Early today, the Laser Interferometer Gravitational-Wave Observatory (LIGO) announced that it had made a direct observation of a gravitational wave for the first time. LIGO consists of two instruments, and both had recently been upgraded to make them more sensitive (and thus increase the chance of discovery). Back in September 2015, after the upgrade, a signal had been detected by both instruments. After analysis, it was determined that these signals were consistent with two black holes in a close "death spiral." They spiraled closer and closer until they collided and merged to form a single black hole. One of the black holes was 29 times the mass of the sun, the other 36 times the mass of the sun. This occurred about 1 billion years ago and resulted in a gravitational wave that was detected by both of the LIGO instruments. This result was keep secret (except for occasional "leaks" of information) until earlier today (February 11), when LIGO gave a press conference releasing details of the discovery.
This is an important result, but why?
These videos from PBS Digital Studios will be of interest.
A video recorded after the announcement, explaining what the discovery is all about...
LIGO's First Detection of Gravitational Waves https://youtu.be/gw-i_VKd6Wo
As you may have seen in an earlier blog post, rumors of this result were known for a while, here is a video recorded a few months ago, asking if gravitational waves have already been discovered. The fact is they already had been, but only a few people directly involved with LIGO knew this for sure.
Have Gravitational Waves Been Discovered? https://youtu.be/1Tstyqz2g7o
Some other videos discussing different aspects of General Relativity. General Relativity is Einstein's theory of gravity, and it predicts that gravitational waves exist.
"Are Space And Time An Illusion?": https://www.youtube.com/watch?
"Is Gravity An Illusion?" https://www.youtube.com/watch?
"Can A Circle Be A Straight Line?" https://www.youtube.com/watch?
"Can You Trust Your Eyes In Spacetime?": https://www.youtube.com/watch?
General Relativity and Curved Spacetime https://youtu.be/AwhKZ3fd9JA?"Is Gravity An Illusion?" https://www.youtube.com/watch?
"Can A Circle Be A Straight Line?" https://www.youtube.com/watch?
"Can You Trust Your Eyes In Spacetime?": https://www.youtube.com/watch?
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