Science Talk

Paul Dirac: "The Strangest Man" of Science, Part 2

Award-winning writer and physicist Graham Farmelo talks with podcast host Steve Mirsky about The Strangest Man, Farmelo's biography of Nobel Prize-winning theoretical physicist Paul Dirac. Part 2 of 2. Web sites related to this episode include and

Award-winning writer and physicist Graham Farmelo talks with podcast host Steve Mirsky (pictured) about The Strangest Man, Farmelo's biography of Nobel Prize–winning theoretical physicist Paul Dirac. Part 2 of 2. Web sites related to this episode include and Facebook page for The Strangest Man

Podcast Transcription

Steve:        Welcome back for part 2 of our conversation with Graham Farmelo, author of The Strangest Man, the award winning biography of the great theoretical physicist, Paul Dirac. But, first I'm happy to let you know that we have fished out the 1963 Scientific American article by Paul Dirac and posted it on our Web site, where it will be available free until July 24th, 2010. The article is called the "Evolution of the Physicist's Picture of Nature," and a shortened URL for it is Now back to Graham Farmelo. We were talking about Dirac's conviction that formulations in physics had to be beautiful.

Steve:        I forget who said it—maybe you said it actually, as the narrator—that "letting the beauty be your guide may only work if you're one of the few super geniuses of the field, where you can appreciate the beauty." If you're even a slightly lesser light of a physicist, maybe you are not able to put that kind of beautiful thing together, where beauty can be your guide. And then you really have to make sure that you are agreeing with experimental verification.

Farmelo:     That is right, that is right. I have to say one thing because although I admire, Dirac—as all [theoretical] physicists, I'm a renegade theoretical physicist now, but all theoretical physicists really admire Dirac—but it has to be said that in his later career, though he did first rate work until he was, what 61 years old, was it revolutionary [like] the work he was doing between 25 and 33? But he was doing really first grade work. But, thing is that when he tried to use beauty as his lodestar, there are very few examples, right, where that was successful. But can I give you one example which I think is absolutely extraordinary, and it is only part of this book that I amended because I thought the example was so powerful. Dirac, in one of his early visits to the Institute in Princeton, he was attempting to do something that strikes one, [well] most of us, as being bizarre. He was trying to come up with mathematics that might have a physical application, right. So he was really taking seriously this idea that mathematics should lead physics rather than experiment. Sounds farfetched but he really believed that was the way forward; that was the philosophy he set out in his great 1931 paper, the one with the monopole and antimatter in it. So, I thought, when I actually finished writing the book, right that all of those projects were stillborn. Now, let's cut right to two years ago, at a tea time at the Institute for Advanced Study in Princeton where [Juan Maldacena], who in [the] mid-1990s produced one of the greatest contributions in modern theoretical physics, right. What [Juan] did was to show a duality between string theory and quantum field theory, right, a way in which you could relate those two things. And it was a wonderful, wonderful piece of work, right, widely celebrated, still a fecund field now, right. Now, this was what [Juan] told me. A few months after he did that work, he found that the mathematics that he had used to do that had been done by Dirac and had been between 1963 and 1936. So Dirac was working on mathematics that had an application in the hands of Maldacena decades later. And I simply had to put that in because I had to admit that I had been little bit patronizing, here I thought with this stuff, none of it came to [any]thing, and there we are. So, you know, he was smarter than some people gave him credit for, even smarter.

Steve:        And it's going a little too far to say that he even anticipated string theory, but in the '50s, he thought it might be worthwhile to consider the electron as a string.

Farmelo:     That is absolutely correct. He just shortly after he nearly died actually, he nearly died on a sabbatical. He actually went [on that] sabbatical because he was one of the physicists in [the] McCarthy [era] who was denied entry to the States. So he went on a separate visit and then he came back after his visa was permitted, and he got into his mind that the reason why quantum electrodynamics,  [that's] the theory of photons and electrons, doesn't work—he was constantly unhappy with that theory incidentally; he thought it was so ugly; it offended his aestheticism—that he decided that instead of the electron being a point particle that it would be productive to think about it as an extended particle and he called that a string, right. So, he was in on the side of the extended representation of things like the electron. But, you are absolutely right to say, the mathematics he was using, there was not in any way similar to the stuff that string theories now use. But, he was already thinking about the possibility of an extended representation of what we normally call the fundamental particle.

Steve:        And he was very impressed with Ed Witten's work…

Farmelo:     He was.

