RAS question
Gravitational waves were first directly detected in 2015 by:
Correct answer: (B) LIGO.
Gravitational waves were first directly detected in 2015 using the Laser Interferometer Gravitational-Wave Observatory (LIGO).
Explanation
Scientists first directly detected gravitational waves in 2015 using the Laser Interferometer Gravitational-Wave Observatory (LIGO). NASA Space Place describes LIGO as the extremely sensitive instrument used to record the signal. The signal was recorded on 14 September 2015. It came from the merger of two black holes that had occurred about 130 crore years earlier. The resulting ripples reached Earth in 2015. As gravitational waves pass Earth, they squeeze and stretch space. LIGO detects these tiny changes in its long arms using lasers, mirrors and extremely sensitive instruments.
Why the other options are wrong
- (A) Hubble Space Telescope observes electromagnetic radiation, whereas the first direct detection of gravitational waves in 2015 used LIGO.
- (C) ISRO is a space agency; the first direct detection of gravitational waves in 2015 was made by the LIGO observatory.
- (D) CERN is associated with particle physics, whereas LIGO was used to detect gravitational waves in 2015.
Concept
In RAS Science and Technology, students study major scientific discoveries and the instruments used to make them. Gravitational waves connect fundamental physics, black-hole mergers and scientific research conducted at modern observatories.