Field of Science

Freeman Dyson (1923-2020): A personal remembrance

I am terribly, ineffably sad to learn that my longtime correspondent and friend Freeman Dyson has passed on to the ages at age 96. I have written quite a bit about Freeman's science, but above all it's my personal correspondence with him over more than ten years and the wisdom and kindness that he imparted that I will cherish the most and that has left an indelible impression, a profound intellectual influence and, now, a palpable gap in my life. I feel like I have lost a close member of my own family.

No doubt much will be written about this remarkable man who was one of the leading scientific and literary lights of the 20th century. His imagination and contributions ranged over an entire universe of disciplines - pure and applied mathematics, theoretical and particle physics, game theory, nuclear reactor and spaceship design, origins of life, space exploration and astrophysics, genetic engineering - whose only unifying thread seemed to be the diversity of ideas they contained. Most of these he explored in rigorous scientific papers with reams of mathematics; some of these he explored in elegant prose written for the general public. He made groundbreaking contributions to an untold variety of fields, and as evidenced on his 90th birthday celebration, even his "minor" contributions would start ten or twenty year explorations. His many books contain deep humanism and originality and speak to uncommon wisdom, and they introduced an entire generation of non-scientific readers to the wonders of science. For Freeman diversity was the predominant, celebratory feature of the universe and human life.

It seems like only yesterday, but it's been twenty years since I first saw a strange, dusty book in the recesses of the college library titled "Disturbing the Universe", written by an author whose name I had never heard. The book was utterly captivating, and it displayed both a clarity and an eloquence that I had never seen in scientific writing before. Even now it remains one of the best introductions to the mind, life and credo of a working scientist who also embodies unusual humanity and sensitivity to human affairs. In crystal clear prose and often quoting the great poets and writers, Dyson described his journey in physics, engineering, arms disarmament, genetic engineering and other fields. 

But the book is also a portrait gallery of the people he met on his way. Not only did Freeman describe his close association and friendship with many of the greats of physics - Feynman, Oppenheimer, Bethe - but it was also clear that he was part of this rarefied tribe himself. He disagreed with Oppenheimer, proved himself to be Bethe's best student and had a unifying vision of light and matter on a memorable cross-country drive with Feynman. That he was extraordinarily precocious - elected a fellow of the Royal Society and made a professor at Cornell, all without ever having a PhD before he turned 30 - was also obvious. Scientifically he would be remembered most of all as one of the architects of modern quantum electrodynamics and particle physics. It's a measure of the man's achievements that the book was written when he was only 55, so by that time he had already accomplished more than what most brilliant scientists would in their lifetimes.

But there was something else that struck me even when I first read his memoir. This Dyson was not just a brilliant mathematician and physicist but he seemed to have a rarer, more interesting streak: he seemed to actually like saying outlandish things that go against the grain, and he then took them seriously and did calculations on them! He took the idea of extraterrestrial civilizations and humanity venturing into outer space seriously, and he wrote staid scientific papers arguing for life existing limitlessly in an expanding universe. He came up with the idea of Dyson spheres and civilizations disassembling planets to capture energy, and he saw an age when people would genetically engineer their favorite plants and animals in garages. He even suggested that people should seriously investigate extrasensory perception. And he was serious when he helped build a spaceship powered by hydrogen bombs and wanted to be among the first human beings to reach Saturn by 1970.

This was my first taste of what was probably Freeman's most enduring quality: he was a contrarian and a maverick, someone who liked playing the devil's advocate, the guy who always had his hand raised in a room full of nodding heads, not because he wanted to get a rise out of people but because he believed that science best progresses not through consensus but around the edges, when people ask questions. And he played this role throughout his life with such playfulness, warmth and genuine conviction that nobody could ever hate him for it. His favorite motto was the founding motto of the Royal Society - "Nullius in verba", or "Nobody's word is final". It's the founding motto of science itself.

Fast forward to ten years ahead when I was a lowly postdoc in New Jersey. Princeton was only about fifteen miles from where I lived and Dyson worked there. Would he respond to an email? I still remember how, barely an hour after I wrote he responded: "Yes, we can meet in Princeton. I hereby invite you to lunch at the institute. Please call me so we can decide on a date." I had to pinch myself but it was true. A few minutes later I heard his soft, cordial voice on the phone and we had a meeting scheduled.

