Transcript from an interview with Tsung-Dao Lee, 1957 Nobel Laureate in Physics, on 9 December 2007. The interviewer is Adam Smith, Editor-in-Chief of Nobelprize.org.
Tsung-Dao Lee, co-recipient of the 1957 Nobel Prize in Physics together with Chen Ning Yang, welcome to Stockholm. You are back here in 2007 to celebrate the 50th anniversary of that award. Looking back at your being awarded the Nobel Prize in 1957, do you think the public perception of the Nobel Prize has changed between then and now.
Tsung-Dao Lee: I’m not a good person really to measure the public but certainly I would not be surprised if that would be the case. And this is because even though in -57 the Nobel Prize was totally well known, but it had only 56 years of experience but by now more than a century I would say that at least the Nobel Prize in Physics really chronicle the whole development of physics during the 20th century and the beginning of this century. I think that has been a tremendous period and a tremendous record.
Do you think that the coverage of your winning the prize was as great in 1957 as it would have been now? For instance, you were at Columbia in 57 already, were you? Did they host parties for you when you won, as they do now?
Tsung-Dao Lee: I think that probably started at the beginning of the Nobel Prize and going through all the years because it’s a big event.
The prize amount, the value of the prize, was a lot smaller back in -57, I think.
Tsung-Dao Lee: Numerically yes.
In terms of the festivities here things haven’t changed very much. They do the same things now pretty much as they did then.
Tsung-Dao Lee: They have been very consistent and outstanding.
You were awarded the prize for overturning what was thought to be one of the fundamental laws of physics. You showed that there was not parity in weakened directions of elementary particles, which as I understand it basically means that you showed that elementary particles possess a handedness, that they possess the property of being either right or left handed. Is it still the case that people can do work that changes one’s view of the fundamental laws of physics or has that time passed?
Tsung-Dao Lee: I would hope it’s still true. We are constantly, as we struggle against nature the challenge is never diminished of our understanding and lead us to a further puzzle.
I remember I went to a lecture by Ivar Giaever who won the Physics Prize in -73 and he quoted Richard Feynman as saying that Feynman had enjoyed being a physicist when he was a physicist because he said now is a time in which we are discovering the fundamental laws of nature and this time will never come again. So he was rather implying that he was there at the right moment to be a theoretical physicist.
Tsung-Dao Lee: I think quite often people may think, especially people who have been successful, that they are clearly at the right time for them. But to think that such time will not come for future generations I don’t agree.
You won the prize extremely rapidly after your discoveries, that it was almost immediate effect of your work. That is certainly an unusual situation at any time but I suppose might be more unusual now.
Tsung-Dao Lee: Maybe, maybe not. Hard to say. One has to first ask how come? Not about you got the prize within a year. How come an idea which is quite deep and yet within a year everybody convinced is true. So that one has to ask. Not about prize. This is because in physics discovery there are, I think, many more important discoveries than parity. But all the great discoveries have a pattern because of human endeavour vis-à-vis nature. Now take for example general relativity, special relativity, any of these examples. Usually when you have an idea which is brilliant and turn out to be true later, but when you formulate that idea and in order to re-establish as a fact, that takes the lead time, and the reason is because all the experimental evidence and theoretical ideas they usually come hand in hand.
Now I will give you an example of Michelson and Morley’s measurement of velocity of light. Being independent of earth rotation. You measure the light travelling going with earth rotating and against it. It’s the same velocity. Now that measurement if it was instantly, everybody would realise something very peculiar has happened, but the experiment took decades. It’s always on margin being true or not quite true. And that struggling in compound with the forming of the theoretical idea, so even if you had a theoretical idea, which in this case would be Einstein‘s special relativity, it took time to verify this, and because of this time and the time for the theorists to have the idea and that lead time is, and the time to get advice would be even longer than that.
Now that’s not true with parity. One has to understand the special circumstances. After the parity non conservation once it was pointed out, and experiments started within the Wu experiment and Ambler, the experiment took a few months. Even that I’m pretty sure. But once everybody knew it was true you look right and left and within a few days there exists almost nearly 100 different kinds of experiment. It’s all true everywhere. It is because it was a mental block. Nobody looked for it.
