Budget is cleared, stage set for India’s biggest facility to probe the universe

Two years later, in 2017, this experimental verification of the century-old theory received the Nobel Prize in Physics.

LIGO-India is part of the plan to expand the network of gravitational wave observatories in order to increase the chances of detecting these waves from anywhere in the observable universe and improve the accuracy and quality of information gleaned from them.

Until now, at least 10 events producing gravitational waves have been detected. Besides the United States, such gravitational wave observatories are currently operational in Europe and Japan. LIGO-India will be the fifth, and possibly the final, node of the planned network.

To be located in Hingoli district of Maharashtra, about 450 km east of Mumbai, LIGO-India is scheduled to begin its scientific runs from 2030. The final approval, involving a budget of Rs 2,600 crore, has taken several years in coming.

The initial proposal to set up a LIGO in India was made as early as 2013, but before the government could take a call, elections intervened. A new government meant the proposal had to be submitted afresh.

An in-principle approval to the project was granted on February 17, 2016, days after the first detection of gravitational waves was announced (the actual detection was made on September 14, 2015). However, the location of the project had still not been finalized.

Hingoli was competing with two other sites, one in Rajasthan and another in Madhya Pradesh. Hingoli was finally selected later in 2016, and the land acquisition process completed by 2018. A fresh proposal was moved in 2019 seeking government’s final clearance and financial allocation. The delay in prompt approval was attributed to the Covid pandemic, but this has meant that the project, which was initially estimated to be ready by 2024, has been pushed back by four to five years.

The decision brought jubilation in the scientific community, nonetheless. “Rare instance when I am unable to express my feelings in words…,” tweeted Tarun Souradeep, director of Bengaluru-based Raman Research Institute.

Souradeep, one of the nation’s most distinguished experts in cosmology and gravitational wave physics, has been a former spokesperson for LIGO-India, and is part of the scientific management committee overseeing the project.

One of the lead proposers of the LIGO-India project in 2011, Souradeep  told The Indian Express that the project would have several spin-off benefits to Indian science, apart from making India an integral part of one of the most prestigious international scientific experiments.

“LIGO-India will be a unique platform that brings together in India the frontiers of science and technology of the quantum and the cosmos. The observatory will enable dramatic returns in astronomy and astrophysics. Indian science and technology will leapfrog in a number of cutting-edge frontiers of great national relevance,” he said.

The LIGO detector in India would be similar to the two that are located in the United States – in Hanford and Livingston.

Like these, the Indian LIGO would have two perpendicularly-placed 4-km long vacuum chambers, that constitute the most sensitive interferometers in the world. LIGOs are designed to measure changes in distance that are several orders of magnitude smaller than the length of the proton.

According to the LIGO website, this is equivalent to measuring the distance to the nearest star, about 4.2 light years away, to an accuracy smaller than the width of human hair. Such high precision instruments are needed because of the extremely low strength of gravitational waves that make their detection very difficult.