Steve:        …in early string theory.

Farmelo:     Yes, he was. Again this is an example of where I had underestimated him. I thought he was completely out of it, I mean, when I was a jobbing theoretician in the St. John's, my PhD , you know, I thought that Dirac was sitting in his [redoubt in] Florida State University and wasn't keeping up. [In] fact very near the end of his life, he nominated Edward Witten, great string theorist, for an award and he [said]  [Edward's] work was absolutely mathematically beautiful and Edward did meet him. He did meet him, he actually had a photograph, which Edward very kindly lent me, and Edward remembers that conversation, what Dirac was saying right to him was "Ignore quantum electrodynamics, right; it is wrong." That was the theory that Dirac coinvented, right. He thought it was such an ugly theory with these infinities, which he abominated, right, and he urged Witten and the other brilliant people in his generation to move on from that. An amazing thing is as Dirac was lying dying in Tallahassee that was that very time that the string revolution was happening where Witten and others, Green and Schwarz in particular, were coming out with a theory that didn't have those offensive infinities in it. So you could argue, as I say at the end of the book, you could argue, that Dirac's obdurate, [his] stubborn resistance to the modern quantum electrodynamics was validated by the fact that there was perhaps a theory without those infinities lying ahead.

Steve:        There's a great line by physicist Eugene Wigner, his brother-in-law. [He] says, it was said about Richard Feynman; he said of Feynman, "Feynman is a second Dirac, only this time human."

Farmelo:     Yes. You know, Dirac's wife, Manci, Wigner's sister, I mean, most people I think, I think it's reasonable to say, that most normal behavior, a man would introduce his spouse [as],
"This is my wife." Dirac didn't. He would introduce Manci as, "This is Wigner's sister."

Steve:        You have a section, a very small scene in the book between Feynman and Dirac, and let's actually perform that. It's very short.

Farmelo:     Let's do it.

Steve:        And I'm American, so I'll be Feynman. They run into each other. Feynman says, "I am Feynman."

Farmelo:      "I am Dirac."

Steve:        "It must have been wonderful to be the discoverer of that equation."

Farmelo:     "That was a long time ago. What are you working on?"

Steve:        "Mesons."

Farmelo:     "Are you trying to discover an equation for them?"

Steve:        "It is very hard."

Farmelo:     "One must try."

Steve:        It really is [Pinter-esque.]

Farmelo:     It is. Actually that's Dirac in a talkative mood.

Steve:        Right, right. It's talkative.

Farmelo:     Feynman said to several of his friends that, he said that Dirac was one of his heroes; he said that [to] many people and he regarded as a superior physicist, again something he said very often. But he also said with some frustration he couldn't get anything out of Dirac. It was [a] great, sort of, disappointment.

Steve:        When one embarks on a biography, one has to be prepared to spend years with this person. So, what was it that motivated you to write this book and gave you the courage to dive into the deep end of the Dirac pool and spend so much time there?

Farmelo:     Well, the short answer is foolishness. Because I'd never believe that it would take that long. I mean, it took me six years to research that book. But, perhaps a more serious answer is that Dirac, for me and for many, many other people who have worked with [theoretical physics], is seen as the first truly modern theoretical physicist, often called the theoretician's theoretician. He is English, of course, and the idea where I could compare myself to Dirac would be say that he came from a modest home—and he was [the] only of the quantum physicists like that incidentally, no professors in the family, right; from a pretty ordinary upbringing, right. And I was just fascinated at how these, works of great beauty and how his conception of physics emerged from this very humble beginning. And as I said, it was with some foolishness I took it on. I thought that I would simply go through the, you know, material in the books. To [tell you the truth, Steve], I look back now with considerable embarrassment—I didn't even know that there was an archive. Now that really is foolish. You really should not embark on a biography unless there's an archive. And when I saw it I realized this was a treasure, a total treasure. Because Dirac was a hoarder; he kept these letters. So when he and his wife fell out or when he fell out with Cambridge University or when he wrote to Heisenberg, he kept all these letters. So, you know, it gave you a very, very strong sense of his personality. And then thanks to the generosity of Dirac's children, in particular his younger daughter; she gave me some letters that Dirac wrote. [And] these, I have to say, this was one of those goose-bump moments that I'll never experience again. But I went to visit Monica, and she gave me access to these letters that Dirac wrote, hundreds of them, when he was in effect falling in love with the woman he eventually would marry. And instead of having this person, who could not string a sentence together, it consisted of more than one word, right, you have this tremendous outpouring of honesty about what it feels like to be someone who is regarded as, you know, as a great character, but a very, very odd character; as someone who [had] such a terrible upbringing. I mean, lines like, "if you don't understand what it's like to come from a family like mine, you'd never understand me." I mean, he really meant this, you know, he really, really meant it. And also the nonsense that physicists believed for years that Dirac had no interest[s], this is absurd. If you go and talk, you read his letters, you talk to people who knew him well, Dirac had lots of interest. He read Tolstoy, he loved Beethoven, he listened to music, he loved to go to concerts, his favorite character was Mickey Mouse.

