Astrophysicist Priyamvada Natarajan: ‘There is an overall obsession with just our lifetime, without thinking about future generations… We need to move from this short-termism’

In order for a field to mature and to be in a golden age, what you really need is a confluence of ideas and instruments. They have to align and converge in a way that can open up discovery space faster and more efficiently. What has happened in astrophysics and cosmology over the last 10-20 years is that we have had some fantastic space telescopes — the Hubble Space Telescope, Chandra X-ray Observatory, and now the James Webb Space Telescope. These are three very different pairs of eyes that look into the universe in very different wavelengths. To have them simultaneously look at the universe, we have never had something like this before.

Viewing from space has huge advantages. The Earth’s atmosphere, much as we need it, actually causes a lot of perturbation, distortions, in the light. So, when we get images, we have to do a lot of processing before we can remove that effect. You need to have imaging and spectra from space. In combination with advances in computing, we are now able to simulate portions of the universe. The goal is to make this volume larger. That has happened with the advances in computing, chip technology and parallel computing. For theorists like me, the sophistication of the conceptual models that we build has also advanced over the last decades. Astrophysics has always been a science that has moved at a pretty fast pace because we have always had data. We are sort of the original big data science.

Priyamvada Natarajan, Joseph S and Sophia S Fruton Professor of Astronomy and Professor of Physics at the Yale University. (Express photo by Abhinav Saha)

Amitabh Sinha: Many of us have an intuitive understanding of what a black hole can be, but I assume most non-specialists are stumped by dark matter or dark energy. Do you have an easy explanation for what they are?

No. If I had an easy explanation, I would be walking to Stockholm, right? So, no.

We know how matter and radiation interact with each other, and they put out energy in different wavelengths. The intriguing thing about dark matter is we know how it manifests in the universe incredibly well, in great detail, but we don’t know what it is made of. And from what we can infer so far, it seems very peculiar. It is matter, but it does not interact with anything. There’s no interaction with any kind of energy on any wavelength. Not infrared, not x-ray, not gamma rays, nothing. The only impact is gravitational, which is how we infer that this is matter. It is physical. We believe it’s some kind of particle that formed in the very early universe, and there’s a lot of it and that it has gravity. Ultimately, it’s a particle. We need to find out what particle it is.

Amitabh Sinha: Given the massive improvements in observation and computational capabilities, what are the few mysteries in your field that you are very hopeful would probably get solved in the next few years?

The future of science is very hard to predict because serendipity plays a very important role in discovery. You never know who might come along and make a connection that is so out of the realm of possibility right now that it might just click and solve one of the bigger, great mysteries.

One thing we do know is that Einstein’s theory of general relativity is not the final word. We think that — this is a belief, but it’s a fairly well-grounded belief — all the forces of nature should be integrated in some way. At the moment, gravity is not integrated. In the sense that we don’t have a micro-physics of gravity that’s well understood. We understand the micro-physics of how radiation works, how electromagnetic forces work, but we don’t for gravity.

I am really hopeful that in all three big areas in cosmology — black holes, dark matter, dark energy — there are going to be major breakthroughs, we are already seeing some hints.

Amitabh Sinha: We are also supposed to be at the cusp of major technology breakthroughs, not just in astrophysics but in other areas as well. Often the mention of AI and quantum comes in, but also other things like clean energy technologies. Would you say that in the next 10 to 50 years, life as we see it would be very different from today?

I think we have to accept that AI is going to be a transformative force for society, for science and our daily lives. The question is, how do we harness it for good? It is very clear that in fundamental research in any field, AI is going to be transformative. It is just that we cannot exactly see how it is going to transform the discovery process. That last leap of human creativity, intuition and the sort of inexplicable stuff that brilliant scientists are able to come up with to make connections that were not thought about for generations before them… that part of the creative process, which seems beyond comprehension, I don’t know whether AI would be able to replicate. That’s the big uncertainty. I don’t know how it’s going to transform that creative arc, but that it is going to transform the processes is completely a given.

