SSC
What is the full form of LIGO, the observatory that first detected gravitational waves?
Answer (Detailed Solution Below)View answer ▾Hide ▴
Answer: Option C — Laser Interferometer Gravitational-Wave Observatory
Detailed Solution
LIGO is a large physics experiment in the United States designed to detect gravitational waves. It has two observatories about 3,000 kilometres apart: one at Hanford, Washington, and one at Livingston, Louisiana. Each has two arms, 4 kilometres long, arranged in an L shape.
Gravitational waves are ripples in the fabric of space-time caused by the acceleration of very massive objects, such as two black holes or neutron stars orbiting and merging with each other. Albert Einstein predicted them in 1916 on the basis of his General Theory of Relativity. They are extremely weak by the time they reach the Earth, so detecting them was a huge challenge.
LIGO works on the principle of laser interferometry. A laser beam is split into two and sent along the two arms, where it bounces off mirrors and returns. Normally, the two beams cancel each other out when they recombine. When a gravitational wave passes, it stretches one arm and squeezes the other by a tiny amount, less than one-thousandth of the width of a proton. This changes the interference pattern of the light, which is detected.
On 14 September 2015, LIGO made the first direct detection of gravitational waves, from the merger of two black holes about 1.3 billion light-years away. The discovery was announced on 11 February 2016. Rainer Weiss, Barry Barish and Kip Thorne received the Nobel Prize in Physics in 2017 for this work. In 2017, LIGO and the European Virgo detector also detected waves from merging neutron stars.
India is building a third LIGO detector, LIGO-India, in the Hingoli district of Maharashtra. It was approved by the Union Cabinet in April 2023 and is expected to start operations in about 2030. Indian scientists were part of the team that made the 2015 discovery.
Good to know
The other expansions are incorrect.
Quick tip
Remember: LIGO = Laser Interferometer Gravitational-Wave Observatory (USA), first detection 14 September 2015, Nobel 2017 (Weiss, Barish, Thorne); LIGO-India at Hingoli, Maharashtra.
💬 Discussions on this question
Ask a doubt ›Still stuck on this question? Ask our faculty and fellow students — answers appear here.
Ask a doubtMore Gravitation Questions
View all ›More General Knowledge Questions
- Q1.The techniques of Rasa and Bhava used in Indian classical dance trace their origin to which ancient text?Indian Dance Forms
- Q2.Lavani, Powada, Koli, Waghya Murali and Dhangari Gaja are folk dances of which state?Indian Dance Forms
- Q3.The one-act play associated with the Sattriya tradition of Assam is called:Indian Dance Forms
- Q4.Which dance form of Goa is known as the 'Warrior Dance'?Indian Dance Forms
- Q5.Manipuri dance is based on the Rasleela themes of:Indian Dance Forms
Gravitation — Preparation
This question tests your understanding of Gravitation, a key topic in the General Knowledge section. The detailed solution above uses a step-by-step approach to show the reasoning, and where available, a shortcut that helps you solve similar questions in under 90 seconds during the actual exam.
This topic covers Newton's law of universal gravitation, the acceleration due to gravity and how it varies, mass and weight, escape velocity, orbital velocity, satellites, Kepler's laws and weightlessness. Common questions ask how the value of g changes with height, depth and latitude (it is greatest at the poles and zero at the centre of the Earth), the Earth's escape velocity (about 11.2 km/s), and why astronauts feel weightless. Remember that mass stays the same everywhere, while weight changes with gravity. Practise the gravitation questions below, written in the style of the general awareness sections of exams such as SSC, banking, railways, CUET GAT, MAH CET and CLAT. Each question comes with a detailed explanation that adds related facts, so every question helps you revise more than one point.