Before scientists were even sure black holes existed, an Indian astrophysicist did the math behind Einstein's predictions of what would happen if two black holes collided.

Transcript

MARY LOUISE KELLY, HOST:

The history of science is littered with researchers who made absolutely critical contributions to understanding the fundamental forces of the universe. Many of their names are largely unknown or forgotten. Today NPR science correspondent Joe Palca brings us the story of an Indian scientist whose calculations helped lay the groundwork for the most important discovery in physics this century.

JOE PALCA, BYLINE: Fifty years ago, C.V. Vishveshwara was a physics graduate student at the University of Maryland known to his friends as Vishu. His thesis advisor had given him a problem to solve. Figure out what would happen if two black holes collided.

SMITHA VISHVESHWARA: Study the whole process, computing all the characteristics of the emitted gravitational radiation.

PALCA: That's Smitha Vishveshwara, Vishu's daughter, who is herself a physicist. Albert Einstein predicted gravitational waves, but he thought they might be too faint to ever detect. So at the time, Vishu was trying to solve a completely theoretical problem with no way to know if he was right. Vishveshwara says her father realized the problem was too complex to solve in one go.

S VISHVESHWARA: What he did was to break it up into parts.

PALCA: As he worked on the parts, Vishu made a fundamental insight. Black holes had a kind of structure, and if you were able to bang on a black hole, it would vibrate like a bell when you hit it with a mallet. He wrote a paper about his discovery that appeared in Nature, a top scientific journal.

KIP THORNE: This is the very first time that we realized that black holes could be dynamical objects that could vibrate or ring like a bell.

PALCA: That's Kip Thorne, a theoretical physicist at Caltech. He knew Vishu back then. He says the paper was one of those aha moments, a characteristic of black holes everyone had missed up to that point.

THORNE: It became obvious after we saw Vishu's simulation.

PALCA: But this was just a theoretical prediction. You can't bang on a black hole with a mallet. But if a gravitational wave happened to bang into one, a wave would be emitted from the black hole that would show a vibration like the sound of a bell. And then in 2016, Vishu's prediction went from theoretical to proven.

S VISHVESHWARA: It's been nearly a 50-year wait, and it happened. It happened.

PALCA: A team led by Kip Thorne made what has to be one of the most significant discoveries of the century. Using an instrument called LIGO, Thorne and his colleagues were able to make the world's first recording of a gravitational wave. Thorne and two colleagues won the Nobel Prize just one year later. And sure enough, when they looked carefully at the wave they recorded, they saw the signature of that ringing bell in the wave, what Vishu predicted you would see nearly 50 years earlier. And Vishu lived to see it happen.

He was a bit of a celebrity in his native India. In the days after the LIGO discovery was announced, he was swamped with requests to speak about his work. Here he is at one of those talks, displaying the dry wit he was known for.

(SOUNDBITE OF ARCHIVED RECORDING)

CV VISHVESHWARA: There's a story of a physicist who had a nightmare that he was giving a talk and woke up and found that he was. So I'm in that situation because of all the excitement in the last three days. I have not been able to sleep.

PALCA: Vishu died in 2017. On the 50th anniversary of his 1970 paper in Nature, it seems like an appropriate time to remember his contribution.

Joe Palca, NPR News.

(SOUNDBITE OF RAMIN DJAWADI'S "BLACK HOLE SUN") Transcript provided by NPR, Copyright NPR.

Tags: ligo  gravitational waves  black holes  physics