On February 28th this year, the world lost a remarkable scientist, thinker, writer and humanist, and many of us also lost a beloved, generous mentor and friend. Freeman Dyson was one of the last greats from the age of Einstein and Dirac who shaped our understanding of the physical universe in the language of mathematics. But what truly made him unique was his ability to bridge C. P. Snow’s two cultures with aplomb, with one foot firmly planted in the world of hard science and the other in the world of history, poetry and letters. Men like him come along very rarely indeed, and we are unfathomably poorer for his absence.
The world at large, however, knew Dyson not only as a leading scientist but as a “contrarian”. He didn’t like the word himself; he preferred to think of himself as a rebel. One of his best essays is called “The Scientist as Rebel”. In it he wrote, “Science is an alliance of free spirits in all cultures rebelling against the local tyranny that each culture imposes on its children.” The essay describes pioneers like Kurt Gödel, Albert Einstein, Robert Oppenheimer and Francis Crick who cast aside the chains of conventional wisdom, challenging beliefs and systems that were sometimes age-old, beliefs both scientific and social. Dyson could count himself as a member of this pantheon.
Although Dyson did not like to think of himself as particularly controversial, he was quite certainly a very unconventional thinker and someone who liked to go against the grain. His friend and fellow physicist Steven Weinberg said that when consensus was forming like ice on a surface, Dyson would start chipping away at it. In a roomful of nodding heads, he would be the one who would have his hand raised, asking counterfactual questions and pointing out where the logic was weak, where the evidence was lacking. And he did this without a trace of one-upmanship or wanting to put anyone down, with genuine curiosity, playfulness and warmth. His favorite motto was the founding motto of the Royal Society: “Nullius in verba”, or “Nobody’s word is final”.
Many chapters from Dyson’s own life illustrate this spirit of rebellion; some of it was by choice, some by necessity. First was his rebellion from pure mathematics. Dyson had learnt mathematics from G. H. Hardy, a man for whom the purity of mathematics was so sacred that, in a short and beautifully written book, he said he was actually proud of working on things that had absolutely no practical use. Dyson learnt mathematics from Hardy during the cold, dark days of the Second World War, when most of the students at Cambridge University had left to fight and Hardy taught a handful of students including Dyson in his rooms. Decades later Dyson could remember the tired, shrunken figure of Hardy lecturing from his chair, with the 17-year-old occasionally feeling like giving the old man a hug. Hardy imparted Dyson with a genuine love for the beauty of mathematics, and while Dyson worked on an astonishing variety of pure and applied problems during the rest of his life, his first love never left him and he kept coming back to it; when I attended his 90th birthday celebrations six years ago, about a third of the talks were about his occasional escapes into mathematics and the flowers they sprouted in other people’s gardens.
As war raged on the continent, Dyson was once taking a walk with a friend of his, the Indian mathematician Harish-Chandra who later became his colleague at the Institute for Advanced Study in Princeton. Harish-Chandra had started as a physicist, studying under Paul Dirac. Dyson had already started getting a taste of applied mathematics, working for Bomber Command where he was using statistics to figure out the most effective way to bomb Germany into surrender. “I am planning to leave physics for mathematics”, said Harish-Chandra. “I find physics to be unrigorous, messy, elusive”. “Interesting”, replied Dyson. “I am planning to leave mathematics for physics for exactly the same reasons.” Dyson was farseeing, and while mathematics would continue to be a rich source of discoveries, he could see that it was physics that was becoming the most promising discipline then. The atomic bomb, which as far as most people were concerned had won the war, sealed the decision in his mind to become a physicist and told him that physics and America were where the action was.
But Dyson was not even the most unconventional figure in this regard. Right after the war he ran into Francis Crick who had spent a depressing time during the war working on magnetic mines for the British admiralty. He was just then planning to switch to biology and join the famous Cavendish Laboratories where researchers under the physicist Lawrence Bragg were working on deciphering the structures of proteins. Bragg himself was one of the pioneers of x-ray crystallography and had decided to change the Cavendish’s direction, from its early pioneering work in physics under J. J. Thomson and Ernest Rutherford to new research in biology. When Dyson met Crick he explained his decision to switch to biology. Dyson told him biology was interesting but it was too early to be able to make major contributions to it. As Dyson recalled, he was happy that Crick disregarded his advice and went on to become perhaps the most important biologist of the 20th century, not only cracking the structure of DNA but deciphering the genetic code and influencing an entire generation of molecular biologists. I tell these stories to make the point that while Dyson was certainly an unconventional mind himself, it helped quite a bit that he was surrounded by equally unconventional and odd minds during his formative years as a student, people who switched fields with impunity and worked on completely new things. One might in fact argue that Cambridge was then a breeding ground for contrarians; in the next decade or two it would house minds like Thomas Gold, Fred Hoyle, Roger Penrose and Stephen Hawking, all known for the audacity and unconventional nature of their ideas.
