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Interview of Sheldon Glashow by David Zierler on June 3, 2020,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
In this interview, Sheldon Glashow, Professor of Physics Emeritus at Harvard University and Professor of Physics Emeritus at Boston University, reflects on his career and Nobel Prize winning work. He discusses his childhood friendship with Steve Weinberg and his passion for science from a young age. He reflects on his decision to attend Cornell University for undergrad and details the physics curriculum at the time. Glashow describes his time as a graduate student at Harvard University studying under Julian Schwinger. He discusses his time as a post-doc at the Institute for Theoretical Physics in Copenhagen working on the SU(2)XU(1) theory, which would later win him a Nobel prize in 1979. He speaks about working with Murray Gell-Mann while at Caltech and their collaboration on a paper together. Glashow details being hired as a full professor at Harvard University. He discusses his frequent collaboration with Alvaro De Rujula. He discusses the concept of string theory and how it has evolved over the years. He discusses the loss of the superconducting super collider and reflects on where particle and theoretical physics may be today had it been built. Lastly, Glashow reflects on his goals for "Inference: International Review of Science", of which he is the editor-at-large.
Okay. This is David Zierler, oral historian for the American Institute of Physics. It is June 3, 2020. It’s my great pleasure to be here with Professor Sheldon Glashow. Shelly, thank you so much for being with me today.
Great pleasure, David. Looking forward to our talk.
Okay. So, to start, please tell me your title and institutional affiliation.
I am retired, doubly so. I remain the Higgins Professor of Physics at Harvard, Emeritus. I was, until about two years ago, the Metcalf Professor of Mathematics and Sciences at Boston University. Now I am a Professor of Physics Emeritus there as well.
Okay. And now let’s—
I’m also the editor-at-large for the magazine that I mentioned to you, Inference: International Review of Science.
Right. Right. And what’s the publication schedule for that? Is it a quarterly?
It’s quarterly. The last issue came out just a few days ago.
Okay. Wonderful. So now, let’s take it right back to the beginning. First, tell me a little bit about your parents and their journey to New York.
Yes. My father came at the age of approximately fifteen to—from Babruysk, which is in today’s Belarus and he immediately went to work and went to school and within a short period—within five years he started bringing his relatives back. One of them was his cousin and he married her, Bella Glashow, and then they began to have a family. They had two boys before me, born in 1914 and 1918. And I was born in 1932.
What were your parents’ mother tongues? Did they speak Yiddish?
I didn’t meet many of my grandparents, only my grandfather who did speak English to some extent. My father had fluent English, of course, by the time I met him. And he also spoke Yiddish. At home my mother and father would occasionally speak in Yiddish when they didn’t want me to understand.
But normally, it was in English—it was mostly an English speaking—99% an English-speaking home.
And how did your father develop his profession as a plumber?
He worked as a laborer for a time. He remembered his various anti-Semitic incidents while he was a worker. And then, he switched to plumbing. And at some point around 19…in the 1920’s he got his plumbing license, and I’m not too sure of the detailed history, but he soon became the owner of a plumbing shop, which was at 1622 Amsterdam Avenue in New York. And amazingly enough, although he left the company sometime before his death in the 1960’s, it still exists. It’s called L. Glashow Plumbing. It’s in the Bronx now, not in Manhattan, and its trucks are all over the place. They are white and I have a wonderful photograph of my son next to one of them.
He actually introduced himself to the driver, pointing out that he was the grandson of the founder of the company, and they were delighted. They invited him to come to the plumbing office in the Bronx and there he could view my father’s original license which was framed there. The company now has been in existence for practically one hundred years.
Oh my. That’s great (laughter).
How did your family fare during the depression?
Well, I’m a little young to remember that. We did not suffer because by that time, our family was definitely upper middle class, and I don’t remember any privations at that time. The privations began after the beginning of the Second World War, when of course the whole country was subject to rationing and all sorts of constraints. But no, I didn’t suffer from the—I don’t consider myself a Depression baby.
And did you grow up in multiple neighborhoods or in one general place?
We grew up in one house—it was 65 Payson Avenue, a private house. We had a few apartments that we let out, but most of the house was ours.
And this is in the Bronx?
No, no. It’s in Manhattan.
Oh, it’s in Manhattan.
Just north of Dyckman Street.
Which is 200th Street. And for example, I walked to local public schools. When I got to high school, I would walk to the 207th Street bus station and take the bus across the river to Fordham Avenue, or I would take the subway down to 168th Street then go back up into the Bronx. Ours was a lovely neighborhood. Ten or so private houses facing Inwood Hill Park and that was my playground, Inwood Hill Park. At that time, it was a well-kept, rather beautiful park. Still very beautiful but not at all well-kept.
Yeah. Now, was your family mostly secular? Were they Jewishly connected?
They were Jewishly connected enough to be members of the local shul and they—my parents would religiously go to temple about twice a year at the serious holidays, occasionally dragging me along. And yes, I did prepare for a bar mitzvah. It was just after the end of the war, so it was a minimal affair without much of a party or anything like that. But yes, we did the minimum, just as I and my wife have done for our children. The minimum.
I’m curious if your family had a sense of the horrors that were going on in Europe during World War II?
I don’t really think so. Most of the family he had brought back. He had five brothers, all of whom came back, and his sister and whatever surviving grandparents there were. My maternal grandmother, who lived with us, died the year that I was born, so I never met her. Both my brothers joined the Army and served in Europe. And in particular, my younger brother—who was a doctor, was the first doctor to enter into Dachau. He sent back horror pictures of what things were like. Piles of bodies and starving survivors. It was horrifying to the whole family.
His job was to provide—
His job was to provide medical care to the surviving prisoners?
He was doing that, yes, among other things. That was among his chores.
It was not—not easy.
Yeah. Well, in happier times, I’m curious about your education. Are you a product of the PS system in New York?
At first, I attended Mrs. Stern’s Kinder Garden, which was a few blocks away. But for first through third grades, I attended PS 52. Then we were shunted off to PS 152, which was a rather longer walk from my house. That was for fourth, fifth and sixth grades. After a truncated seventh, eighth and ninth grades was held back at Junior High School 52, which was in the same building as PS 52. Afterwards I attended the Bronx High School of Science.
Now, in your earlier years did you start to exhibit excellence in math and science, or would that come later?
No. I think I was quite—I was not a gifted mathematics student, but I was certainly ahead of my class and I was quite competent mathematically and scientifically. In reading, I was far advanced. So, I knew a great deal more science than my fellows. When I was in ROTC some years later as a physics major at Cornell, I was obliged to spend two years in Air Force ROTC—there, I was asked to give a lecture to my fellow students on how airplanes fly. In high school—well, before high school, when my brothers went off to war, I inherited, at least temporarily, a very nice telescope and my brother’s medical microscope. So, I did lots of investigations with the microscope including playing around with all kinds of paramecia and other Blepharisma and other protozoans that I could dredge out of the woods across my house.
I also had a laboratory, a chemistry laboratory in our basement.
Yes. I became rather an expert on selenium chemistry while I was in high school, which is not a safe thing to play with. And I was amused when—I had published a short article in a magazine published by Science Service for teenagers, called Chemistry. My article somehow it found its way into a government agency in South Dakota—where selenium is well known. It is collected by certain plants. When the cows eat those plants, which they seem to like, they get very sick. I received letter asking me if I would consider employment in South Dakota. I had to reply that I’m only a high school student.
(Laughter) Well, that would have been a very different life.
Yes, it would.
Now, in thinking about high school, were the options to stay on in public school or to go to one of the specialized science schools in New York—Bronx Science, Stuyvesant or Brooklyn Tech?
We were living throughout my childhood in Inwood in Manhattan, which is in the northern tip of Manhattan. The local high school, Washington High School, was up in The Heights, and it had a very bad reputation. Even though both my brothers had gone there, in the years since it had declined. My parents definitely didn’t want me to go there. Thus, I applied to Bronx Science. I actually missed the entrance exam because I had an attack of Appendicitis. Which my brother, then a physician, nursed me through without an operation. I took a make-up exam and was admitted to the Bronx High School of Science.
Did you consider Stuyvesant?
No. At that time, that was too far away. I guess it’s the same distance. In terms of time it would have taken the same time to get there. But it was somehow not what I nor my other classmates considered. Science was physically closer, and it was what we thought of as the science school. Stuyvesant at that time was not quite so specialized in science.
And I imagine Brooklyn Tech, for the same reason? It was just too far away?
Yes. But one of my good friends in pre high school, in junior high school, went there and thrived, becoming a well-known physicist at—Ken Lande, who is and remains a respected neutrino physicist, at the University of Pennsylvania.
I talked to him two weeks ago.
Did you really?
He’s doing great. Wonderful person (laughter).
(Laughter) I haven’t been in any contact with him since. But just by coincidence, today, or yesterday for some reason I thought to look up my junior high school friend who I knew had died, Fred Rein, and read his obit. When I was in junior high school, Rein was thought to be a very likely science person, but he was the best in science, and he won the science prize. And, in fact, this young fellow won a prize from the Manhattan government for an essay he wrote called “My Borough.” And it was very moving, apparently. It won the prize and he became president of the Manhattan Government for a day. He sat in a big chair and hired his mother as his personal assistant. Then, on October 9, a month into our first at Bronx Science, I was at the bus stop again, at 207th Street and Broadway, my classmates told me that he had died of polio. This wonderful, promising good friend of mine I lost during my first year at high school. I just recall that now because another of my high school friends who is a Professor of Physics at the University of Massachusetts had organized an online—70th reunion. And what he structured was that each of the graduates in the class of 1950 who cared to, should submit an essay about what they have done since. Each essay was then distributed to all other graduates of 1950. I am thinking that I should write a little note reminding them of someone that they probably don’t remember because he was only in our class for a month or so. [Indeed, I have done so.]
That would be a very nice tribute.
Now, I’ve heard it said of Bronx Science that the education there was so good that when you got to college, sometimes you would be bored in those freshman and sophomore classes. Was that the case for you?
To some extent. It is certainly true that courses in literature, history, civics (which at the time was an important course, has gone away, unfortunately.)
—were very good. And mathematics was spectacularly good. Our teacher, a Hungarian, Dr. Hlaverty had leftist tendencies. Later on, he would get in trouble with McCarthy. But those courses were first rate and I remember typically getting 100% on the Regent’s Exam in geometry, among others. However, calculus was not taught in high school. I picked up a little bit of calculus from another friend of mine who was a little bit more mathematically advanced than I was while in high school. He, Daniel Greenberger, became a professor of physics at the City University of New York. The science courses were less impressive. The author of my physics textbook was written by one Charles E. Dull. A well-known textbook at the time. Excruciatingly dull it was. The physics was terrible. When I got—well, college—after Steve Weinberg [yes] and I made a little trip around to the schools to where we were accepted to Cornell, Princeton, and M.I.T.