Amitabh Sinha: Do you believe that at some point AI would become creative enough to be able to ask meaningful research questions?

I don’t know. I think it’s hard to tell because cognitive neuroscientists are really trying to figure out how we do it. People have been trying to figure out what is really going on with creative processes when human beings come up with it. AI has not cracked that problem yet, but I see no fundamental reason to say AI will never do it.

Priyamvada Natarajan, Joseph S and Sophia S Fruton Professor of Astronomy and Professor of Physics at the Yale University. (Express photo by Abhinav Saha)

Ritu Sarin: You have been using telescopes since you were a child. Have you used all three (Hubble, James Webb (JWST) and Chandra/Spitzer) space telescopes?

The way it works with space telescopes is that you make a proposal for getting time to look at a patch of sky that interests you. That proposal is evaluated by peers and if it gets picked, they will point the telescope and gather the data for you and then tell you. You can then download it and see it on your computer. So, yes, I successfully got time on all three space telescopes. It’s super exciting. But with a space telescope, obviously, you’re not looking through anything. It is in space, so computer commands are sent to the telescope to say something like Natarajan’s proposal needs you to look here, so they will turn and look there for the amount of time I have asked for. It will then turn back and go look at somebody else’s proposal. There are some really spectacular ground-based telescopes in Chile and Hawaii. I have been to those telescopes as well, but we no longer actually look through them. They’re all robotically controlled and we look at a computer screen showing data from the patch of sky that the telescope is looking at.

Ishan Bakshi: What would it take to set up a lab like yours in India? What are the constraints — access to researchers or money?

I’m a theoretical person. I need a lot of computing. That can be reproduced in India. I think the thing that’s missing is the research ecosystem that is there in the US. For the last 30-40 years, the US has dominated fundamental science and technology. The reason for this is the existence of many research universities where there is constructive competition as well as the ability to attract the best talent from around the world.

In my research group of seven people, I have five nationalities. This kind of ability to tap top talent from wherever, the ecosystem where there are different groups with whom you’re collaborating and competing, and the kind of infrastructure that is very promptly provided, are all very important. You need money, but you also need a lot of enthusiastic people to set up and maintain this research ecosystem. That’s what I think a lot of countries like India have a real opportunity in now.

Amitabh Sinha: There is this talk in India about getting scientific talent back. If that suggestion ever comes to you, what are the considerations that would weigh on your mind? Also, does a scientist today really need to be located in a particular geography to be able to do frontline science?

The research ecosystem not being as well set up as it is in the US would be a big handicap in wanting to come back. The thing that is a big plus in India is the talent. It is the research ecosystem that is not quite in place. And, you know, there is a mindset. We need to shift into that mindset. We haven’t done that yet in our scientific establishment. We have fantastic institutions. We have brilliant people in those institutions. But there’s a slight impedance mismatch in terms of setting up what I think could be an incredibly productive and successful ecosystem. The other thing is, at some level at this moment in history and technology, it doesn’t matter where you are, but the interactions matter. So I think interacting, collaborating with other leading institutions will also help.

As an example of the kinds of advantages I have in the US, every summer I go to the Aspen Center of Physics, where all kinds of top people come. There are workshops in different fields, different subject areas in physics. I go, I learn something new. I talk to some people and I start a collaboration. You need these catalyst points, these places of community where people come together, learn from each other, compete, spar and debate, all constructively. We don’t quite have that in India yet. And some parts of day-to-day life in India are still really tiresome. I am sure things have become better from when I was here 30 years ago but I still think there is something to wear you down, like the pollution, for example.

The promise of what can happen here is tremendous, just because the talent is here. There are some really great institutes right now. What would be great is if there was more respect for people doing science in society. We need to pay scientists to be able to live well and we need to respect them.

I don’t think that we are valuing the producers of knowledge across fields as much as we should.

Amitabh Sinha: In the US, government funding for science is being cut. Some of the gap is being filled by the private sector and billionaires — how do you see their role in science?