This spirit of rebellion stayed with Dyson as he moved to the United States and started his apprenticeship under the tutelage of Hans Bethe, the legendary physicist who won a Nobel Prize for working out how the stars shine and led the theoretical physics division of the Manhattan Project. At Cornell where Bethe held court, Dyson met an even freer spirit, Richard Feynman. Dyson’s great mathematical skills were ideally suited to understand the new realm of quantum electrodynamics which Feynman, wunderkind Julian Schwinger and others were trying to understand. On a cross-country drive which became the stuff of folklore, Dyson had the unique opportunity to hear first Feynman’s version of his theory and then Schwinger’s of his, two versions which seemed irreconcilable. Dyson would show that they were two ways of looking at the same physical reality.
Years later Dyson would write a memorable essay called “Birds and Frogs”: some mathematicians are frogs who like to play in the mud and solve problems, he would say. Others are birds who soar and survey the landscape from a great height. Although he put himself squarely in the camp of frogs, the crucial work he did bridging Feynman and Schwinger’s theories and providing a unified view of quantum electrodynamics made him a bird. Throughout his life he was able to expertly navigate between the two domains.
Dyson was unconventional not just in his science but in his view of the social aspects of science, a view that he applied to himself with abandon. He famously never received a PhD; by that time it had become clear that he did not need one. Without a PhD the prodigy became a professor at Cornell and a fellow of the Royal Society, both before he turned 30. Over the years, dozens of PhD theses would be written based on Dyson’s work, but he would become a sharp critic of the entire system, a view that seems increasingly valid in an age when graduate students and postdoctoral researchers are often regarded as a source of cheap labor to grind out results and papers. Dyson thought that the PhD had become a kind of union card, forcing students and especially women who might want to start a family to spend most of their twenties working on single problems so that they would be deemed worthy enough to join a hallowed guild. It is also unfair to inventors who almost never have a PhD. I have worked with both PhDs and non-PhDs during my career and on balance can say that the non-PhDs have been more approachable, more hardworking and more creative. Unfortunately our research system, both in academic and industry, puts a premier on people having PhDs.
With his lack of a PhD and his disdain for a system that forces both students and professors to spend years working on a problem, Dyson the frog clearly realized that he wasn’t suited to a conventional academic career. But it also made him reassess what his particular strengths were. His great accomplishment had given him an enviable lifetime appointment at the Institute for Advanced Study in Princeton; Robert Oppenheimer who was the director had himself sung Dyson’s praises. For the next seven decades Dyson would become one of the most famous residents of the institute, but even his home institution was not spared from his contrarian take. He always thought the institute was too ivory tower and too much like an alien transplant in America– in contrast Ithaca and Cornell where he had lived before were the real American deal. He also disdained the tribalism among the institute’s mathematicians and their successful efforts to shut down John von Neumann’s computer project, a project which if it had been supported would have put the IAS on the map in the annals of modern computing.
During the early years Dyson kept on working on particle physics which had been his first proving ground, but a high water mark in Dyson’s career as a particle physicist came when he had a fortuitous meeting with Enrico Fermi in Chicago in 1953. Dyson and his students at Cornell were working on some results on particle scattering which seemed to give very good agreement with experiments done by Fermi. Fermi demolished the agreement in one fell swoop, saying that Dyson had neither a consistent mathematical theory nor a clear physical picture to explain the results. As far as the good curve fitting between theory and experiment was concerned, he quoted his friend Johnny von Neumann; with four parameters one can fit an elephant to a curve, with five one can make him wiggle his trunk. The conversation with Fermi, barely lasting fifteen minutes, dashed Dyson’s hopes to be a conventional physicist of high caliber. But his frustration was actually an astute observation and an epiphany: Fermi was the epitome of what a great physicist was supposed to be, combining great facility at experimentation and visualization of the physical picture with an equally good facility at calculation. Dyson’s forte was calculation.
