# A ‘Rebel’ Without a Ph.D.

A conversation with the mathematical physicist Freeman Dyson on quantum electrodynamics, climate change and his latest pet project.

Illustration by Robbert Dijkgraaf

Video: “I had this skill with mathematical tools, and I played these tools as well as I could just because it was beautiful,” said Freeman Dyson in a wide-ranging interview.

Freeman Dyson — the world-renowned mathematical physicist who helped found quantum electrodynamics with the bongo-playing, Nobel Prize-winning physicist Richard Feynman and others, devised numerous mathematical techniques, led the team that designed a low-power nuclear reactor that produces medical isotopes for research hospitals, dreamed of exploring the solar system in spaceships propelled by nuclear bombs, wrote technical and popular science books, penned dozens of reviews for The New York Review of Books, and turned 90 in December — is pondering a new math problem.

“There’s a class of problem that Freeman just lights up on,” said the physicist and computational biologist William Press, a longtime colleague and friend. “It has to be unsolved and well-posed and have something in it that admits to his particular kind of genius.” That genius, he said, represents a kind of “ingenuity and a spark” that most physicists lack: “The ability to see further in the mathematical world of concepts and instantly grasp a path to the distant horizon that’s the solution.”

“I’m not a person for big questions. I look for puzzles. I look for interesting problems that I can solve.”

Press said he’s posed a number of problems to Dyson that didn’t “measure up.” Months and years went by, with no response. But when Press asked a question about the “iterated prisoner’s dilemma,” a variation of the classic game theory scenario pitting cooperation against betrayal, Dyson replied the next day. “It probably only took him a minute to grasp the solution,” Press said, “and half an hour to write it out.”

Together, they published a much-cited 2012 paper in the Proceedings of the National Academy of Sciences.

The next year, Press traveled to Princeton, N.J., for a two-day celebration of Dyson at the Institute for Advanced Study, Dyson’s intellectual home for the past six decades. In honor of Dyson’s 90th birthday, there was seemingly boundless cake, a forest of long, white candles, 350 guests — including his 16 grandchildren — and lectures recognizing his eclectic achievements in math, physics, astronomy and public affairs. H. T. Yau of Harvard University commenced the math section, launching into Dyson’s work on the universality of random matrices. George Andrews of Pennsylvania State University and Kathrin Bringmann of the University of Cologne followed with the implications of Dyson’s early contributions to number theory, which he began contemplating in high school. William Happer, a physicist at Princeton University and a fellow skeptic of the perils of anthropogenic climate change, closed day one with a talk provocatively titled “Why Has Global Warming Paused?”

Courtesy of the Dyson Family Collection

Dyson’s unfinished science fiction story, “Sir Phillip Roberts’s Erolunar Collision,” written in the early 1930s when he was 8 or 9.

Dyson admits to being controversial when it comes to climate science. But during an hour-long interview with Quanta Magazine in December, he said: “Generally speaking, I’m much more of a conformist.” Still, he has written fondly of science as an act of rebellion. In his 2006 anthology of essays and reviews, “The Scientist as Rebel,” Dyson writes, “I was lucky to be introduced to science at school as a subversive activity of the younger boys.” With characteristic concern for social issues, he goes on to advise parents: “We should try to introduce our children to science today as a rebellion against poverty and ugliness and militarism and economic injustice.”

On the second day of the 2013 celebration in Princeton, after numerous speakers had recounted past collaborations with Dyson, alternately feting and roasting his brilliance, Press took a different tack. Referring to their collaboration on the prisoner’s dilemma, Press — a professor at the University of Texas, Austin — said he “thought it would be a little extreme to reminisce with Freeman about a paper that was just published.” Instead, he described his own recent result on safer “adaptive” clinical trials, adding that although he had solid computational data, the mathematical analysis proved too formidable. “I wish I had worked on it with Freeman — and maybe still will get the chance to do so,” he said slyly.