So from the experimental front you set the parameters for the experiments that needed to be done in your theoretical work and then there was no technological barrier?
Tsung-Dao Lee: Wu’s experiment was not the easiest experiment, but it was a sure bet that they would test the idea. And that requires low temperature so took a few months. And it’s a 100% effect. So there is no doubt about the accuracy. But once it’s known then within a few days there are more than a dozen experiments. And people did that. And then within a month there are nearly 100 experiments. So the accuracy of the theoretical idea to nature can be verified without any doubt within a short time and that also made it easier for the Nobel committee to make a decision. So that perhaps explains.
With Einstein for instance you had to wait for an eclipse in order to do one of the tests.
Tsung-Dao Lee: Because theoretical idea and experiment accuracy usually comes hand in hand. They are even paced. So one makes a move and the other takes decades to be sure it’s right. So even in the best circumstance it takes longer.
Let’s concentrate on what you said that it was a change of mind-set. People had just accepted the idea that parity existed and they couldn’t think outside of that.
Tsung-Dao Lee: This is only partly true because the parity idea was a much older idea. When quantum mechanics started to develop people realised the parity. Based on the symmetry idea. Then the existent “test” you verify, so they are /- – -/. But what turns out to be these are not verification. Although the parity idea was used and people tested it. Fit the data. But actually the data did not support the right-left symmetry or the right-left non symmetry for that matter. And a very good example was an experiment by Cox /- – -/ I think it was done in the 30s.
He first did an experiment using electrons. And tried to verifiy a theoretical formula. And it did not check. And then everybody said that’s wrong because the vowel is parity. Surely the experiment cannot be right. And then it so happened his source of electron, first experiment, was beta TK and now that’s a weak electron beam. Then he changed it into thermionic images by heating. Then it checks. So that’s very good. This is an example of how people said yes.
So people saw it there in the 30s there it was in the beta decay it was there to be seen.
Tsung-Dao Lee: Yes but the experiment of course was marginal, but intensified and repeated experiments with the stronger source. And then did the checks. But the strong source was not beta decay. It was by heating thermionic emission. So that doesn’t check because nobody wants to question it and people thought that the agreement shows. So there are many examples because people used the idea of parity to classify. And what they found consistent with this idea so they thought they had verified. So we’re now talking about hundreds of experiments. Not just one.
So you and Professor Yang took it upon yourselves to look across all this experimental evidence and see whether it held up.
Tsung-Dao Lee: Across the level of the whole visit. And we conclude there was no evidence whatsoever. So we had to perform specific experiment to test it. Now the technology to do these experiments was all ready so once it was discovered within a very short time, a few days after the first threshold was crossed, so the truth is established beyond doubt in a few months’ time.
Again it begs the question what is it that causes a couple of people in their early 30s to challenge such an accepted tenant? I meant your age. What was it that caused you to challenge this?
Tsung-Dao Lee: I think that one was the behaviour of what one called the strange particles. This was from cosmic radiation. It’s called the Theta-Tau Puzzle. It may be too long to explain. Anyway there was a puzzle and it was two particles. Obviously they are different because they have different parity. They have the same lifetime. And they have the same mass. So why should there be a doubler.
So this was an observation that you and other people had seen?
Tsung-Dao Lee: I did not see but the experimentalists saw it. And I saw their work. But this was discussed intensely, this puzzle, the Theta-Tau puzzle. And this was two or three years before the work of parity non conservation. And then it took, probably because I learned physics in a different way, probably with a different approach so I was questioning what proof do we have. And so this inquisitiveness, to question that and then, that maybe had to do with my own background. And then, this was in 1956, there was an experiment in strange particle which /- – -/ too few. The experiment was done by Steinberger and Schwartz. Both of them got Nobel Prize for other experiment. Close collaborators of mine at Columbia later. It came out the result was ambiguous.
But once that was done then I realised that it can be applied in a general way, in particular the things about beta decay and that I did the second test. The beta decay the source would be very strong. Instead of using cosmic radiation or even machine produced particles. And that was the experiment of Wu and that made a decision. But it does involve a very different mindset to not to regard something to do with right left symmetry which seems to be very good. As a priori true.