It was partly the meeting with Fermi that convinced Dyson that his great strength was to apply mathematics to diverse problems rather than make great advances in what was then most fashionable in physics. This cleared the way for a remarkable career. His contributions in quantum electrodynamics were important enough, but after that Dyson switched to other fields, in particular condensed matter physics. In this realm his most important contribution concerned a fundamental question that can be asked simply: if most of the atom is empty space, what makes ordinary matter stable? Using a laborious proof that only one who was skilled in the highest realms of mathematical manipulation could muster, Dyson proved that the Pauli exclusion principle which prevents two electrons from occupying the same quantum state essentially keeps electrons apart and makes matter stable. The proof involved pages of hairy mathematics and was improved later by other researchers, but it did demonstrate Dyson’s great strengths as a professional calculator without peer. It also cemented his reputation as someone who would regularly toss gems aside that others would pick up and build into great edifices.
Until then, whatever some of the contrarian turns he took, Dyson was still known primarily as a theoretical physicist working in diverse parts of physics. But it was his work in the 1950s on engineering problems that truly demonstrated not only the scope of his intellect but the wondrous ambition of his ideas. The first engineering project he worked on was to design a nuclear reactor with physicist Edward Teller and others which would be intrinsically safe and “idiot-proof”; the safety in the reactor would have to come not from decisions by the operator but from the laws of physics. This reactor would be designed by collaboration between physicists, chemists and engineers. Dyson had to essentially learn an entire field of engineering, but at that time there were no true experts so the scientists who had gathered in a former red schoolhouse in La Jolla taught each other. The result of their deliberations was the TRIGA, the only nuclear reactor which has made a profit for its company. During TRIGA’s inauguration Dyson got a chance to take a solitary walk on the beach with the great Niels Bohr himself, but Bohr’s famous mumble and soft voice kept Dyson from receiving any enlightenment.
If TRIGA was earth, Project Orion was heaven. Buoyed by the enthusiasm of space travel, nuclear energy and rocketry in the 1950s, a small group of dreamers decided to build a spaceship powered by nuclear bombs. The idea was to sequentially explode bombs at a distance under a pusher plate on a spaceship and let the momentum carry the rocket away at great speed. “Saturn by 1970” was their motto, and it would also be a nice way to get rid of all those dangerous nuclear weapons lying around. Project Orion tested Dyson’s faculties and allowed his imagination to soar like nothing else. Once again we see the scientist as rebel, applying his skills to an audacious idea which had never before been explored and which could lead to a brave new world. The engineers on Project Orion remember being astonished by Dyson’s versatility as they saw a pure theoretical physicist calculate friction coefficients and load ratios, visualizing giant bombs going off under giant spaceships; while the project initially used small, tactical nuclear weapons, Dyson later imagined bigger, fusion-based weapons propelling the craft. A colleague named Brian Dunne captured Dyson’s unique style:
Freeman doesn’t have the Handbuchderphysik, the last-word sort of German precision. He doesn’t have the French quality of slap-dash, a point here well taken but the rest of it wrong. He doesn’t have the stiff British restraint. It’s a style he has developed that’s all his own.
Project Orion came to an end when radioactive fallout became a public concern and the test ban treaty of 1963 banned nuclear explosions in the atmosphere, but it had been a wild ride for this unconventional thinker. It was also an act of rebellion in another regard: ever since he hired him at the institute in Princeton, Robert Oppenheimer had thought that Dyson would continue his work on the purest of fundamental physics that Oppenheimer thought was the only thing worth doing. While forays into other areas of physics and nuclear engineering utilized Dyson’s abilities handsomely, Oppenheimer made it clear that he would not welcome Dyson back if he kept working on these areas for too long. Fortunately Dyson the contrarian found other ways to channel his unique abilities.
One of those ways was to think about communicating with aliens, another mainstay of 1950s and 60s interests. In 1960 Dyson wrote a serious paper in Science describing how an advanced extraterrestrial civilization might be able to disassemble a Jupiter-sized planet and surround itself with its pieces, trapping its parent star’s energy inside and utilizing it. Became these star systems would be cloaked by the shell of the planet’s fragments they would not be visible, but because they trapped energy it would escape as infrared radiation which could be detected. Unusual infrared radiation signatures could therefore be a way to find extraterrestrials. The original idea had not been Dyson’s and had been described by science fiction writer Olaf Stapledon in his story “Star Maker”, but its serious extension became emblematic of Dyson’s originality; take an audacious idea, even one that belongs to the realm of science fiction, and turn it into a serious scientific paper filled with mathematical calculations. Since the 1960 paper was published, Dyson Spheres have become a staple of modern science fiction, even making it into ‘Star Trek’.
The search for life in space was one of Dyson’s enduring interests and it gave voice to his creativity like little else. He disdained ideas like the Drake Equation that relied on highly uncertain armchair speculation without suggesting experiments. Along with Dyson Spheres, he also came up with an idea to find life on Europa by searching for freeze-dried fish in its orbit instead of water under its surface (the logic being that the former, while it sounds outlandish, is much easier to look for than the latter which involves very expensive drilling) and a way to grow giant plants in the reduced gravity of comets. But even assuming that humanity could escape the bonds that have always bound itself to planet earth, how long can life keep this up, this constant hopping around between inhospitable environments?