November 10, 2010: With some trepidation I remember climbing the stairs to his office at the famous Institute for Advanced Study which once housed Einstein, Gödel, Oppenheimer and von Neumann. Inside was an elfin man hunched intently at a computer. "Prof. Dyson", I asked. No response. I asked again a bit more loudly, and the man in the chair jumped two feet in the air: Freeman Dyson's powers of concentration were legendary. 

The next three hours over lunch and in his study were utterly memorable, and it felt like taking a walk through a garden of intellectual treats. I was looking fondly yesterday at some of the notes I took from our meeting (I remember darting to a cafe after leaving and furiously scribbling this down, not knowing whether I would get a chance to meet Freeman again!), and the topics were really all over the place: climate models, water in molecular models, Obama, religion, South Africa's nuclear weapons program, gravitational waves, socialism, gravitons, reading on the Kindle, getting his genome sequenced, memories of physicists Subrahmanyan Chandrasekhar and Frank Yang, education in India, books about World War 2 and poetry. He was interested in every topic, no matter how grand or how mundane, and while he has written about the big picture many times, he has always said that he is first and foremost a problem solver. For me our conversation certainly confirmed Freeman's astonishingly wide ranging mind and interests, but it also confirmed how immensely approachable and down to earth he was, talking to me on at same level as he would to anyone else.

For the next few years, until I moved to California, I had the privilege of meeting him once almost every year. Each time he would invite me to the institute for lunch. Each time the conversation would last at least three hours if not more. Each time it would range over an incredible set of topics. There were clearly a few among these that we both were interested in; among them were the history of physics, good scientific writing and science as a tool-driven revolution. That last topic was of special interest since he had written a book about it and because chemistry is the preeminent example of a tool-driven revolution. Freeman was especially interested in chemistry, and he confessed it was the only discipline whose details he didn't know much about. He would always ask me to tell him what the latest developments were in the world of chemistry, especially protein chemistry.

Both of us shared our skepticism of computer models. He told me about problems with modeling water and clouds in climate models, I told him about problems with modeling water in proteins. He talked about statistical problems in image processing and related data analysis, I talked about similar problems in model validation in chemistry and drug discovery. Climate change was a topic that we sometimes discussed, but contrary to his portrayal in the media, it wasn't one he was very much interested in at all. I know that his skepticism about climate change will be discussed as part of his legacy, but for me it's a dead letter. I never once remember him denying or arguing the basic facts of climate; his objection was to the exaggerated claims, the intense politicization of the topic and the demonizing of those with dissenting opinions even when these opinions mirrored the basic facts but differed in the details. He questioned not the facts but the exact nature of the consequences, and he thought we simply don't know enough to understand the net balance of pros and cons and some humility should therefore be in order. Sadly the reaction his opinions drew from the public only reinforced his beliefs.

Even beyond his versatile mind and diverse interests, Freeman's overriding interest was always in people and this contributed to the kindness and generosity he always showed. I would say that as much as people have praised his brilliant contributions to science, the words "wise", "kind" and "generous" are the ones that have shown up the most in all the internet tributes to Freeman that I have seen. Science and people were certainly the two main themes that we discussed. This human warmth was reflected in his own family: six children and sixteen children, all of whom are accomplished and doing well. His son George who is an especially accomplished thinker and writer sent some of us a picture of Freeman blowing out candles on his 90th birthday celebration, surrounded by doting children and grandchildren. I would discuss my own family with him: I wrote to him when my beloved father very suddenly died and spoke of my father's overwhelming hunger for knowledge, and he told me how he had read William Prescott's account of the conquest of Mexico to his mother when she was old and unable to read and thought that the writing was so vivid that he was convinced Prescott was there. He recollected his visit to Tasmania where he had been to the densest forest he had seen in his life; I sent him some photos from my own trip to Tasmania when I visited my sister. For Freeman, as important as science was, people were the most important, and the overriding feeling he projected was one of optimism, always convinced that the combination of human decency and technology would make life better for everyone.