You mentioned that your background, which I’d like to come to later in this discussion, has prepared you to question the truth and question proofs that had been found previously. But one would hope that all theoretical physicists were constantly searching for the truth and were questioning previously foundations of knowledge.
Tsung-Dao Lee: Of course we all do that so it’s very difficult to say what makes one person different from another one. That I cannot answer. But my own beginning of entering science is I think very different from other people. So that perhaps is the reason.
For whatever reason it was you who was the person who …?
Tsung-Dao Lee: The thing is you see my own education was interrupted by war. So I didn’t really, in the beginning, go through the formal training. More in the middle years.
Let’s talk about those early years now. So you were born in China and what sparked your interest in physics? Where did that come from?
Tsung-Dao Lee: I grew up in a family of learning. But then in 1941, it’s really after Pearl Harbour, then I left my home, my father’s home. And then I did not know the physics. Zero idea. So therefore from there, before I went to the US, my education was totally interrupted from second in the high school … six year of middle school and then after that you go to college. So I had four years and then I left home so that was interrupted. Then during the war I had two years of college later. But in that period of course I tried to learn things in an unorganised way. So therefore I tend to think in my own way more so.
But several things to ask about that. You came from an environment of learning so you were keen on learning but then even in that difficult time when things were a little uncertain your desire was at that point to learn. I imagine just getting by and surviving must have been quite hard as well.
Tsung-Dao Lee: Well you see learning and learning physics is a subset but they are not identical. Our family was learning but not physics. I didn’t know anything about physics. I encountered physics during the time when I was without schooling. I accidentally saw some physics books. And there exists laws of nature. That’s a new concept. This is very different from the traditional Chinese training. There wasn’t any. There are laws of nature. There are laws on human conduct. I look at that and saw they exist. Newton’s Laws. So that made me question. So I just developed my own system of judgement and I think it’s perhaps different from other more fortunate ones.
But without formal instruction in how to read physics how did you teach yourself to work with the maths involved?
Tsung-Dao Lee: Maths is easy because that follows … you take the beginning and you get the end. That is easy. You see. physics is much more … I can give my own reaction because I remember it vividly. Accidentally I saw one book was by Tuff. American. I think it was college physics. And the other was a Chinese book. This was accidental. And then I learned there were Newton’s three laws. I thought that’s very interesting. There are laws of nature. Then there are three laws. The first you know everyone knows. And I looked at that and say this is very good. There must be something in it. First law and third law. I said that seems to be very reasonable. It was the second law that I had … But in the book that’s Newton’s greatest contribution. /- – -/
Now my own reaction is still very vivid in my mind. On the left hand side you have f which you don’t know what it is. The right hand side you have acceleration which you want to find out. So what kind of law is that? The left hand side you don’t know. The right hand you want to find out. So I thought and thought and I looked at the book and I realised that there are two cases. Newton realised the force is a function of space. And he knew the function. One was elasticity. It’s linear in the distance. And the other one is gravitation. So once the left hand side is a non-function of space and right hand side is acceleration. Then you can solve it to be right. I thought that’s interesting. But that was not the thing that was stated in the book and so this is my approach.
How old were you when you were having these thoughts?
Tsung-Dao Lee: I was 16. In China is where we’re fortunate, if you had no formal education during the war years, you could take what they call equal ability which is much harder, but if you perform well then you can enter college. So I had two years of college and then I got a fellowship for graduate studies in Chicago and then I studied under Fermi and then once you get that you are alright.
Your own reading of physics which led you to start questioning the laws you were reading about took you to university in China briefly to study physics.
Tsung-Dao Lee: And then from there to the US.
Were you satisfied with the physics education that you received at university given that you’d approached it in this novel way and you hadn’t come out of some formal training system? You were training yourself and then you stepped into a formal environment of university, did you find that pleasurably, did you like what you found at university?
