Symmetry (Physics)

In this interview, Oscar Wallace (Wally) Greenberg recalls his experiences growing up in New Jersey as the child of Jewish immigrants from Eastern Europe and his accelerated education at Rutgers University and Princeton University, where his advisor was Arthur Wightman. He discusses his dissertation called “The Asymptotic Condition in Quantum Field Theory,” postdocs at Brandeis with S. S. Schweber and at MIT with Francis Low, and early work on high-energy limits and the general structure of quantum field theory. He reflects on his landmark proposal that quarks have a three-valued charge, later called color, as well as the delayed acceptance of the idea, his prediction of later measurements of the excited states of baryons, and his propensity not to promote his contributions. Greenberg also discusses his acceptance of a position at the University of Maryland, where he would spend most of his career, as well as visiting appointments elsewhere, and he offers anecdotes about his interactions with J. Robert Oppenheimer and Albert Einstein at the Institute for Advanced Study. The interview concludes with discussions of what remains unknown in particle physics and of cosmology as a “laboratory” with particle energies not available on Earth. A technical addendum to the interview lists 24 of Greenberg’s key contributions to physics.

Interview with David Gross, Chancellor’s Chair Professor of Physics at University of California in Santa Barbara and a permanent member of the Kavli Institute of Theoretical Physics (KITP). Gross begins by describing his childhood in Arlington, Virginia and his family’s later move to Israel. This led to his decision to enroll at the Hebrew University of Jerusalem for his undergraduate studies in physics and mathematics. Gross recalls his acceptance at Berkeley for his graduate studies, where Geoffrey Chew became his advisor. He explains his early interests in strong interactions, quantum field theory, and S-matrix theory. Gross then describes taking a fellowship at Harvard after completing his PhD, where he recalls his early involvement in string theory. He speaks about his subsequent move to join the faculty at Princeton, as well as his introduction to Frank Wilczek, one of his first graduate students with whom he later shared the Nobel Prize. Gross takes us through the discovery of asymptotic freedom, the development of quantum chromodynamics, and the impact these had on the Standard Model. He discusses his decision to leave Princeton for UCSB, where he focused on growing the KITP and securing funding. Gross describes how his research interests have shifted over the years across topics such as confinement, quantum gravity, and more recently back to string theory. Toward the end of the interview, Gross speaks about his work to develop institutes similar to KITP in other countries, as well as his term as President of the American Physical Society in 2019.