Deepak Dhar, born in 1951 in Pratapgarh, India, obtained his Bachelor in Science in 1970 from the University of Allahabad, and his Masters in Physics from the Indian Institute of Technology, Kanpur in 1972, and   PhD  from  the California Institute of Technology. After returning to India in 1978, Dhar joined the Tata Institute of Fundamental Research (TIFR) as a Visiting  Fellow. He became a regular faculty member in 1980, and served until 2016.

Currently, he is at the Indian Institute of Science Education and Research, Pune (IISER) as a  Distinguished Emeritus professor.

It is not the first time in your career that you win an award, but this time you are the first Indian who wins the Boltzmann award. What does it mean for you?

I am of course very happy to get this award. But I feel that "first Indian to get the Boltzmann medal" seems to imply that not much notable research work in this area was done by Indians before me. But one should not forget the fundamental and pioneering works of S.N. Bose and Meghnath Saha in Statistical Physics in the 1920’s, before this award was instituted.One comment that was made on social media was to compare this to the Indian victory in the cricket world cup in 1983, which was also a “first”, (and followed by many more in later years). Of course, I do hope and expect many more such awards to Indian science in near future. But let me emphasize the important difference between awards in sports and in science. I think it is fair to say that winning is the primary aim of competitive sports. But, in science, the aim of research is not to get awards. They are only the incidental benefits. 

Clearly, the quality of science in India does not increase by the announcement of the award. But the public perception of the quality, does, and that may be useful.

Which are the traits and qualities that a scientist should cultivate in order to succeed? Has this changed over time?

I would say that the basic qualities that are needed are curiosity, scholarship, ability to think in a different way, and intellectual honesty. These remain unchanged. What changes is the relative weight of these. 

Clearly, awareness and appreciation of other people’s work is very important. But this has become much easier with search engines like Google, and easy electronic access to journals. 

Some skills were rare in old times, and hence highly valued. For example, a mathematician may become very famous if he has the knack that he can suggest a simplifying change of variables on seeing an indefinite integral. Similarly, there were people who were very encyclopedic in their knowledge, and given a new topic, they would be able to tell you of earlier related work. Such experts are also being replaced by Mathematica and Google.

What led you to become interested in Statistical Physics? What has changed most significantly in this field since you became a researcher?

Reading the textbook by Reif, I was attracted by the logical structure of the subject, and the fact that one can explain so much of macroscopic behavior in terms of a few simple-to-state laws.

There is a story that Abdus Salam once told about a Physics teacher in a provincial school in Punjab. He was explaining the four fundamental forces to students thus, `` We all know gravitation. In Lahore, there is also electricity, and in Europe, one also encounters weak and strong forces...”. Coming from a less-developed country, I honestly can relate to that. What happens when two pions collide somehow seemed to be a question I had no feel for.

If you could go back in time, would you still choose to study Physics?

Yes, surely. I have enjoyed my work in trying to unravel some questions in Physics. I have tried to dabble in other subjects, but have not had any great success.

Are there applications from your discoveries for which you are most proud of?

The main focus of my work is aimed at getting better theoretical understanding, and not so much towards applications. There is one work on electroporation that I was involved in with Sukhendu Dev, that does find application in actual clinical practice for drug delivery in treatment of some types of cancer. My role in this work was limited to find approximate formula the electric field for different electrode geometries, which was useful in optimizing the design. This paper continues to be cited.

What specific problems/challenges in (statistical) physics would you like to still see solved during your active career?

Let me just mention two such problems that I have found very interesting.

The first is to construct a zeroth level model that shows the solid, liquid, and gas phases, using realistic
interactions between particles, and that is exactly solved. We have models that are good, and show one
of these transitions, but not both!

The second problem is of understanding the `geometrical’ phase transitions in models with only hard core interactions. For systems of particles of specified shape one finds a multitude of orderings, and phases. The determination of the exact equation of state is hard. In fact, even theoretically predicting what phases would occur in which order, as we increase the density, is not possible yet.