Tsung-Dao Lee: I was very fortunate because I was allowed to, even though this was during the war years, I actually entered two different universities. First year, the second year was different because the war. The first year I didn’t finish and everybody had to move. The second one was in Kunming. But in both places I was treated very nice. The second year I was a second year student but I could go to any classroom I wanted to provided I took exams. So I actually tried to cross the whole college so that’s why I got the fellowship for graduate student school in the US.
When you say cross the whole college do you mean in physics?
Tsung-Dao Lee: In physics. Maybe also mathematics. The others I didn’t take any courses. The professor they were very good for the college education and they also give enormous freedom and I was lucky.
You obviously graduated with extraordinarily high honours because you won this scholarship that did take you to the University of Chicago.
Tsung-Dao Lee: Yes I didn’t graduate but I had the scholarship. That made me go to the US -46, just after the war. And then it was also very hard to enter graduate school because I didn’t have a college degree. But then Chicago, and Enrico Fermi was there and they made the effort so I became his PhD student.
That’s a remarkable statement in itself. Enrico Fermi had won the Nobel Prize in 1938. He took into his lab a person who’d just come out of China without a degree. How did that happen?
Tsung-Dao Lee: It’s too late for me to ask Professor Fermi.
I have to dwell on it a bit how did he find out about you?
Tsung-Dao Lee: That actually I never asked him, but later I learned from Chicago that the department made an exception to admit me as a graduate student. Since I had some formal training but only two years of college. From there I learned physics in a very deep … This was an extraordinary experience for me.
How did they find you? How did they know? You won the scholarship, but was the scholarship connected with the University of Chicago?
Tsung-Dao Lee: No, not at all.
I still don’t understand how they were able to locate you.
Tsung-Dao Lee: I of course located myself to Chicago.
So you applied there.
Tsung-Dao Lee: And within a very short time the doors were opened. So I didn’t quite understand the mechanism but then I became Fermi’s PhD student. Also the Chicago then was a very remarkable … still is … but after World War II was extremely remarkable because when I entered Chicago in -46 there was only one Nobel Prize in Physics. That’s Fermi, and if I count just before I came here I tried to understand the process with the Nobel Prize then between -46 to -56 in the physics departments students or faculty who later or during that period got a Nobel Prize, then in addition to Fermi I counted 11. So it got to be a very good time.
A golden age.
How was Fermi as a supervisor? What was he like to work with?
Tsung-Dao Lee: He took very few students. Because I was his theory student. And he would have each week we spent one afternoon with us just talking, the two of us.
You say you were his theory student. Did he have one theoretical student at a time?
Tsung-Dao Lee: At that time when I was his student he only had one theory student. He had other experimental students. You see that is very time consuming. He spent an afternoon each week. He was at the zenus of his career.
Giving a whole afternoon every week is amazing.
Tsung-Dao Lee: Of course later I realised that this was tremendous. And essentially it was just talking to each other.
Did you feel a great burden that you had to prepare for each of these afternoon sessions?
Tsung-Dao Lee: He had what I would call and later I realised a tremendous technique. You see he said there are things I would like to know. He called me Lee because Tsung-Dao was much too difficult. Lee, why don’t you look up and give me a lecture next week. He was preparing something. I was very happy to teach Fermi. Of course this is an excellent way of building the student confidence and then he would ask questions and I would have to answer. Everything has to be proved just like that and why the reason. Later I realised that this was a fantastic effort of Fermi’s part. Personally guiding. To transfer his knowledge to build up the young man’s confidence. I mean this was a phenomenal thing. this is why Fermi produced so many good students.
Highly selective in his choice.
Tsung-Dao Lee: You cannot take more. He was himself of course extremely busy. He was doing experiments but also, after WWII, he was the one who really contributed and creating the energy, the nuclear energy. And to this I think I will always remember what a great teacher and what a great physicist Fermi was and I benefited by that.
And he died in -54 so you did know him for some time after you have finished your PhD. Did you keep an association during that time or did you go your own way?
Tsung-Dao Lee: I passed through Chicago and I visited him. And he was also invited to other places. Looking back, I felt much more. Being young it’s like the children where you have parents who are that good to you but the realisation of the depth usually come even stronger years after that.
A shame he didn’t last another three years and see his protégée get the prize. And disprove the parity law.