Was he your classmate, Steve?
Steve Weinberg and Gary Feinberg were [unintelligible] classmate—not just classmates but close, intimate friends indeed. Gary attended Columbia, where he remained though out his career.
So was Mort Sternheim, who also became a professor of physics at the University of Massachusetts. Yeah, they were very close friends. Steve and I, driven by his father in their car, visited these three schools and both of us decided that we would, for more or less the same reasons, attended Cornell rather than Princeton or MIT.
Okay. Now, were you thinking already that you were going to major in physics? Was that part of the calculation?
Despite our failure to study calculus at Bronx Science, both Steve and I enrolled in a physics course as Cornell freshman. The course was difficult and fast moving. It was taught by a cosmic ray physicist who did not compromise. There was no calculus in the course, but nonetheless it was tough. And we did have to work with that course. I am very grateful to that teacher because we already had picked up a little calculus so we could jump into the second semester of calculus, and we both spent—I took many math courses as well as physics courses at Cornell.
So, Shelly, this begs the question—given that your physics education in high school was figuratively and literally dull and was not first-rate—how did you know, despite that, that it was physics that you wanted to specialize in, even as a eighteen-year-old?
Oh because (laughter)—the answer to that is clear. I think it began in 7th grade. I knew I wanted to do physics or at least something like physics. One of the incidents I remember most clearly was the teacher explaining to us that the earth revolves around the sun and it rotates about its axis. By the way, she was very insistent that we revolve about the sun and rotate about our axis. They cared about the words, as well as the science. But she also told us that the moon revolves the earth. But I realize that not only does it rotate about the earth, but it must revolve about its axis as well, because otherwise we would not always see the same side of the moon. And I asked her why the period of rotation and revolution of the moon were identical to each other. It seemed an outlandish coincidence. And she said, “That’s a very good question.” And I was very impressed that “B”, she didn’t know that answer, and “A”, that I had asked a very good question.
So, you were onto something and you knew it?
I was onto something back in 7th grade, yes. For sure. I was a little disappointed that Fred Rein had won the science prize and I did not. But yes. Indeed.
Now, why Cornell as opposed to some of the other top schools that you were considering?
Well, Princeton was, from our point of view, far too stuck up. The men there had to go to dinner in these robes, thus imitating Cambridge and Oxford at the time. I think there were no girls at Princeton at that time. That was enough. The wonderful thing about Cornell is we saw things we had never seen before—chickens and cows and pigs and things like that, and lots of open space. It’s not there anymore, these empty spaces.
Yeah, Ithaca must have felt like a small town back in those days.
Cornell—the city was a small town, and the city that was down in the flats and the school was on top of that mountain more or less, with deep and impressive ravines on either side. And it was mostly empty space. It was very impressive. Then we went to MIT and found it to be a sort of closed in, city school. I didn’t want that. Neither did Steve.
Who were some of the luminary professors at Cornell that you became close with as an undergraduate?
Yes. My advisor was a man named Tomboulian. He was not to my knowledge a very distinguished guy, but he was very sympathetic with my interest in taking courses that were above my—above normal expectations. So, I took a lot of graduate courses while I was there. The professors, among the impressive professors I had were several. One was Mark Kac—was a mathematician, a very famous mathematician. He assigned almost undoable problems to us, which very challenging. Lots of fun. Very rewarding. I worked on those problems with other students, which was probably not a legal thing to do, but we probably learned more by working together than by being confused by ourselves. Kac was most impressive! Then, as I mentioned, the cosmic ray guy, Kenneth Greisen—who was extraordinarily impressive for that first year of teaching. Afterward, I took courses with Hans Bethe and Philip Morrison, who later came to MIT. He was a most impressive teacher indeed. But there were other fine teachers at Cornell; Ralph Agnew taught me analysis, J. Barkey Rosser taught me mathematical logic. The mathematicians. Rosser was a professor of logic. Very impressive. It was Ralph Agnew who taught me real variables. And Edwin Salpeter taught me electricity and magnetism. Richard Feynman had been there at the same time for a bit, but I did not meet or see him.
Was your sense Feynman was generally inaccessible to undergraduates?
No. I think he was pretty accessible, but I think the overlap was only in my freshman year. He had left Cornell after I did.
I later encountered him at Caltech when I spent a year there, and he was certainly completely open to postdocs at that time, undergraduates, graduates, everyone even people on this street. He was regarded as a really tough teacher because the Feynman lectures were essentially incomprehensible to the audience for which they were intended. It was too sophisticated. He expected too much—
Can you talk a little bit about the curriculum? The physics curriculum at Cornell? The kinds of courses that were emphasized? The kinds of subfields that, you know, in the hierarchy of subfields were considered most important during those years?
The requirements were typically a pain in the ass. I had to take an intermediate electricity and magnetism course after having taken the graduate course. Nonetheless I had to take that silly undergraduate course. The requirements were absurd. Most of the courses I took in physics were graduate courses. I took the graduate quantum mechanics and the graduate quantum field theory which were not on the curriculum for undergraduates. I got into little wars with some of the teachers at—elementary electricity and magnetism course—we were assigned a problem which was undoable. He didn’t realize that the problem was as hard as he—basically, it was a hemispherical boss on a plane with a second plane above and that’s one tough problem. He apologized, after we had spent hours figuring the solvent. The Professor, Dale Corson, later became Cornell’s President. Yeah, we had a—there was tension between we who were fairly advanced—there were a bunch of us who were fairly promising physicists there at the time, and the administration was very staid and did not encourage us. Fortunately, my advisor was totally sympathetic. I will always remember Diran Tomboulian.
What was your sense of the relative divide between the experimentalists and the theorists of the faculty? Were they considered sort of equally esteemed? Was there a hierarchy there?
I cannot answer that question because I dealt mostly with theorists in most of the things I did. The courses I took that I appreciated were all courses by theorists except for my freshman physics advisor, for which our professor was Kenneth Greisen a notable cosmic ray experimenter. I didn’t know much about whatever experimental physics might have been going on at Cornell at that time.
So that’s an answer in a sense that it must have been pretty divided for you to, you know, to have that perspective.
Yeah, but I think that was true at Harvard too when I went as a graduate student. I was not much involved with the experimenters there as well.
So, this already tells me that your—your self-definition as a physicist was pretty well cemented as a theorist even during your undergraduate years.
Oh, yes. That cement was put in place in high school among the three of us, Steve Weinberg and Gary Feinberg and I. We all knew we wanted to be theoretical physicists. We hung out from time to time on Fourth Avenue where all the used book shops were and plucked out some interesting old books on quantum mechanics and other such things. We were definitely into theoretical physics.
Right. Were there summer internships that you had as an undergraduate that were relevant to physics?
There was nothing available—I mean, when, in high school?
As an undergraduate at Cornell.
As an undergraduate at Cornell, the only things I did were in one summer I stayed home—that is at home in Manhattan—and I went to school at Columbia, summer school, took two courses, one in probability and one in ring theory: Both mathematics courses. That was one summer. Another summer I went to what was called the Research Institute for Advanced Science which was created by Martin Marietta in Baltimore. And it existed for just a couple of years or so. It was created by the father of Edward Witten and tried to be an industrial counterpart to the Institute for Advanced Study. We were on our own to do whatever research we wanted to do. Actually, I did that while I was in graduate school.
Something else that happened in graduate school: I went to a summer encounter with JASON. I needed very high clearance and it sort of embarrassed me that on the table open for us to read at that time in Washington was the Air Defense Plan for the United States. I could read if I wanted to. Anyway, the first thing that happened there was that we were asked to decide whether we wanted to work for war or for peace. Not in those words, but substantively. Just three of us chose peace; Arthur Keruan from M.I.T., Charles Schwartz from Berkeley, and me. The three of us voted for peace. I don’t clearly remember if this was a joint project or just my project. I think it was joint. We were to look at all of the classified and unclassified literature on aerial surveillance and we were asked to create an unclassified document based on these classified documents, a document explaining what the capabilities were of such aerial surveillance. Could they do what they were supposed to do? We had access to all available data, whether classified or not. We completed our document, submitted it to JASON, and it was immediately classified.
Yeah. Right. Never to be seen again.
The JASON encounter was their attempt to recruit other scientist, like Steve Weinberg, who would join JASON. I wanted nothing to do with it.
Right. Now given your interests and talents in theory and the fact that you were already taking graduate courses, going straight onto graduate school was virtually preordained, I assume?
Oh yes. It was preordained, except that I had managed to fail a solid-state course because I had an utterly horrible teacher. His name was Sack and I despised him, and I despised his—not the subject but his means of teaching the subject. So, I failed the course, and that I guess prejudiced some schools. Although as an undergraduate, I had been accepted by Princeton and rejected by Harvard, when I applied to graduate school I was accepted by Harvard and rejected by Princeton.
(Laughter) That’s great. So, Harvard, that was the clear winner for you in terms of where you wanted to go.
It was the clear winner for me. Steve went to Princeton.
Yeah. Yeah. Did you keep in touch with Steve during your graduate years?
Oh yeah. The graduate years, no, not very much, but we came together again some years later at Berkeley. We both taught at Berkeley at the same time for a few years in the 60’s.
Right. Right. Now, when you went to Harvard, were you thinking there was a particular professor that you wanted to work with?
Absolutely. There was only one professor who was doing particle physics, particle theory and that was Julian Schwinger.
So, then we had—fortunately, would be willing to accept up to a dozen or so students at the same time, giving them not that much help but lots of inspiration. I wanted to be his student.
Did you know that Schwinger’s group was that large going in?
Nope. No, I was quite naïve about such matters. I came there wanting to do particle physics and there was this guy called Schwinger that I had never heard of, and I knew that I wanted to work with him.
How long had Schwinger been on the faculty by the time you got there?
Some years. He had quite a reputation. And when I was a graduate student, I met more advanced graduate students. In fact, one of them became a close friend, Chuck Zemach. He was finishing up as a student of Schwinger. Having had a long and successful career at Los Alamos, he is now retired—one remarkable feature of Chuck Zemach is that he has rafted down the Grand Canyon at least a dozen times.
Oh wow (laughter).
With and without his old father and his wife’s friends—he’s an expert at that particularly difficult adventure.
Do you remember your first encounter with Schwinger?
