Why do we need theoretical research in physics? What did it mean to be a young physicist in the Soviet Union? And finally, which characteristics should a good student of physics have? Dirac medalist and member of the National Academy of Sciences, Prof. Mikhail Shifman answers these questions and more for Math is in the Air. Mikhail (Misha) Shifman, a Russian theoretical physicist based in the US, at the University of Minnesota, is one of the leading scholars in quantum chromodynamics and quantum field theory.
MM: Professor, can you tell us something about your scientific journey, from Russia to the US?
MS: My scientific career started in the early 1970s. I was a graduate student in Moscow, at the Institute of Theoretical and Experimental Physics (ITEP), from ’72 till ’76. That was a fortunate time for young people in theoretical high energy physics: this was the time of great experimental discoveries. Theorists were guided by breakthroughs in experiments. I was a little bit late: my life would have been completely different if I had started a year earlier, because I became a graduate student in 1972, at the time when Yang-Mills theory was proven to be renormalizable and the Weinberg-Salam model appeared. Shortly after, in the spring of 1973, asymptotic freedom of Yang-Mills theory was discovered. This was the beginning of Quantum Chromodynamics (QCD), the theory of strong interactions.
So, I couldn’t participate at the initial stage, but I delved into the area very early, especially after the November revolution of 1974, when particles with charmed quarks were discovered. I lived through these years of general enthusiasm. This was a very exciting time. Young people should work on new things! It is much easier to build a career in this way. There is less competition if discoveries come almost weekly.
So, I participated at very early stages of QCD. Another fortunate event for me was supersymmetry –the first serious expansion of our space–time after Einstein. It was invented in 1971, in Moscow, first by Golfand and Likhtman and two-three years later at CERN by Wess and Zumino.
At first, I didn’t pay that much attention to supersymmetry. There was no evidence of empiric support for it. In the early 1980s I got interested in a completely different aspect of supersymmetry -- non perturbative phenomena. These phenomena occur at strong coupling. In 1982, Valentin Zakharov and Arkady Vainshtein suggested me to consider strong coupling effects in supersymmetric Yang-Mills theory. This paved the way to a novel direction of research which is extensively used even now.
About my personal life. Starting from the early ‘80s I was receiving invitations to give talks at international conferences, review talks or lectures. Exchange of ideas, fresh ideas from outside, are very important in theoretical physics. However, I was not allowed to leave the USSR. At least, not until Gorbachov came to power, which happened in 1985. And then, with Perestroika, in 1989, I was invited for a year to lecture in Switzerland, at Bern University. This course was supposed to last two semesters, so, it was a long-term journey. I made an attempt to obtain permission from authorities, and a miracle happened: they allowed me to go with my family. Previously, this would have been completely unconceivable, but this time, after a number of adventures, finally I got permission to go to Bern. But without my older daughter, who had to stay in Moscow as a “hostage.” I started to lecture there, and then, our older daughter got permission to join us. Another miracle. I visited many major labs to talk physics with my colleagues. In the spring of 1990 the USSR became unstable, which made me nervous. On the other hand, I was sort of happy. The day of the Soviet invasion in Czechoslovakia in 1968 was an eye opener. I understood that ideology of communism is inhuman.
The Soviet Union collapsed in a year or two. All obstacles were eliminated. In spring of 1990, my daughter who had been studying at a University near Moscow, obtained an exit visa to join us, and exactly at that time, I got a letter that I did not expect.
Larry McLerran, who is a theorist at the borderline between nuclear and high energy physics, sent a letter informing me that his newly opened institute at the University of Minnesota had some senior vacancies and invited me to come. I was invited to visit Minnesota. We came there, all my family. I got offers also from a couple other places, but we decided to accept McLerran’s offer because there were a few people in his institute whom I knew very well from Russia. Also, Minneapolis is a nice city, with lots of cultural events. And we were not that much afraid of the cold winters, they reminded us winters in Moscow as they used to be 30 years ago.
