Freeman Dyson, 96, wrestled with questions of physics, morality

Freeman J. Dyson, a mathematical prodigy who left his mark on subatomic physics before turning to messier subjects like Earth’s environmental future and the morality of war, died on Friday at a hospital near Princeton, New Jersey. He was 96.

His daughter Mia Dyson confirmed the death.

As a young graduate student at Cornell in 1949, Dyson wrote a landmark paper — worthy, some colleagues thought, of a Nobel Prize — that deepened the understanding of how light interacts with matter to produce the palpable world. The theory the paper advanced, called quantum electrodynamics, or QED, ranks among the great achievements of modern science.

But it was as a writer and technological visionary that he gained public renown. He imagined exploring the solar system with spaceships propelled by nuclear explosions and establishing distant colonies nourished by genetically engineered plants.

“Life begins at 55, the age at which I published my first book,” he wrote in “From Eros to Gaia,” one of the collections of his writings that appeared while he was a professor of physics at the Institute for Advanced Study in Princeton — an august position for someone who finished school without a Ph.D. The lack of a doctorate was a badge of honor, he said. With his slew of honorary degrees and a fellowship in the Royal Society, people called him Dr. Dyson anyway.

Dyson called himself a scientific heretic and warned against the temptation of confusing mathematical abstractions with ultimate truth. Although his own early work on QED helped bring photons and electrons into a consistent framework, Dyson doubted that superstrings, or anything else, would lead to a Theory of Everything, unifying all of physics with a succinct formulation inscribable on a T-shirt. In a speech in 2000 when he accepted the Templeton Prize for Progress in Religion, Dyson

quoted Francis Bacon: “God forbid that we should give out a dream of our own imagination for a pattern of the world.”

Relishing the role of iconoclast, he confounded the scientific establishment by dismissing the consensus about the perils of manmade climate change as “tribal group-thinking.” He doubted the veracity of the climate models, and he exasperated experts with sanguine predictions they found rooted less in science than in wishfulness: Excess carbon in the air is good for plants, and global warming might forestall another ice age.

In a profile of Dyson in 2009 in The New York Times Magazine, his colleague Steven Weinberg, a Nobel laureate, observed, “I have the sense that when consensus is forming like ice hardening on a lake, Dyson will do his best to chip at the ice.”

Freeman John Dyson was born on Dec. 15, 1923, in the Berkshire village of Crowthorne, England. His father, George Dyson, was a composer and conductor. In the family archives is an unfinished novel Freeman began writing when he was 8 years old about an imaginary expedition to the moon to observe the impending impact of an asteroid. (Later in life he probably would have devised, at least on paper, a means of heading off the celestial crash.) The boy’s reading included, in addition to Jules Verne, nonfiction by James Jeans and Arthur Eddington, British physicists with a flair for popularization and a literary bent.

After finishing high school at Winchester College, where his father taught music, he entered the University of Cambridge, Trinity College, and excelled in mathematics.

Looking for a way to serve the war effort while satisfying his pacifist leanings, he took leave in 1943 to work as a civilian scientist for the Royal Air Force Bomber Command. He was charged with using mathematics to plan more efficient bombing campaigns. Years later, in an interview with the physicist and historian Silvan Schweber, he agonized over what he saw as his own moral cowardice, comparing himself to Nazi bureaucrats “calculating how to murder most economically.”

Excited by the theoretical frontiers opened by wartime research on nuclear fission, Dyson returned to Cambridge and concentrated on becoming a physicist. With a bachelor’s degree in mathematics, he entered the graduate physics program at Cornell in 1947, studying under Hans Bethe, who had been a leader of the Manhattan Project.

It was while touring the United States the following summer that Dyson resolved a pressing problem in theoretical physics.

Richard Feynman, a young professor at Cornell, had invented a novel method to describe the behavior of electrons and photons (and their antimatter equivalent, positrons). But two other physicists, Julian Schwinger and SinItiro Tomonaga, had each independently devised a very different way. Each of these seemed to satisfy the requirements of both quantum mechanics and special relativity — two of nature’s acid tests. But which one was correct?

While crossing Nebraska on a Greyhound bus, Dyson was struck by an epiphany: The theories were mathematically equivalent — different ways of saying the same thing. The result was QED. Feynman called it “the jewel of physics — our proudest possession.”

By the time Dyson published the details in 1949, a doctorate must have seemed superfluous. He was appointed professor of physics at Cornell in 1951. Teaching, he soon realized, was not for him. In 1953, he became a scholar at the Institute for Advanced Study, where he spent the rest of his career.

Dyson did not begrudge Feynman, Schwinger and Tomonaga the Nobel they received in 1965. “I think it’s almost true without exception if you want to win a Nobel Prize, you should have a long attention span, get hold of some deep and important problem and stay with it for 10 years,” he told The Times Magazine in 2009. “That wasn’t my style.”

He preferred to move from problem to problem, both theoretical and practical. In the late 1950s, consulting for General Atomics in San Diego, he helped design the Triga reactor, which is used for scientific research and nuclear medicine, and worked on Project Orion, which aimed to explore the solar system with an enormous spaceship powered by exploding nuclear bombs.

With the signing of the Limited Nuclear Test Ban Treaty of 1963, Dyson’s dreams of reaching Saturn by 1970 were put to rest. Despite his disappointment, he came to support the treaty and, sometimes as a member of Jason, an elite group of scientific advisers, consulted with the government on disarmament and defense.

But his interests were not moored to the earth’s surface. Any advanced civilization, he observed in a paper published in 1960, would ultimately expand to the point where it needed all the energy its solar system could provide. The ultimate solution would be to build a shell around the sun — a Dyson sphere — to capture its output. Earthlings, he speculated in a thought experiment, might conceivably do this by dismantling Jupiter and reassembling the pieces.

Little about the world, profound or mundane, escaped his curiosity. Among his work is a short paper deriving a mathematical equation — beautiful in his eyes — describing the seam of a baseball.

In the late 1970s Dyson turned full force to writing. Anyone with an interest in science and an appreciation for good prose is likely to have some Dysons on the shelf: “Disturbing the Universe,” “Weapons and Hope,” “Infinite in All Directions,” “The Sun, the Genome and the Internet.”

He also entered literature in a different way. He appeared in John McPhee’s book “The Curve of Binding Energy” (1974), a portrait of Ted Taylor, the nuclear scientist who led the Orion effort, and in Kenneth Brower’s “The Starship and the Canoe” (1978). In a memorable scene, Brower wrote of Dyson’s reunion with his son, George, who had turned his back on high technology to live in a treehouse in British Columbia and build a seafaring canoe. George Dyson later returned to civilization and became a historian of technology and an author. Dyson’s daughter, Esther Dyson is a well-known Silicon Valley consultant.

They survive him, as do his daughter Mia; his second wife, Imme Dyson; their three other daughters, Dorothy Dyson, Emily Dyson Scott and Rebecca Dyson; a stepdaughter, Katarina Haefeli; and 16 grandchildren. Dyson’s marriage to the mathematician Verena Huber-Dyson ended in divorce. She died in 2016.