Press’ comment proved prescient. After the celebration, Dyson began mulling over the problem — unbeknownst to Press, who didn’t find out until Quanta contacted him in March about the new “collaboration.” “I’m glad to know it’s on his stack of things to do!” he said. “I’m looking forward to seeing what he comes up with.”

Quanta Magazine interviewed Dyson at the institute, just days after his 90th birthday. An edited and condensed version of the conversation follows.

QUANTA MAGAZINE: Technically, you retired from the Institute for Advanced Study 20 years ago. What are you working on now?

FREEMAN DYSON: I used to be a scientist and did a lot of calculations. It was a competitive world, and when I got older, I decided I wouldn’t compete with the bright, young people anymore, so I write books instead. And now I’ve become a book reviewer for The New York Review of Books. About once a month, I write a review, and then I get a lot of response and correspondence, people who are finding things I said which aren’t true.

What did you do prior to writing book reviews?

I was trained as a mathematician, and I remain a mathematician. That’s really my skill, just doing calculations and applying mathematics to all kinds of problems, and that led me into physics first and also other fields, such as engineering and even a bit of biology, sometimes a little bit of chemistry. Mathematics applies to all kinds of things. That’s one of the joys of being a mathematician.

Why math?

I think the decisive moment was reading the book “Men of Mathematics” by Eric Temple Bell. Bell was a professor at Caltech, and he wrote this book, which is actually just a wonderful collection of biographies of mathematicians. Historians condemn it as romanticized. But what was wonderful about this book is that he showed the mathematicians as being mostly crooks and people of very mixed kinds of qualities, not at all saints, and many of them quite unscrupulous and not very clever, and still they managed to do great mathematics. So it told a kid that “if they can do it, why can’t you?”

What are some of the big questions that have guided your career?

I’m not a person for big questions. I look for puzzles. I look for interesting problems that I can solve. I don’t care whether they’re important or not, and so I’m definitely not obsessed with solving some big mystery. That’s not my style.

What kinds of puzzles first intrigued you?

I started out as a pure mathematician and found problems that just arise out of the very nature of numbers, which are amazingly subtle and difficult and beautiful. That was when I was about 17 or so, just at the end of high school. I was interested in numbers before I was interested in the real world.

“I translated Feynman’s ideas into mathematics so it became more accessible to the world, and, as a result, I became famous.”

What is it about numbers that made you want to figure them out?

It’s just like asking, “Why does a violinist like to play the violin?” I had this skill with mathematical tools, and I played these tools as well as I could just because it was beautiful, rather in the same way a musician plays the violin, not expecting to change the world but just because he loves the instrument.

You’re known for your work in quantum electrodynamics — which describes interactions between light, matter and charged particles — and in solving the renormalization problem — which helped rid the mathematics of unwanted infinities. How did that work come about?

When I arrived in Cornell in 1947, there just had been done a beautiful experiment at Columbia on the hydrogen atom. The hydrogen atom is the simplest atom, and you ought to be able to understand it if you understand atoms at all. So, these experiments were done by Willis Lamb and his student Robert Retherford at Columbia, observing for the first time the very fine behavior of hydrogen using microwaves to examine the hydrogen atoms, and Lamb got very precise results. The problem was the quantum theory wasn’t good enough to explain his results. Dick Feynman, who was an absolute genius, had understood more or less how to explain it but couldn’t translate his ideas into ordinary mathematics. I came along and had the mathematical skill, making it possible to calculate precisely what the hydrogen atom was doing, and the amazing thing was that my calculations all agreed with the experiment, so it turns out the theory was right.

I didn’t invent anything new — I translated Feynman’s ideas into mathematics so it became more accessible to the world, and, as a result, I became famous, but it all happened within about six months.

Did it lead to other questions that you wanted to explore?

I got job offers from everywhere in America and also in England, but the problem was that I didn’t actually want to settle down yet and become an overburdened professor with lots of students. So I escaped to England and had two happy years at Birmingham without any responsibilities and continued working on other problems.

