Monday, February 15, 2016

RIPPLES IN TIME - Einstein Was Right

"What’s the sound of two black holes colliding?  Proof that Einstein was right" PBS NewsHour 2/11/2016


SUMMARY:  Gravitational waves -- ripples in the fabric of spacetime -- aren’t just an Einstein theory any more.  A team of international scientists announced Thursday that they confirmed the waves’ existence after recording feedback from a black hole collision a billion light-years from Earth.  Hari Sreenivasan learns more from Dave Reitze of the California Institute of Technology.

HARI SREENIVASAN (NewsHour):  Now some truly cosmic news.

The sound of two black holes colliding more than a billion years ago, it was recorded by a team of scientists at the LIGO Observatory, proof of gravitational waves, or ripples in time and space, first theorized by Albert Einstein.

We explore this monumental moment in physics with Dave Reitze of Caltech, executive director of the LIGO Laboratory.

Now, that was a rudimentary attempt at explaining what a gravitational wave is. But what are they, and why is it such a big deal to find one?

DAVID REITZE, California Institute of Technology:  Actually, you did a pretty good job.

So, gravitational waves are fluctuations in space-time.  And any time you have a mass, something that has matter in it, accelerating, all right, it produces a gravitational wave.  All right?  And that’s a consequence of Einstein’s Theory of General Relativity.

Now, these particular gravitational waves, in order to be able to detect them, you need really, truly massive objects.  So, in this case, these were black holes that had about 30 times the mass of the sun in them.

So, why gravitational waves are so interesting is that they tell us something about the universe that you can’t get from any other kind of astronomy.  So, if you think about optical astronomy, that looks at certain classes of light.  If you look at radio astronomy — so gravitational waves are completely different.

They come from a different sector of the universe, and that’s why they’re so exciting.

HARI SREENIVASAN:  OK.  So Einstein is sitting at his patent clerk’s office thinking about this big thought, and what is the connection to space-time?


HARI SREENIVASAN:  Does time and space bend?  And if you heard or saw, so to speak, this moment, does that mean that time and space bent just a little bit at those points?

DAVE REITZE:  Oh, in fact, this particular event was, as my colleague Kip Thorne calls it, a storm in space-time.

All right?  As these two black holes came together and collided, they really disrupted space-time and produced this burst of gravitational radiation.  It’s interesting that you mention Einstein.  Gravitational waves were first predicted actually 100 years ago.  And Einstein himself, all right, thought it was an interesting consequence of the theory of relativity, but didn’t think that it had any practical value, because he said that the effect is so tiny that we will never be able to measure them.

And it took 100 years from the time that he predicted them to the time we have been able to measure them.

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