Steve:        And he had this big thing for Cher.

Farmelo:     He loved Cher, he bought his own color TV so that he could watch Cher. So this most austere of theoreticians in 1970 was sitting at the screen, looking at Cher, [strutting] her stuff, looking at Sting, looking at Elton John, in his rather with his Sphinx-like concentration. And that's what he was doing.

Steve:        One of the great compliments he thought he was paying his daughter was to tell her that he thought she looked like Cher.

Farmelo:     [It was] his granddaughter, [but] yes that's absolutely right. He was obsessed by Cher. I have to say Dirac was not in anyway accused of being unfaithful. As far as I know, he was very faithful to his wife. But he did love beautiful women. Mary once told me that he hadn't spoken for days, when he was in Princeton, and he walked past the desk and said of a lady who just passed, "She's a beauty"—the only words he spoke for several days.

Steve:        Do you have any evidence that Cher knew Dirac had a thing for her?

Farmelo:     Well I sent her a copy of the book, [lets put it] like that, but she hasn't responded yet, but I'm sure she will.

Steve:        So you've just begun a sabbatical at the Institute of Advanced Studies?

Farmelo:     Yes, I'm fortunate enough to be a visitor at the Institute for the summer.

Steve:        What will you be doing there?

Farmelo:     I'm working on my next book, and I'm afraid that's under wraps at the moment. But I'll come back and tell you about that another time. I hope it won't be six years incidentally, Steve. Oh I can't stand the thought of that! but, no, I'm still talking about Dirac. I mean, Dirac if you like, is my "grand project"; it's the thing I really wanted to do. And I had such amazing good fortune with the archive, with his friends and family were so helpful. People really wanted, you know, to get under the skin of Dirac and I wanted to honor that.

Steve:        I got to tell you it reads like a novel. It's somewhat like a Dickens novel because of the horrible upbringing, and yet it's, sort of, an adventure story because he is gallivanting all over the world. And these other more familiar people, like Einstein, Schrödinger, Heisenberg, Bohr, they're these supporting characters in this book and he is going to the Soviet Union to try to lobby on behalf of a friend who's sort of under house arrest.

Farmelo:     Oh definitely. And he [gave] up his work then. That's a classic, I must say this because we haven't looked at this [yet]. He was absolutely at his peak working [in the] office next door to Einstein, and his best friend, Peter Kapitza, the Soviet physicist, was detained at Stalin's behest and Dirac stopped everything. He basically stopped working for months trying to get, with the help of Rutherford, Kapitza out of the Soviet [Union]. This is where he really did have empathy, you see. This is an example of that. When he felt it was an injustice like that, he was absolutely on the case. And he did not, he really left, as I say, no stone unturned to get Kapitza released. He didn't do that [incidentally], but he only saw him later on in 1966, [it was a] great homecoming, which I describe in the book.

Steve:        But you know, it's such an amazing thing. As you say, he throws down what he's doing. He gave up months of his work and his personal life.

Farmelo:     Yeah, yeah. And it's the same thing incidentally; his loyalty is extraordinary, absolutely extraordinary. I mean, he had friends, or if you look at his friends, they're all over the spectrum during the second world war. I mean, Kapitza was working in among Stalin's scientists; Heisenberg famously stayed behind in Germany, yes—most [people accept that he] wasn't a Nazi, but he was certainly working in support of the German project. Schrödinger had a strange trajectory because he wrote this letter declaring his support for the Nazis apparently and then changing his mind. Dirac would hear nothing against any of them.

Steve:        And he was very close with Oppenheimer.

