LAHORE: Professor of Physics and Dean of the School of Sciences at the Massachusetts Institute of Technology (MIT) Nergis Mavalvala kicked off the Afkar-e-Taza ThinkFest 2021 online on Thursday in a discussion with Professor Pervez Hoodbhoy.

Hoodbhoy introduced the Karachi-born as astrophysicist, saying she had done ‘marvelous work on gravitational waves and the cooling down of systems to incredibly low temperatures as well as the Heisenberg uncertainty principle’.

The keynote address, titled ‘Gravitational Waves: Opening a New Window into the Universe’, gave a completely new way of looking at the universe. The old way comprised of looking at the universe through the concept of light.

“When we look out at the galaxies of stars, much of that information comes to us through the different ranges of light and its colours,” said Ms Mavalvala and added that “With dark objects you have to do something different. And that is where gravity comes into play”.

The slideshow she presented was based on a discovery that won the Nobel Prize in 2017 and it was called the discovery that shook the world.

Gravitational waves are actually ripples of spacetime, Nergis said.

“Space is never truly empty, nor does it sit around – it can actually warp and ripple, it can even tear. Spacetime ripples are gravitational waves. Whenever two objects orbit each other, these waves are sent out as ripples. In the 1960s and 70s, with the discovery of black holes, and neutron stars, theorists began thinking what kind of emissions could they give out. Eventually, they stumbled upon the answer as gravity.”

Ms Mavalvala said long detectors were laid in different places in the US, Europe, India and Japan to detect the distance between the waves. They received their first signal in 2015, which she showed in a picture of a graph, depicting the ripples of spacetime. The process, she added, helped identify where in the sky the objects were located as well as many of the properties of the source, including weight and mass of the black holes, how far they were. The scientists discovered that the black holes had been 1.3bn light years away and they had been moving half the speed of light when they collided and a new black hole was formed, which was three solar masses lighter than it should have been. It all showed that it was a very violent system.

Published in Dawn, February 12th, 2021