Freeman Dyson

Freeman J. Dyson, theoretical physicist and writer, died on February 28 in Princeton at the age of 96.

The following obituary was published by the Institute for Advanced Study, where Dyson was a scholar for more than 60 years:

Dyson generated revolutionary scientific insights, including calculations bridging the quantum and human worlds. His contributions stem from his work in numerous areas, including nuclear engineering, solid state physics, ferromagnetism, astrophysics, biology, and applied mathematics.

“No life is more entangled with the Institute and impossible to capture — architect of modern particle physics, free-range mathematician, advocate of space travel, astrobiology and disarmament, futurist, eternal graduate student, rebel to many preconceived ideas including his own, thoughtful essayist, all the time a wise observer of the human scene,” said Robbert Dijkgraaf, IAS director. “His secret was simply saying ‘yes’ to everything in life, till the very end. We are blessed and honored that Freeman, Imme, and their family made the Institute their home. It will be so forever.”

In 1941, as an undergraduate at Trinity College in Cambridge, Dyson studied physics with Paul Dirac and Arthur Eddington and found an intellectual role model in the famed English mathematician G.H. Hardy, who had previously mentored the mathematical prodigy, Srinivasa Ramanujan. As a mathematician, Dyson published papers on number theory, analysis, and algebraic topology, developing the concept known as “Dyson’s transform” as part of his proof of Mann’s theorem, which serves as a fundamental technique in additive number theory.

During the World War II, Dyson worked for two years as a civilian scientist conducting operations research for the Royal Air Force’s Bomber Command. He then enrolled at Cambridge University and graduated with a bachelor’s in mathematics in 1945.

Dyson was awarded a Commonwealth Fellowship in 1947, bringing him to Cornell University, where he continued to focus his mathematical acumen on theoretical physics, pursuing his graduate work with Hans Bethe and Richard Feynman.

In the spring of 1948, Dyson accompanied Feynman on a fabled cross-country road trip that culminated in one of the most remarkable breakthroughs of 20th century physics. After being steeped in the work of Feynman for months and spending six weeks listening to Julian Schwinger’s ideas in Ann Arbor, Dyson was able to prove the equivalency of their two competing theories of quantum electrodynamics, which describes how light and matter interact. Dyson recalled the moment of discovery as a “flash of illumination on the Greyhound bus.” He had been traveling alone for more than 48 hours, making his way to Princeton to begin his first membership at the Institute for Advanced Study.

The paper outlining Dyson’s discovery was published by The Physical Review in 1949 under the title, “The Radiation Theories of Tomonaga, Schwinger, and Feynman.” While this question was a central problem of physics, the solution was a mathematical one that Dyson was uniquely positioned to solve given his quantitative training. Dyson’s insights — a Rosetta Stone of physics — provided a more precise understanding of subatomic particles consistent with quantum mechanics and special relativity, enabled the first use of Feynman diagrams in calculating scattering amplitudes, and showed how perturbative QED could be logically understood. Shinichiro Tomonaga, Julian Schwinger, and Richard Feynman were jointly awarded the Nobel Prize in Physics in 1965 for their work in this area.

At the invitation of J. Robert Oppenheimer, Dyson joined IAS as a Member in 1948 and stayed there ever since. In 1956, Dyson began a three-year association with General Atomic, where he worked to design a nuclear reactor that would be inherently safe, or, as colleague Edward Teller put it, “not only idiot-proof, but PhD proof.” The TRIGA reactor is still in production today and used mostly by hospitals.

In 1958, he took a leave of absence from the Institute and moved to La Jolla, California to join General Atomic’s “Project Orion,” working with forty scientists to design an atomic spaceship capable of riding a wave of controlled nuclear pulses into deep space. Dyson recalled the fifteen months spent on the short-lived project as “the most exciting and in many ways the happiest of my scientific life.” The ambitious project had once set its sights on “Mars by 1965, Saturn by 1970.”

Dyson was engaged in the public debate regarding the nuclear test ban treaty and whether or not an exception should be made for purposes of experimentation. In 1960, he was elected to the council of the Federation of American Scientists, and selected as its chair two years later. From this post, he became an effective advocate for the creation of the Arms Control and Disarmament Agency, which existed until 1999 when it was merged with the U.S. State Department. Dyson’s work with this newly created agency gave him greater opportunities to examine the potential consequences of a nuclear war. Concluding that further nuclear testing was “wrong technically, wrong militarily, wrong politically, and wrong morally,” Dyson testified before the U.S. Senate in favor of the nuclear test ban treaty in 1963.

Dyson continued to educate the public on important questions of science, becoming a highly sought-after lecturer and frequent contributor to popular scientific publications on a wide variety of topics, including the relation of science to religion, the prospective colonization of the solar system, harnessing the energy of stars, and climate change.

Dyson produced a steady stream of books geared for the scientifically curious among the general public, beginning with Disturbing the Universe (1979) and ending with Maker of Patterns (2018), which is an autobiographical account of Freeman’s life through letters written to his parents.

For his contributions to science, mathematics, and public policy, Dyson has been honored with over 20 honorary degrees and has been elected to numerous learned societies.


Constance Greiff, 90, on March 1. A prominent Princeton architectural historian and a pioneer of the historic preservation movement in the U.S., she co-authored “Princeton Architecture: A Pictorial History of Town and Campus” and “Morven: Memory, Myth and Reality.” She is also the author of several other important books, including “Lost America: From the Atlantic to the Mississippi,” “John Notman, Architect,” “Independence: The Creation of a National Park,” “Robert Smith, Architect, Builder, Patriot.” For more on Greiff, see U.S. 1, May 27, 2015.

Goro Asato, 88, on February 26. He worked for the American Cyanamid Company for 33 years.

Mary Jane Groh, 89, on February 26. She retired from Applied Data Research in Princeton and then worked for NJ Manufacturers Insurance.

John P. Carroll, 75, on February 27. He was an electrical engineer for Sarnoff Research in Princeton for 40 years.

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