I was very much interested in space travel, and so the next exciting thing I did was to work with a company in California called General Atomics for a couple of years building a spaceship. In those days, people were willing to take all kinds of risks, and all kinds of crazy schemes got supported. So there was this bunch of crazy, young people — the leader was Freddie de Hoffmann, who had been at Los Alamos [National Laboratory] and knew all about nuclear bombs — and we decided we would go around the solar system with a spaceship driven by nuclear bombs. We would launch the ship into space — “bomb, bomb, bomb, bomb,” about four bombs per second — going up all the way to Mars and then afterwards to Jupiter and Saturn, and we intended to go ourselves.

George Dyson

Freeman and Imme Dyson traveled to the Baikonur Cosmodrome in Kazakhstan in March 2009 for Charles Simonyi’s second trip to the International Space Station.

What happened to Project Orion?

I spent two wonderful years in San Diego having grand dreams of spaceships. We not only did calculations, we also flew little models about a meter in diameter with chemical explosives, which actually went “bomb, bomb, bomb, bomb” a few times a few hundred feet up. It was amazing we never got hurt. I think we didn’t even have to buy the explosives. We had some Navy friend who stole it from the Navy. Anyhow, we certainly borrowed the test stand from the Navy where we did these little flight tests. That lasted for two years. By that time, it was clear that the competition was actually going to win, the competition being Wernher von Braun and the Apollo program, which was going to go with ordinary rockets to the moon.

The Orion spaceship sounds like something a child might dream up. How disappointed were you that this “grand dream” wasn’t realized?

Of course we were very disappointed when it turned out that the Orion never flew, but it was clear that it would make a horrible mess of the landscape. These bombs were producing radioactive fallout as they went up through the atmosphere, and although at that time we were exploding bombs in the atmosphere for military purposes, which were much bigger than the ones we proposed to use, still we would have made a contribution to the general contamination, and that was the reason why the project failed, and I think it was a good reason.

You’ve developed a reputation as a maverick scientist with contrarian views. Where do you think that comes from?

I think the notion that I always like to oppose the consensus in science is totally wrong. The fact is there’s only one subject that I’ve been controversial, which is climate. I spend maybe 1 percent of my time on climate, and that’s the only field in which I’m opposed to the majority. Generally speaking, I’m much more of a conformist, but it happens I have strong views about climate because I think the majority is badly wrong, and you have to make sure if the majority is saying something that they’re not talking nonsense.

With a majority of scientists on the other side of this issue, what would it take to convince you to switch sides?

What I’m convinced of is that we don’t understand climate, and so that’s sort of a neutral position. I’m not saying the majority is necessarily wrong. I’m saying that they don’t understand what they’re seeing. It will take a lot of very hard work before that question is settled, so I shall remain neutral until something very different happens.

You became a professor at Cornell without ever having received a Ph.D. You seem almost proud of that fact.

Oh, yes. I’m very proud of not having a Ph.D. I think the Ph.D. system is an abomination. It was invented as a system for educating German professors in the 19th century, and it works well under those conditions. It’s good for a very small number of people who are going to spend their lives being professors. But it has become now a kind of union card that you have to have in order to have a job, whether it’s being a professor or other things, and it’s quite inappropriate for that. It forces people to waste years and years of their lives sort of pretending to do research for which they’re not at all well-suited. In the end, they have this piece of paper which says they’re qualified, but it really doesn’t mean anything. The Ph.D. takes far too long and discourages women from becoming scientists, which I consider a great tragedy. So I have opposed it all my life without any success at all.

Verena Huber-Dyson

In the summer of 1955, below Yosemite Falls in California.

How is it that you were able to escape that requirement?

I was lucky because I got educated in World War II and everything was screwed up so that I could get through without a Ph.D. and finish up as a professor. Now that’s quite impossible. So, I’m very proud that I don’t have a Ph.D. and I raised six children and none of them has a Ph.D., so that’s my contribution.

I’ve now been active for something like 70 years, and still I use the same mathematics. I think the main thing that’s changed as a result of computers is the magnitude of databases. We now have these huge amounts of data and very little understanding. So what we have now — I forget who it was who said this — are small islands of understanding in a sea of information. The problem is to enlarge the islands of understanding.

