Oscar Wallace Greenberg (born February 18, 1932) is an American physicist and professor at University of Maryland, College Park. He posited the existence of a hidden, 3-valued charge, called color charge, of subatomic particles, ``quarks,'' in 1964, the same year that quarks were posited as constituents of hadrons by Murray Gell-Mann and, independently, by George Zweig.
- 1952 Bachelor's degree, Rutgers University
- 1954 Master's degree, Princeton University
- 1957 Doctorate degree, Princeton University
- 1956 Instructor at Brandeis University.
- 1957 Air Force Cambridge Research Center, 1st Lieutenant, USAF.
- 1959 NSF postdoctoral fellow at MIT.
- 1961 Assistant professor, University of Maryland.
- 1963 Associate professor, University of Maryland.
- Fall, 1964, Member, Institute for Advanced Study.
- 1964 Proposed the existence of color charge.
- 1965-66 Visiting Associate professor, Rockefeller University.
- 1967- Professor, University of Maryland.
- 1968-69 Visiting Professor, Weizmann Institute of Science and Tel-Aviv University.
- 2013- Member of Adjunct Faculty, Rockefeller University.