We moved in August/September of 1990, that is, 29 years ago! We settled there and I never had any regrets. It’s a good place. I have done a lot of good physics here, and my children grew up here. I think that our Institute is very nice..
In Russia, our group at ITEP was one of the best in the USSR –this was my salvation from the insanities of the external world around me. ITEP was very isolated. Journals arrived with a long delay. It was difficult to report achievements. But that was what we had there, the so-called developed socialism. Isolation bothered me a lot. This is one of the reasons why I decided to not go back to Moscow, at least, not immediately. I got a couple of offers from Germany and France, but still decided to accept the offer from Minnesota. I love Europe, this is my culture, but to start a new life from scratch is easier in the US.
MM: During your career, you received several awards, including the Dirac medal. Which one do you consider as the most important one, and which one is the dearest to you?
MS: In 1999 I got my first recognition, this was very encouraging! And then, a number of other awards. In particular, the Lilienfeld Prize in 2006 meant two things: it is awarded for theoretical physics achievements and the ability to explain them to the general public. Communicating with the general public is my hobby.
I wrote a few books on history of quantum physics in the ’30s and ‘40s — the greatest achievements — that occurred despite the mad world in which physicists lived, in Europe and the USSR at that time. The work required many weekends. I was working on that just for personal satisfaction.
Quantum mechanics, quantum field theory, and nuclear physics are my favorites from the school days in the the Soviet Union. I learned lessons of Landau, using his famous eight-volume course of theoretical physics.
Recently, I published a book based on the letters between Sir Rudolf Peierls and his Jewish-Russian wife Genia Kannegiser.
Their life was full of adventures and misadventures, full of love and physics. This book is also based on archival materials, memoirs of their friends and relatives, and conversations with their daughters. Genia Kannegiser came from a huge family of the Mandelshtams which is nearly extinct now. It gave Russia Osip Mandelshtam, arguably the greatest poet of the 20-th century. He perished in a Gulag camp.
After the Lilienfeld prize, I received, as an award, the Blaise Pascal chair of the CNRS in France. A year I spent there was a very happy time. I was surrounded by good people.
And, finally, in 2016 came the Dirac Prize…
MM: Dirac medal: can you describe us, in a nutshell, the research that led you to this prestigious award?
MS: I was awarded with the Dirac medal and prize in 2016. It is especially important to me for two reasons. First it is given only for significant achievements in theoretical physics. Second, they have a great company there: Witten, Zeldovich, Polyakov, Zumino, Gross, Green, Schwarz, Wilczek, Parisi – all my good friends and people whom I admire.
I received the Dirac Medal with Nathan Seiberg and Arkady Vainshtein. Arkady is my collaborator from 1973-74, we wrote lots and lots of paper together. In fact, he was my informal teacher. Basically, most of what I learnt, I learnt from from him when I was a student in Moscow. He’s recently retired, but we are still in touch.
Nathan Seiberg is a younger theoretical physicist from Israel, who has been since many years in Princeton. He was doing great work on topics overlapping with our earlier research, such as strong coupling and supersymmetry. Together with Witten he immensely advanced research in this area. This field is still very much alive and thriving these days. Nati is an exceptionally good physicist.
I had never met him in person before I came to the US. In Moscow, I used to read almost all papers he authored on arrival. Also Witten’s papers. They were inspirational for me.
MM: We are now used to emails and fast internet communication. How was it doing research and communicating in the 70s in the Soviet Union?
MS: Well, once in a while, somebody from the West would come to our institute. I remember James Bjorken used to come pretty often, as well as Marshall Baker. These visits to a small extent broke our isolation. People sometimes came to conferences in Moscow or elsewhere in the USSR. But these were rare occasions. Besides, to be able to attend such a conference, one needed a special permission. I remember I was denied such a permission for Neutrino-75.
We could write letters. Letters addressed outside the USSR required another special permission. Sometimes it could takes weeks or months before the letter to a Western addressee would arrive. We could send our papers to European journals. And guess what… again a number of permissions were need. It was hard to communicate with the Western colleagues in the Soviet Union. The official doctrine was that all of them are enemies by default.
