Watch the scientists behind the detection of gravitational waves explain what's special about them
Why is the discovery of a "chirp" from 1.3 billion years ago so important?
"Then I would have been sorry for the dear Lord; the theory is correct."
— Albert Einstein, on being asked what would happen if experiments did not support his theory.
Perhaps the most remarkable thing about the confirmation that gravitational waves exist is the fact they they prove theory right.
Science proceeds in two ways: sometimes empirical discoveries are made, and then the findings are fitted into a consistent theory. But many scientists believe that the more elegant way is to fashion the theory first, and wait for experiments to prove (and sometimes disprove) them.
So it is with the discovery by the Laser Interferometer Gravitational-Wave Observatory (LIGO), made in September 2015. The detection of the gravitational waves created 1.3 billion years ago by two black holes which came together to form a bigger one has confirmed what Albert Einstein's theory had stated.
In the video below, scientists Kip Thorne and David Reitze, among others, explains what the theory said and why it was so difficult to prove it.
According to Einstein, spacetime is like a giant fabric. If you were to suddenly place a heavy object on this fabric, the act would create ripples in it. The ripples would spread along the fabric, but get progressively fainter. These ripples are what were known as gravitational waves, caused by heavy objects, but their existence was not proven, until now.
Because gravitational waves are so hard to find top scientists at the LIGO sometimes inject a false signal into the system just to check if the team of 1000 scientists can work in harmony to verify the data. One of them was Karan Jani who joined the collaboration in 2014.
Much of Jani’s work consisted of identifying black holes and then simulating what happened when they collided. He was part of the search team that first saw the signal on September 14. When he compared the incoming blip with simulations he had created he found that they matched 95%.
Jani describes the Eureka moment amidst the scepticism over what LIGO was really seeing. “I was happy that the algorithm that we were building to check if you could make a direct test of the signal was working. It’s a mixed feeling. I feel a lot of the weight of the legacy now.”
Among other things, this finding further cements every aspect of Einstein's theories about the universe, which represents a giant step forward for science.