The legendary inventiveness of physicist Freeman Dyson (1923-2020)

Dyson’s brilliance shone through in his formal work and his grand speculations

March 04, 2020
Dyson in 2007. Photo: Wikimedia/Monroem
Dyson in 2007. Photo: Wikimedia/Monroem

When the physicist Freeman Dyson died on 28th February, it suddenly seemed that everyone had a Dyson story to tell. That alone was a testament to both the extraordinary vigour he showed well into his ninth decade, and to his passion for intellectual engagement. My own Dyson story doesn’t reveal any great insight into his mind or character, but it certainly showcases those two attributes of vitality and curiosity. For he was in his 80s when I met him at a conference on synthetic biology (see my report in Prospect, August 2007) in a remote town in Greenland, and he was as keen as the rest of us to take a boat trip around the icebergs under the midnight sun.

These stories also testify to Dyson’s brilliance: if you met him, you didn't forget it. He was one of the last remaining links to the truly legendary figures of 20th-century physics. He worked alongside Albert Einstein at the Institute for Advanced Study in Princeton, where its first director J Robert Oppenheimer appointed Dyson as a visiting member in 1948. Dyson collaborated with Richard Feynman, and the two were good friends. He knew all the giants from the Manhattan Project era, such as Hans Bethe and Edward Teller, although he was also a lifelong opponent of nuclear arms.

Dyson was born in Berkshire to a prosperous family, and was educated at Winchester College, where his father, a composer, was the music instructor. His precocious mathematical talent saw him working on calculations for the Royal Air Force Bomber Command during the war while reading mathematics at Cambridge. In 1947 he went to Cornell University as a graduate student in the physics department headed by Bethe, and he made his career in the United States ever after, becoming a US citizen in 1957.

Much has rightly been made, in the obituaries, of Dyson’s fertile imagination. He speculated about advanced alien civilisations that might construct gigantic structures around their sun to harness most of its energy. The discovery in 2015 of strange, irregular dimming of a star 1500 light years away, as if it was being partly occluded by some unknown obstacle, led to excited and inevitably inconclusive discussion about whether we had found such a “Dyson sphere” (or more properly, a cloud of solar collectors called a Dyson swarm), and thus evidence of intelligent life in the cosmos. He speculated about space colonies built inside hollowed-out comets, where genetically engineered trees could create a breathable atmosphere. He argued that intelligent life might eke out its existence almost forever in a universe that was declining towards a heat death (the loss of any remaining concentrations of energy) by slowing its thought processes to a glacial rate. It was precisely this sort of inventive thinking that got him invited to that Greenland conference: Dyson had no special knowledge of biology, but could be relied on to think about it obliquely and imaginatively.

But all this playful sci-fi speculation creates its own Dyson swarm that partly occludes the real reasons why Dyson was revered by physicists. He played a central part in the development of the theory that explains how light interacts with matter, called quantum electrodynamics. It was for this theory that Feynman won his Nobel Prize in 1965, alongside Julian Schwinger and the Japanese physicist Sin-Itiro Tomonaga. Many feel—and rightly so—that Dyson would have been included too, if the three-person limit on Nobels had not precluded it.

It was to learn about quantum electrodynamics from Schwinger in Michigan that Dyson ended up hitching a ride with Feynman in the summer of 1948. The route, starting in New York state, didn’t make much sense—Feynman was driving to Albuquerque (in the hope of a romantic tryst), thousands of miles from Ann Arbor where Schwinger was lecturing. But Dyson decided to go anyway, partly to see the American west but doubtless partly also to spend time talking to Feynman about physics. The journey, which sealed their friendship, was a classic Feynman experience, a long way from Dyson’s refined English upbringing. During a rainstorm in Oklahoma they ended up discussing quantum electrodynamics in a seedy brothel (that doubled as a motel), and the trip finished in a New Mexico courthouse where the duo had to pay a hefty speeding charge.

Watching Schwinger’s lectures paid off, though. Schwinger had a different approach to quantum electrodynamics from Feynman’s, sharing much in common with Tomonaga’s work. But on the Greyhound bus back east to Princeton, Dyson realised that he could show that all three physicists were basically saying the same thing using different mathematical languages. Dyson’s unification, published in early 1949, was an immense contribution to the field, and probably his most important scientific work.

Feynman and Dyson offered an interesting contrast not just in personality but in scientific style. “While Bethe and Dyson were truly brilliant at calculations,” writes Feynman’s biographer Paul Halpern in his book The Quantum Labyrinth, “they took clear, straightforward steps.” Quoting the mathematician Marc Kac, Halpern says that “Feynman, in contrast, was ‘no ordinary genius,’ but rather, in his seeming ability to pull results out of thin air, ‘a magician of the highest caliber.’” Dyson himself once described a meeting with Feynman at Cornell University: “That afternoon, Feynman produced more brilliant ideas per square minute than I have ever seen anywhere before or since.”

But the truth is that Dyson had no interest in being a magician. He sought clarity and transparency, while Feynman actively cultivated his reputation by seeming to leap to the right answer intuitively. In fact Feynman had developed a shortcut for working out the difficult calculations of quantum electrodynamics, using diagrams that summarised all the different interactions between quantum particles and fields—a trick he didn’t reveal for some time. These so-called Feynman diagrams are one of Feynman’s most famous and enduring contributions—but he developed the rules for using them in discussion with Dyson, and early on both men were given credit for the pictorial method of calculation.

Dyson, like Feynman, liked to celebrate doers over thinkers—he always preferred the concrete realities of astronomy over the abstract mathematical fancies of string theorists, and self-taught amateurs over self-proclaimed experts. But he was much more ready to engage with deep and wide-ranging philosophical ideas, and could write about them beautifully, for example in his 1988 book Infinite in All Directions.

Yet one of the pitfalls of a mind as dazzling as Dyson’s is that you may come to trust your own judgment in areas where you are no longer the expert. Dyson was generally modest, with a commendable readiness to accept the possibility of being wrong—but not, sadly, when it came to climate change. “Environmentalism has replaced socialism as the leading secular religion,” he once complained. For someone so astute and meticulous, his scepticism about global warming surely demands some psychological explanation. He always had a contrarian streak—he entertained the possibility of extra-sensory perception, and he liked to claim that PhDs (he was proud that he did not possess one) were a waste of time.

He was complicated, for sure; stories of his intellectual generosity abound, but he could be snappish and rude too (as I once discovered). But on climate change, Dyson seemed to see what he wanted to and believe what he wanted to—and as a distinguished critic of the consensus, his position did real harm. In 2009 he said of the Greenland visit where I met him that “the people there love [the warming]. The people there hope it continues. It makes their lives a lot more pleasant.” It is dismaying to think that, as we stood before the vast field of ice and witnessed at first hand how it had been retreating for decades—the accelerated warming there now makes some glaciologists fear for the entire ice sheet, the collapse of which would be catastrophic—this was the message Dyson was taking away: if this goes on, Greenland will be a nicer place to live. It was of a part with his overall vision: we’ll be fine in warmer world, where crops will grow better and only the cold places will get hotter, making them more clement.

Perhaps it all comes down to Dyson’s scepticism about Big Science and grand interventions: he was never a fan of the International Space Station or gigantic particle accelerators, which led to some friction with particle physicists. Of course, nothing could be more ironic coming from a man who thought about living inside comets and taming stars. And it’s precisely that kind of grand thinking that we shall now miss.