My first encounters were impersonal because even in my first year there, I took a course with him. And I took a course with him and looked forward to such a thing each year, I was at Harvard. My original impression of him was only as a teacher. And as a teacher he was quite impressive. He had a radio announcer’s voice, very clear and precise. He had extremely good handwriting and he would use the whole blackboard, four blackboards, or maybe more than once in his very small handwriting. We would try to copy down everything he would write but it was very dense and very complicated. He would always organize things to complete his lecture at the very last blackboard so that he could immediately run out the door and disappear, trying to avoid the dozen graduate students who would try to find him and get some advice. However, once I became one of his many students, I was able to have lunch with him and get advice from once or twice each semester.
Was he approachable as a person? Could you talk with him?
Yes. If you could catch him. Once or twice, his charming wife Clarice, would insist that he invite us to dinner at their home. And we enjoyed a couple of pleasant occasions like that. He eventually became a friend that I could indeed talk to. Usually about physics, not so much about life and never politics.
Yeah. Yeah. How did you go about developing your dissertation topic? Was it connected with Schwinger’s own research?
Yes. Schwinger’s research was wide ranging on particle physics and in particular, on his formulation of quantum field theory which was different from anyone else’s. I took his courses in quantum field theory. I can’t say that I became an expert on quantum field theory from those courses because his language was so different from what was used outside of Harvard. But in any case, early in my second year I showed up in his office as one of many students who wanted to work with him. We were about a dozen. I can list a half a dozen of them right now. Marshall Baker very soon after graduating got a job at University of Washington where he remained. Charlie Sommerfield, soon after his thesis, unsolicant got assistant professorship then a professorship at Yale. Danny Kleitman was a student of both Schwinger and Roy Glauber. Years later he switched to mathematics and became my brother-in-law as I married his wife’s sister.
Ray Sawyer, became a professor at University of California, Santa Barbara. Lots of people were there, a dozen, approximately. Charlie Warner, Bob Warnock, Harold Weitzner and more. Schwinger accepted everyone and eventually after sending us away to solve a problem which we solved collectively and came back as an ensemble of twelve people again, there we were—we had passed the test. So, he had to give us all problems. I was last on the list. So, Charlie was given the challenge to calculate the fourth order magnetic moment of the electron with a muon. It had been done already, but Schwinger suspected (correctly) that the guy who did it made an error. So, Charlie did it and this was before computers, so we had had to sum up 100 diagrams or so. It was quite a challenge. With a Marchant. A Marchant is not a person from Mars, but it’s an electromechanic calculating machine that can take square roots. That’s about the limit of its ability.
What does the Marchant look like?
Looks like a typewriter. It was produced by Smith-Corona and marketed in the 1920’s. Only the best for Harvard in the 1950’s.
Except it didn’t print anything. That kind of thing. It was a mechanical, sophisticated electromechanical device. There were two kinds of calculators, Marchant, and a superior device called Friden: another typewriter manufacturer. It was a time, a good decade before there would be handheld things or anything in the way of computers. So yeah, no significant computer assistance whatever. Anyway, he did fine. He got the right answer first, a world first, and got his job at Yale. Marshall Baker wrote a thesis on the N over D method, which was some cockamamy thing that Schwinger had devised doing calculations, and he did well and went to Washington and stayed at Washington. By the way, my friend Gary, from high school, had gone to Columbia, where he stayed for the rest of his life. And so, it went.
By the time Schwinger got to me, he had more or less rid himself of all of the obvious problems that he had in mind. So, he came back to a fascination of his that he had published before; the possibility that there could be a unified theory of weak and electromagnetic interactions. And he gave me some reasons to believe that there might be such a theory and told me to find it. Which was kind of a big deal. I mean, I didn’t know how to do that. In fact, I failed. I managed to find some further evidence that there should be such a theory, and that if there were an intermediate boson, it had to be a vector boson. He knew that, as well. But it had to be a charged vector boson and there was several indications, one coming from the work of Gary Feinberg, that the most promising theory of that kind would be a gauge theory in the sense that was introduced in particle physics by Yang and Mills. Schwinger didn’t mention the Yang and Mills or gauge theories. I had to figure that out on my own. And I became convinced that it had to be a gauge theory and I had some good reasons for that. But that’s all I could do. I couldn’t make it work. Not then. Not at Harvard.
I’m curious looking back, to what extent would this research be relevant to the later search for a grand unified theory?
Oh, it’s the same thing, so to speak. I mean—
But this, of course, is before string theory.
Of course, it was before string theory. No, what Yang and Mills had done was to base the—is to create a gauge theory based on Heisenberg’s isotopic spin group. And what I finally realized—and I didn’t realize that until I went off as a postdoc to Copenhagen—is that the problem was that the underlying gauge group had to be something more elaborate. And in particular it had to be the simplest elaboration. SU(2)XU(1) Once physicist began thinking about symmetry groups larger than SU(2), symmetries that could describe strange particles as well, many suggestions were made, using groups with names such as G2, SO(7) or SU(2)XSU(2). The correct choice, SU(3), was found by Yuval Ne’eman in Israel and Murray Gell-Mann at Cal-Tech— while I was a post doctoral fellow in 1961. But these were approximate global symmetries, not gauge symmetries.
The problem was to find a theory to resolve both the strong interactions and the weak interactions. And the trouble there, which Gell-Mann and I noted in 1961, was that it appeared that any attempt to make a theory of strong interactions would get in the way of a theory of weak interactions, and conversely. It was impossible to reconcile the symmetry properties of the strong interactions with those with the weak interactions. The solution had to await the inventions of quarks and of quark color later in the 1960’s.
Who was on your dissertation committee?
(Laughter) You ask my favorite question, because I remember that all too well. Schwinger had by the summer of ‘58, when I had completed my thesis, had lost interest in pursuing particle physics or formal quants field theory. Instead, he and Paul Martin were among the first to apply quantum field theory to statistical physics. With that interest, they went off to Madison, Wisconsin, to work on such matters. Thus, I had to schedule my oral exam in Wisconsin. I had to go out to Wisconsin. I didn’t mind doing that because I was very good friends with Paul Martin, who had also ran-off to Madison for the summer.
What was the draw to Madison for them?
I don’t know. I have no idea why they went to Madison, Wisconsin. But to Madison I went. I stayed at Chez Paul Martin. Paul and his wife Ann were very good friends. So, I stayed with them happily and had an enjoyable time while I was there. Had my thesis exam, and then after the exam, we had a party, a very boisterous party. It had consequences in the neighborhood. But let’s go back to the exam. Before we could have a party, I had to have my exam. But there were indications that things were going to be weird, because before the exam I remember being in Schwinger’s baby blue Cadillac. He had not yet progressed to Italian sports cars. He was still into Cadillacs. We were sitting in his Cadillac late at night—it must have been after midnight—talking physics. Parked someplace where nobody else was parked, and then we got water bombed, because the neighbors didn’t like to see suspicious people sitting in a fancy Cadillac.
Talking physics no less (laughter).
Well, we began to realize that the neighborhood was not what we were used to. It wasn’t Cambridge. When Schwinger’s wife wanted to cook a fancy dinner she wanted, she desperately needed the Indian condiment, Chutney.
Which is universally available in the civilized world, but Madison was not yet part of the civilized world. We had to go all over the place looking for Chutney. We couldn’t find it anywhere. Anyway, coming back to my exam. The committee consisted of Julian Schwinger, Paul Martin from Harvard. And me. Well, I was not on the committee. Then there was the chairman—the then-chairman of the Physics Department who was a nuclear physicist, whose name slips my mind. And filling out the complement of four investigators, was Frank Chen-Ning Yang, who was also among the fancy visitors to Madison.
The exam began. I started describing what I had done. And at some early point in the presentation, I mentioned that I would, of course, assume that electron neutrinos and muon neutrinos are distinct, because I had been taught that by Schwinger. Included within his approach to physics was the requirement, based on aesthetic principles, that the electron neutrino and muon neutrino had to be different. As soon as I mentioned the possibility that electron neutrino and muon neutrino could in fact be different particles, Yang interrupted me—saying, “Shelly,” or “Mr. Glashow”—I forgot how he addressed me. He said, “that makes no sense at all. There is no experimental way at all to distinguish the two neutrinos from one another…” He went on like this. I didn’t know how to respond to this objection. Schwinger interrupted, “Shelly, I’ll take care of this.” And he very patiently explained to Yang, that there’s a straightforward experiment that could be done—It hadn’t yet been done; it would be done in 1963, but this was 1958—to demonstrate whether the neutrinos are the same or not. It is a meaningful question and a central one. I was told to continue. Everything went fine and I passed the exam.
Now, Shelly, were you—did you feel that you could have answered that question yourself, had Julian not stepped in for you?
I don’t think I could have. I was probably too nervous to have thought of the experiment that would be done by Schwartz, Lederman and Steinberger just a few years later.
But what was Julian getting at? Was he aware that this experiment was in the pipe or it was just his genius?
He was aware that such an experiment could be done.
Schwinger was not about to propose such an experiment. He would never so such a thing; he was never close to experimenters in that sense. But he was close enough to realize that it was technically possible to do it.
Is that a unique way of thinking? Just to step back for a little bit. A theorist to be certain that there is some future experiment to validate the theory, right? Isn’t the thought process a little more, I don’t know what the right word is, ambivalent or unsure about that? Don’t you just sort of propose a possibility and then you wait for the experiment to confirm it? It sounds like, Julian, at least in this case, he was quite certain that it was only a matter of time before what you had been postulating would be proved correct?
It wasn’t a question of being certain. The question was an in principle question of whether it could be determined that the electron neutrino were different from the muon neutrino, or not.
So, what exactly was Yang asking?
What exactly was Yang asking?
He was saying that there was no way of possibly distinguishing the electron neutrinos from muon neutrinos which was flatly wrong. But listen to the conclusion. So, I passed my exam, okay? Six months later or it might have been a year, Lee and Yang publish a paper explaining how it could be that electron neutrinos and muon neutrinos are different from one another and how one could demonstrate that fact. And in response to that paper, my friends Lederman, Schwartz, and Steinberger, set out to do the experiment to show that they are different. So, Yang had flatly stolen the idea. And ten years ago, or so, when I was in China, I encountered Yang and told him this story. I asked him if he would agree with what I said because what I said was rather damning. And he said, “Shelly, I agree completely with what you said.”
Uh-huh. Wow. It’s rare to hear that at a graduate dissertation defense, such fundamental discoveries come as a result. So that’s pretty amazing.
I don’t know if they came as a result. I suspect that Lederman and company would have done the experiment in any case. Because it was an idea that had been bandied about by others at that time including Murray Gell-Mann, who I had not yet encountered. He had talked about that possibility in 1959 but did not cite Schwinger’s earlier hypothesis.