Tsung-Dao Lee: I think partly he was dealing with radioactivity.
Shortened his life.
Tsung-Dao Lee: He was radiation damaged.
Yes he died very young. The things you learnt from him about the way you should treat students is that something you’ve carried on in your own teaching career?
Tsung-Dao Lee: I try. Also I maintain with my PhD student … I always spend similar, whole afternoon, talking. And different people you do slightly different things.
I imagine it’s very rare to find somebody who actually responds to this in a really productive way.
Tsung-Dao Lee: That’s because Fermi was such a great teacher and I am not.
What do you hope you can give your students?
Tsung-Dao Lee: You try to give part of your love for physics and the way that you do things to a younger generation. And this of course is on top of that we teach. And the teaching is to a much bigger class.
Do you manage to have small interactions?
Tsung-Dao Lee: I am now not at university because of my age so teaching I’m not doing. But I have colleagues which work together.
You came to physics with this very questioning approach and I imagine most young brilliant physicists come in with a less questioning approach because they’ve been receiving and absorbing all the facts. Can you tell people to be more questioning when you get them?
Tsung-Dao Lee: I don’t know about that. I think these things cannot be specific. Each person is different. And most questioning is … how do you ask the question and that has to do with the temperament and the past history. So I don’t think that really can be taught. Whatever went down with one. I think the whole physics science you have to be inquisitive. So questions, yes everybody asks questions, but what are the questions you should ask about future physics, that’s very difficult. So far I think the profession has been lucky.
Talking of questions, you had addressed a very large range of questions across your career and you continually find new things to look at. How do you select the questions you want to work on?
Tsung-Dao Lee: That is a difficult question in itself. Usually it’s by what criteria. So first you have to get something that appeals to you that you feel has a future. And then you would ask if the answer to this … what would be the consequences. If the answer is that what are the consequences. Then if there is a questioning which is fundamental no matter how it turns out it will have tremendous effect. Then you should pursue to see if you can find the answer. So that probably is the way you balance what kind of questions you want to put effort into.
One thing you didn’t mention in that is whether you can solve the question.
Tsung-Dao Lee: Then after a little while you will come immediately into that. And then to solve the questions there are several ways. One is by your own sheer thinking. The other is you may require new experiments which give you hints. So then you do both. If you can get the experiment to give you more information, then the thing will propagate by itself. If it doesn’t then you ask a different question. So that’s how you move on.
Do you have a list of questions, as well as the successes, are there questions that you’ve approached during your career that have not really yielded solution?
Tsung-Dao Lee: That would be at least ten times more. But you should keep on doing that. And usually it’s also perhaps important when you have one question that has led to a development of a field. Just as it goes high you should ask different questions. When it already booming then the questions are more detailed. So keep on trying to pump new waves. That perhaps is the way to it.
At the moment I see that one of the things that you’re working on is new ways of solving the Schrödinger equation. And that seems from my non understanding of it that seems to have been something that was done, so I was interested to ask why one would revisit a question such as Schrödinger equation.
Tsung-Dao Lee: Mainly because we might have a new way of solving it. So if you have a new way of solving it then you want to test it. Actually at the moment I’m working on both. I have a new way of solving the Schrödinger equation and it’s … so for a certain limited type of problem I had solutions. You have a solution that has a little higher energy but going down. And you can also have a lower one. Now that technique has never been encountered before. Accidentally together with my colleagues we will try to develop. In the meantime, the questions that really occupy me at the moment is the new way of understanding particle structure. The Schrödinger equation I did a few years ago. And it’s developing. And now I have started another wave.
You’re obviously tackling questions that are immensely complex, it sounds like you tend to go for problems that are as you say starting a new wave. They’re not already being investigated by lots of people. But they’re new challenges lying out there on the horizon. That sounds like they’re problems that one needs to address alone a lot of the time.
Tsung-Dao Lee: Yes or no. Let me give you a concrete example. Here’s a problem I’m working on now. Now whether I get the answer I don’t know. You see, the physics today is very much like the physics 100 years ago. The problems are deeper. The challenges are larger. It’s … this is different from the physics of the 1950s. If you look at the physics at the beginning of the last century and the physics in the mid-century, which when I started my career, and the physics now. The physics now is very much like the physics at the beginning of the 20th century.
