Laser Interferometer Gravitational-Wave Observatory (LIGO)

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April 11, 2023

Why in news?

The Union Cabinet has cleared Rs 2,600-crore project to construct and set up a Laser Interferometer Gravitational Wave Observatory- India (LIGO-India), which is likely to be completed by 2030.

What are Gravitational waves?

  • Gravitational wave - A gravitational wave is an invisible yet incredibly fast ripple in space.
  • Their existence was initially predicted by Albert Einstein in 1916 in his general theory of relativity.
  • Properties - Gravitational waves travel at the speed of light.
  • The waves can squeeze and stretch anything in their path as they pass by.
  • Causes - The gravitational waves are caused
    • When a star explodes asymmetrically (supernova)
    • When two big stars orbit each other
    • When two black holes orbit each other and merge
    • When neutron star collide each other
  • The objects that create gravitational waves are far away and sometimes, these events only cause small, weak gravitational waves making them hard to detect.

What is LIGO?

  • LIGO - LIGO stands for "Laser Interferometer Gravitational-wave Observatory”.
  • It is the world's largest gravitational wave observatory.
  • It is an ambitious project by U.S to detect the faintest ripples from cosmic explosions millions of light years away.
  • LIGO exploits the physical properties of light and of space itself to detect and understand the origins of gravitational waves (GW).
  • LIGO Comprises two large observatories located 3000 kilometers apart - at Hanford in the State of Washington, and at Livingston in Louisiana.


  • Working - Each LIGO observatories consists of two arms of laser interferometers that can merge two or more sources of light to create an interference pattern.
  • The interference patterns generated by interferometers contain information about the object or phenomenon being studied.
  • A passing gravitational wave causes the length of the arms to change slightly.
  • LIGO's interferometers are designed to measure a distance 1/10,000th the width of a proton.
  • LIGO cannot detect electromagnetic radiation such as visible light, radio waves and microwaves because gravitational waves are not a part of the electromagnetic spectrum.
  • First detection - In 2015, LIGO physically sensed gravitational waves generated by two colliding black holes 1.3 billion light-years away.

Other detectors

  • Virgo – A gravitational wave located outside of Pisa, Italy
  • GEO600 - A 600 m interferometer located near Hannover, Germany.
  • KAGRALocated in Japan

What is LIGO India?

  • The LIGO India [roject is an international collaboration between the LIGO Laboratory and three Indian lead institutions.
  • The project is piloted by the Department of Atomic Energy (DAE) and Department of Science and Technology (DST).
  • Aim - To improve the detectors’ collective ability to pinpoint sources of gravitational waves in the sky.
  • It is to be located in Hingoli district, Maharashtra, India.
  • LIGO India will consist of a detector (3rd detector) to be built in the image of the twin LIGO instruments already operational in the U.S.

What are the opportunities for India?

  • India could become a global site of gravitational physics research.
  • Training and the handling of precision technologies could improve the current status.
  • Big Science projects could be increased.
  • It has the potential to provide employment opportunities.
  • Indian society’s relationship with science could take a new dimension.

Quick facts

Einstein’s General theory of relativity

  • It was conceived by Einstein in 1915.
  • General relativity is understanding of how gravity affects the fabric of space-time.
  • It expanded the theory of special relativity.



  1. The Hindu│LIGO India
  2. LIGO│ About LIGO
  3. LIGO│ India About LIGO India
  4. LIGO│Other Detectors
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