Now, when you were thinking post-dissertation, was Europe definitely your target? Did you want to go to—?
My target was to spend a year or possibly more in the Soviet Union. And I had exchanged mail about such a visit with Igor Tamm, a Russian theorist, who won the 1958 Nobel Prize in Physics. He invited me to come to the Lebedev Institute in Moscow for a year. I decided I would do just that. I had won, by this time, a National Science Foundation post-doctoral fellowship so I was—actually, that complicated matters because the Russians wanted to pay me directly in rubles and wanted to have—my equivalent, who was a Russian named Sergei, who had the same initials as I did, SG. He would, of course, go to Harvard. And of course, Harvard was not too happy about this. But I think they agreed in the end and everyone agreed, and our State Department said, “Agreed, yes, okay we can arrange to defer if necessary—the fellowship.”
So, everything was fine except, I didn’t have a visa. I was told it would take a long time. So, I wrote to Niels Bohr in Copenhagen. I said, “Can I come to Copenhagen until I get my Russian visa?” He said, “Sure. By all means, come.” I went to the Institute for Theoretical Physics in Copenhagen, where there were some Russians that I befriended, Soviets, one of whom because a very good friend of mine. And in fact, he was present when I first met my wife to be, but that’s another story that took place years later. Anyway, this fellow, Venyamin Sideron and I, struck up a friendship. We were living in the same off-campus house. It was a rooming house that had about six renter bedrooms in Fredriksberg, near Copenhagen. He knew the Russian consul. So, we invited the Russian consul to our party. In fact, to several parties. He would always bring vodka, a very nice gesture. I would often—every time I would see him which was three or four times—I would say, “Is my visa coming?” He said, “Yes, yes. Visa coming.” But the visa didn’t come. So, after some weeks, in November—I went to CERN. And by that time, I had acquired a car. So, I drove down to Geneva in my new red triumph, and on the way I stopped in Bern at the Russian embassy. I asked them when my visa is coming. This was just after Gary Powers had been shot down, okay?
Oh yeah. Right. Right.
And this man said, “Visa not coming.” That put an end to my thoughts of going to the Soviet Union. I went back to Copenhagen, and it was in Copenhagen that I—in the late spring of 196—that I found the missing ingredient to unified theory of weakened electromagnetic interactions. It was the choice of the gauge group, and I focused on SU(2)XU(1) and published the paper that would earn my share of the Nobel Prize in 1979— almost two decades later.
Right. Now you were at CERN during this time as well?
Back and forth, yes. I would commute between Geneva and Copenhagen, often giving talks in Germany in route.
What were some of the big projects that were going on at CERN at the time?
I was still not much into the latest experimental data. So, when I went to CERN, yes, their proton synchrotron began running late in 1959. The antiproton had already been discovered at Berkeley in 1953, I think something like that. So that machine was operative at high energy, and the Europeans would have a similar machine, the PS or proton synchrotron. I was not so much into the details of what was going on because nothing seemed to be very exciting as yet. The age of the population explosion elementary particles beyond the strange particles had not yet begun. It was only in 1954 that the first pion nucleon resonance was discovered. Later on, many more resonances were found, and it wasn’t until 1961 also until the population explosion with particles really began mostly at Berkeley, Bevatron, and the CERN PS.
So, things were not yet exciting. Well, one thing at the time. At CERN, he and André Petermann told me that he had calculated the 2nd order correction to the muon magnetic moment prior to the work of my friend Charles Sommerfeld. In fact, he had made an estimation of it even before Charlie had done the exact calculation. Also, first met Jeffrey Goldstone at CERN— Goldstone of the “Goldstone meson”. He had just discovered how spontaneous symmetry breaking could lead to the appearance of massless “Goldstone bosons”—a concept that would prove to be very important. During my 2-years broad, I was working on my own stuff, but not talking with a experimenter, I was learning to ski and dating lovely ladies in Copenhagen and Geneva.
(Laughter) Now were you aware of Gell-Mann’s work before you got to Caltech? His most recent work?
Well, yes. While in ‘59, while he was spending the year in Paris, he invited me to Paris and asked for me to give a talk, and I gave a talk—which he appreciated—as I’ll explain in a moment. But he also took me to a three star—I had been to three-star restaurants before, but he took me to one and insisted that I eat the fish dish. And I told him, “I hate fish.” He said, “No. Eat this fish dish!” I realized the mistake that I had been making all these years, when I discovered what could be done with fish. And he appreciated what I had done. And that summer, the summer of 1960, I think it was, he introduced my work at the so-called Rochester meeting. Which was not in Rochester, but in some place in the Soviet Union that year. He presented my work, giving me due credit, He obviously appreciated what I had been doing, and soon afterward, when I getting to the end of my two-year post-doctoral fellowship in Copenhagen. In those days, for whatever reason, I was not worried about where I—what would happen to me next. I had enough self-confidence at that time. Not so much about the paper I wrote that would win the Nobel Prize. I was not convinced that that work was useful. But I had been doing some things, and I thought I was a pretty decent physicist. I was not worried about a job, so I made no attempt to solicit a position, which is incredible from today’s point of view.
But I received two unsolicited offers. One was from David Finkelstein at Yeshiva University. And those were the days that Yeshiva University had a first-rate group of theoretical physicists, which has since been destroyed because the university canceled it.
But in those days, it was fantastic. I considered that offer seriously, but I also had an invitation to be a postdoc at Caltech.
With Murray. And it was hard to resist that. I had never been to California except briefly. Oh, I forgot—one of the summers in graduate school—you asked me about summers in graduate school. One of last summers, Charlie Sommerfield and I drove off to an around-the-country tour, where we—oh no, this was another trip. Later on, Charlie Sommerfield and I wrote to Boeing for the possibility of a summer job at Boeing, or possibly a long-term job, I forget which. So, we went to Boeing and we were interviewed. We had first-class tickets so we could stop and visit all of our friends in Chicago and in Denver and in other places.
Finally, got to Seattle and were interviewed. The interviewer was very straightforward with us. He said, “I have several possible things that you can work on.” He asked whether we could work a flush mounted radar antennas?” We rational, and he said, “What about the design of missile entry cones?” And we indicated very little competence in such possibilities. And there was a third possibility was, which was equally impossible. So, he said, “I hope you guys have a nice time flying home. Very useful talking to you, but I don’t think that we have a possibility for you. Thank you very much.” We shook hands and we then stopped in five more cities on our way home, just seeing the country and enjoying ourselves. That was our one and only attempt to get a real industrial job. We were both at the RIAS, at the Research Institute at another time, a short lived “Research Institute for Advanced Science,” in Baltimore.
Now, did Gell-Mann reach out to you or how was that connection made to get you to Caltech?
Oh, he spontaneously wrote to me and said, “I did not solicit the job offer any more than I did the job offer from Yeshiva. They just came in the mail.” So, I accepted Murray and sent my regrets to Yeshiva.
And he was aware of what you were doing in Copenhagen? Was that mostly what was attractive to him do you think?
I told him what I—I didn’t tell him about the SU(2)XU(1) work because I hadn’t done it yet, as I remember. That would be in my last spring in Copenhagen. It was the work that I had been doing on the nature of universality it had to do with the universality of weak interactions, as exemplified by the so called “puppi triangle”, and also it had to do in part with what became known as current algebra. All these ideas—that Schwinger taught me although current algebra—is now said to have been invented by Gell-Mann. It is a long and complicated, intricate story. Lots of developments in theorical physics were done first by Schwinger, but are credited to others.
Yeah, so it sounds like Gell-Mann clearly was looking at you as a very productive potential collaborator.
That’s right. Indeed. And we did collaborate. We wrote a very fine paper together in 1961, in the year that I was there, but it is also the year in which he revolutionized my thinking, because he introduced the SU(3) theory of the eightfold way, which was also independently—and at the same time T34—Yuval Neeman in Israeli.
Right. Right. But you were only in Caltech for one year?
I was only there for one year, 1960-1961. He explained that I could stay on indefinitely as a research fellow or a research assistant professor, but that there was no faculty line position, no tenure track position available at the time, and he was very regretful about that. I applied elsewhere, and in particular to Stanford. I spent my second year in California at Stanford as an assistant professor.
Now, before we get to that, you said you did have interaction with Feynman at Caltech?
Mostly parties. But one interesting facet that nobody knows—and I hope I didn’t invent it, but I think it’s true. When Gell-Mann first got interested in creating a higher symmetry group, or elementary particle, he was working together with Feynman. They were studying group theory with a Caltech mathematician whose name I have forgotten. And the original version of the paper which was—ultimately it became Caltech Synchrotron Lab Report Number 20, was co-authored by Feynman and Gell-Mann. At some point, when the work was only a typed manuscript, Feynman insisted that it was too crazy. He didn’t want to be affiliated with such speculative ideas and insisted his name be removed. And so, it became Gell-Mann’s paper.
I was a surprised.
I wonder if Feynman would come to regret that.
Well, Feynman was a stubborn bastard. He didn’t believe in quarks for many years. He introduced the notion of partons, and it wasn’t for many years until it was demonstrated by experiment that he read that his parton was a quark. It was a strange time. Perhaps Feynman’s refusal was a precursor to personal dispute that developed between Feynman and Gell-Mann.
Oh, but it was personal. It wasn’t a professional dispute?
No. I don’t think it was ever professional. But it became he had—Feynman had a different point of view than Murray. He couldn’t go along with this notion of a fractionally charged quark. But quarks, incidentally, were invented by several people at the same time. The first of them being André Petermann at CERN. He had the idea of fractionally charged particles which was published in French, in 1963, but wasn’t well recognized. In addition, George Zweig introduced an equivalant concept at CERN. His work was never published as anything more than a CERN internal report. I spent the year 1961-1962 as an assistant professor at Stanford University.
Right. And this is a pretty exciting time because SLAC as a concept is being dreamed up by Panofsky?
Right. And yes, indeed. I was not part of that dream. That was accelerator physics and certainly not something that I would be terribly informed about. But I did some interesting work with Marshall Baker and had fun teaching. This was my first time as a professor. So, I was entirely occupied with teaching a course on electricity and magnetism and enjoying meeting my fellow postdocs and fellow—and the students. It was terribly exciting from that point of view.
Did somebody recruit you to Stanford?
No, I just wrote to them and asked for a job.
Were you aware of this idea that assistant professors at Stanford do not get tenure?
