Sidney Arnold Bludman, professor emeritus of physics in the School of Arts & Sciences, died on August 21, 2026. He was 99.

Dr. Bludman was born in New York. He graduated from the Bronx High School of Science in 1943 and attended the City College of New York before transferring to Cornell University, where he earned his bachelor’s degree in 1945 at age 18. He served in the United States Navy at the Naval Ordinance Laboratory from 1945 to 1946; he then earned his master’s degree in physics in 1948 and his doctorate in physics (studying under notable physicist Gregory Breit) in 1951, both from Yale University. 

Dr. Bludman’s teaching career began in 1950 at Lehigh University, but two years later he took a position on the staff of the Lawrence Berkeley Laboratory, where he worked on high energy physics and helped to design an important magnetic spectrometer. He stayed at the laboratory until 1961, when he joined the physics department in Penn’s Faculty of Arts & Sciences (now School of Arts & Sciences) as a professor. He held that position for 37 years until his retirement in 1998. 

During his time at Penn, he conducted research on supernovae and their neutrino signals. Dr. Bludman sent a historic fax from Penn to colleagues at the University of Tokyo about Supernova 1987A, which encouraged the Kamiokande group to detect the neutrino signal from the explosion; this work later contributed to a Nobel Prize-winning project. Other research interests at Penn included covariant field theory, general relativity, properties of ultradense matter, gauge symmetries, and the rapidly accelerating universe. Dr. Bludman was named a fellow of the American Physical Society in 1996.

Dr. Bludman’s work was highly regarded by his peers. In 1956, he won a Gravity Research Foundation award for the essay “On the Existence of Gravitational Insulators.” He addressed the 2004 IAU meeting on the tercentenary of Kepler’s Supernova.  Dr. Bludman was also heavily involved in scientists’ rights, particularly dissidents and refuseniks in the Soviet Union.  In 1984, when the University of Pennsylvania awarded Soviet physicist and human rights advocate Andrei Sakharov an honorary degree, Dr. Bludman wrote the baccalaureate response “The Blessing and the Curse of Science.”

Dr. Bludman is survived by his wife, Ellen Schaffer; his sons, Joel Wittenberg and Lee Bludman; his grandchildren, Evan Schiff, Emily Stearns, Laurie Spiegel, Ruthie Wittenberg, and Rachel Wittenberg; and his two great-grandchildren. 

In lieu of flowers, donations may be made in his memory to the American Physical Society Forum on Diversity and Inclusion, 1 Physics Ellipse Drive, College Park, MD 20740.