While Einstein’s theory about the existence of gravitational waves has been proven through the now popular LIGO project, a theory proposed by a Bengaluru scientist about ‘quasi-normal modes’ or scattered waves from the black holes 45 years ago, has also come true through the discovery.

Years ago, even before the term ‘black holes’ was in common parlance among astrophysicists and cosmologists, Prof C V Vishveswara, a black-hole physicist, started his work on the subject from around 1968 onwards, making major contributions to the nature and structure of the black holes.

“Back then, everything was pure theory and there was no possibility of experiments like now. When I wrote my first paper, even the term had not been used properly. John Wheeler (noted theoretical physicist), who was my guru’s guru, popularised the term and it caught on. I myself used the term while writing my third paper on the scattering of gravitational waves,” he said.

He spoke to Deccan Herald on the sidelines of a programme in the City.

The LIGO project, while discovering the gravitational waves, also detected quasi-normal modes, something Prof Vishveswara had written about in the scientific journal ‘Nature’ in 1970. Prof Bala Iyer, a theoretical physicist at the Raman Research Institute, who is also a member of the LIGO Scientific Collaboration and chairperson of the IndiGO consortium, the gravitational wave community in India, said:

“The understanding is that nothing comes out of a black hole. So, how do you know about its existence? He (Vishveswara) had the idea that if there is a black hole, there will be some signatures of the black hole.” While the discovery of the gravitational waves is referred to as a “chirp”,

Prof Iyer said quasi-normal modes were more like the ringing of the bell with a certain frequency and decay. “He (Vishveswara) was one of the first persons who prophesied that by looking at quasi-normal modes, one can say something about the properties of the black holes. This has also been mentioned in the study about gravitational waves,” he said.