Lincoln Wolfenstein

Lincoln Wolfenstein, an internationally acclaimed Carnegie Mellon University (CMU) professor emeritus, died Friday, March 27 in Oakland, Calif., of cancer. He was 92. Wolfenstein was famous for his theoretical research on neutrino physics, which always connected to experimental observations. He was also a well-known political activist, advocating for the elimination of nuclear weapons, and the use of diplomacy rather than war.

Wolfenstein was born in Cleveland, Ohio on February 10, 1923. He received his Ph.D. from the University of Chicago in 1949 and became a faculty member at CMU, known until 1967 as the Carnegie Institute of Technology. Wolfenstein taught for 52 years at the university until his retirement in 2000. Even after retirement he continued to go to his office in CMU’s Wean Hall almost every day and to teach classes. He also remained active in the international world of physics. Following his relocation to Oakland, Calif., in 2014, he began going to the Lawrence Berkeley Lab weekly until four weeks before his death.

He is best known for his contributions to the understanding of neutrinos, particularly his 1978 article “Neutrino Oscillations in Matter” (Phys. Rev. D17, 2369) which proposed that oscillations of neutrinos in matter would be different from oscillations of neutrinos in a vacuum. Two Russian scientists applied this theory to the problem of missing solar neutrinos. This became known as the Mikheyev-Smirnov-Wolfenstein (MSW) effect in particle physics. This theory has been used by many particle theorists in studying neutrino oscillations for neutrinos travelling through the earth, an essential aspect of recent long-baseline experiments using beams of neutrinos produced by accelerators. These experiments on neutrino oscillations are especially important for testing symmetries such a CP and time-reversal violation.

Wolfenstein was elected to the National Academy of Sciences in 1978. In 1992 he was awarded the American Physical Society J.J. Sakurai Prize for Theoretical Particle Physics for “his many contributions to the theory of weak interactions, particularly CP violation and the properties of neutrinos.” In 2005, with Alexei Smirnov, he was the recipient of the Bruno Pontecorvo Prize, which honors distinguished scientists for the most significant investigations in elementary particle physics.

Wolfenstein was much more than an accomplished scientist. His passion for peace led him to a lifetime of political activism, particularly against the proliferation of nuclear weapons. He argued that no nation should have nuclear weapons in its military arsenal, an argument he made cogently in many articles and in courses that he taught at CMU. He was a founding member of the original Pittsburgh SANE (Committee for a Sane Nuclear Policy) and a member of the Union of Concerned Scientists. In 1986, Wolfenstein was awarded the New Person Award by the Thomas Merton Center in Pittsburgh for his work in pursuit of nuclear disarmament. He led a lifetime of advocating for responsible science as well as for individual rights and liberties.

He devoted himself to teaching courses at CMU, the training of PhD candidates, and helping CMU faculty members, postdoctoral fellows and graduate students in understanding particle theory related to neutrinos and symmetries. He also taught courses at the CMU Osher Lifelong Learning Institute: Evolution of the Universe, The Future of the Earth, and The Future of Nuclear Weapons and Nuclear Power. These courses were based not only on Wolfenstein’s broad experience in particle physics and cosmology, but also on his devotion to working for peace.

The physics community, his students and friends in many nations, will long remember his contributions to particle physics, education, and peace on earth.