Not when I first arrived at Stanford. Afterward, however, they fired—or they told people they would not be renewed—Marshall Baker and several other junior facility. Marshall left Stanford and went to University of Washington and has had a very good career there. Several people were fired at the same time, and it became evident to me that there was such a policy. So I went to Chairman Schiff sometime in the middle of the year, perhaps after the first semester, and asked him if there were any chance at all that this would be a tenure track position, that I would have any chance to have tenure. And he said, “Quite honestly, no.” That you would not. That’s not how things went at Stanford.
That’s not a statement about you. That’s just a statement about the system.
That’s right. And so, I said I—you know, “I quit as of end of the year.”
You were thinking, “I’m not even going to wait until the fourth or fifth year”?
Not even the second year! So, I wrote to my friend Chuck Zemach, who had been my roommate for a year at Harvard, and he advised me that Berkeley was like the civil service. You’ll come as an assistant professor and you will soon be promoted.” So, I went to Berkeley and was soon offered tenure.
You know, it’s interesting; I talked with Cliff Will yesterday about the tenure system at Stanford, and it seems like what an incredibly destructive way to treat up-and-coming assistant professors. I’m curious what is to be accomplished by sticking to this process and policy so staunchly. Do you have any ideas about that?
I think it was a crazy policy. I remember at one time—I don’t think I can reproduce the people. There were a half a dozen people who were junior faculty members at the Stanford Physics Dept. who were not promoted but who later won Nobel Prizes.
Yeah, right. So, Shelly, you’re so well positioned in terms of your time at Caltech and then at Stanford and then at Berkeley. I wonder if you could reflect a little broadly about how physics was the same and how physics was different—theoretical physics—at each of these three major institutions?
My oldest collaborator at Caltech was Sidney Coleman. Technically, he was Murray’s graduate student, but he soon became my close friend and my de facto graduate student. His thesis was—based in large part—on work we had done together. He and I became disciples of Murray’s eight-fold way, and we spread the word throughout the physics world. In passant, we discarded our first and only eponymous result: the Coleman-Glashaw Electromagnetic Mass Formula. I also wrote one paper with Murray: it was extremely prescient, but largely ignored. It described what would later become known as Cabibbo Universality and Grand Unification. It was written just a bit too soon. Fred Zachariasen—a well known Caltech theorist—was also among my basic friends at Caltech.
I regret that I remained at Caltech for just one year. When I went to Stanford, I was largely by myself except for Marshall Baker as a collaborator. It was just one-year and I was not collaborating with other people, and I really don’t recall many external collaborations at that time. Things changed radically during the three and a half years I spent at Berkeley. I became very close with the experimental group, led by Luis Alvarez, often attending its weekly group meetings as…an unofficial member of the collaboration. They were discovering new particles almost every week and I was kept busy arranging then into multiplets of Murray’s eight-fold way. Our weekly meetings were both social and scientific. Alvarez once taught me how to entangle a bottle of liqueur with a man’s jacket in such a fashion that almost nobody could safely extract the bottle from the jacket. It’s a cute trick.
Another of Alvarez’s tricks, which I cannot reproduce in detail involves tying up a telephone cord with a scissors in a certain way. These were mire topological tricks. But more more important were the experimental indications of new particles, and I remember writing a—one of the only papers I wrote with an experimental collaborator, with Art Rosenfeld, now deceased, who became very important in arms control and negotiations. Art and I wrote a paper on the classification of newly discovered particles and I also wrote collaborative papers in those days with my old friends from Harvard, John Sakurai and Rob Socolow.
Shelly, just listening to you, it sounds like the distinctions that you emphasize between the theoretical and experimental physicists at both Cornell and Harvard, these lines were much less blurred at Berkeley, it sounds like.
Yes. It was at Berkeley that I learned the value of speaking with my experimental colleagues.
Both socially and substantively, it sounds like.
This is true. There were many more experimenters there. At Harvard—the Cambridge Electron Accelerator was conceived—but that had not been developed until the sixties.
So, I was not much aware of that while I was there. But they were talking about the electron accelerator that they would build. And that was very exciting. But that was one contact with experiment I did have. I remember sometimes Gill going to talks at the Cyclotron Laboratory and hearing the latest plans about the electron accelerator. But I was not deeply involved. You’re reminding me of things that I had long forgotten.
Now, you were happy at Berkeley. That was a very productive time in your career.
I was happy at Berkeley. It was scientifically a good time. Actually, I don’t know if I wrote anything really very exciting at that time. Along with Sidney Coleman, we were propagandizing the successes of the eightfold way that Gell-Mann had introduced. And that climaxed in 1964 while I was at Berkeley with the discovery of the omega-minus particle.
That was Brookhaven. Oh, for years I had been interested—that reminds me of something from earlier, from my college times—my friendship with Gary Feinberg persisted during the college and graduate school years, and we would frequently find ourselves at Brookhaven Labs. I think I spent some summers there, a couple of them, but I also had visited as a speaker or as a collaborator. So, I had contact with Brookhaven experimenters while I was a graduate student. Not so much with experimenters at Harvard, but at Brookhaven, and in particular with Nick Samios and his bubble chamber group.
Yes. Right. Now, I’m curious on the social side—you left Berkeley in 1966. Were antiwar protests starting up in Berkeley at that time, do you recall?
Oh yes. I think they had started up—what were Johnson’s years as president?
‘63 to ‘68.
‘63 to ‘64, I was marching for peace in—I’m not sure whether it was New York or San Francisco, but it was written up in the Times as a—as riot rather than a peaceful demonstration and I and my colleagues published a letter in the New York Times [I can’t find the date the letter was published.]
In 1966, Berkeley was much ahead of the curve, relative to most places in terms of campus protests, so that must have been a large part of your experience during your latter years there.
I remember when Mario Savio, who had been a physics major, was the one who got on top of the cop car and organized the demonstrations. And I knew him quite well, but he didn’t do well in the end. He got his degree, became a University lecturer, but died young of heart disease. Yeah, the so called “free-speech” movement was disturbing but it was by no means the reason I left. The reason I left was related to my father’s death in ‘61. My mother was living alone in New York. I wanted to be closer to her. She would come and visit me from time to time in California, but that was difficult for her. So, I wanted to be nearer to my mother and to Schwinger’s very attractive secretary.
So, Harvard—Harvard beckoned.
I couldn’t resist the Harvard offer. As soon as I got it, I said yes. I didn’t negotiate at all, to my later regret.
Who was the lead in recruiting you to Harvard?
I don’t remember, oddly enough. I think it was somebody not memorable, some factotum in the department who sent me the letter. But I was very well received when I came. I had no complaint about that. When I came, I immediately became friendly with people like Wendell Furry who was there, who had experienced some trouble during the McCarthy era.
Right. You came on as a full professor.
Oh, I came on as full professor, or almost so. Soon afterward I became the Mellon Professor of the Sciences for a few years and there after the Higgins Professor of physics. They took good care of me. They tried to take good care of me, except that our salaries were not up to what we deserved.
Yeah. Shelly, what were some of your most significant research endeavors while you were at Harvard during your first decade or so? Like 1966 to 1976?
Yes. Those were very exciting times. Not 1966 and not 1967; they were fairly quiet. But there were a number of postdocs that played important roles in my life. Some of them were post docs are Arthur Jaffe doing formal quantum field theory, but they became social friends of mine. But also—very soon I attracted to Harvard—John Iliopoulos became and remain very close friends. We did our work in 1969 with Luciano Maiani, who was another postdoc in 1969 on what’s called the GIM mechanism—Glashow-Iliopoulos-Maiani. That was a tremendous experience. John spent some years, four years or so, as a postdoc at Harvard, because it was very fruitful for him and eventually, he would get the job of his dreams in Paris. But before that, he was very happy to be at Harvard. The GIM mechanism attracted a great deal of attention. Its fifteenth anniversary was celebrated by a conference in Shanghai in 2019. A second such celebration in Rome was cancelled because of Covid-19. So, John had a wonderful experience with me. Afterwards, I was able to find Alvaro De Rujula to come to Harvard. We wrote papers together—31 all told. And we—also as a third choice for a junior faculty position— we hired Howard Georgi who accepted, and he became of course became an extremely good hire. Wonderful guy. And I wrote another 35 papers with him. So those years, the decade preceding my Nobel Prize, were the most exciting in my life, both personally and professionally.
Did you keep up your collaboration with Bj Bjorken after your work with him in the prediction of the charm quark?
(Laughter) Yes. Well, as friends, absolutely, but we met only sporadically. In terms of publications, we never published anything more together. But I remember him in recent years dropping into my office unexpected. He would make these impromptu tours to visit his old buddies. I was one of them. And he would try to explain the exotic things he was doing, which did seem, indeed, to be quite crazy. Our collaboration in 1964 was a very minor experience for him. He didn’t much like charm. It was too questionable, too speculative for him. But he reluctantly signed that paper with a slightly pseudonymous name. He didn’t sign it James D. Bjorken. He signed it Bj Bjorken.
That’s Bj. That’s it.
(Laughter) It was the only paper that he published under that name.
Capital “B,” lower case “j”—Bj.
(Laughter) Now, to what extent was that work with Bj—to what extent was that a precursor to the GIM mechanism from 1970 and the two quark (Unintelligible)?
(Unintelligible) We realized that the neutral current that would result from the introduction of the charm quark as we had done led to an innocuous neutral current. The commuter at the weak current with its adjoint produced a strangeness conserving neutral current. If we had applied our notion to my electroweak theory the theory covered then describe both leptons and hadrons. But quarks had just newly been discovered. Quarks were introduced in I think January of ‘64 by Murray, and they remained highly speculative. So, I can only blame myself for not realizing that we had the secret to making the electroweak theory applicable and known particles in matter. But I simply didn’t realize it at the time. That was ‘64. It was not until ‘69 that the three of us, the GIM collaboration, realized that simple fact. And we exploited it in a paper which was not committed to the electroweak model. We pointed out that this was an issue in any theory of the weak interactions, there would be induced strangeness changing neutral currents one way or another, and that we showed that that would not happen in the presence of the charmed quark. So, we were so very foolish. I deserve a great deal of blame for not realizing how useful had been what I had done with Bj.
Right. When did you first come into contact with the idea of the string theory?
Initially, string theory was simply an attempt to provide a theory of strong interactions, and I was not much into that game at all. That again has to do with the Berkeley situation as it had been. One of the persons who was responsible for hiring me, I would find out, was Geoffrey Chew. Chew was extremely friendly throughout my experiences there. He was pushing not string theory, but rather his bootstrap mechanism.