In what way?
Tsung-Dao Lee: This takes a little time to explain. Let’s first take the physics at mid-50s. At mid-50s after World War II there is lots of energy and Professor Fermi was the leader and there was new information coming from cosmic radiation. From accelerator newly built. So they were pressing. Within every few months there were new physics coming in. That was tremendously exciting and it that shaping to parity or if you look at the Nobel record of the last 50 years. Now you turn to the beginning of the Nobel Prize. Beginning of the 20th century. How do you view the physics then? It’s tremendous of course. But it came with a different time beat. It’s not every few months. It’s every few years. The problems were deeper.
You see that from relativity, 1905, general relativity, 1912, Bohr atom. And the beginning of the last century, Rutherford, alpha, beta, gamma. Now alpha is the strong interaction. Beta is the electromagnetic interaction. Beta is the weak interaction. Gamma is the actual magnetic interaction. But that solution really lasted the whole century. All these big leads. That’s the beginning of 20th century. Then you compare that physics in the mid-20th century. Mid-20th century the pace was much faster. But if you ask about the depth then maybe the beginning of the 20th century was deeper and we are now in such a period.
That is exciting. How did we regain the period? What happened?
Tsung-Dao Lee: What happened to the period? You see you have to ask apart from dark matter and dark energy that of course is another thing of our universe. But just the normal kind of matter. That’s our kind of matter. 5% of the big bang universe. Now the non-kind of matter, what are they made of? They go much beyond proton. Much beyond neutron. Now you see parity in non-conservation was discovered 50 years ago. Let’s ask what are the non-kind of matter the elementary components constitutes? Now we know it’s made up of six quarks and six leptons. 50 years ago only two were known. So that difference 50 years ago and now is very much like what now is the new beginning of a new century of search for physics like the beginning of the 20th century. Alpha, beta, gamma.
So we’ve set the ground rules from which we can start an exploration and deeper questions.
Tsung-Dao Lee: In time wise at this moment we now know all our non-kind of matter are made of six quarks and six leptons … now the six quarks … 50 years ago nobody knew it even as a problem and even six leptons, only electron and neuron were known. The neutrinos then were none of the real neutrinos that we now regard. So we are now placed in a period very similar to the beginning of the 20th century.
One has a feeling about the beginning of the 20th century that people had more time then to sit and think and work things out in a slower way. And that now the pace of life is so rushed and that everybody is always worrying about getting money for their next grants or building their next collider or how their university is going to carry on functioning that there isn’t the space for the reflective thought anymore. But maybe that’s just not true in theoretical physics.
Tsung-Dao Lee: I think for most people that’s maybe the case, but you want to find for the next century of the Nobel Prize winner that shouldn’t be the way to go at it.
That was Alfred Nobel’s original thought that he’d give people the money to just go off and pursue.
Tsung-Dao Lee: But what I want to say is that this is a very exciting period now. The pace for physics is an extremely challenging period. Like the beginning of the 20th century. You see the beginning of the 20th century … the first 25 years led to the relativity and quantum mechanics. The mid-century, where I started, it was exciting. It was a different period. So we did other things faster pace to make the realisation of relativity and quantum mechanics. But we are now facing challenges equally big as the beginning of the 20th century. And presumably the solution will be equally profound like relativity and quantum mechanics.
Is this message getting down to the level of people who are entering physics? Do young people coming in realise what they might encounter?
Tsung-Dao Lee: Whether we have done our job I don’t know, but I think many people probably do not realise that because they think physics has gone. But I think this is totally wrong because apart from dark matter, dark energy, which is in our universe but even our kind of matter. The basis constituents 50 years, we now know 12, but were only two. And so this is extremely exciting period for the new Einstein. For the new Bohr. For the new Fermi.
That’s a thrilling challenge, not a challenge, a thrilling offer isn’t it?
Tsung-Dao Lee: It’s also a challenge for the younger generation. So I feel this is good for you as a chronicler of Nobel Prize I think there will be the next Einstein. Next Bohr. True giants. They will be coming.
