Laser Interferometer Gravitational-Wave Observatory (LIGO)
Why in the news?
Recently, the Government approved the construction of the Laser Interferometer Gravitational-Wave Observatory (LIGO) project after seven years of in-principle approval.
It will be built by the Department of Atomic Energy and the Department of Science and Technology with the U.S. National Science Foundation and several national and international research institutions.
What is LIGO-India Project?
- The project aims to detect gravitational waves from the universe.
- The Indian LIGO would have two perpendicularly placed 4-km long vacuum chambers, that constitute the most sensitive interferometers in the world.
- It is expected to begin scientific runs from 2030.
It will be located in the Hingoli district of Maharashtra, about 450 km east of Mumbai.
Purpose and Significance:
- It will be the fifth node of the planned network and will bring India into a prestigious international scientific experiment.
- It will make India a unique platform that brings together the frontiers of science and technology of the quantum and the cosmos.
Benefits of LIGO-India:
- The LIGO-India 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.
- The observatory is expected to enable dramatic returns in astronomy and astrophysics, as well as leapfrog Indian science and technology in cutting-edge frontiers of great national relevance.
What are Gravitational Waves?
- Gravitational waves were first postulated (1916) in Albert Einstein’s General Theory of Relativity, which explains how gravity works.
- These waves are produced by the movement of massive celestial bodies, such as black holes or neutron stars, and are the ripples in space-time that propagate outward.
What is LIGO?
- About: LIGO is an international network of laboratories that detect gravitational waves.
- LIGOs are designed to measure changes in distance that are several orders of magnitude smaller than the length of the proton. Such high precision Instruments are needed because of the extremely low strength of gravitational waves that make their detection very difficult.
First Detection of Gravitational Waves:
- The LIGO in the US first detected gravitational waves in 2015, which led to a Nobel Prize in Physics in 2017.
- These gravitational waves were produced by the merger of two black holes, which were about 29 and 36 times the mass of the Sun, 3 billion years ago.
- Black hole mergers are the source of some of the strongest gravitational waves.
Besides the United States (in Hanford and Livingston), such gravitational wave observatories are currently operational in Italy (Virgo) and Japan (Kagra).
To detect gravitational waves, four comparable detectors need to be operating simultaneously around the globe.
- LIGO consists of two 4-km-long vacuum chambers, set up at right angles to each other, with mirrors at the end.
- When light rays are released simultaneously in both chambers, they should return at the same time.
- However, if a gravitational wave arrives, one chamber gets elongated while the other gets squished, causing a phase difference in the returning light rays.
- Detecting this phase difference confirms the presence of a gravitational wave.