What scientific advance do you see on the horizon that will have a big impact on society?

People are often asking me what’s going to happen next in science that’s important, and of course, the whole point is that if it’s important, it’s something we didn’t expect. All the really important things come as a big surprise. There are many examples of this, of course, dark energy being the latest example. Anything I mention will be something that, obviously, is not a surprise.

“The Ph.D. takes far too long and discourages women from becoming scientists, which I consider a great tragedy.”

Are you currently working on a math problem?

The question of what I do with my time is a delicate one. I’m not really doing science competitively, but I like to have a problem to work on. I’m very lucky to have a friend, Bill Press, who is an expert on clinical trials, which actually turns out to be an interesting mathematical problem.

He published a paper explaining how to do clinical trials in a really effective way with a minimum loss of life. He’s a computer expert, so everything he does is worked out just with numbers, and so I have taken on as my next task to translate what he did into equations, the same way I did with Feynman. I’m not sure whether it will work, but that’s what I’m thinking about at the moment.

What does it mean for someone with so many intellectual pursuits to be retired?

When I retired as a professor of the institute, I kept all the privileges. The only thing that changed is the paychecks stopped coming. I still have an office and all the secretarial help I need, plus a place at the lunch table. One more advantage is not having to go to faculty meetings.

• orbiters says:

Thank you for this video interview of one of our times greatest thinkers. Freeman Dyson is a classic. The shot of him eating his lunch, alone, in the cafeteria is both brilliant and very moving.

• LL says:

Many people can sing or play a musical instrument without knowing how to read music scores. They say they do no know music theory. The fact is, however, that music theory lives in them. They are practicing the music theory without being aware of it. Music scores, like mathematical notations, formulas and equations, are but tools to help people express in tangible terms the beauty and harmony found in nature. Such tools or “languages” make understanding, communication and collaboration possible. They are the very reason for the continuity and great advances in science we have been witnessing. Hats off to Freeman Dyson for applying his talents to solving scientific problems, and sincere thanks to him for sharing his experience and views in this interesting interview, which may serve as an inspiration to many a budding scientist or mathematician.

• Freeman Dyson had more to say about Project Orion elsewhere. In last year’s January issue of National Geographic Magazine, he said a few words about how it could be adapted to send probes to nearby stars at about 3% of the speed of light, so that a probe could reach the Alpha Centauri system in about a century. He had quite a lot more to say about this in:

“Interstellar Transport,” Physics Today, October 1968, pp. 41-45.

He even gave cost estimates of two different models, in 1968 dollars, and remarked:

Nobody in his right mind would consider building such ships at a time
when our Gross National Product is only a few times the cost of one of them.
But if we are thinking on a time scale of centuries, our GNP is far from a fixed
quantity. Presumably the human race will either destroy itself or continue
its economic growth at something like its present rate of 4% per year. If we
destroy ourselves, space ships are not going to be of interest to the survivors
for quite some time. If we continue our 4% growth rate we will have a GNP a
thousand times its present size in about 200 years. When the GNP is multiplied
by 1000, the building of a ship for $10^11 will seem like building a ship for$10^8 today. We are now building a fleet of Saturn V which cost about \$10^8
each.

Saturn V’s were built at the rate of about one a year, which was only part of NASA’s annual budget. This budget in turn was only a small fraction of the defense budget for those years.

Since we are in the midst of a slowdown of our economy, the 4% rate would at first seem to be negative. But if space travel picks up once again, which it might for a number of reasons, we can expect our moon, and some asteroids, to be mined for their minerals (and water, for the more distant ones), thereby greatly increasing the resources at our disposal, and we might be back on track for that 200 year figure.

• I’m new to the editing quirks of this website, so let me say that the quote from Dyson is all in one long paragraph. Also, the word “negative” in the last paragraph should read “overoptimistic.”