I wrote a short article on that. From it you can understand the conditions of isolation and how we survived.
MM: But isolation is not always a bad thing. Oppositely to ‘publish or perish,’ Prof. Shifman writes that:
“Now I would like to mention one more aspect which concerns me at present, a very strong pressure existing in our community, to stay in the “mainstream”, to work only on fashionable directions and problems which, currently, are under investigation in dozens of other laboratories . This pressure is especially damaging for young people who have little alternative. Of course, a certain amount of cohesion is needed, but the scale of the phenomenon we are witnessing now is unhealthy, beyond any doubt. The isolation of the ITEP theory group had a positive side effect. Everybody, including the youngest members, could afford working on problems not belonging to the fashion of the day, without publishing a single line for a year or two. Who cared about what we were doing there anyway? This was okay.”
About admissions at ITEP, Professor writes: “ITEP was more than an institute. It was our refuge where the insanity of the surrounding reality was, if not eliminated, was reduced to a bearable level. Doing physics there was something which gave a meaning to our lives, making it interesting and even happy.” Admissions were difficult, and “Even extremely bright students, who were too mathematically oriented, like, say, Vadim Knizhnik, were having problems in passing these examinations.”
Vadim Knizhnik lived only 25 years, but his contribution to mathematical physics was relevant; it includes developments in string theory and algebraic geometry, as concisely described in the obituary published by the Circolo Matematico di Palermo.
According to Prof. Shifman: “We had a wonderful feeling of stability in our small brotherhood. A feeling so rare in the Western laboratories where a whirlpool of postdocs, visitors, sabbatical years come and go, there are a lot of new faces, and a lot of people about whom you do not care so much. [At ITEP], The rules of survival were quite strict. First, seminars – what is now known worldwide as the famous Russian-style seminars. The primary goal of the speaker was to explain to the audience his or her results, not merely to advertise them. And if the results were non-trivial, or questionable or just unclear points would surface in the course of the seminar, the standard two hours were not enough to wind up. Then the seminar could last for three or even four hours, until either everything was clear or complete exhaustion, whichever came first.”
“Scientific reports of the few chosen to travel abroad for a conference or just to collaborate for a while with Western physicists, were an unquestionable element of the seminar routine. Attending an international conference by A or B by no means was considered as a personal matter of A and B. Rather, these rare lucky guys were believed to be our ambassadors, and were supposed to represent the whole group. In practical terms, this meant that once you made your way to a conference, you could be asked to present important results of other members of the group. Moreover, you were supposed to attend as many talks as physically possible, including those which did not exactly belong to your field, make extensive notes and then, after returning, deliver an exhaustive report of all new developments discussed, all interesting questions raised, rumors, etc. The scientific rumors, as well as non-scientific impressions, were like an exotic dessert, usually served after nine. I remember that, after his first visit to the Netherlands, Simonov mentioned that he was very surprised to see a lot of people on the streets just smiling. He said he could not understand why they looked so relaxed. And then he added that he finally figured out why: <<... because they were not concerned with building communism...>> This remark almost immediately became known to “Big Brother” who was obviously watching us this evening, as usual, and it cost Simonov a few years of sudden “unexplainable allergy” to any Western exposure.”
MS: My first paper was published in 1972, that is, 47 years ago! A few years ago I counted that I had 64 different collaborators from all over the world. This number is growing. I always liked working with people, not only after I moved to the US, but also in the Soviet Union. From 1990, since I’m in the US, I’ve been collaborating with the Americans, French, Italian, Swiss, German, Russian, English, Israelis… wherever people do theoretical physics.
MM: Why do we need abstract research in theoretical physics in today’s world?
