Night sky stokes human curiosity, gives you permission to dream: Astrophysicist Priyamvada

Natarajan, a professor of astronomy and physics at Yale University, US, has published pioneering research on black holes and dark matter — considered the ‘enigmas’ of the universe.

“The spirit of curiosity is fundamentally human, it’s part of our DNA, to make sense of the cosmos and our place in it — to understand the regularity of cosmic events, such as what causes day and night, seasons — to go beyond the wonder and fascination, and seek an explanation. As human beings, we’ve always been preoccupied with the cosmos and fascinated by it,” Natarajan told PTI in an interview earlier this month at Ashoka University, Haryana.

She was part of a team inaugurating the Ashoka-ZEISS Core Imaging Facility, equipped with microscopes of advanced resolution to view a cell and its internal structure. She is also on the university’s Science Advisory Council.

“When you look at the night sky, you see something that’s much bigger than yourself, there’s an inevitable sense of awe — the sky is for everyone, and it gives us the permission to dream and soar,” Natarajan said.

A black hole is usually considered to form in the ‘dying’ stage of a star’s life. Made of highly compact matter, a black hole possesses a gravity so intense that even light cannot escape.

However, in 2005-06, Natarajan proposed for the first time in theory that there must be another way for black holes to form, bypassing the formation of a star first, evidence in support of which she and her colleagues at Yale would go on to publish in Nature Astronomy and The Astrophysical Journal Letters in December 2023.

In a 2017 paper, Natarajan’s team predicted what the James Webb Space Telescope might detect, much before its launch in December 2021 by the US space agency NASA.

Looking at images of the early universe, the team found a galaxy ‘UHZ1’ harbouring an overmassive black hole at its centre, which possessed all the properties as predicted — it was a few million times the mass of the Sun, heavier than expected and firmly in its place already in the very young universe.

“And so, if the first black hole is just a few times the mass of the Sun, and the only way to form these seeds was from the explosion of the first stars as per the traditional path very early in the universe, then there’s very little time in the universe to grow to a billion solar masses. How can you grow that much, so fast? There has to be a resolution,” Natarajan, recounting the time she came up with the idea, said.

“That was what motivated us to ask, ‘Ok, is there has to be another way to make a black hole whose birth mass, or the mass of a black hole when it’s born, is not a few times the mass of the Sun, but actually 10,000 or even 100,000 times the mass of the Sun, so that then you don’t have to grow that much to account for what is seen already,” she said. The idea is referred to as ‘direct collapse.’ The work brought Natarajan multiple accolades, including being featured on TIME’s 100 Influential People of the Year list — “unusual” for a scientist. She was also elected a fellow to the American Academy of Arts and Sciences.

“A lot of the creative pursuits, such as poetry, music, astronomy, don’t generate monetisable returns in the short-term, per se. But that does not make them any less valuable,” she said.

Natarajan is also noted for her philosophy on mapping dark matter in clusters of about a thousand galaxies, held together by gravity.

Unlike ‘ordinary matter,’ dark matter is said to have peculiar properties, including being invisible as it does not interact with light. It, however, does have gravity, just like ordinary matter, as it is believed to be made of particles created in the early universe.

The “highest resolution contour map” of how dark matter is distributed in space, “similar to a topological map of the Himalayas, revealing all the peaks and valleys,” was published in the journal Monthly Notices of the Royal Astronomical Society in February 2017.

“One of the things I was not aware of is that the algorithms that we devised to create and generate these maps have inspired colleagues in medical imaging who analyse data from X-ray machines or MRIs to understand what’s going on inside our bodies,” Natarajan said.

“Similarly, in astronomy, there have been monetisable discoveries that you can’t point, a direct line as to how they will impact and transform our daily lives practically — it’s not that you discover something today and tomorrow, it’s going to become a product.

“So, this whole idea of how to tackle an extremely complex problem — how you pare it down to the bare minimum details, and then you add all the bells and whistles, and then solve it — all of these are ways of producing new knowledge that are translatable,” she added.

Speaking about the Ashoka-ZEISS Core Imaging Facility, Natarajan said the state-of-the-art instruments will help move scientific research up a notch, opening up spaces that are hard to imagine today.

“Because now in biology, we’re at this incredible moment when we can manipulate individual cells and entities inside them. What is very clear is you need these instruments now to make discoveries and there’s a lot that is uncharted in the biological sciences at present. I expect this (facility) to be deeply impactful,” she said.

Natarajan is also actively engaged in disseminating science and is currently writing a book on the practice of science, describing “a new way to think about science itself.” “Not everyone has to pursue a career in science. But learning about science, and how its rigorous methods work, are essential to critically engaging with the world. It’s about asking questions and figuring things out, being curious. It’s a powerful lens through which to view the world and comprehend nature,” she said. PTI KRS VN VN