4th gravitational wave detected by LIGO

• A fourth gravitational wave has been detected — this time with help from Italy-based equipment — after two black holes collided, sending ripples through the fabric of space and time.
• The newly produced spinning black hole has about 53 times the mass of our Sun. While this new event is of astrophysical relevance, its detection comes with an additional asset: this is the first significant gravitational wave signal recorded by the Virgo detector.

About Virgo detector:

• The Virgo collaboration includes more than 280 physicists and engineers belonging to 20 different European research groups.
• The Virgo detector — an underground L-shaped instrument that tracks gravitational waves using the physics of laser light and space — recently underwent an upgrade, and while still less sensitive than its U.S. counterparts, it was able to confirm the same signal.
• Known as interferometers, these high-tech underground stations do not rely on light in the sky like a telescope does, but instead sense vibrations in space and can pick up the “chirp” created by a gravitational wave.

About Gravitational waves:

• It comes a century after Albert Einstein’s general theory of relativity held that acceleration of massive bodies should produce gravitational waves, which travel through the universe at the speed of light. The gravitational waves detected, and announced to the world, were produced more than a billion years ago by a cataclysmic collision of two black holes, one of them with a mass 36 times that of the Sun and the other slightly smaller at 29 times, into one black hole. The gravitational waves give scientists insights into the final moments before the merger.
• Gravitational waves are disturbances in the fabric of spacetime. If you drag your hand through a still pool of water, you’ll notice that waves follow in its path, and spread outward through the pool. According to Albert Einstein, the same thing happens when heavy objects move through spacetime.But how can space ripple? According to Einstein’s general theory of relativity, spacetime isn’t a void, but rather a four-dimensional “fabric,” which can be pushed or pulled as objects move through it. These distortions are the real cause of gravitational attraction.

India's contribution:

• This giant step for science is the result of truly global cooperation, but Indian Scientist contributed immensely toward this project. About 60 researchers from more than a dozen institutions in India were part of the over-1,000-strong army of scientists in the collaboration.
• Nearly 35 Indian scientists are co-authors of the landmark scientific paper that describes the results. The way to find the signal buried in the noise came from an Indian scientist. Similarly, the oscillation of cosmic bodies after a collision was predicted by an Indian scientist back in 1971.
• Several observatories widely separated from one another will help in determining the direction of any event with greater accuracy and also confirm the genuineness of the signal.
• Now, Government of India approved to construct the proposed Rs.1,260-crore gravitational wave observatory in India which could help obtain unique information about the universe; unlike light, gravitational waves can pass through the universe unobstructed and hence carry otherwise unobtainable information. The facility would also provide a much-needed technological boost and immensely benefit researchers based in India. There will be then possibility to hear "chirp" sound of gravitational wave.

By: Vishal