Gravitational waves

Gravitational Waves Detected A Century After Einstein Predicted Them, Scientists Term It ‘Discovery Of The Century’

Gravitational waves, a phenomenon that was predicted by Albert Einstein, remained in existence only in theories for almost a century. Einstein first talked about gravitational waves when he published his general theory of relativity 100 years ago. Ever since, scientists and researchers across the globe were on a hunt to detect gravitational waves, which, in layman’s terms, can be referred to as ripples in the fabric of spacetime. While they knew of its existence, in theory, there was no actual physical evidence of the same. The study of gravitational waves was also previously marred by false signals.

However, a breakthrough by researchers at the Laser Interferometer Gravitational Wave Observatory (LIGO) in Livingston, Louisiana, has reportedly detected the presence of gravitational waves from a distant black hole. This time, they have confirmed that this is the real deal — no false signals.

According to BBC News, researchers from LIGO have been working for years to detect gravitational waves. If you’re wondering why these waves are so difficult to detect, here is the reason. Gravitational waves are generated when events of giant magnitude take place. In this case, the event was the collision of two giant black holes believed to be 30 times the mass of our Sun. While the gravitational waves emitted by this event would have been huge, it happened more than 1.3 billion light years away from us. By the time the gravitational waves released by such events reach the earth after travelling huge distances, they end up having very small amplitudes, which means it would take an extremely sensitive detector to “catch” them. If that wasn’t all, these waves need to be filtered out of an array of other sources of “noise.” In short, the search for gravitational waves was akin to searching a needle in a haystack.

The breakthrough for the LIGO team came on September 14, 2015, at 5:51 a.m. ET, when two detectors located at different places in the United States detected the feeble gravitational waves emitted after the supermassive black hole collision that occurred 1.3 billion years ago. Researchers cross verified the data received by both the detectors, studied them thoroughly over and over again to ensure that this was not a false positive before they went public with their groundbreaking announcement. The LIGO detectors are located at Livingston, Louisiana, and Hanford, Washington.

Here is a video that briefly explains gravitational waves. The speaker in the video is Associate Professor Laura Cadonati from the Center for Relativistic Astrophysics.

The official Twitter account of LIGO has been tweeting about the latest discovery as well. Here are a few tweets from them.

Back in 2014, astronomers from the Harvard–Smithsonian Center for Astrophysics had erroneously claimed they detected the first conclusive evidence of gravitational waves. Their claim was later retracted after it was found to be a false positive.

The origins of LIGO dates back to 1992 when it was co-founded by scientists Kip Thorne and Ronald Drever of Caltech and Rainer Weiss of MIT. However, it wasn’t until 2002 that the first functional LIGO experiment started. It ran for 8 years – from 2002 to 2010 without any detections. Not to be fazed, it underwent a series of upgrades that took five years to complete. The upgrades ensured that the new set-up was four times more sensitive than the original detectors from 2002. In fact, plans are underway to increase the sensitivity even more, with the instruments expected to attain full sensitivity by 2021.

Following the announcement by LOGO, an elated Rainer Weiss said, “The description of this observation is beautifully described in the Einstein theory of general relativity formulated 100 years ago and comprises the first test of the theory in strong gravitation.”

He further added, “It would have been wonderful to watch Einstein’s face had we been able to tell him.”

[Photo by Andrew Harnik/AP]

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