Federal government needs to be involved in funding science and technology. There is room for philanthropists and private foundations but ultimately philanthropy and individual billionaires have their pet causes. Partnerships are possible but we can’t turn over the entire research and development enterprise over to that. Corporate players have a very short timeline, and in fundamental research, the timeline is unpredictable.

Raj Kamal Jha: You spoke about the absence of a research ecosystem. What needs to happen to build that?

What would help build this overall research ecosystem is a mindset and a key part of that mindset is scientific temper. Keeping an open mind where you interrogate your ideas, and ideas that have the support of evidence when keeping that kind of socio-cultural mindset, developing that, building that and nurturing that, is really essential. If that could be built in India and made stronger, it would help in overall research.

Historically, we’ve had very strong intellectual traditions in science, astronomy and mathematics. In our ancient wisdom, at least in the texts that have survived, we are able to see that there was a very sophisticated understanding of the kind of openness of mind that you needed to have to make progress in understanding the physical world. For example, ancient India kept alive this idea of the possibility of both a geocentric universe and a heliocentric universe. That kind of mindset of being open and willing to change your mind, we need to develop that. These are small things about society and culture that actually translate into much bigger things.

And, of course, funding. Sustained funding, not funding at the whims and mercies of some political cycle, but sustained long term funding. Funding to sciences has gone up but it’s still not high enough as a function of our GDP. It should be much higher.

Shubhajit Roy: You spoke about the importance of serendipity in science. Can you give an example?

I can give you from my own work. I have grown up reading the work of Subrahmanyan Chandrasekhar on how very massive stars live their life out and then leave behind a black hole. But when data started to show that there were many massive black holes in the very early universe, when there wasn’t much time for them to grow from one of Chandra’s little black holes to a black hole that is a billion times the mass of the sun, it was clear that you needed something else to explain this. Either there’s some physics that we don’t know which force feeds a black hole and makes it grow much faster, or maybe there were other ways to make a black hole.

It sounds really cliché to give an example of having a deep thought in your shower, but that is what happened. When I was doing my PhD in England, I had got into the habit of taking long baths. When you pull the plug of the bathtub, you see the process of water going down really fast in a vortex. Observing this process, one day, got me thinking. I thought maybe what I need for my black hole problem was a vortex and fluid instability. I conjured up the physics, figured the things that have to happen, and was able to propose an alternative way of black hole formation.

Raj Kamal Jha: If you were to design the university of the future, for the next 50 years, how would it look different from the ones now?

Before the pandemic, MIT (Massachusetts Institute of Technology), my alma mater, had a task force on the future of education. I was on that task force. They asked exactly this question — how would you imagine what your ideal MIT will look like? I was a very strong proponent of the fact that my vision for MIT or any top future university would not have departments, it would have vertices. There would be a vertex where different disciplines converge because the future breakthroughs in science or even in humanities or social sciences are going to come from interdisciplinary collaboration. My idea of a future university will have knowledge vertices and not departments. There wouldn’t be these silos.

Kaushik Das Gupta: You noted that fundamental research might not yield immediate benefits. Has society progressed or regressed with respect to valuing knowledge that seems abstract or does not offer immediate utility? Also, does interdisciplinary research lead to weakening of foundations in core areas?

We as a society and culture have regressed in the sense that we have become short-termists. A lot of that has to do with some of our technologies for global connection, social media and so on, that have reduced our attention span. There is an overall obsession with just our lifetime, without thinking about future generations, a short-term thinking about return on investments. We have been irresponsible with the planet, with utilisation of resources. We need to move away from this short-termism and start thinking more long-term.

Your question about interdisciplinarity is a really good one. There is a little bit of tension with interdisciplinarity and this idea of competence and domain knowledge and anchoring in a discipline. And you do need to be anchored in your training in a discipline to be able to think interdisciplinarily. You will definitely need to have foundational knowledge that gives you domain mastery and competence. Those domains may also get a little redefined. That’s what I’m hoping when I said those vertices, that those sharp definitions and boundaries will start to expand and blur.