A Scientist's Perspective


Prof. Narayan Banerjee, in conversation with Suvadeep Roy

  Professor Narayan Banerjee is an eminent Indian physicist, acknowledged for his contribution to Gravitation and Cosmology. He was the recipient of the Prestigious Vaidya-Raychaudhuri Endowment award in 2017. Currently, he is a professor at the Department of Physical Sciences in IISER Kolkata and has been an inspiration to generations of scientists and continues to inspire young minds.

  Interviewer: We are really very honoured to have you with us, Sir. You have truly been an inspiration to generations of scientists and continue to be so. Thank you for lending me some of your valuable time for this conversation. You are a recipient of the prestigious Vaidya-Raychaudhuri endowment award, which has two eminent physicists in the name. However, they themselves did not get the popular recognition that they deserved. We see the trend continuing, with other Indian scientists as well. What do you think is the reason behind this?
  Prof. Banerjee: You are right. They are not well known amongst the common people although their contribution to knowledge is so fundamental. But see, scientists are not really public figures. So, it is in a way expected. Vaidya found out the exact solution of Einstein's equation for a radiating star and the stars do radiate you see. And Raychaudhuri’s equation deals with singularities. We hear so much about Hawking-Penrose singularity theorem, that in the realm of general relativity singularity is bound to happen if some energy conditions are fulfilled. That can be ascertained from Raychoudhuri’s equation. But the Hawking-Penrose energy theorem is much more abstract, which involves a lot of mathematical structure. On the other hand, Raychaudhuri’s equation is much simpler. Their (Vaidya and Raychaudhuri) work easily stand out in the field of gravity and cosmology, and they have far reaching effects. Of course they are widely respected amongst the gravity community, all over the world, but not other than that because their work did not find any everyday application. I think that is the reason but anyway, I don't believe that scientists will ever be public figures like a football player, a film star or a cricketer.

  Interviewer: Recently India is making a name in the world stage for doing rocket science on a shoe-string budget, the latest achievement being that of Chandrayaan 2. Also, the recent invention of room temperature semiconductors, by Indian scientists is making legitimate news. But pseudo-scientific ideas are making a lot more noise. How do you think the scientific community should tackle this?
  Prof. Banerjee: The attitude of a scientist should be to question everything and test everything against logic as well as observation. So, I think the most important responsibility of a scientist or scientists, as a community, is to make people aware that you should ask the rationale, the logic and what are the observations, logical explanation before believing pseudo-scientific ideas. As a scientist one has a responsibility in his own way to work in at least a smaller scale. Try to train your friends and members of your family and anybody who comes close to you about asking questions and help them understand that they have to logically accept something before believing it. Of course there will be people who will oppose these but everyone has at least a minor responsibility to train people around them to think scientifically.

  Interviewer: Nowadays, curtailing of research funding is a global issue of concern among the scientific community. On one hand, we see some taking to the streets to ‘March for science’ and on the other hand, we find some scientists keeping themselves excluded from social and political affairs. What is your take on this?
  Prof. Banerjee: When you live in a society, you have some responsibilities towards that. One cannot forget that a scientist is a social being, as a social being a scientist has his or her responsibility as well. Right? And with the social aspects, invariably comes politics. I'm not talking about a definite political philosophy, I am talking about the social requirements. I do not support this idea of staying away from all social issues.
One should not forget, that industry is fine, we cannot survive without that. But although Science and Technology are intimately related, but they're not identical. And today's science research is costly. So, for the sake of civilization, one needs to fund science, without expecting an immediate industrial application. However, every scientific discovery sooner or later gives birth to some kind of technology!

  Interviewer: You have actively been involved in scientific research for more than three decades now. So, why did you choose Theoretical Physics in the first place, specifically Gravitation?
  Prof. Banerjee: As a student, I was interested in two things, one is general relativity, the other is elementary particles. It worked out like that I ended up doing general relativity.
Presently I'm interested in various aspects of gravitation and cosmology. One is, that our universe, our habitat, is expanding. But you know that gravity is attractive. So that the universe expands is fine. That maybe due to some initial condition, initially, there was some push for it's expansion, but the expansion should have been decelerated. The two galaxies are moving away from each other, but they attract each other, right? So, the velocity of separation should be decelerated. That was the expectation. But, but for the last 20 years, we know that the universe is actually expanding with an acceleration as if someone is pushing the galaxies away from each other, so, that is quite surprising, goes against your knowledge and belief. The gravity is attractive. So, there are all sorts of attempts to explain this kind of an acceleration. The kind of matter that gives rise to an accelerated expansion or repulsive gravity is called a dark energy. So, one of my present interest is to look at different aspects of dark energy. I try to construct models of dark energy.

