Interview with Professor Shiraz Naval Minwalla

Shiraz Naval Minwalla, a professor of theoretical physics at the Tata Institute of Fundamental Research (TIFR), Mumbai, won the New Horizons in Physics Prize for 2013 on November 5. The $100,000 prize, which recognises “promising researchers,” is awarded by the Fundamental Physics Prize Foundation, which was set up by Russian billionaire Yuri Milner in 2012. Dr. Minwalla has been cited for his contributions to the study of string theory and quantum field theory, especially in improving our understanding of the equations governing fluid dynamics, and using them to verify the predictions of all quantum field theories as opposed to a limited class of theories before. On November 12, he was also awarded the Infosys Foundation Prize in the physical sciences category. Here are excerpts from an interview done on Tuesday with Vasudevan Mukunth, through Skype.

Why do you work with string theory and quantum field theory? Why are you interested in these subjects?

Because it seems like one of the roads to completing one element of the unfinished task of physics. In the last century, there have been two big developments in physic. The quantum revolution, which established the language of quantum mechanics for dealing with physical systems, and the general theory of relativity, which established the dynamic nature of spacetime as reality in the world and realized it was responsible for gravity. These two paradigms have been incredibly successful in their domains of applicability. Quantum theory is ubiquitous in physics, and is also the basis for theories of elementary particle physics. The general relativity way of thinking has been successful with astrophysics and cosmology, i.e. successful at larger scales.

These paradigms have been individually confirmed and individually very successful, yet we have no way of putting them together, no single mathematically consistent framework. This is why I work with string theory and quantum field theory because I think it is the correct path to realize a unified theory quantum of gravity.

What’s the nature of your work that has snagged the New Horizons Prize? Could you describe it in simpler terms?

The context for this discussion is the AdS/CFT correspondence of string theory. AdS/CFT asserts that certain conformal quantum field theories admit a reformulation as higher dimensional theories of gravity under appropriate circumstances. Now it has long been expected that the dynamics of any quantum field theory reduces, under appropriate circumstances, to the equations of hydrodynamics. If you put these two statements together it should follow that Einstein’s equations of gravity reduce, under appropriate circumstances, to the equations of hydrodynamics.

My collaborators and I were able to directly verify this expectation. The equations of hydrodynamics that Einstein’s equations reduce have particular values of transport coefficients. And there was a surprise here. It turns out that the equations charged relativistic hydrodynamics that came out of this procedure were slightly different in form from those listed in textbooks on the subject, like the text of (Lev) Landau and (Evgeny) Lifshitz. The resolution of this apparent paradox was obtained by (Dam) Son and (Piotr) Surowka and in subsequent work, where it was demonstrated that the textbook expectations for the equations of hydrodynamics are incomplete. The correct equations sometimes have more terms, in agreement with our constructions.

The improved understanding of the equations of hydrodynamics is general in nature; it applies to all quantum field theories, including those like quantum chromodynamics that are of interest to real world experiments. I think this is a good (though minor) example of the impact of string theory on experiments. At our current stage of understanding of string theory, we can effectively do calculations only in particularly simple - particularly symmetric - theories. But we are able to analyse these theories very completely; do the calculations completely correctly. We can then use these calculations to test various general predictions about the behaviour of all quantum field theories. These expectations sometimes turn out to be incorrect. With the string calculations to guide you can then correct these predictions. The corrected general expectations then apply to all quantum field theories, not just those very symmetric ones that string theory is able to analyse in detail.

How do you see the Prize helping your research work? Does this make it easier for you to secure grants, etc.?

It pads up my CV. (Laughs) So… anything I apply for henceforth becomes a little more likely to work out, but it won’t have a transformative impact on my career nor influence it in any way, frankly. It’s a great honour, of course. It makes me happy, it’s an encouragement. But I’m quite motivated without that. (After being asked about winning the Infosys Foundation Prize) I’m thrilled, but I’m also a little overwhelmed. I hope I live up to all the expectations. About being young — I hope this means that my best work is ahead of me.

What do you think about the Fundamental Physics Prize in general? About what Yuri Milner has done for the world of physics research?

Until last week, I hadn’t thought about it very much at all. The first thing to say is when Milner explained to me his motivations in constituting this prize, I understood it. Let me explain. As you know, Milner was a PhD student in physics before he left the field to invest in the Internet, etc. He said he left because he felt he wasn’t good enough to do important work.