Chew’s bootstrap immediately led to string theory. But one of the things about Geoff Chew, which I found admirable, was that he had his own program for what the future of physics was in terms of his thoughts, but he made no attempt to dominate the department with people who followed his ideas. In fact, he did everything he could to avoid this. He would send his best students elsewhere when they became mature scientists. Instead, he would hire people like Steve Weinberg and me who had nothing to do with this type of physics. That was the way one should be. If you have your own ideas—yes push them by all means—but don’t contaminate your school with your own followers. The same is said more succinctly but less properly in the military. He never did that. Nor, of course, did Schwinger.
So, your work with Howard Georgi in 1972, 1973—you were not specifically influenced or thinking much about string theory at all during that time. When you’re looking about gauge forces and fitting them into the standard model?
Absolutely not. We had little or nothing to do with string theory. They were hoping that string theory would answer all our questions about fundamental physics. No one in those days understood where the top quark was. The bottom quark was just discovered in ‘77. How many quarks were there? What is going on? Why are their masses? What they are? The string theorists claimed they would answer all these questions. Today, they know that they cannot do so.
They have come to the very opposite conclusion, that there are an infinite number of universes, each with its own particles, forces, and physical laws. Of these, we live in the best of all possible universes. The so-called Anthropic Principle reflects an attitude that I cannot countenance. I could not countenance it from the beginning. They may be right, but they are unable to answer any of the questions that they set about trying to answer, whereas, we have answered some of those very questions already, same, but not enough.
What is your understanding of the relationship between the string theory and superstring theory? Because you are much more prominently known as a critic of superstring theory and not string theory itself.
So far as I know, the words are synonymous.
String theory may have originated in the different sense. It wasn’t very super. But the dividing line was when they realized that string theory incorporated naturally a theory of gravity. That made it super.
I don’t think it’s super in any other sense than that, except that it implies (or requires) supersymmetry.
In retrospect, Shelly—how well do you think—has both string theory and your criticism of it aged over the past 30 years?
Well, it’s hard to answer that. String theory has become an established part of physics departments throughout the world, more so in Europe than in America. We still have some universities which are proudly string-free, like Boston University. We also have an awful lot of string theorists around who are twiddling their thumbs. It is not clear that string theory is going anywhere. I expect that string theorists would disagree with that assessment. But they are actually considering many other circumstances such as black holes in other spaces than ours, and there are all kinds of interesting things being done in mathematics, in physics, elsewhere by string theorists but with no relationship to the questions that interest me. They cannot answer the questions they set out to answer. That much is clear.
That’s as clear to you—
That was clear from the beginning, I think.
Yeah. Shelly, let’s talk a little bit about the run-up to the announcement of your Nobel Prize. It’s always interesting the gestation period of the original research and when the announcement actually happens. So, I’m curious if you had any idea, you know, 1979 was the year.
by the late 1970s I began to think of myself as a Nobel contender. But I was under the impression that my old friend Steven Weinberg was doing everything in his power to keep the prize for himself and Salam. In particular—at a conference that he attended in Tokyo—he went out of his way to avoid mentioning my name at all while presenting the history of weak interaction theory. I got very upset by that omission. It was the issue which terminated our friendship. In the summer of 1979, I was invited to a meeting in Stockholm, to discuss the current state of physics ideas and others. Prior to the meeting, I sent a transcript of my talk to Steve. He was violently against my giving the talk. Because it examined various alternatives to what was then known as Weinberg/Salam theory. In fact, it was an open-minded talk in which I was discussing whether their—or more properly—our theory was a correct one or not. But it was such a heated discussion that I eventually had to simply hang up on him, because I had no intention of revising my talk. And I did not.
Was his assessment of your paper accurate in your mind?
I did talk about alternatives to the Weinberg-Salam theory. Yes. I was not yet convinced that it had to be true.
And what was your sense of why this was so unacceptable to him?
He thought it would endanger the Nobel Prize that he had campaigned for and anticipated for Salam and himself. Recall that Salam made a great deal of noise about why the prize should be given to he, Salam. I’ve been told that there were dozens and dozens of nominations of Salam. In fact, there’s a whole paper written about his shenanigans, which I can refer to you; written by Norman Dombey. Everything he says is true, to my knowledge. As it turned out the Nobel Prize was given in 1979 to the three of us. It was given to me explicitly for the one paper I wrote in 1960, which was published in 1961. In it, I introduced the SU(2)XU(1) theory. When I was at the Stockholm meeting. I encountered an elderly physicist, not nearly as old as I am today. He interrogated me, asking: “This angle that’s called the Weinberg angle, is that the same as the angle that you introduced in your paper of 1960?” I said, “It might differ by 90 degrees.” He said, “No. It’s exactly the same.” I took that as a good omen for my Nobel Prize. There is no question at all in my mind that that one paper was all they considered. They were not considering the fourth quark or the work I had done with charm or any of my other work. They considered this one paper and my Harvard thesis exclusively for their decision.
And so, you never collaborated directly with Salam?
No. But let me continue with my narrative. My Nobel Prize depended on that one paper written in 1960. Steve’s Nobel Prize depended exclusively on that one paper he wrote in 1967, a wonderful paper which applied the notion of spontaneous symmetry breaking to the—my electroweak model. So, the question arises, what did Salam do? He introduced the electroweak—the SU(2)XU(1) model in 1964. That was over three years after I did. He copied my work but did not cite me.
Shelly, let me ask—do you think that there is any possibility that this would be a multiple independent discovery?
Absolutely not. He knew my work when I wrote a paper—falsely claiming that the Yang-Mills theory would be renormalizable when masses were put in by hand. I claimed it would be renormalizable. I spoke about that work in London when I visited in 1959. Salam listened patiently to my work. And when I got back home, there were two articles awaiting me from his institution, one by him, another by a Japanese coworker, each of them showing that I had made a stupid mistake and that my paper was wrong. So, he certainly read my papers carefully. I have no doubt that he had read my 1961 paper as well, because the similarities were too great in his 1964 paper. In any event even if independently conceived, it was fully three years later.
Do you want to comment on why then he would have been a co-recipient of the Nobel Prize with you for this copy of your work?
I’ll explain it in a moment. But let me come back to—he also claims to the first to introduce spontaneous symmetry breaking in the paper that he wrote in 1968, one year after Steve wrote his paper. But that paper even cites Steve’s paper, so it is hardly the first time. He did what each of us had previously done, but much later. So why did he get a Nobel Prize? Very simply, he was nominated many times. Because he was Director of the International Center for Theoretical Physics in Trieste, Italy and he was very close with the directors of physics institutes in many countries; almost 100 of different institutions. And many of them wrote letters, by his instruction, using his words in some cases, encouraging the Nobel Committee to give the prize to him and also Steven. All of this documented, in fact, by the paper by Norman Dombey, who had access to Salam’s files in Italy, and has copies of the letters that he sent to other people encouraging them to nominate him. So, I think he shared the prize because he made a point of doing just that. Only after our award did the Weinberg-Salam theory become the Glashow-Salam-Weinberg theory.
This must have been an incredibly awkward and intense few months in your life.
Well, no. I’m only rarely awkward and intense. It really wasn’t. I would have been very surprised had I not shared in the prize. But the question was—I didn’t have dozens of Nobel nominations. Neither did Steve. I believe I had two. One was from Murray, the other from Sidney Coleman, perhaps there were others.
Were you ever able to repair your friendship with Steve?
Only enough to go and give a talk in Austin, maybe 10 years ago. And I have tried to—recently contacted him and tried to solicit his writing with me a paper having to do with fears related to the COVID epidemic, namely fear for support of physics in the post-COVID years. The fear is that ambitious attempts to pursue “useless” science like particle physics and astronomy are doomed, because NASA may not funded to do the kind of basic research it has done in the past. And I don’t think the accelerators—I don’t think we will be enabled to work at the European accelerator or at other accelerators when and if they are built because we will not be supported. So that’s it. Steve thought such a paper might be inadvisable, and he may be right.
To the extent that you can separate such things in your mind, did you feel more personally or professionally hurt by this episode?
Oh, my closeness as a friend, which was intense when we were in high school and persistent for many years afterwards, had dissipated long before. In particular, his article at the Japanese conference terminated any possible personal friendship in the future.
I wonder if you have ever reflected on the fact that you had been so close, if that may have felt that he had more leeway to treat you in the way that he did. In other words, if he was an impersonal colleague, perhaps he would have not felt so comfortable or aggressive in telling you not to pursue this particular line of questioning.
We were colleagues for years, something like two or three years at—three years at Berkeley. And then we were colleagues at Harvard for many years until he moved to MIT. Over the years we did collaborate on three papers, two of them moderately interesting, the third quite important.
No. He was at MIT. Then he moved to Harvard, and then he moved to Texas. But there was an interim when he and I were both at Harvard. At that time, it was a difficult relationship.
Yeah. Particularly because in the end, your views did not endanger his receipt of the Nobel Prize.
But Steve’s actions surely endangered mine.
Shelly, a happier kind of question—receipt of the Nobel Prize is obviously a quantum leap in terms of the level of recognition and the fame it bestows upon the recipient. And so inevitably, if you want it, it gives you a larger megaphone, right? You have a much larger profile and that comes with possibly the opportunity to talk about things that might be personally or professionally important to you that might not have anything to do with the research for which you are recognized. So, I wonder if you ever recognized or reflected on that kind of opportunity to, you know, raise issues that were important to you that might not be so directly related to the research? And if you used that opportunity.
Well, I don’t think that I particularly made use of my notoriety, so to speak, aside from supporting various initiatives and signing petitions. Most recently, 77 Nobel Prize winners objected to the way in which an American researcher was treated. Because some of his research was done at Wuhan University. That action was inspired by Trump, and NIH responded obligingly by canceling a contract for no sensible reason. Yes, I certainly am very happy to sign documents of that kind, and I’m asked to do that quite frequently. I will sign such initiatives whenever I agree strongly with its arguments.
How would you describe your personal politics, and to what extent have they changed over the decades?
My personal politics are primarily disgust with the present administration and the prayerful hope that Biden will be elected this year. And I would certainly—we certainly intend to support him, as we have supported Elizabeth Warren, for whom my wife, I and some of our friends sponsored an event where we collected over $50,000 for her. So, I have been involved in things of that kind and will likely be so involved again. Trump has made it embarrassing to be an American with a president who is cruel, incompetent and corrupt. There is not much to be done but vote. I would certainly do anything I could to promote sanity, but I don’t know how that can be done.
Do you see your life—your professional life at least—as a pre-Nobel and a post-Nobel kind of distinction? In other words, after winning the Nobel Prize, I wonder in what ways was it more difficult to continue on with your research, and in what ways was it easier? In other words, winning the Nobel Prize might open some doors and increase your notoriety, but it certainly pulls your attention in many other directions that you might not have had before.
