John N. Bahcall 1934–2005

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Christine Ferrara

John Norris Bahcall, Richard Black Professor of Astrophysics in the School of Natural Sciences at the Institute for Advanced Study in Princeton, N.J., recipient of the National Medal of Science, president of the American Astronomical Society, President-Elect of the American Physical Society, and a prominent leader of the astrophysics community, passed away on August 17, 2005, in New York City. He was 70.

Dr. Bahcall had a long and prolific career in astronomy and astrophysics, spanning five decades and the publication of more than five hundred technical papers, books, and popular articles. Dr. Bahcall came to the Institute in 1968 as a Member. He was appointed to the Faculty in 1971, and had served as the Richard Black Professor since 1997.

Peter Goddard, Director of the Institute, stated, "John Bahcall was a true pioneer in the fields of astronomy and astrophysics. His contributions have had an indelible impact. Always generous with his time, John Bahcall was an inspirational teacher and mentor who shaped the careers of a generation of scientists. His passing is deeply felt at the Institute."

James D. Wolfensohn, Chairman of the Institute's board, stated, "John Bahcall was one of the great treasures of the Institute for Advanced Study. His personal leadership, his professional achievements and his devotion to the Institute made a contribution that helped shape our lives. We loved John and will miss him sorely."

Dr. Bahcall's most recognized scientific contribution was the novel proposal in 1964, together with Raymond Davis Jr., that scientific mysteries of our sun -- how it shines, how old it is, how hot it is -- could be examined by measuring the number of neutrinos arriving on Earth from the sun. Neutrinos are weakly interacting elementary particles that travel at nearly the speed of light. They are produced as byproducts of the nuclear fusion reactions that power stars. Measuring the properties of these neutrinos tests both our understanding of how stars shine and our understanding of fundamental particle physics.

Observations by Raymond Davis Jr. in the 1960s and 1970s revealed a clear discrepancy between Bahcall's predictions, based on standard solar and particle physics models, and what was measured experimentally. This discrepancy, known as the "Solar Neutrino Puzzle," was examined by hundreds of physicists, chemists, and astronomers over the subsequent three decades. In the late 1990s through 2002, new large-scale neutrino experiments in Japan, Canada, Italy, and Russia culminated in the conclusion that the discrepancy between Bahcall's predictions and experimental results required a modification of our understanding of particle physics: neutrinos must have a mass and "oscillate" between different particle states. These results led to the 2002 Nobel Prize being awarded to the leaders of the American and Japanese neutrino experiments, Raymond Davis and Masatoshi Koshiba.

Dr. Bahcall contributed to many areas of astrophysics in addition to neutrino astrophysics, including the study of dark matter in the universe, quasar properties, galactic structure, the evolution of stars, and the identification of the first neutron star companion. His most lasting influence, however, may be the promising young scientists whom he nurtured, and who went on to successful careers and scientific leadership positions in the academic and scientific community. He created the astronomy group at the Institute for Advanced Study, which became the leading training ground in the country for post-graduate researchers. He also helped establish the astronomy groups at the Weizmann Institute and Tel Aviv University of Israel, among others. He derived tremendous pleasure from building a culture and community that attracted, encouraged, and stimulated the best young scientists.

Dr. Bahcall was a powerful driving force in the astronomy and scientific community of the United States. He led the effort to create the Hubble Space Telescope in the 1970s together with Lyman Spitzer; chaired the National Academy of Science committee that created the decade roadmap for U.S. astronomy research, which came to be known as the Bahcall Report; served as President of the American Astronomical Society from 1990-1992 and as president-elect of the American Physical society this past year. He was active in many areas of science policy relating to astronomy and physics, chairing numerous committees of the National Academy of Science, the U.S. National Committee of the International Astronomical Union and the National Underground Science Laboratory Committee, and advising or serving on Congressional committees.

Dr. Bahcall received numerous awards and prizes including the 1998 National Medal of Science from President Clinton; the Hans Bethe Prize of the American Physical Society; the Dan David Prize of Israel; the Gold Medal of the Royal Astronomical Society; the Fermi Award (with Raymond Davis); and the Benjamin Franklin Medal in Physics (with Raymond Davis and Masatoshi Koshiba). He received Honorary Doctorates from University of Pennsylvania, University of Chicago, University of Notre Dame, Hebrew University of Jerusalem, and the University of Milano. He has been a member of the National Academy of Sciences since 1976.

John Bahcall was born in Shreveport, Louisiana, and began his first year at Louisiana State University convinced he wanted to study philosophy and perhaps become a rabbi. He soon decided that physics, and eventually astronomy, best-suited a lifelong "quest for the truth." He transferred to the University of California at Berkeley, where he received his A.B. in 1956. He received an M.S. from the University of Chicago in 1957, and a Ph.D. from Harvard University in 1961. He was a Research Fellow at Indiana University before joining the faculty at CalTech, where he was strongly influenced by leading physics and astronomy luminaries including Richard Feynman, Murray Gell-Man, and William Fowler.

He is survived by his wife, three children and brother Robert. His wife, Dr. Neta Bahcall, is a Professor of Astrophysics at Princeton University. Her work focuses primarily on cosmology. She was elected to the National Academy of Sciences in 1998; they were the only astronomy couple who were both members. His eldest son, Dr. Safi Bahcall, 36, is currently the President and Chief Executive Officer of Synta Pharmaceuticals, a Massachusetts-based biotechnology company developing drugs for cancer and inflammation. He received a Ph.D. in theoretical physics from Stanford University. His second son, Dr. Dan Bahcall, 34, completed his graduate research in cognitive psychology at Rutgers, The State University of New Jersey. His daughter, Dr. Orli Bahcall, 29, is currently an Associate Editor of Nature Genetics, and was a recipient of the Marshall Scholarship. She completed her graduate research in epidemiology at Oxford University and Imperial College, London. John's brother Robert lives in Baton Rouge, Louisiana, with his wife Sandy.

With a scientific mind that delighted in questioning and a spirit of discovery and perseverance, John Bahcall actively continued his research until his final days. He suffered from a rare blood disorder that advanced rapidly. He passed away peacefully in his sleep in New York, surrounded by his family, reiterating his satisfaction at a long and fulfilling life, and telling jokes until the end. He was tremendously loved, admired, and respected, and will be much missed.

A Tribute to John N. Bahcall was held at the Institute for Advanced Study on October 29, 2005. More information may be found here.

To view a letter from the Bahcall family to friends, visit

The family of John Bahcall wishes to have contributions sent to the Institute for Advanced Study for the purpose of endowing four John N. Bahcall Memberships in the School of Natural Sciences. These John N. Bahcall Memberships will recognize the legacy of Professor Bahcall in the training of young scientists.

Gifts to this fund can be sent to:

Institute for Advanced Study

Einstein Drive

Princeton, New Jersey 08540