After four months of analysis, a consortium of scientists— including from India — confirmed Thursday that they had detected a signal from space from 1.3 billion years ago. The signal, which travelled as a gravitational wave was from the fusion of two black holes into a single one — the first time ever that such a phenomenon was observed — and registered as a “çhirp’’ at two highly sensitive detectors, called the Laser Interferometer Gravitational Wave Observatory (LIGO) located in Washington and Louisiana.
Scientists say that this detection is as momentous as Galileo, 400 years ago. first using the telescope and getting a glimpse of what several celestial objects looked like magnified. “This is the first time that the universe has spoken to us in the language of gravitational waves,” said David Reitze, Executive Director of the LIGO Project. The discovery is proof that researchers, through gravitational waves, can now observe a new class of astronomical phenomena just as observing x-ray signals from space brought alive pulsar, neutron stars and a host of other unprecedented celestial objects.
Though the detectors were American, Indian scientists have contributed significantly in terms of designing algorithms that were used to analyse the signals registered by the detector and be sure that it was indeed from a gravitational wave. Indians have also made, three decades ago, theoretical contributions to understand how such black holes may collide into each other.
“It is an extremely significant find and Nobel worthy,”” said Bala Iyer, a theoretical physicist and among the leaders of the Indian consortium that contributed to the find. Immediately after the confirmation of the waves were formally announced, Prime Minister Narendra Modi tweeted his congratulations and announced approval for a project to have a gravitational-wave detector in India, a project that has been on the anvil for several years.
(“Piled Higher and Deeper” by Jorge Cham. www.phdcomics.com)
Gravitational waves are the last, unobserved prediction from Albert Einstein’s iconic general relativity equations that were developed 100 years ago. These equations are the reason space and time — in the eyes of contemporary science — are seen as malleable shape-shifting entities rather than fixed and eternal, as our senses suggest to us. Black holes, which result when stars die, can collide with each other and sometimes birth new universes. These collisions are so violent that they can distort space and time around it, just as dropping a heavy ball on a tarpaulin sheet can massively wrinkle it. These wrinkles propagate, as gravitational waves through space-time but are extremely hard to detect. The LIGO detectors built between 2002-2010 to spot these waves but to no avail.
Last year, both detectors got a $200 million upgrade, so much so, that they were renamed advance-LIGO. Research and analysis of data from the detectors is carried out by a global group of scientists, including the LIGO Scientific Collaboration (LSC), which includes several Indian scientists.
The detectors are made to be extremely sensitive to the slightest of vibrations and that makes it a technical challenge to be sure that these detectors have caught a gravitational wave and not a, say the rumble of a passing truck.
THe black holes that were detected were roughly 25 to 30 times the mass of the sun and squeezed into a diameter of 150 kms. Their collision was after they swirled into each other at half the speed of light releasing the gargantuan shockwaves.