Einstein was right

“We have detected gravitational waves. We did it.”, announced David Reitze, executive director of LIGO in a press conference in Washington, on Feb 11 2016. After a century of research, Einstein was proved right. First ever detection of gravitational waves is easily the discovery of the century, that many say, is likely to earn Nobel Prize. Since the birth of our species, we have been observing universe through what we could see, the visible light from the first star gazers, ultraviolet light and infrared light from hubble space telescopes and microwaves and radio waves blasting from the distant galaxies. But there are other vibrations which we cannot see.

A hundred years ago, in 1916, Albert Einstein proposed general theory of relativity. He predicted that the acceleration of massive objects would disturb the fabric of space and time, sending out gravitational waves, nobody has detected one, until now. Gravitational waves, in the simplest words, are ripples in space-time. These ripples carry gravitational energy away from the accelerating massive objects in the cosmos, with the speed of light. Just like the ripples produced across the surface of a pond, when a pebble is dropped into water. Gravitational waves are produced by extreme events, such as colliding black holes, merging neutron stars or exploding stars.

Roughly 1.3 billion years ago, two black holes, one with 36 times the mass of sun and other with 29, spiraled into each other and eventually collided. As a result of collision, about 3 times the mass of sun was converted into energy, in a fraction of second. Thus the collision unleashed this energy in the form of gravitational waves, still spreading outwards. As gravitational wave travels, it compresses the space in one direction and stretches space in the other, like sound waves. This push and pull weakens with the distance. The waves ultimately fade to a whisper that Physicists long thought that gravitational waves would never be measured on Earth. But it finally happened at LIGO laboratories.

Laser interferometer gravitational wave observatory, LIGO, is a system of two identical detectors, one located in Livingston, Louisiana and the other in Hanford, Washington, constructed to detect incredibly tiny vibrations from passing gravitational waves. The project was created by scientists from Caltech and MIT, funded by National Science Foundation. On Sep 14, 2015, at 5:51 am Eastern Daylight time (9:51 UTC), when everybody in US was slept, LIGO computers detected a loud signal at Livingston site. Seven milliseconds later the signal hit Hanford site. The signal was converted into sound and heard by scientists at LIGO as a chirp which lasted merely for one fifth of a second. That is how the gravitational waves produced by collision of two gigantic black holes traveled through the universe and reached Earth after 1.3 billion years and got captured by LIGO detectors. Listen it yourself:

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Dr. Weiss, a Physicist at Massachusetts Institute of Technology, who came up with the idea of LIGO was on vacation in Maine, found out when he logged on to his computer that morning. “It was waving hello. It was amazing. The signal was so big, I didn’t believe it.”, he was ecstatic. “It is by far the most powerful explosion humans have ever detected except for the big bang.” said Professor Kip Thorne of California Institute of technology and one of the founding fathers of LIGO. “I think this will be one of the major breakthroughs in Physics for a long time.” said Szaboles Marka, one of LIGO scientist and Columbia University professor. “Everything else in astronomy is like the eye. Finally astronomy grew ears. We never had ears before.”

They were going to make such a big claim that it took them so long to confirm the data. The discovery was announced in a press conference in Washington on Feb 11, 2016. The scientists of LIGO, along with scientists from VIRGO Collaboration published it in a report in Physical Review Letter with more than 1000 authors, on the same day. Proudly mentioning that one of the co-authors of this landmark publication is a Pakistan-born AstroPhysicist Dr. Nergis Mavalvala, Associate Department head of Physics at MIT. In a field dominated by men, Dr. Mavalvala is an inspiration, as we need more women in STEM fields and more glorification of STEM careers.