One aspect of your career that has been also a big part of what you’ve done is the running of large organisations. You were director of the Brooke Haven National Laboratory RIKEN research centre. Is that something that you also enjoy as well as addressing big questions?
Tsung-Dao Lee: In the sense that I can see it develop. And you ask why does one want to do that? One only has to ask that question. In order to find the answers one requires a collective mould. A single person can do whatever the person is good at. But there are answers to the search for physics requires a collective mode and I will explain. You see I had the idea some years ago to, which now I actually firmly believe this is related to dark energy. To cosmological constant. In other words … the other fields we have found, there is one which is an inertia field. What field can change inertia? And I believe that is identical to what we also call the Higgs field. We have discovered the WZ and all these new particles and very important electrons but we have not discovered but we know it exists. It’s a question of technology.
All these particles have spin. Angular momentum. The zero angular momentum is the Higgs field. It has not been found. That is because I believe our method of finding Higgs field is using what we call the resonance. But not all particles can be found using resonance. Any particle which has a complex structure cannot be found. A good example would be super conductivity, the Cooper pair. The basic Cooper-pair… Leon Cooper got the Nobel Prize. But you cannot discover the Cooper-pair by resonance because I think there is too many channels couples. It’s too wide. So it cannot be picked up like a needle. It’s a collective mode. So to discover collective mode we require different ways. Higgs field has a transformation like inertia. Therefore, if you take a large volume the Higgs field we have an average value and we define that value and inertia to be proportionate.
So you have to vary the change the inertia of every particle in there will change. And that kind of collective mode is something we have no experimental hold on. And to do that requires heavy ion collision. So about 30 years ago, I and a colleague of mine, Gian-Carlo Wick, we tried to work out a theoretical model and then we realised you need realistic heavy ion collision. And then you can change the background. Now perhaps this idea is correct. But that requires an immense experimental effort. Now I don’t do the experiments. I would like to encourage and to contribute and that’s why I try to help the experimentalists build the new facilities. And to use it in a new field which has now had some initial success.
So you brought an organisational ability to pull it together to make it happen.
Tsung-Dao Lee: I encourage other people. Because I may see the physics involved so I give whatever support. But I think that is important. Without that you wouldn’t know it. You see the physics cannot merely go with one person’s thinking. You need that collective mode especially if you want to have like nature in collective mode. So you seem to lack the effort too. And this is something I have conscientiously put aside part of my time to help younger people and to also help the experimentalists to some organised effort for nature.
And the RHIC collider is that’s coming together?
Tsung-Dao Lee: That is coming together. Even just two years ago, one of the American physicists had a great discovery. The nature of this collective mode is not known yet and it could be /- – -/ plasma. But I really believe it’s the same thing as dark energy in the long run. It’s a collective mode which can change inertia. Maybe true, maybe not true, but worth the effort. It seems the cosmological constant has changed since the Big Bang. So how come now we have 75% of energy that goes to dark energy? I mean that’s true in our universe and we have to understand it.
It’s still unexplained.
Tsung-Dao Lee: It could be as simple as the same as Higgs field. So that option exists. And for me I believe that that will be the answer. We have to verify this and you cannot verify it just by pure theories. You need experiments. And you need collective … people work on it. But I think it’s extremely exciting.
Another thing that you’ve contributed time conscientiously to is the relationship between the US and China and you’ve nurtured Chinese scientists through the establishment of scholarship programmes. Can you talk a bit about that?
Tsung-Dao Lee: That was part of it and that particular CUSPEA programme I started in -79 to -88. That is because that was a period China just emerged from cultural revolution. There was no way for a Chinese college graduate to go to United States or Canada or any place to study apart from the money problems. So I put in an effort. Organised for a limited period, ten years, for physics. Although it has other friends of mine have propagated it to other things. Biology and so on. Each year during that period roughly 90 students were selected and placed. All expenses. It’s a personal effort for that and it has been very successful. The group now have contributed in a way. Some in the US, some in China and jointly for the future development. In some way I tried to realise that if I did not get the help of my professor in China and Professor Fermi I would be totally gone.