In Dyson’s view – literally until the end of time. In 1979, he wrote “Time Without End: Physics and Biology in an Open Universe”, perhaps his most audacious serious paper, covering thirteen pages in the distinguished journal Reviews of Modern Physics. In it he argued that living creatures could keep on feeding off dwindling sources of energy in an expanding universe and even keep communicating with each other, although admittedly not in a form that would be easily recognizable to modern day human beings. With this paper, he hoped to “hasten the arrival of the day when eschatology, the study of the end of the universe, will be a respectable scientific discipline and not merely a branch of theology.” Like all contrarians who deal with speculative ideas, Dyson was prepared to accept that this one might be incorrect. In the 1990s a new era in our understanding of the universe dawned when it was found that the expansion of the universe is accelerating. In this universe Dyson’s creatures would be doomed since they would be competing against energy sources rapidly going to zero and distances between galaxies going to infinity. Dyson graciously accepted as much in a new edition of his set of Gifford Lectures, “Infinite in all Directions”, but he still found solace: “If it turns out that we live in a constantly accelerating universe, we may complain that God designed it badly as a home for intelligent creatures, but we can be thankful that he gave us at least a few trillion years to enjoy it before the final darkness falls.”
1979 was also the year when Dyson started a new career, taking a step that is truly contrary for most working scientists. He wrote his autobiography, “Disturbing the Universe”; “Life begins at 55”, he said, because that was when he wrote his first book. Among top scientists there are very few who can write genuinely well, partly because there are very few who are genuinely steeped in both their scientific specialization as well as the broader traditions of literature. Fortunately Dyson’s upbringing had given him a unique facility with both science and the humanities – his mother was a lawyer who fought for women’s rights and his father was Sir George Dyson, one of England’s most well known composers of the time; his parents were highly cultured and socially responsible people, and they endowed Freeman with an unusual sensitivity to human affairs. He himself acknowledged his two strengths as “calculation and English prose”. Transitioning from largely doing hard science to largely doing writing and giving lectures served both Dyson and the world exceedingly well, and by doing this he was following a maxim G. H. Hardy once told him: “Young men should prove theorems. Old men should write books.”
“Disturbing the Universe” remains a remarkable book, filled not only with sharp observations on great scientists like Oppenheimer and Feynman but sprinklings from T. S. Eliot and Blake, full not just of discussions of physics and genetic engineering but reflections on world peace and human nature. It’s perhaps the finest memoir I have read of the scientist as citizen. All of Dyson’s ensuing books have mirrored these themes, combining highly original scientific ideas with meditations on war, peace and human affairs. He always saw people’s flaws astutely, but also saw their greatness and saw how both of these qualities combined to make a complete person. And he was as comfortable discussing minor but enlightening issues of family and friends, as he was the fate of the world. Most of all he cared about his family and was proud of his six children who now have sixteen children in all and are productive citizens.
Even when he was mainly writing books Dyson kept on making strikingly original contributions to science. In a 1999 interview he was asked what he thought would be his most important contribution to science. It would be hard to know until he had been dead for a hundred years, he sensibly said, and added that his son thought his contributions to the origins of life might be most important. Dyson was referring to a slim volume he had just published in which he had made the striking argument that life might have arose twice, once as pure metabolism and once as pure replication. Dyson’s starting point was Erwin Schrödinger’s equally slim book “What is Life?” and a set of lectures on self-reproducing automata that Johnny von Neumann had given in the 40s. Just like Dyson, Schrödinger and von Neumann were physicists and mathematicians who had made a side foray into biology. Just like Schrödinger’s book, Dyson’s book might stand the test of time and turn out to be an unusually important contribution. In fact recent findings of life arising by pure metabolism in hot vents under the sea could well support Dyson’s theories. This was Freeman Dyson at his best, starting multiple lines of research even during a minor trip off the beaten track into a field that he previously knew nothing about.
More original ideas followed including two from 2012 (when he was 89): one arguing that it might be impossible to detect individual gravitons and dissolve the wall between quantum theory and general relativity, and a paper on game theory that upended conventional wisdom in the field. He became somewhat controversial for arguing that extrasensory perception might be real but it may be just outside the bounds of our standard measuring equipment and experiments; I have similar feelings about traditional Chinese and Indian medicine, much of which deals with small but significant holistic effects and differs from person to person and therefore may escape the design of standard double blind clinical trials.
