Gravitational waves detected

Question: Recently Scientists have detected gravitational waves first time from a newly born-
(a) Black hole
(b) Star
(c) Neutron Star
(d) Elliptical Galaxy
Answer: (a)
Related facts:

  • In September 2019; scientists have detected gravitational waves first time from a newly born black hole.
  • This discovery was made by the researchers from Massachusetts Institute of Technology (MIT) in the United States. The study, published in the journal Physical Review Letters.
  • They observed that these gravitational waves have ringing pattern of the waves just as the sound waves emanating from the ringing bell.
  • Scientists say that ringing pattern of gravitational waves predicts the cosmic body’s mass and spin and it provides more evidence for Einstein’s General Theory of Relativity.
  • Einstein’s General Theory of Relativity predicted that a black hole of a given mass and spin can only produce tones of a certain pitch and decay.
  • This discovery increases the possibility that black holes exhibit only three observable properties – mass, spin, and electric charge.
  • All other properties, the study noted, could be swallowed up by the black hole itself, and are unobservable.
  • Researchers from the MIT in the U.S calculated the mass and spin that the black hole should have using physicist Albert Einstein’s General Theory of Relativity, given its ringing pattern.
  • These calculations, according to the study, matched earlier measurements of the black hole’s mass and spin.
  • Researchers say that Einstein’s general relativity theory for the first time is being confirmed by this way.
  • By concentrating on the last few milliseconds of the signal, immediately following the chirp’s peak, the researchers were able to observe the newly formed black hole’s ringing.
  • Researchers detect an overall gravitational wave signal that’s made up of multiple frequencies, which fade away at different rates, like the different pitches that make up a sound.
  • Each frequency or tone corresponds to a vibrational frequency of the new black hole.
  • The team used the equations of General Theory of Relativity to calculate the newly formed black hole’s mass and spin using the detected information on its pitch and decay.
  • Their calculations matched with calculations of the black hole’s mass and spin which were made previously.

Gravitational waves and their detection:

  • When an object accelerates, it creates ripples in space-time, these space-time ripples are known as gravitational waves.
  • In another way we can understand gravitational waves just like a boat causes ripples in a pond or an accelerating electrical charge produces an electromagnetic wave.
  • Gravitational waves are extremely weak so are very difficult to detect.
  • It should be known that the gravitational waves, for the first time were detected on September 14, 2015, the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.

Links:
https://www.thehindu.com/sci-tech/science/gravitational-waves-detected-for-first-time-from-newly-born-black-hole-study/article29408037.ece
https://www.digitaltrends.com/news/black-hole-albert-einstein-gravitational-waves-chirp/
http://www.physics.org/article-questions.asp?id=138
https://www.ligo.caltech.edu/news/ligo20160211