Most of what I have accomplished in physics with a few exceptions, was done before 1979. So, yes, I’ve continued doing research and I have written some papers of which I am quite proud. One paper of 1998, with Alvaro De Rujula and Andrew Cohen showed that we do not live in a universe which matter/antimatter symetric. That is, we know there is no local antimatter, but it was an open question as to whether distant objects could be antimatter. And it is a seemingly rational possibility but we have shown that those regions, if they exist, the regions of matter and antimatter have to be larger than the visible size of the universe. Our paper disappointed my dear friend Sam Ting, whose AMS experiment was originally designed to discover antimatter in space. It has since been redirected toward more achievable goals. That’s no longer—it has been renamed and retitled. It is no longer a search for antimatter in space, in part because we showed there can’t be any, and in part because he hasn’t found any.
(Laughter) So, I am curious, Shelly, you said that your most significant work was pre-Nobel.
Do you ascribe winning the Nobel Prize as having a deleterious effect on your research?
Absolutely not. What I attribute it to is the lack of discoveries that have been made post 1979. It’s true and it’s astonishing that we were successful in finding the Higgs boson. But that was 2012, as I remember. That was one of the only recent discoveries in particle physics. The top quark—yes, it was discovered. It was observed in 1998. But these were both expected discoveries. Have there been any unexpected discoveries since 1979? Aside from the differ reaction of gravitational waves and merging black holes I cannot think of any.
So, if you can reflect more broadly, what does that mean? Are there just diminishing returns on what’s to be discovered? Are we waiting for the next Einstein? Is the technology or the computation waiting to catch up with that?
Well, we were experimentally guided, and it is experiment that tells us where to go. At this point, I think it’s up to the experimenters. We—I was very distressed—one of the saddest days of my life professionally was in 1993, when the American superconducting super collider was canceled.
That was the machine that might well have answered our questions because it was three times more powerful than the not-all-that-large hadron collider which the Europeans mercifully were able to improvise.
So, Shelly, let me ask you specifically on that—I am talking to Fred Gilman tomorrow, so this would be a good prep for that. To what extent was CERN able to simply pick up the ball that SSC dropped and to what extent is that not true? That what you envisioned for SSC would have gone beyond whatever CERN was able to do?
The design energy of the SSC was three times the maximum attained energy of the CHC had the SSC been completed. I am certain that many of our most vexing questions about particle physics would have been answered long ago. Upon the cancellation of the SSC project, CERN stepped in by designing and constructing the LHC. The concept was brilliantly conceived and well executed, as proven by its discovery of the Higgs boson in 2012. The LHC has become the crown jewel of elementary particle physics. However, in its 12 years of operation, the LHC has found no departures from the predictions of the standard model, nor any signs of physics beyond the standard model. We remain hopeful that the upgraded high-luminosity LHC, soon to be deployed will discover something new and exciting.
So, invariably it is going to be a speculative answer but I’m curious—had the SSC been built, where would particle physics, theoretical particle physics, be today and how might you use that as a justification for the tremendous taxpayer commitment to funding such a project?
Yours is a doubly hypothetical question. There are many ways to justify fundamental research in such recondite (useless) fields as particle physics and astronomy. Spinoff is one, much as the world-wide-web, the air-handling system at Meyrin Airport, the provision of inexpensive ventilators to Covid-19 patients in poor countries, CERN’s recent proof of the authenticity of a painting by Raphael, and much more. These disciplines also offer profound challenges to physicist and engineers, thereby developing skills that can be deployed in more practical disciplines. Yet the most important reason to pressure the most fundamental sciences is simply to pursue our sacred obligation to understand, as best we can, the universe in which we find ourselves.
So, Shelly, I’m asking you—let me ask just as bluntly as possible—make the case, right? Why should it be done? Why should something like the SSC be funded by the American taxpayer?
Our government, as well as those of many other nations, have been very supported of basic research in both particle physics and cosmology. I believe that people thru through out the world are excited by such discoveries as quarks and quasars, Higgs bosons and colliding black holes. I hope that this support will continue, especially in this troubled time of pandemic and climate change.
Yeah. On that idea, right, I wonder if—particularly with your opposition to string theory, right—do you see yourself as part of an intellectual tradition where you can trace your way of thinking back to that of your mentors or contemporaries of your mentors? Do you see these things in those terms? Because inevitably, philosophy—a philosophy of science—you know, bumps into the way that you see how the world works and the way that science should be done.
Difficult question to answer (laughter). I’ve never been much of an enthusiast about the philosophy of science except in the hands of a very few people. I no longer feel so strongly about string theory. Why beat a dead horse? String Theory does not answer the questions that I’m interested in. I’m sad about that. I hope that they’re wrong. I have no reason to think that their horse is, in fact, dead, but it’s dead from the point of view of being useful to my way of thinking about physics. And I think that many experimenters feel exactly the same way, because string theorists say nothing about experiments that have or could be done. They only speak of experiments that cannot be done, which is somehow not interesting.
No, I feel that I am in the tradition of people like Gell-Mann and Schwinger, who have been my mentors, or people like Bj who have been my collaborators, or people like Sidney Coleman, who has striven to try to understand quantum mechanics as best as possible. It’s a tradition which I hope will continue, and I think that other nations will build larger accelerators. The contenders: the Japanese, the Chinese, and CERN. And one or more of them is very apt to build the next accelerator. A very modest suggestion by the Japanese is the International Linear Collider for which there is a design that was created by my good friend, Barry Barish and his collaborators. There is a tremendous future for the new science of gravitational wave astronomy, and in particular LIGO in space, known as LISA, a project of the European Space Agency.
There’s a big future for that kind of research. Our standard models of particle physics and cosmology are both manifestly incomplete. There’s a problem, as you know, a tension, they say, between different measurements of the Hubble constant, a very disturbing situation. LIGO may shed light on this problem? I don’t know the status of the Japanese ILC or the Chinese large electron-positron collider which is their first step toward a large hadron collider. It’s not in the current five-year plan, but it might be in the next. But that work is probably not going on right now because of the nature of the relationship between our governments. What’s going to happen at CERN? The high luminosity upgrade to the LHC will be deployed and may prove fruitful. Afterwards, CERN will seek new challenges. CERN has always succeeded in what it seeks to accomplish.
Are you more or less bullish now than you were in the early 1970s when you started to think about the Grand Unified Theory in a systematic way? Are you more bullish or less bullish now that this is an achievable pursuit?
The simple models that Howard Georgi and I considered are basically ruled out. We don’t have sensible alternatives. Of course, people play all kinds of games, but there is nothing that shines out as being a correct implementation of the idea of grand unification. Perhaps we will, at some point. Not even the string theorists have claimed to have such a thing. They have no way to choose among the countless realizations of string theory. Nothing favors one to the other except the fact that we are here, which offers a very thin argument. String theorists will persist and may be successful. But can my discipline survive the threat to the cosmic sciences posed by Covid, climate change, and political incompetence?
I think that was Viki Weisskopf’s term.
Yeah. Shelly, over the course of your career, when and how did you pay much attention to general relativity? And to what extent was general relativity useful for your own research?
(Laughter) I took a course in general relativity taught by Paul Martin at Harvard, and he made a miserable job of it. I studied general relativity by myself and am fairly familiar with it, but it hasn’t affected my actual research program at all.
What do you see is its place as a contributing factor to the Grand Unified Theory?
Grand Unified Theory, as defined, has nothing to do with general relativity. That was not included in the original modest hope. The hope was merely to get a satisfactory unified theory of strong, weak and electromagnetic interactions. It’s much more ambitious to include gravity, and it would be lovely to be able to do so. One may hope that such a unification will come about. Of course, the string theorists claim that they have already done that but not in a manner that satisfies me.
Shelly, we focused so much on research questions. I want to ask you a few questions about your career as a teacher and a mentor. So first, on the teaching side. In teaching undergraduates, what are your favorite courses to teach? And in particular, those classes where you might be teaching undergraduates who are not going to pursue a career in physics, and you might have a singular opportunity to share with them some fundamental concepts that they should really know. What are those concepts and in what courses are more enjoyable to teach them?
For several years before I had left Harvard in 2009. I had stopped advising graduate students and teaching graduate courses. I was mostly taught a physics-for-poets type course, for which I wrote a remarkably unsuccessful textbook. From Alchemy to Quarks. It’s a wonderful book, but a little bit too sophisticated for that audience. I enjoyed teaching the course very much—college kids ought to know something about the major achievements of physics in the twentieth century, such as the special theory of relativity and elementary quantum mechanics. They should understand how we understand the atom in great detail and in at a deeper level than it’s taught in typical courses for non-scientists. I found that it can be done in small groups but not in large courses. Large courses have been unsuccessful in that respect. When I came to BU, I created a course for their newly designed honors program. That program did not exist when I first came to BU. Instead, I began my BU experience as a member of their Superlature University Professors Program. Upon Bob Brown’s accession to the BU presidency, he appointed me to a committee whose charge was to abolish John Silver’s program. The new honors program would arise from its ashes. During my first years at BU, I taught half-time within the University Professors Program. The course dealt with energy ands the environment. It continued after the UPP was terminated as a Freshman seminar in the new honors program. The seminar was limited to 15 gifted Freshman. I got much enjoyment teaching this course each year. The students appreciated the threat of climate change, and several of them chase to dedicating their careers towards fighting the threat.
And was that one of the things that was attractive about switching over to BU—that you could help build this program?
I didn’t know when I came to BU that I would have such an opportunity the first few years I was teaching in the University Professor’s program. We were to deal with small numbers of students at the graduate level and it was fine. But I never had a thesis student in that program because the program didn’t make sense for students of the hard sciences. To be a physics major, you must devote a good proportion of your courses to physics and mathematics. And if you don’t, you cannot be really a good physics major. Being a physics student was not compatible with being a student in the UPP. Nonetheless Being a University Professor was a great honor and the program seemed well conceived, but it didn’t fit in with physics. The new program is intended for undergraduates who have demonstrated competence in most fields of human thought. The kids in the honors program were bright and receptive. They were a delight and privilege to teach.
Yeah (laughter). And on the graduate side, can you talk a little bit about your style as a mentor, particularly in light of the fact that you were a protégé of Schwinger and Gell-Mann and people of this stature? How would you describe your own style as a mentor and who have been some of your most productive collaborators both as graduate students and postdocs?
