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>> Next up will be Deborah Ferguson speaking on testing General Relativity with gravitational waves world to the idea of a black hole a concentration of mass so dense that not even light can escape its grasp our universe is filled with these black holes each out there spinning dancing on its own and Einstein described what it would look like if 2 of these were to collide the collision one involved and in Spiral during which the black holes are far apart each spinning on their own but also orbiting each other and getting closer and closer then after billions of years they would get close enough that they would merge and form one single highly distorted black hole which would then ring like a bell as it loses those distortions and becomes one single spinning black hole and Einstein explains to us how we can take those 2 and Michelle spins and determine that final spin but how do we know if he's right especially when we can't even see black holes well remember how Earlier I said that these are exceedingly massive That means that throughout this entire process there are violently distorting spacetime think about an object moving through a pawn and how it sends out waves in every direction while now a century after Einstein came up with this idea we have the technology to be able to detect those waves thanks to why go the laser interferometer Gravitational Wave Observatory in Washington and Louisiana so using their data we're able to find that final spin and use it to test Einstein's predictions.

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But the question is which part of the wave should we use to actually find that final spin Einstein answers about with ring down that last part of the collision because the waves emitted during bring down directly give us that final spent so in theory it seems perfect unfortunately we don't live in an ideal world and so we have to deal with whatever the universe gives us and the waves admitted during bring down are really small so they can be easily overpowered by the sound of a car driving by or a bird pecking on the detector so we can't detect it right now when frankly we may never be able to detect it so what do we do well it turns out that instead of using rain down we can use the merger because I have found that it contains the same information that's available to us specifically that final spent and merger the waves it releases are big so we can detect it right now and why go has detected it right now many times and expect to detect many more murders This means that right now a century after Einstein developed his theory we have the data to detect his theory now thank you.