Farmelo:     He was. Oh that was again one of the, perhaps[not] the loves of his life, but he had enormous affection for Robert Oppenheimer. And when Dirac almost died, Oppenheimer made a visit to see him in Canada—and I have to say that it's very important to stress this because a lot of people say, "Why did Dirac end up in America?" right. And I have to say on that one that Cambridge in particular, that Britain as a whole, never really valued Dirac as perhaps as much as they should have done. I think they rate him as [brain], there's no question about that, [but] whereas it would be sensible and courteous to offer him a position after he retired, basically he was cast out after his Lucasian chair ended; and then it was American universities who were trying to get him there. And one of the staff that got [him] to Tallahassee, when the other staff [said] "Why do we want this old guy here?" he said "This is like having Shakespeare in the English faculty," right?

Steve:        Great.

Farmelo:     That's a great line. And Dirac had a very happy retirement in Tallahassee. I have to say he was made very welcome and his wife, who hated Cambridge, she hated when she saw the sexism of the place, the way it excluded her, and she absolutely loved the fact that she and Dirac were embraced in that community. And incidentally she took vengeance on this, right because the Dirac archive which is very well looked after in Tallahassee, she ripped that out of Cambridge. She was not going to let that stay, so there was a very, very strong loyalty to their new friends and family in Tallahassee.

Steve:        I should say that, Graham Farmelo is a wonderful person to follow on Twitter. Your Twitter name is Graham Farmelo.

Farmelo:     Yeah, yeah.

Steve:        And G-R-A-H-A-M-F-A-R-M-E-L-O and you'll get tweets about a lot of interesting stuff, not just physics, culture, music. Interestingly you remind me, Dirac loved the movie, 2001. He sat in the theater and watched it over and over again.

Farmelo:     Absolutely and he kept doing it, too. If he had a video, apparently he would have watched it all the time. Seriously, he saw it, he went back several times and then his friends told me that whenever it came anywhere near Tallahassee, he would go and see it again. He absolutely loved it.

Steve:        And there was something about the way that Kubrick presented things visually that really appealed to him because of his own way of thinking visually, probably

Farmelo:     Well I think, I mean, I was trying to—I mean, I love 2001 too, that's irrelevant, I suppose—but I was trying to work out why, what the appeal was at this and it just occurred to me that when I was reading about, one of Kubrick's interviews about 2001, that he said he wanted to make a film where there was virtually no dialogue. I mean, there's hardly a word spoken in there for half an hour or something.

Steve:        And the computer has most of the lines.

Farmelo:     That's [the best] character in the movie, ye[s]. You know, you're right. Dirac just loved it. Again, it goes back to this visual sense that Dirac had; his sense of visual beauty. He was constantly referring to that, you know. And I think that film speaks to us perhaps more effectively than any other movie about the beauty of space; which you could in certain moods say, well you know, [some people would say "It's] boring there's nothingness." But it brings you the yearning to know about it, right. And in a way Dirac was yearning in the same way for inner space, right, in his working of quantum mechanics.

Steve:        Just to finish off, I'm going to ask you to read a section of the book.

Farmelo:     The surplus of matter of antimatter at the beginning of the universe is still not understood and thousands of physicists are working to understand it. Their main sources of experimental information are particle detectors where antimatter is produced by smashing ordinary particles into each other and then quickly separating off the antimatter before it's annihilated by matter. By comparing the decays of particles with those of their antiparticles, experimenters hoped to get to the bottom of the matter-antimatter imbalance. Everyday particle accelerators now generate about a 100,000 billion positrons and 5,000 billion antiprotons, a total of roughly a billionth of a gram. Although this quantity is only tiny, the ability to produce it at will demonstrates that Homo sapiens now, a million years after our species evolved, uses antimatter as a tool. Today, positrons are routinely generated in mass produced equipment all over the world. Doctors use positron emission tomography (PET) to see inside their patient's brains and hearts without the need for surgery. It's a simple technique. The patient is injected with a tiny amount of a special radioactive chemical that spontaneously emits positrons, which interact with electrons in the tissue, where the chemical settles. The photograph is a record of the radiation given off in the electron-positron annihilations. Within just a few decades, positrons changed in the eyes of scientists from appearing outlandish novelties to being just another type of subatomic quantum. The public has become more familiar with antimatter, too, from the fictional treatments of it in, for example, Star Trek and Dan Brown's, Angels and Demons. But what is most remarkable about the story of antimatter is that human beings first understood and perceived it not through sight, smell, taste and touch, but through the purely theoretical reasoning inside Dirac's head.


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