Well, I have to say that I haven’t been very effective as a teacher of graduate students. I have about a dozen Ph.D.s that I directed over the course of my research experience. Only one was a woman who had majored in English literature, later becoming interested in physic. However, she worked hard and was able to overcome this omission. She earned her doctorate with me at BU and went on to become a professor at Penn State.
Sidney Coleman had been a graduate student at CalTech, but he was my student de facto while I was a post doc at CalTech. He was my best student by far. Coleman and I became intense collaborators for a long time during the sixties, when we created, among other things, the Coleman-Glashow mass formula. We also showed how you can get many of the consequences of flavor SU(3) from simple three-by-three matrixes rather than from Gell-Mann’s eight-by-eight matrices, and that fun to do accomplishment. So, we did a few things, we did some wonderful work later in his career on tests of the special theory of relativity. In fact, one of my most cited papers, was written with him about tests of Lorentz invariance. So, we had a lot of fun there for a while. So, it was very strange—at the very beginning of his career and at its very end, Coleman’s papers were with me. However, his really important stuff was carried out in the time between.
I’m struck by you; said a dozen graduate students over the years. That reminds me of the number you cited of Schwinger just in the year that you joined his group where he took on 12 a year. Right? So what do you think accounts for the fact that he would take on 12 in one year and you have had 12 in a career?
He was a much better mentor than I. That’s for sure. I found it difficult to think of research projects for my graduate students. I was much more effective working with as post- doctoral fellows, such as Alvaro De Rújula, John Iliopoulos, Luciano Maiani, and Howard Georgi. I wrote 35 papers with Howard and 31 with Alvaro. I profited enormously from those collaborations, as did my collaborators.
I want to ask you a question that’s—invariably it’s going to touch on philosophy—and that is, to what extent do you see your research helping to understand what is perhaps the most existential question in physics which is, do the laws of physics allow for a situation in which the universe could create itself?
Let me put it this way—how else could the universe have been created? So, of course, I believe that the universe created itself. And it brings us to the question, far outside my field, of what is the origin of life? Or more precisely, what is the origin of life on earth? That’s a truly fascinating question. We do not have the answer.
So, physics, if not today, at some point in the future you believe will be able to answer that question of how the universe could have created itself? And life for that matter.
And life for that matter. Yes, I think that you might find that some string theorists might feel that they have answered this question, although the answer might not be illuminating to us mortals.
(Laughter) Shelly, I want to ask some broadly retrospective questions in the last portion of our interview and then maybe a few looking to the future. The first is, what do you feel personally that you truly understand about physics now that as a graduate student when you were really sort of defining your own professional expertise and identity as a physicist—what do you truly understand now that you didn’t 40 or 50 years ago?
Well, the answer in brief is a hell of a lot. Quantum electrodynamics arose in the forties, but we had no theoretical understanding of the strong interactions or the weak interactions. When I was a graduate student, we had a so-called meson theory of nuclear forces, where it was imagined that pions did the job. Pion exchange was the mechanism underlying nuclear forces the meson theory did not suffice. This became obvious when the population explosion of elementary particles took place. It became increasingly clear that something else was going on. The weak interactions were a mess. For example, why weaker the weak interactions of strange particles weaker than the weak interactions of other particles? That question was answered by Gell-Mann in 1959 and more explicitly, by Cabibbo in 1963. Parity violation was discovered in the 1950s, CP violation a decade later.
Parity violation was incorporated within our impearl model of weak interactions by Marshak and Sudarshan, and slight later by Feynman and Gell-Mann. That’s an interesting story in itself about the history of physics. Feynman agreed thoroughly that it was first done by Marshak and Sudarshan. Sudarshan recently died and was never properly recognized for the work he had done. He was a good friend of mine in graduate school and afterwards. But the idea of the idea and implementation of electro weak unification was wonderful and even more the theory of quantum chromodynamics. These two parts of the standard model fit together perfectly. The crazy idea of para-statistics that my friend Oscar Greenberg at Maryland had introduced in 1964 became quark color in the hands of people like Gell-Mann and Harald Fritzsch. QCD has become the accepted theory of the strong nuclear bond. Our computer friends are more and more learning how to use OCD to make substantive quantitative calculations of observed particle masses. The Standard theory offers a correct, complete and consistent description of particles and their interactions it is an incredibly accomplishment. Yes, it does leave many open questions and those are the things that still fascinate.
And to flip that question on its head, what is as mysterious to you today as it was 40 or 50 years ago?
Almost everyone recognizes that the masses of the different quarks and leptons are not what they are by happenstance. And there must be some way, if not of calculating them all, of some relations among them. Nobody anticipated the top quark would be hundreds of times heavier than the charmed quarks. It seemed crazy. The neutrino masses are completely a puzzle. Again, simple three-by-three matrices appear sufficient to describe neutrino phenomena just as they are sufficient to describing weak interaction phenomena among the quarks. But why these particular three-by-three matrices? There are too many parameters in the standard model—about two dozen of them, and that is just absurd. Can we get that down to a manageable number? Would be nice to need just two or three parameters but I’d settle for a dozen.
Now, if it’s true that the rut that theoretical particle physics has been in for the past 40 or so years remains the same, if there is a graduate student who is very talented in physics, in theoretical physics, who comes to you and says “Shelly, give me some career advice. What do you think that I should do? What are the things that I should pursue that are going to propel my career for the next 20 or 30 years?”—what kind of advice would you give?
I have not been so approached for over 20 years. The answer is that I have not been taking graduate students for quite a long time, for perhaps 25 years. I don’t know where to send them, nor what they should be doing. My erst while colleagues, people like Iliopoulos, DeRéjula and Howard Georgi, they too don’t know really where to go at this point.
And so, you’re speaking of theory as a whole now, not just your particular field.
I’m thinking of particle theory.
Theory lives on without further particle theory. The work that is being done on information technology, on quantum computing, both theoretical and experimental is very exciting. The work that is being done at high pressure to find and to exploit the properties of metallic hydrogen is something which Harvard is deeply involved. Ike Silvera’s work is to me, very exciting. I’m not broadly informed about the things that are going on, other than particle physics, but a few things I do. The work that Lene Hau has done on slowing down light and creating circumstances in which light is virtually stopped—very exciting. Even if not fundamental. The search for electric dipole moments which will eventually be successful, which Norman Ramsey was pursuing throughout his life, is still being pursued and will be pursued by another factor of ten or 100 in the next few years, and I think that is very promising. Ditto for neutrino physics. My colleagues are certainly looking for CP violation there and they will probably find it within my lifetime. We are also beginning to collaborate with the Chinese. The Chinese have begun doing some exciting experimental physics, will continue, especially at the Daya Bay Laboratory, with American collaboration. Even more interesting are the experiments now under way at China’s Jinping Underground Laboratory. BU is involved in a promising experiment on muon conversion. They search for muon captured by a nucleus, very rarely converting into electrons. The discovery of such lepton favor conversion would be astonishing! Ditto the search for neutrinos double beta decay which is being pursued all over the world. The Chinese may pursue the most sensitive research. Gravitational waves astronomy, as premiered by LIGO, maybe the next frontier of fundamental science. Especially when combined with other astronomical searches, thereby yielding multi-disciplinary synergies.
(Laughter) Shelly, we’ve touched a little bit about the problems that the coronavirus is creating in terms of advancing scientific research, and perhaps even having an effect to dry up entire areas of research. But there is another crisis we haven’t talked about with regard to COVID, and that is the social crisis of the disconnect between science and what scientists do, and the broader public understanding of that. And we are living in a society now where you know, things like wearing a mask is a political act and people are suspicious of vaccines and things like that, right? I wonder if you could reflect a little bit, over the course of your career, about how we might have gotten to this position and what might we do as people who work in the general field of science to correct that, to get our country in the strongest possible position going forward?
Many portions of the American population harbor a profound dislike and distrust of science. Sometimes the objectives are religious, such as to abortion, birth control, evolution and big-bang cosmology. Others results from various forms of conspiracy theories: anti-vaccines, GMO opponents, belief in the deliberate creation of the Covid-19 pandemic, the assassination of JKF, ands by the American government of the 9/11 disaster. At the moment, the antivaxxers and those they influence may make it impossible to contain the Covid-19 pandemic. I have great confidence that one or more safe and effective vaccines against the virus will soon become available. But the vaccine will be of no use if many people fear to take it. There are other consequences of science fear and scientific illiteracy. They include climate change denial and opposition to nuclear power. A better educated population is prerequisite to the solution to our two mask existential problems: climate change and pandemics, Covid-19 and its inevitable successors.
Are you surprised that we’re here as a nation, where there is this strong anti-science portion of the American population? How did we get here?
I don’t know. We haven’t always been here.
That’s why the question is how did we get here, because we didn’t used to be.
Perhaps American generosity to science began with the Marie Curie radium Fund, created by American women. By 1921, they enabled Mme. Curie to purchase one gram of radium. Eight years later, upon Mme. Curies next visit to the states, she was given sufficient money to buy another gram. The gifts were presented to her by President Harding and Hoover, respectively (both Republicans, by the way) These generous gifts amounted to more than $2,000,000.00 in todays dollars.
After World War II, having spent the equivalent of 30 billion in 2020 dollars on developing nuclear weapons, funding basic science grew rapidly. The 200-inch Hale Telescope saw first light in 1949. It would remain the world’s largest telescope for 44 years. Two powerful proton accelerators were built soon afterwards: the Brookhaven Cosmotron in 1952, the Berkeley Bevatron in 1954. Each of these facilities cost roughly 100 million in 2020 dollars. As telescopes and accelerators became more powerful, they grew even more costly. The large Hadron Collider at CERN and NASA’s soon to be launched James Webb Space Telescope each has a total cost exceeding ten billion dollars. Many people argue that the cosmic sciences have become too expensive to pursue further. I cannot believe them. Human curiosity is too powerful to be constrained by financial considerations ingenuity together with international cooperation will ensure that the search will go on.
Well, Shelly, for my last question, you certainly fit the trend of the fact that eminent physicists never retire. They always remain active. And so, I want to ask you personally, what still excites you? What motivates you? What are the projects that continue to motivate you to remain active in the field? And what do you want to hope to accomplish for the rest of your life?
To be honest, I’m not doing research much any longer. What I have written recently has had to do with the history of physics rather than its substance. I just don’t feel competent to dip into research again. Instead, I am quite happy acting as an editor of The Inference: International Review of Science. We are trying to make it into a more substantive magazine if we can get the funding. We intend Inference to become the premiere scientific periodical in the niche between the professional and the popular, with editions in several different languages.
Shelly, it has been so fun talking with you today. I am so appreciative of our time together. Thank you so much.
Thank you, David. It has been a pleasure.