May 25, 1921, Bad Kissingen, Germany—died December 12, 2020, Geneva, Switzerland) was a German-born American physicist who, along with Leon M. Lederman and Melvin Schwartz, was awarded the Nobel Prize for Physics in 1988 for their joint discoveries concerning neutrinos.
Steinberger immigrated to the United States in 1934. He studied physics at the University of Chicago, receiving a Ph.D. there in 1948. He was a professor of physics at Columbia University, New York City, from 1950 to 1971, and from 1968 to 1986 he was a physicist at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland.
In the early 1960s Steinberger, along with his Columbia University colleagues Lederman and Schwartz, devised a landmark experiment in particle physics using the accelerator at the Brookhaven National Laboratory, New York. The three reseachers obtained the first laboratory-made stream of neutrinos—subatomic particles that have no electric charge and virtually no mass. In the process, they discovered a new type of neutrino called a muon neutrino. The high-energy neutrino beams that the three researchers produced became a basic research tool in the study of subatomic particles and nuclear forces. In particular, the use of such beams made possible the study of radioactive-decay processes involving the weak nuclear force, or weak interaction, one of the four fundamental forces in nature.