Woman of Substance: Dr. Nipuni Palliyaguru:

The Lankan who helped prove Einstein right

by Himal Kotelawala

The scientific community and the world at large was taken by storm in early February this year, when an international team of scientists managed to detect gravitational waves, finally confirming renowned physicist Albert Einstein's century-old theory of General Relativity and opening up a brand new vista of the cosmos. This team, known as the Laser Interferometer Gravitational-Wave Observatory, or LIGO, contains some of the brightest minds on the planet, and one of them just so happens to be Sri Lankan. Here LIGO member, astronomer, and postdoctoral researcher at the Texas Tech University in Lubbock, Texas, Dr. Nipuni Palliyaguru, talks about her contribution to this monumental discovery.

Having joined LIGO as part of her postdoctoral research, about six months ago, Dr. Palliyaguru became involved in a collaborative effort to pinpoint the elusive signal whose existence Einstein had predicted in 1905. "It is a collaboration that consists of many scientists from around the world who are working on different aspects of gravitational wave signals. I am part of the electromagnetic follow-up team of LIGO," she said.

As to how it works, in her own words, "the idea is, when a signal comes in, we send out alerts to partner telescope facilities all around the world. Usually, LIGO can't pinpoint the exact location of the astrophysical system in the sky, because there are thousands of galaxies within the region. So it is important to do an electromagnetic follow-up in order to find out where the signal is coming from, and also to extract additional information about the gravitational wave sources."

Unpredictable

According to Dr. Palliyaguru, team members take turns to be on-call, as these events tend to be unpredictable and can occur anytime of the day. Special care is taken to ensure the validity of a detection, which means there can be no room for false alarm.

"You have to carefully check for instrument status and for glitches in the data to make sure an event is real. Then we decide whether or not to alert the partner astronomers. It is a lot of fun to be on shift, especially when a trigger comes in. Then, because I'm also an astronomer, I got to do the actual follow-up observations for this event," she said.

A lot has been said about LIGO's detection and its significance, but as is often the case with popular science (pop-sci), there seems to be a lot of miscommunication surrounding the discovery. For example, a Sri Lankan TV news segment described it as a confirmation of the wave-like property of gravity, in a strictly Newtonian sense of the concept. As a real scientist who was actually part of the project, Dr. Palliyaguru helped shed some light on this.

"Sometimes you have to use analogies to make the information more accessible. We say gravitational waves are ripples in spacetime, kind of like ripples in a pond. Gravitational waves basically distort the space so the time that light takes to travel between two points in space changes. This is the basic principle of any gravitational wave detector. They are called waves because they actually follow the usual wave equation in physics," she said.

Going into further detail, Dr. Palliyaguru explained that light, as we know it, or more specifically electromagnetic radiation, is generated from accelerating charges (such as electrons). Gravitational radiation is generated from accelerating masses.

Waves

"Even my waving hand can produce gravitational waves, but they are very very weak. To get detectable levels of gravitational waves, you need huge masses and for that you have to turn to the sky."

When she was reading for her PhD at West Virginia University, USA, Dr. Palliyaguru heard what she called a very inspirational talk about efforts to detect gravitational waves using pulsar timing arrays (PTAs). It was then that it hit her: She was in this for life.

"Ever since then, I knew this was what I wanted to work on, for the rest of my career. So I worked on PTAs for about five years for my PhD. Then I got the offer to work with the Texas Tech group as a postdoc on LIGO science. I was thrilled to get the opportunity to continue gravitational wave science with a sophisticated detector," she said.

It's not a stretch to say that, even in the 21st century, being a female scientist is not without its drawbacks. Sexism in the STEM (science, tech, engineering and math) fields has been well documented. According to Dr. Palliyaguru, however, things seem to be changing for the better.

"I think women have to work a lot harder to prove themselves. STEM fields require a lot of hard work and sacrifice, which is why women are discouraged from advancing in these careers. But I think this is changing. People are a lot more aware of the situation and I'm fortunate to know many male colleagues who are very supportive and that make a huge difference," she said.

A product of the Sri Lankan education system, Dr. Palliyaguru spoke about her days as a student in the island.

"Before any of this, I was physics major at the University of Colombo and a student at CMS Ladies College in Colombo even before that. So yes, I did go through the local system and had very inspiring physics teachers from a very early stage," she recalled.

The implications of LIGO's work are many and will continue to have a profound impact on our understanding of the universe. Needless to say, it is every science student's dream to be even a small part of something so groundbreaking. Dr. Palliyaguru has some great advice for anyone looking to make that dream a reality:

"I'm still in the early stages of my scientific career, so I'm not sure if I can say a whole lot, but I think perseverance and grit is what it takes. Also, not letting opportunities go to waste. When bad things happen, you cry for a day, and the next day you wake up and pick up from where you left off," she said.

(A version of this article was published by roar.lk)