• Howard Handlen says:

Dyson’s greatest contribution to the world may well be his ability to convey what pleasure thinking, particularly about science, can be to people who think just the opposite. Famous as he is for translating Feynman’s thinking into mathematical language, he ought to be even more so for the greater feat of translating mathematics into ordinary language.

• Gordon Danning says:

Interesting article, but it includes an error in the caption to the picture of Yosemite Falls — they are not in Tuolumne Meadows

• thomas says:

@Gordon: Thank you for pointing out the mistake in the caption. It has been fixed.

Thomas Lin, Quanta Magazine

• Stew says:

Lovely. Only thing is: Tuolumne Meadows is above Yosemite Falls. What’s below the Falls is Yosemite Valley.

• roger desmoulins says:

George Dyson, Freeman’s father, was a fair classical composer in his day.
Freeman Dyson is one of the great minds of our era. I thought he was a physicist by training, not a mathematician. His level of intellectual activity, given that he just turned 90, is utterly astounding.
I agree that the scientific foundation of modern medicine leaves a great deal to be desired.
Dyson’s first marriage did not work out well. His daughter Esther, of Release 2.0 fame, has never married. Hence I was astounded to read that he has 18 grandchildren.

I agree that we should curb our emission of warming gasses into the atmosphere. But the easiest way forward here is more nuclear power in the first world. Next is to do our town driving in battery powered cars that recharge from the grid at night. That said, I find the scientific methodology and integrity of global warming enthusiasts deplorable in the extreme. They have done things which, by rights, should by now have completely discredited the global warming Cassandras. I respect Freeman for standing up to them.

Regarding global warming it seems really apparent to me that Freeman’s position is very sensible. That’s not to say we shouldn’t take steps to address pollution and energy, only that the certitude of the global warming is problematic. Freeman says “they don’t understand what they’re seeing.” To me that is a humble and legitimate position. People don’t like uncertainty, so they manufacture certitude. You see it all the time in science, medicine, etc… Premature certainty. There isn’t even truly good evidence that sodium is a risk factor for high blood pressure. It may be, but he evidence is weak.

• John Blake says:

Re global warming, spot on. Computerised projections of future conditions (climate, stockmarkets…) seem to disable people’s critical faculties.

• Thomas Cliff says:

The data supporting global warming seems to be increasing, matching the past century’s radically increasing amounts of heat retaining CO2. Nuclear fission power adds heat and hot piles of plutonium, so it should be untouchable. Solar, wind, and tidal power with storage into compressed gas seems the safer path overall without adding heat beyond that received from the sun. Carbon burning into CO2 needs to stop…save it for making recyclable plastics or carbon fiber. But if the Earth is hit by a comet that we can not divert in time, the present climate change will be insignificant.

• peter hoffman says:

Dyson has made extremely important contributions to science and mathematics.

To my mind it is a shame that his ‘climate’ position (2nd quote below) may not be well understood, or at least is not accurately portrayed by the unreasonable, even dangerous, ‘denyers’, who would like to use his scientific prestige to their advantage.

As for the quotes, here are two of his from the interview, with only one other sentence between them:

“…I think the majority is badly wrong,…”

“I’m not saying the majority is necessarily wrong. ”

His position cannot be both. It seems far more likely to be the second, despite the ‘denyers’ being far more likely to quote the first, and give no context.

On a different aspect, it is quite amusing to see the contrast in enthusiasm for giving regular lectures to undergraduates, between Dyson and Feynman, with both being famous for many things, but quantum electrodynamics being the biggest one in both cases.

• None says:

Dyson’s position on climate science makes no sense. If no-one knows anything about the climate, he can’t say that the majority is wrong, unless all he means is that they’re wrong to think they know anything. But to say no knowledge of the climate is possible at all is just silly.

• Cathal says:

Agreed with “none”, Dyson’s comments on climate change are nothing but confusing. He seems to consistently change his position. He says here that the majority is both badly wrong, and not necessarily wrong.

