The detection of ripples in space-time, known as gravitational waves, here on Earth marks a watershed moment for astronomy and for science as a whole. The detection at once improves our understanding of the workings of the universe and, more important, throws open a big opportunity to study it from completely new angles. It opens the way to get information about the evolution of galaxies and black holes. There is also a symmetry to the timing of the discovery: 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 on Thursday, 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. The signals of gravitational waves were detected on September 14, 2015 by twin Laser Interferometric Gravitational-wave Observatory (LIGO) detectors located about 3,000 km apart at Hanford, Washington and in Livingston, Louisiana, in the United States. Though the observatory is capable of picking up gravitational waves produced by binary neutron stars colliding and merging, signals from such a collision from the same distance would have been extremely weak for LIGO to pick up; neutron stars are much smaller in size than black holes and produce weaker signals. The successful capture of gravitational waves by LIGO is a testimony to humankind’s scientific and engineering expertise to build extraordinarily sensitive instrumentation capable of detecting variations of the order of a thousandth of the diameter of a proton.
Fittingly, this giant step for science is the result of truly global cooperation. 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. Quick approval to construct the proposed Rs.1,260-crore gravitational wave observatory in India 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. And for years to come, we will continue to listen to the ‘chirp’ sound produced by the gravitational waves, and marvel at science’s capacity to detail ever more minutely the place of humankind in the vastness of space and time.