(p. B12) 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 [February 28, 2020] at a hospital near Princeton, N.J. He was 96.
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As a young graduate student at Cornell University in 1949, Dr. 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.
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Dr. Dyson called himself a scientific heretic and warned against the temptation of confusing mathematical abstractions with ultimate truth.
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Relishing the role of iconoclast, he confounded the scientific establishment by dismissing the consensus about the perils of man-made 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 Dr. 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.”
Dr. Dyson’s distrust of mathematical models had earlier led him to challenge predictions that the debris from atomic warfare could blot out the sun and bring on a devastating nuclear winter. He said he wished that were true — because it would add to the psychological deterrents to nuclear war — but found the theory wanting.
For all his doubts about the ability of mortals to calculate anything so complex as the effects of climate change, he was confident enough in our toolmaking to propose a technological fix: If carbon dioxide levels became too high, forests of genetically altered trees could be planted to strip the excess molecules from the air. That would free scientists to confront problems he found more immediate, like the alleviation of poverty and the avoidance of war.
He considered himself an environmentalist. “I am a tree-hugger, in love with frogs and forests,” he wrote in 2015 in The Boston Globe. “More urgent and more real problems, such as the overfishing of the oceans and the destruction of wildlife habitat on land, are neglected, while the environmental activists waste their time and energy ranting about climate change.” That was, to say the least, a minority position.
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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 Sin-Itiro 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, Dr. 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.”
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Dr. Dyson’s mind burned until the end. In 2012, when he was 88, he collaborated with William H. Press on a paper about the prisoner’s dilemma, a mathematical concept important to understanding human behavior and the nature of evolution.
In his 90s, Dr. Dyson was still consulting for the government — on nuclear reactor design and the new gene-editing technology called CRISPR. In 2018, the year he turned 95, his book “Maker of Patterns: An Autobiography Through Letters” was published.
For the full obituary, see:
(Note: ellipses, and bracketed date, added.)
(Note: the online version of the obituary has the date Feb. 28, 2020, and has the title “Freeman Dyson, Math Genius Turned Visionary Technologist, Dies at 96.”)