He also says “What I’m convinced of is that we don’t understand climate” yet said elsewhere that measurements “transformed global warming from a vague theoretical speculation into a precise observational science”. Yet again elsewhere: “[m]y objections to the global warming propaganda are not so much over the technical facts, about which I do not know much, but it’s rather against the way those people behave and the kind of intolerance to criticism that a lot of them have.” So it’s both a precise science and we apparently know nothing, and Dyson both does not know the technical facts but is convinced we don’t understand climate. This is all very confusing

• Robert Twizell says:

The last few posters have just proven that if you take a person’s comments out of context and mix them all together you can discredit them by making an ad-hominem argument that said person is confused. Nice try, attacking the speaker is one of the rhetorical methods of the empirically bereft.

In fact if you read all the statements in context they are consistent, as one would expect from the statements of a mathematician of Dyson’s calibre.

For example, while our ability to measure variables of the climate is becoming increasingly precise we only have that accurate measurement for a small time period in the history of the global climate. Hence it is possible for climate research to both be ‘precise’ and ‘observational’, but for us not to understand climate as such understanding is concerned with what sense we can make of the data.

Critical reading of Freeman Dyson’s statements as in this example (even in interview texts which may not be verbatim) reveals that they are broadly consistent. Wilfully characterising his statements as confusing and inconsistent simply reveals that his attackers have an ideological rather than a scientific argument.

Like many scientists Dyson has sensed a ‘bad smell’ in climate science. For someone of his calibre this intuition is important and we should all take notice of what he is saying because ‘crying wolf’ has consequences. If as a result of the last 20 years of political interference in climate science we alienate the public, as has already happened to a large degree, then it will be that much harder to convince them if and when the theory of catastrophic anthropogenic climate change is proven.

• david joyner says:

Thanks for the well-done interview with Dyson. Excellent cinematography and editing, too.

• Linda says:

In claiming that climate scientists “don’t understand climate” and so (he seems to be implying) can’t make reliable predictions, Dyson is making an elementary error. An example should make the point clear. I don’t understand how my computer works (electronics not being my field). But I can predict – with complete confidence – that if I hit it very hard with a hammer it will stop functioning.

• Eduardo says:

Simply , cool, amazing
Thanks!

• Gustavo says:

Good interview. Talking about space travelling. I have the impression america is laging in many aspects with Russia. The space station can not survive without the Russian module anf they plan to detach and that is the end of us presence in space. Wow!! Look at the usaf, compromised with an f35 that hardly flies. Compare that with the Russian Sukoi t50 that blows the socks out of everyone. Lockheed martin is an ill partner to the usa Space and air force. But who else we turn to?

• Prof.N.Ram says:

Whether you need a PhD to pursue research or you do research and end up with a Ph.D is time, space and environment dependent event. An orderly way to learn is to go through formal knowledge about the physical world, mental world and so on and suddenly discover you have a deep interest in a particular area of knowledge. So, Why-What and How can come to inquisitive and creative people at any time in their life. A Ph.D certifies that you are capable of taking up a problem in fundamental field (not the applied field which is after the fact learning) and come up with solution(s). This makes your thinking an orderly continuous development (if you are financially, emotionally and maritally lucky) and move on to invent more things. Interdisciplinary training and finding a mentor is all it takes to become a deep thinker and inventor. Ability to transform from physical-bilogical- metnal domain to move to abstract well defined mathematical domain needs inspiration, some event to trigger the quest for asking “Why”. Very few reach that level. Most are happy to be mediocre in their life and accept it as their limitation and fear of failure is the brake.
So, what Mr. Dyson did is a wonderful journey and bless his heart and interest to invent mathematical models extremely useful to human society.
His lament on not having women in science and maths is the result of social bias and obstruction mentality of insecure second rate Professors. Those who are secure in their achievement never look at gender, age, race, religion etc., rather can this person contribute knowledge to the society which will benefit most people in some way. But they are very few and found only in MIT, Stanford, Princeton and other endowment rich institution of higher learning. A sad fact both in the USA and in most part of the world. Men want a daughter, wife, mother, grand mother and sister but not highly acclaimed thinkers, scientist and mathematicians. This is a curse on human kind.