The Union Cabinet has finally granted in-principle approval for a gravitational wave detector in India. The clearance, awaited for five years, comes close on the heels of the detection of the elusive gravitational waves for the first time; the Laser Interferometer Gravitational-Wave Observatory (LIGO) based in Washington and Louisiana in the U.S. found evidence of gravitational waves coming from two black holes colliding and fusing together 1.3 billion light years away. By virtue of having the same sensitivity as the LIGO detectors in the U.S. and being geographically separated by thousands of kilometres, the Rs.1,200-crore LIGO-India project, scheduled to become operational in about eight years, will at once vastly improve the level of accuracy and ability to detect new gravitational wave events. Since all detectors may not be operational all the time — for instance, the VIRGO detector, based near Pisa in Italy, had remained shut on September 14, 2015 — the addition of an Indian detector will increase the chances of detecting events that generate gravitational waves. When the advanced LIGO and LIGO-India detectors reach their full sensitivity, many more events will become detectable and the ability to detect faraway signals would also increase dramatically. For instance, 50 to 100 gravitational wave-generating events a year may become detectable. And in the case of neutron stars, signals from as far away as 600 million light years could be detected as compared with 200 million light years now.
Though Indian scientists were part of the LIGO project, their involvement was limited to theoretical aspects and data analysis. The LIGO-India project will change this altogether as the construction, commissioning and running of the observatory will be India’s responsibility. It will offer unprecedented opportunities for Indian industry and scientists from diverse fields to be actively involved in a scientific project of a scale never before seen in the country. For instance, though many of the critical components such as mirrors and lasers will be shipped from the U.S., an ultra-high capacity vacuum system that can handle one million litres of vacuum (as in the case of the Large Hadron Collider), and secondary optics, have to be manufactured in India. An active programme to develop optics for the laser system that could be used in future upgrades to the detectors is already under way at the Indore-based Raja Ramanna Centre for Advanced Technology. Currently only a few students from Indian institutions are able to participate in the LIGO project, but this will change completely when the observatory becomes operational in India, providing easier access for a larger number of students. Besides playing a pivotal role in gravitational wave astronomy, the Indian observatory could thus be a catalyst in changing the landscape of Indian scientific efforts. Together with other mega projects such as the India-based Neutrino Observatory project, experimental science will at last get a much-needed boost in the country.