After I moved to California I continued our email correspondence. I sent him several posts I had written about a variety of scientific topics and he was always appreciative and had interesting things to say in response. The dozens of emails I am looking at now showcase the same wide range of topics that we discussed in person: physicist Patrick Blackett, family, Oppenheimer, religion, artificial intelligence, Hans Bethe, nuclear energy, black holes, more chemistry and more poetry. It's amusing to see how the trail of our emails roughly correlates with the different companies I worked at during the last decade and the kinds of research I did and how Freeman was always interested in knowing more; DNA-encoded libraries at my first company, protein chemistry at my second, more protein chemistry at my third and automated chemistry and robotics at my current one.

Freeman always had a nice, dry sense of humor delivered with incomparable British understatement, once comparing overzealous climate change activists to Tea Party Republicans and another time telling me how quietly reading a book when he was visiting his daughter in San Diego felt like Samuel Butler's memorable sojourn in rural New Zealand, described so well by George Dyson in his book "Darwin Among the Machines". But it was all in good fun. I loved gifting him books on his birthday: among the ones that he told me he enjoyed were Andrea Wulf's excellent biography of Alexander Humboldt, Peter Conradi's biography of poet and solider Frank Thompson, Lynn Eden's "Whole World on Fire" on how nuclear weapons experts exaggerated their need for more weapons by minimizing the effects of fire, and Leroy Hood's autobiography. Among the books he recommended to me and which I enjoyed were Clara Claiborne Park's "The Siege" about raising a child with autism, Albert Hirschman's "Exit, Voice, Loyalty", about individual choices in challenging organizational environments, and Hans Nossack's "The End", about the bombing of Hamburg. There were many others I will value.

The last time I corresponded with him was barely a month ago. I knew that he would visit his daughter in San Diego each winter, and my work would take me to the city often, so I definitely wanted to see him there. A month or so before my trip I got in touch about dates and he told me that he was not visiting this year because of medical reasons. I had an ominous feeling, but he characteristically asked me to send him latest updates on my work and tell him what I thought about software and robotics, which to him were "a bunch of useful tools smothered in public relations hype", a sentiment with which I couldn't agree more. I sent him a long description of the work that I was doing and told him I would love to see him when I am visiting New Jersey later this year. And then yesterday I heard the news. 

Although I feel devastated by the news, I know that Freeman had the kind of long and successful life that most people can only dream of: he made breakthrough contributions to science and technology over a truly vast range of fields, wrote books communicating the wonders of the cosmos to millions of people, raised a doting family including a bevy of grandchildren and traveled around the world, inspiring both extraordinary as well as ordinary people like myself. Although he's the kind of person who it would be convenient to believe is immortal, what more could one ask for from one's life? I was extraordinarily fortunate to know him for as long as I did.

Like most pieces of sad news this one took a day to sink in. This morning when I woke up, after experiencing that familiar, sweet, brief moment when wakefulness has still not found the terrible facts of the world that sleep has mercifully hidden away, it suddenly hit me with a sinking feeling that I’m in a world which doesn’t have Freeman Dyson in it, and I felt profoundly sad. I am terribly sad that he is no longer around and already dearly miss him, but I also despair that the kind of iconoclastic, rebellious, off-the-beaten-path, always hopeful and optimistic thinking he exemplified so well may not be tolerated so much in our society today with its increasing intolerance to dissenting ideas and rash of pessimistic thinking, and this thought makes his life even more precious and his passing consequently much more devastating in my mind. I dearly hope I am wrong, and now it's up to us to carry on Freeman's good work. 

After reflecting a bit this morning I ended up remembering what Freeman always used to say when we were going to meet, well into his nineties - “I look forward to seeing you. Lots to discuss”. So all I can say is please, let’s keep discussing, thinking, exploring. May we all have the enthusiasm and humanity Freeman had for as long as we can, and may we do it the way he always did: with good humor, eloquence and an untiring optimism and belief in the power of technology and individuals to make the world a better place.


  1. Ashutosh, thanks for your engaging, enlightening article, indeed a breeze-through...bringing out FJD's innate virtues, and yes, possibly idiosyncrasies to a casual observer!
    Such stalwarts are immortal!
    Dyson LIVES through his monumental contributions to diversified fields!
    Your article is "must-read" one: both for an aspiring fledgling in Physics as well as a well-established scientist. I had met with him twice...when he honored us by visiting the Parr group and the Physics Department, UNC- Chapel Hill and during the second time right in IAS Princeton! His uncanny knack for things, his convictions and his British accent were evident from his first hand historical account of Physics before abd after World War 2!


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