It sounds like you may have had that without that help but yes I agree many will be lost if there aren’t programmes. Chinese physics is obviously getting on a more and more robust footing. The changes that are happening in terms of the need for as you say collective experimental facilities, does that mean that physics becomes more globally connected?
Tsung-Dao Lee: I hope so yes. I think this is a good point.
In many disciplines, not necessarily physics, the fact that research becomes more and more expensive means that smaller countries find it more and more difficult to keep up. But in physics, in fundamental physics, is that the case?
Tsung-Dao Lee: We also have this problem because the public is less supportive of physics and this is in part because we have not emphasised perhaps the fundamental nature. If you talk to most physicists, they don’t share my view. In other words, as I see physics is not mathematics and anything in the universe that we don’t understand is a challenge. The physical phenomena to the physicist and we have to find the answers. We cannot let the whole big bang universe that we live in without a serious effort to understand it
There is a tremendous focus on applied knowledge on people wanting research to provide solutions for everyday living rather than the investigation of fundamental nature.
Tsung-Dao Lee: Let’s look at the web. Where does that come from? That came from not too long ago maybe 1993 from CERN, it’s a system of transforming information because of the complexity of the CERN accelerator. It was developed there. And the CERN decided, the council, to give the protocol free to the whole world. Now within one year it was free, up to everybody to use it. Nobody realised it came from high energy physics. If the CERN tax one penny for that and we wouldn’t have any trouble getting funding. The public have to realise that.
Do the experiment and application will follow in unexpected ways?
Tsung-Dao Lee: It has been so far. The laser and all these technologies are from physics. So as I see it the future must remain so. I mean biology is very important, but so is physics.
And Martin Evans, one of this year’s Medicine Laureates, was at great pains in his Nobel Lecture to stress that what he was doing which is working with embryonic stem cells which of course are widely viewed as a lifesaving technology is not really trying to save life but rather to understand nature. He was making a bid for the same thing you’re talking about.
Tsung-Dao Lee: Yes this is why Nobel Prize and the foundation when one reads the record that is the human versus nature and the record of the achievement and the future promise.
That’s a nice though. I wanted to ask, we’re running out of time, and I would like to ask you one last question, when we were preparing for this interview you mentioned that you didn’t really use a computer very much and that might surprise people a little bit. Theoretical physicists don’t use computers. How do you work when you’re in your office, what do you do?
Tsung-Dao Lee: My group actually built a super computer and it’s got quantum chromo dynamics. It’s using the establishment of that. So my group which I supervise and I also try to find and with part of the Brookhaven, RIKEN Institute a third of the resources for that. In fact, the super computer to calculate quantum chromo dynamics the effort was spearheaded by the RBR Brookhaven and Columbia Group my right and left arm. So I help them to organise. But I don’t use it because my own thinking is different. You target different things. So the computers are extremely important to demonstrate the theoretical ideas are basically correct. You need these computers. But to get the route of the theoretical idea there are simple laws. They’re not out of a computer programme and that is the human direct to nature. It’s like a different thing.
Thank you. I think that’s a beautiful point to stop with.
Tsung-Dao Lee: Thank you very much. I talk too long.
Not in the slightest it’s been a real pleasure speaking to you. Thank you very much indeed. It’s been very inspiring and thank you so much for coming back 50 years on.
Tsung-Dao Lee: Thank you.
To celebrate the prize and to talk to us. Thank you.
Tsung-Dao Lee: Well, I am lucky. Thank you very much.
Interview with the 1957 Nobel Laureate in Physics, Tsung-Dao Lee, 9 December 2007. The interviewer is Adam Smith, Editor-in-Chief of Nobelprize.org.
Tsung-Dao Lee talks about his Nobel Prize in Physics, tells the fascinating tale of how he taught himself physics when World War II interrupted his education (16:45), and how this eventually led to a scholarship at the University of Chicago, where he studied under Nobel Laureate Enrico Fermi (24:45). He talks about Fermi’s unique approach to mentorship (28:20) and how he tries to teach his students in the same way (32:46), why we are entering a challenging new era in physics research (39:47), and the need for collective groups and global partnerships in physics (53:39).
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