But in the last decade or so of his life, Dyson became most famous in the public eye because of his views on global warming. I regard this entire affair as unfortunate and blown out of proportion, more emblematic of how we have grown increasingly intolerant in recent times than of anything Dyson said or wrote. During my several meetings and email exchanges with him I discussed global warming, and he never denied the basic facts, only the consequences. I always thought that most of his views were valid and were steeped in sound skepticism and humility. He asked if we know for certain how much the good effects of climate change will outweigh the bad, and in particular whether increased CO2 might not be better for the growth of certain trees and for certain cold regions of the planet. He asked if in our zeal to criticize we are not paying attention to technological solutions that might mitigate the problem. Some of his ideas such as genetically engineering trees that might consume more CO2 were speculative, but one could argue that an extraordinary problem like climate change warrants the exploration of extraordinary ideas.
He realized that the climate is a very complex system about which it’s difficult to know everything, especially when computer modeling plays such an important role. There are some components of the climate like wind patterns that are better understood than others like the soil. One reason I very much empathized with him is because I have spent most of my career doing computer modeling on chemical systems much simpler than the climate. These systems often involve only two molecules interacting with each other, and yet we have found out how complicated modeling the action of different components in these systems are; as he and I often discussed, water especially seems to be a diabolical culprit to understand, both in cloud formation and chemical systems. I also found during our conversations that climate change is a minor interest of his, and most of the controversy seemed to be drummed up by others rather than by Dyson himself. Most of all he lamented the intense politicization of climate change that had made reasoned debate very difficult, and I could not agree more. If certain groups of individuals and groups took his views out of context and used them to shore up their own political agenda, it would be unfair to blame him for it.
When I heard about Dyson’s passing I felt devastated. Devastated not only because I had lost someone who I considered to be the biggest intellectual influence on my thinking after my father’s passing a few years ago, but because I wonder if the world is now willing to tolerate the tradition of skepticism and originality that he and fellow scientists he admired exemplified. When I hear people say that he was a contrarian, I think it should be clear that he was always a contrarian and we are all the better off for it. Being a contrarian enriched his life, took him in unexpected directions and uniquely contributed to his dialogue with the world. And if the word “contrarian” means someone who comes up with highly original ideas that challenge the status quo and bucks the trend, then Dyson was a contrarian in the best scientific tradition. He had displayed these qualities all his life, right from his transition to physics as a student to his forays in very diverse branches of science and engineering to his career as a writer of eloquent prose and his commentary on social issues. But if Dyson was the last contrarian it makes him even more unique and we are in trouble.
The reason I worry is that we increasingly seem to live in an age in which contrarian ideas of the kind Dyson exemplified are not just criticized but criticized through a moral lens. Unfortunately social media has wildly exacerbated this trend. Today when you express a contrarian view on social media, not only do people disagree with you and regard you as mistaken but they are also likely to regard you as immoral and even evil. This is a problem, and it’s a problem especially when a minority of people who are actually immoral get their opinions mixed up with those who are arguing in good faith. Moral criticism makes it much harder for individuals to speak their mind compared to criticism of other kinds. Now of course, throughout history moral judgement has been used as a tool for social ostracism, but as long as it did not expose you to the entire world it kept the criticism contained and within bounds. You may have felt a little dissuaded but you could still preach your gospel. Today when anything that you say to a small group of people can reach thousands of people on social media, when the ensuing din hounds you out of the chambers of debate, the scope of moral criticism gets tremendously magnified, magnified to such an extent that it becomes a whirlwind and silences everyone except those with unusually stout hearts.
We must return to an era when disagreements are just that, disagreements in good faith. There is too much at stake in our world today and the problems we are trying to solve are too complex to allow only one set of voices to be heard and opposing ones silenced. And because the problems are so complex, some of us will inevitably be wrong. But that’s how it should be. The best contrarians always realize that they can be wrong – Dyson once said that he would rather be wrong than be vague, and always admitted the former possibility – and it’s precisely that freedom to be wrong, the freedom to be listened to and disagreed with without moral ostracism and outrage that illuminates the path to the truth.
An old voice from Dyson’s past, his mentor Robert Oppenheimer, once said,
“There must be no barriers to freedom of inquiry. There is no place for dogma in science. The scientist is free, and must be free to ask any question, to doubt any assertion, to seek for any evidence, to correct any errors…and we know that as long as men are free to ask what they must, free to say what they think, free to think what they will, freedom can never be lost, and science can never regress.”
I hope that if Freeman Dyson was the great contrarian, he certainly won’t be the last one.