A mere two weeks ago on October 3rd, the Nobel Prize in Physics was awarded to Rainer Weiss, Barry C. Barish, and Kip S. Thorne. The three men received the prize "for decisive contributions to the LIGO detector and the observation of gravitational waves." The LIGO is the Laser Interferometer Gravitational-Wave Observatory.
Gravitational waves are disruptions in the fabric of space-time that are caused by violent energetic processes. Stronger waves can be emitted by the rotation of imperfectly-shaped neutron stars, the fusion of white dwarf or neutron stars, supernovae, the collision of two or more black holes, and the remains of gravitational radiation from the creation of the Universe.
This video shows how gravitational waves can be emitted as a result of two coalescing neutron stars.
These waves were predicted in 1916 by Albert Einstein through his general theory of relativity. He calculated that ripples could be created in space-time by enormous accelerating objects. These ripples could travel at the same speed as light and could be used to figure out more about gravity and the origins of the waves. In 1974, proof of the existence of gravitational waves was discovered by astronomers in Puerto Rico, who tracked a binary pulsar and discovered that the two stars were getting closer together at the same rate the theory predicted they would get closer. Thus, it was clear that gravitational waves were being emitted.
In 2015, LIGO was able to feel gravitational waves. These were being generated by the collision of two black holes 13 million light years from where they had been felt. This was the first “physical” sensation of the waves, proving their actual existence.
http://www.npr.org/sections/thetwo-way/2017/10/03/555279770/2017-physics-nobel-prize-honors-work-on-gravitational-waves-3-americans-win
This video explains how the LIGO works. Essentially, the LIGO detects the presence of a gravitational wave by observing the sizes of two tunnels that will stretch or squish when a wave passes. This can be detected by flashes of light that occur when a light shot out by the LIGO is recombined and does not cancel out.
Rainer Weiss, Barry C. Barish, and Kip S. Thorne published a paper in 2016 that explained how the gravitational waves had been detected by the LIGO in 2015. The LIGO itself has created major changes for astronomy. It has allowed scientists to observe the universe from a new angle and uncover secrets that could never have been uncovered without this new technology. Barish himself stated, “"I can't imagine that now that we have another way to look at the universe that there isn't going to be some enormous surprises.”
Sources:
https://www.ligo.caltech.edu/page/what-are-gw
https://www.sciencedaily.com/releases/2017/10/171003095828.htm
http://www.npr.org/sections/thetwo-way/2017/10/03/555279770/2017-physics-nobel-prize-honors-work-on-gravitational-waves-3-americans-win
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