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  • LIGO stands for the Laser Interferometer Gravitational Wave Observatory.

  • LIGO is really two observatories that work in unison, in tandem.

  • The LIGO interferometer has arms that are about 2 and 1/2 miles long, 4 kilometers.

  • We have a laser.

  • The laser produces the purest light you can possibly make.

  • It produces light that's so coherent that it's capable of detecting gravitational waves.

  • We have these very massive mirrors.

  • They weigh 40 kilograms, which is about 88 pounds.

  • They're about this thick.

  • And they're just the purest material you can imagine.

  • The NSF, of course, had to be the source of funding for anything that would be as expensive as this.

  • This was going to be a very high-risk experiment.

  • It was from its very inception.

  • If you think about this in the '70s and '80s, I'm amazed at how bold it was to do this, and visionary.

  • It was bold and visionary.

  • There's no other way to describe it.

  • NSF management, the National Science Board, they had to really step up to that.

  • And they had a lot of discussions, brought in a lot of experts.

  • There was great debate going on.

  • But in the end, the people who thought it could be done won the day.

  • And they went after it.

  • Gravitational waves carry the record of cataclysmic events in the universe, like the Big Bang.

  • Gravitational waves were predicted by Einstein about 100 years ago.

  • And they are dynamical perturbations in the fabric of spacetime, ripples in spacetime, if you will.

  • A ripple in the fabric of space and time the same way as a ripple on a pond is a ripple in the shape of the surface of the water.

  • Nobody really believed that you could ever detect them, because the size of the effect is so small...

  • 1,000th the diameter of a proton.

  • Even Einstein himself never thought a detection would be possible.

  • I tried to do this back in the 1960s when I was a student.

  • We couldn't make any progress.

  • We didn't have the technology.

  • In 1968, Rainer Weiss of MIT conceived of a device that could detect gravitational waves.

  • The idea was extremely simple.

  • And it turns out to be the the basis of LIGO.

  • What the gravitational wave does is it stretches space this way and compresses space that way.

  • So you exploit that property.

  • Put one object here and another object over there.

  • And let the gravitational wave go through that system.

  • And it will change the space between these by contracting that one and extending that one.

  • And I came to the conclusion that if you made this long enough, if you didn't make it a little pipsqueak thing like this, but you made it sort of kilometer-scale, you could probably get these extremely precise measurements.

  • 1994, Construction begins.

  • Nobody had ever made something like this before.

  • So there's a lot of technological challenges that needed to be overcome.

  • The precision that was required was just amazing, mind boggling.

  • The MIT Group has typically concentrated on developing new techniques to make the instruments work and then to work on, also, data analysis algorithms that are well-informed by the understanding of the instrument.

  • September 14, 2015.

  • The first direct detection of gravitational waves in human history.

  • We have observed gravitational waves from two black holes forming a larger black hole.

  • Two black holes merging together, literally, nearly the speed of light to produce a bigger black hole.

  • How cool is that?

  • I said, holy mackerel.

  • This is the beginning of a whole new way of studying the universe.

  • It's monumental.

  • It's like Galileo using the telescope for the first time.

  • Every time we have pointed a new instrument into the sky, nature has revealed secrets to us that we haven't known before.

  • And so I feel very confident that this is just the beginning of such an era for gravitational wave observations, as well.

  • Who knows what we'll see?

  • I would love to see Einstein's face if he could read this article that we just put out.

  • I mean, he would have been as dumbfounded as we are.

  • Because it's a wonderful proof that all of this incredible stuff, the strong-field gravity, is in his equations.

  • Just imagine that.

  • To me, that's a miracle that (that) happened... man's thinking, and also all the elegance not only in the theory, but the elegance in the experiment.

  • I mean, that is a human endeavor that, I think, everybody in the world should be proud of.

  • I had to tell you that.

LIGO stands for the Laser Interferometer Gravitational Wave Observatory.

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LIGO Detects Gravitational Waves

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    Ya Ju Hsieh posted on 2016/03/06
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