Princeton’s James Peebles receives Nobel Prize in Physics

Princeton University professor emeritus and 1962 graduate alumnus James Peebles has been awarded the 2019 Nobel Prize in Physics “for theoretical discoveries in physical cosmology.”

A news conference is planned for 1:30 p.m. today in Richardson Auditorium, Alexander Hall, to be immediately followed by a reception in the Rockefeller College common room.

“This year’s prize goes to contributions to our understanding of the evolution of our universe and Earth’s place in the cosmos,” Göran K. Hansson, secretary general of the Royal Swedish Academy of Sciences said today.

“James Peebles took on the cosmos, with its billions of galaxies and galaxy clusters. His theoretical framework, developed over two decades, is the foundation of our modern understanding of the universe’s history, from the Big Bang to the present day,” the academy said.

Peebles is the Albert Einstein Professor of Science, Emeritus, and professor of physics, emeritus. He shares the prize with Michel Mayor of the University of Geneva and Didier Queloz of the University of Geneva, Switzerland, and the University of Cambridge. The prize amount is 9 million Swedish kroner, or about $908,280, with Peebles receiving half of the award.

“When I started working in this subject — I can tell you the date, 1964 — at the invitation of my mentor, Professor Robert Henry Dicke, I was very uneasy about going into this subject because the experimental observational basis was so modest. … I just kept going,” Peebles said during the Nobel news conference by phone. “Which particular step did I take? I would be very hard-pressed to say. It’s a life’s work.”

Princeton President Christopher L. Eisgruber, who received his degree in physics from Princeton in 1983, praised Peebles’ contributions to the field and generations of students at Princeton.

“Jim Peebles is an extraordinary physicist, a man who has thought deeply and clearly about the structure of the universe,” Eisgruber said. “He exemplifies both Princeton’s dazzling tradition of fundamental research in cosmology and gravitation, and also this University’s commitment to put its best scholars in the classroom. During my own time as a physics major, he was a popular teacher and a fixture in the undergraduate program, and I am among the many students who benefited from his superb instruction.”

The honor “is so appropriate,” said Lyman Page, the James S. McDonnell Distinguished University Professor in Physics. “No one else has advanced our fundamental understanding of the universe more. Multiple of his predictions were shown to be correct through measurements. On top of it, he is uncommonly thoughtful, gracious and kind.”

“It is difficult to overstate Jim’s contributions to humanity’s understanding of our place in the universe,” said Bill Jones, associate professor of physics. “In addition to laying a great deal of the theoretical groundwork for modern cosmology, Jim pioneered many of the methods that have made cosmology a predictive science and one that allows us to test our theories with observational data. Generous to his students and colleagues, I doubt a kinder soul has ever been so recognized. Congratulations, Jim!”

Peebles, born April 25, 1935, in Manitoba, Canada, received his B.S. from University of Manitoba in 1958 and earned his Ph.D. in physics from Princeton in 1962. He taught at the University for his entire career — he was an instructor and researcher in the early 1960s, became an assistant professor in 1965, associate professor in 1968 and full professor in 1972. He transferred to emeritus status in 2000.

The laureate joins a number of other Princeton faculty and alumni who have been awarded Nobel Prizes.

Among his many honors, Peebles received the 2005 Crafoord Prize with fellow Princeton astrophysicist James Gunn, also from the Royal Swedish Academy of Sciences. In 2004 he received the Shaw Prize, and gave this account: “When I started work on cosmology, in the early 1960s, I felt uneasy as well as excited, because the long extrapolation from well-established laboratory results to the physics of our expanding universe was supported by exceedingly limited empirical evidence. I remember thinking I might complete two or three projects in this subject and then move on to something less speculative. That never happened because each project led to ideas for others, in a flow that was too interesting to resist.”

Peebles has published several books on cosmology that are considered classics in the field, and his upcoming book, “Cosmology’s Century, An Inside History of Our Modern Understanding of the Universe,” will come out in June 2020 from Princeton University Press.

Members of the media: If you have a request about the Nobel Prize winner, please send an email to with the words “Nobel Prize” in the subject line. Check the University homepage for updates throughout the day. Images of James Peebles and his C.V. are available for use by media.

This story will be updated throughout the morning.

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