MS: There are many reasons. Technology comes after theory. In the last thirty years, we had the Internet, Google, social networks, smartphones, Whatsapp, GPS, and many other things which changed the world, made all people better off. And not only in Europe and North America: in India, Africa, South America – everywhere – people use computers and learn a lot, speak with their friends and relatives thousand kilometers away, buy books and clothing and so on. And all of this is the consequence of the discovery of transistors in 1947 by Bardeen, Brattain and Shockle seventy years ago. Fundamental research is an investment in the future. This is costly investment, but without it the future of our children and grandchildren will not be better. Especially expensive is research in high energy physics. I hasten to add that the World Wide Web, a byproduct of research at CERN, payed off ten-fold or maybe hundred-fold. Another example is MRI. No modern clinic can function without it. Many years ago magnetic resonance in atoms was a part of fundamental research. In the history of humankind people always have been doing things which hardly seemed practical for society. Take Galileo: who could think that his experiments in Pisa would lay the foundation of every single machine operating today? At his time Galileo’s throwing balls from the Tower of Pisa was really obscure. But he opened up physics for us, everything is based on that.
Experimental and theoretical physics grew into a huge tree now. Everything physicists do needs money, resources. Of course, there are limitations because society is not infinitely rich and after all it is society as a whole which pays for fundamental research. Therefore priorities should be set. Some projects could require five years, others ten, still others 20. Funding comes from public funds. Thus, the public has a say. Educated people can have some knowledge in the subject; their opinion is relevant and important.
Some people will always be against costly scientific projects such as accelerators: this is the case of Sabine Hossenfelder, a well known physicist and writer, interested in foundations of physics. She authored a recent book titled Lost in Math: How Beauty Leads Physics Astray. She is an ardent opponent of future accelerators. I understand her motivations. To a certain extent I agree with ideas expressed in this book. But I disagree with her conclusion. If you stop developing a certain area, people who work there will go elsewhere. The scientific and technological culture resides in people. It is like the Olympic flame, transferred from hand to hand. In Germany, Hitler forced hundred or two of their best scientists to leave the country. Not too many, right? But they were the best. Now, 70 years later, German research is far from global dominance – the level it had in the 1910s-30s. Why? The chain was broken. The generation which should have replaced Born and Einstein was not there. One missed generation was enough to lose all what had been accumulated earlier. Germany invests now a lot of money in science, but I will risk to say it will never achieve the status it had before Hitler. If we start building accelerators in ten or 15 years from now (when hopefully people decide to renew experiments in high energy physics) there will be nobody who could do it or could teach young people. Nobody, who could pass the flame to students. If a generation is destroyed, it is very hard to restore this connection.
Therefore, unlike Sabine, I believe we need at least some projects in high-energy physics to keep the scientific culture alive.
MM: This is very intriguing: science relies on people, and, in particular, professors and students. This reminds me of art creating and art schools, where teacher-to-student transmission of knowledge is crucial.
Can you tell us something about your relationship with the world of the arts, and in particular, with music and with the visual arts?
MS: I’m a big fan on painting! I’ve strong opinions about what I like or dislike. I try to support young Russian artists by buying their paintings. Usually they are affordable. I have a small gallery at home, perhaps, ten paintings or so. As far as music is concerned, this is a problem — I don’t have a good ear. My grandchildren have perfect pitch, and they play piano (three of them) and violin (one of them). Maybe they inherited their music talent from my wife, who sings very well.
MM: Which characteristics should a good student of physics possess?
MS: A good student must be very curious. Also he or she must make some compromises in his or her life, sacrifice something: physics takes so much effort and time, a lot of traveling, less friends… Work ethics is also important. Every problem, when you start thinking on it, seems very hard. It is important to be able to overcome initial hesitations. A good student has to read a lot, attend courses of good lecturers, talk to peers, and look through new books and papers. It is very good to find a group of thinkers close to you. If you are alone, it is extremely difficult, almost impossible to be a good student. Science is so broad now, one can easily get lost.
You cannot learn only from books, but also from people: you need other people around with whom to discuss projects. Having around just five or six people interested in a topic is a blessing. There is an interesting article on this issue, written by a Nobel prize in Physics, Gerard ’t Hooft.
MM: Thank you Professor!
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