The Past, Present and Future of Gravitational Waves From Einstein to LIGO The existence of gravitational waves was first proposed in 1893 by Oliver Heaviside, when the self-taught English physicist used an analogy that likened the propagation of gravity to that of electricity. It was more formally established in 1916 by Albert Einstein as one of the key components of his theory of general relativity. Skeptical at first, scientists slowly began to accept the idea in the ensuing decades, as more evidence supporting Einstein's theory of general relativity came to light. But there was a big gap between thinking gravitational waves exist to believing they could be measured. Even Einstein was skeptical about the ability to ever detect gravitational waves.
"[Einstein] saw right away that this was going to be a challenge. He even said that this new thing that he had just invented, or had gotten out of his equations, will never play a role in science," said Rainer Weiss, one of the new Nobel laureates, during a press conference from Cambridge, Massachusetts this morning. A 1962 paper by Russian physicists Mikhail Gertsenshtein and Vladislav Pustovoit was the first to describe how instruments called interferometers could be used to detect gravitational waves. In 1984, a committee, which would eventually lead to the LIGO collaboration, was formed by Weiss and fellow laureate Kip S. Thorne together with Ronald Drever, who passed away this March. When it began operations in 2002, LIGO had the sensitivity to detect vibrations down to one onethousandth the width of a single proton. Today, LIGO can detect vibrations down to one-tenth that size. While this may seem like overkill, the incredible sensitivity proved critical, since it was barely enough for the first ever gravitational wave detection.
That first detection was made on Sept. 14, 2015. Since then, three additional detections have been announced, with the latest coming just this past week. On Sept. 27, the LIGO Scientific Collaboration and the Virgo Collaboration -- which runs a similar gravitational wave detector in Italy -- jointly announced the fourth detection of gravitational waves. The announced detection marked the first time a gravitational wave signal was detected by all three operating facilities. The triple detection enabled scientists to triangulate the signal and locate the source 20 times more precisely than with LIGO alone.
Additionally, Virgo's detector faced the same gravitational waves at a completely different angle, which gave scientists a fundamental new piece of information about gravitational waves -- the polarization of gravitational waves, which is how space-time is distorted in the three spatial dimensions. The future is brighter The brightness of a star is inversely proportional to the square of the distance to that star. For example, the same star would only be one-fourth as bright if it were twice as far away. But gravitational waves
"That's kind of a shocking thing to a lot of people, because it's not an inverse-square law," said Joseph
Giaime, the current head of LIGO Livingston, during an interview with Inside Science. "If you can increase
the sensitivity [of LIGO] by a factor two, you can see twice as far away, and if you can see twice as far
away, you can see eight times more volume in the universe."
Eight times more volume means eight times more observable objects. Because of this incredible bargain,
the teams at LIGO and Virgo are constantly trying to further improve the sensitivity of their instruments.
written by sabrina
Posted by , Published at December 12, 2017 and have
0
comments
No comments:
Post a Comment