  Interviewer: Can you tell something very lucidly about dark energy?
  Prof. Banerjee: Dark energy is some kind of matter which has a kind of effective negative pressure and this negative pressure gives you repulsive gravity. So, my interest is to try to find out what the dark energy is all about. It is still not known. See, in physics it’s all about evolution. So, if something is moving, then you talk about velocity with which it changes its position. Right now, if you see velocity is changing, then you think about the evolution of velocity you know, think about acceleration, right? So, it was thought that the acceleration of the universe was constant. Acceleration is related to a dimensionless parameter called the dissolution parameter which was thought to be a constant. Now, we see that, the acceleration of the universe is evolving. Meaning at some stage the universe had decelerated expansion and in the recent past, let's say for a few giga years, it is having an accelerated expansion. The evolution of velocity is called acceleration. The evolution of acceleration is called jerk. We try to use the observational data to find out an expression for this jerk and from that try to reconstruct the model of the dark energy.

  Interviewer: Do you think learning science in mother tongue can make students understand science better? What are the pros and cons involved?
  Prof. Banerjee: Yes, absolutely. But there are problems as well. It is easier to learn anything in one’s mother tongue, but in science, in any subject for that matter, you have to communicate everyday. You cannot do science, sitting alone under a tree. So, communication will be a problem. The internationally accepted language of communication in science today is English. So I would rather play safe and suggest that students who want to do science should be taught in English rather than anything else at the higher level.

  Interviewer: Please share some stories or happy moments you remember from your scientific career.
  Prof. Banerjee: I'm not so sure. See, every moment is a happy moment in that sense. Because, working in science, it's not likethat you are finding something new all the time, but you are always on the lookout for something. So that gives you fun. But I think, the happiest moments I have spent is the time I have spent with my students.. There are so many happy memories. Don't ask any incident because I shall not be able to do justice which one I am more fond of.
One very exciting moment for me was perhaps the news that the gravity wave has been detected, but the excitement was slightly less than what it could have been, because somehow I had anticipated it. It was not a public news. But I had heard rumours and had anticipated that this is going to be announced shortly.

  Interviewer: On a lighter note you have such a wonderful voice, have you ever thought to use it in theatre or film?
  Prof. Banerjee: No. As a student when I was in college I played in theatres but not for the voice. In fact, most of my friends said that I was a good actor. So, I had some popularity as an actor but no points for the voice. But anyway, when this interview is published, please don’t miss it! I can actually show it to my family that I have some quality, the voice!

  Interviewer: So, as an end-note what is your message to budding scientists?
  Prof. Banerjee: Enjoy! enjoy your science and enjoy doing your science. It needs a lot of hard work as well. Have you ever seen, at least on TV, Kapil Dev fielding? You will see that it is effortless. Do you think that he does it by God's grace? No, there's nothing like that. He worked hard. Worked very hard. What a tremendous effort is required to make it effortless. So, everything if you want to do above a certain level one has to work hard. But the bottom line is that you have to enjoy it. Unless you enjoy it, you can't do that. And as you asked before, whether you actively participate in everything or not, that is a separate stor, but don't forget amidst anything that you are a social being, you have social responsibilities. You will not be able to do everything by yourself. So you have responsibilities too. These two things I would say, and yes, always be true to your own self!

  Interviewer: Thank you Sir, for your inspiring words and for your valuable time. We hope to hear more from you soon.

This interview was conducted by Suvadeep Roy, who is currently a final year BS-MS student in Theoretical Physics at IISER Kolkata. His research work deals with string theory and holographic duality. Apart from being a student of science, he is an artist and writer. Many of his works have been published in print and electronic media. He is also the editor of a bengali little magazine ‘Vorer Pakhi’.

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