He said one motivation was that people who are doing well needn’t found Internet companies. This is his personal opinion, one should respect that. Second: He felt that 70 or 80 years ago, physicists were celebrities who played a large role in motivating some young people to do science. Nowadays, there are no such people. I think I agree. Milner wants to do what he can to push the clock back on that. Third: Milner is uniquely well-positioned because he understands physics research because of his own background and he understands the world of business. So, he wanted to bridge these worlds. All these are reasonable ways of looking at the world.

If I had a lot of money, this isn’t the way I would have gone about it. There are many more efficient ways. For instance, more smaller prizes for younger people makes more sense than few big prizes for well established people. Some of the money could have gone as grants. I haven’t seriously thought about this, though. The fact is Milner didn’t have to do this but he did. It’s a good thing. This is his gesture, and I’m glad.

Are the Fundamental Physics Prizes in any way bringing “validity” to your areas of research? Are they bringing more favourable attention you wouldn’t have been able to get otherwise?

Well, of late, it has become fashionable sometimes to attack string theory in certain parts of the world of physics. In such an environment, it is nice to see there are other people who think differently.

What are your thoughts on the quality of physics research stemming from India? Are there enough opportunities for researchers at all levels of their careers?

Let me start with string theoretic work, which I’m aware of, and then extrapolate. String theory work done in India is pretty good. If you compared the output from India to the US, the work emerging from the US is way ahead qualitatively. But if you compared it to Japan’s output, I would say it’s clear that India does better. Japan has a large string theory community supported by American-style salaries whereas India runs on a shoestring. Given that and the fact that India is a very poor country, that’s quite remarkable. There’s no other country with a GDP per capita comparable to India’s whose string theoretic output is anywhere as good. In fact, the output is better than any country in the European Union, but at the same time not comparable to the EU’s as a whole. So you get an idea of the scale: reasonably good, not fantastic.

The striking weakness of research in India is that research happens by and large only in a few elite institutions. But in the last five years, it has been broadening out a bit. TIFR and the Harish-Chandra Research Institute (HRI) have good research groups; there are some reasonably good young groups in Indian Institute of Science (IIS), Bengaluru; Institute of Mathematical Sciences, Chennai; some small groups in the Chennai Mathematical Institute, IIT-Madras, IIT-Bombay, IIT-Kanpur, all growing in strength, The Indian Institute of Science Education and Research (IISER), Pune, has also made good hires in string theory.

So, it’s spreading out. The good thing is young people are being hired in many good places. What is striking is we don’t yet have participation from universities; there are no string theorists in non-elite institutions. Delhi University has a few, very few. This is in striking contrast with the US, where there are many groups in many universities, which gives the community great depth of research.

If I were to give Indian research a grade sheet, I’d say not bad but could do much better. There are 1.2 billion people in the country, so we should be producing commensurate output in research. We shouldn’t content ourselves by thinking we’re doing better than (South) Korea. Of course it is an unfair thing to ask for, but that should be the aim. For example, at TIFR, when we interview students for admission, we find that we usually have very few really good candidates. It’s not that they aren’t smart; people are smart everywhere. It’s just one reason: that the elementary school system in the country is abysmal. Most Indians come out of school unable to contribute meaningfully to any intellectual activity. Even Indian colleges have the same quality of output. The obvious thing is to make every school in India a reasonable school (laughs). Such an obvious thing but we don’t do it.

Is there sufficient institutional and governmental support for researchers?

At the top levels, yes. I feel that places with the kind of rock-solid support that TIFR gives its faculty are few and far between. In the US many such places exist. But if you went to the UK, the only comparable places are perhaps Cambridge and Oxford. Whereas if you went to the second tier Durham University, you’ll see it’s not as good a place to be as TIFR. In fact, this is true for most universities around the world.

Institutions like TIFR, IIS, HRI and the National Centre for the Biological Sciences give good support and scientists should recognise this. There are few comparable places in the Third World. What we’re missing however is the depth. The U.S. research community has got so good because of its depth. Genuine, exciting research is not done just in the Ivy League institutions. Even small places have a Nobel Laureate teaching there. So, India may have lots of universities but they are somehow not able to produce good work.

We’ve had a couple Indians already in what’s going to be three years of the Fundamental Physics Prizes — before you, there was Ashoke Sen. But in the Nobel Prizes in physics, we’ve had a stubborn no-show since Subramanyan Chandrasekhar won it in 1983. Why do you think that is?

There are two immediate responses. First is that, as I mentioned, India has an anomalously strong string theory presence. Why? I don’t know. India is especially strong with string theory. And the Fundamental Physics Prize Foundation has so far had some focus on this. The Nobel Prizes on the other hand require experimental verification of hypotheses. So, for as long as the Foundation has focused on the mathematics in physics, India has done well.

What are you going to do with your $100,000?

I haven’t seriously thought about it.