RACHEL MARTIN, HOST:
Three U.S. physicists have been awarded this year's Nobel Prize in physics. They won the award for building a remarkable device that can detect something called gravitational waves. Here to tell us more about the award and give us a short physics lesson is NPR's science correspondent Joe Palca. Hey, Joe.
JOE PALCA, BYLINE: Hey.
MARTIN: I don't know how short the physics lesson is going to be if we're going to talk about gravitational waves. That sounds complicated.
PALCA: It's - it's - it's going to be very short. But basically, this is one of those chances where I get to say something that sounds like science fiction but it's actually real.
PALCA: Gravitational waves are - like to be referred to as - well, they don't, but people like to refer to them as - ripples in space time. Don't you love that? Ripples in space time. They were predicted a hundred years ago by a chap named Albert Einstein. And when he wrote the theory of general relativity, basically he came to the conclusion that space, rather than being a flat thing, was curved and that the consequences of thinking of space as a curved thing, it came - out of that came this notion that there were something called gravitational waves. And you can think of it as a smooth surface where occasionally there are ripples, and the ripples are cause for cataclysmic events like black holes colliding or neutron stars colliding. And he said, these must exist, but we'll never detect them, that's - they're too faint.
MARTIN: But they did.
PALCA: But they did.
MARTIN: But people did. Who are the people who did?
PALCA: The people who did, well, they built a machine called LIGO, and their names are Rainer Weiss, from Massachusetts Institute of Technology, Kip Thorne and Barry Barish from the California Institute of Technology. So we have MIT and Cal Tech. And they built an instrument called LIGO, the laser interferom - interferometer gravitational wave observatory.
MARTIN: (Laughter) You almost didn't get it out, for good reason.
PALCA: Yeah. No. It's tricky. But anyway, what it is is, it's basically two measuring sticks (laughter) 4 km long at right angles to one another. So it's like an L, right?
PALCA: And when a gravitational wave comes along, the length - the ripples in space time cause the length of these arms to change by the tiniest amount. And I mean tiny. We're talking atomic-scale changes in length.
PALCA: And the way you detect that is you shoot a laser beam back and forth, back and forth, back and forth down the - down the length of these things, and using a technique called interferometry, you can tell whether the laser beams are in sync, which means the two arms of the same length are slightly out of sync which means they've changed in length slightly.
MARTIN: So what does it mean? I mean, what does it mean for us that they found these waves?
PALCA: Oh, gosh. Well...
MARTIN: How's that for a big question?
PALCA: So listen, I got to go soon.
PALCA: (Laughter). What it means is that there's a whole field of physics and astronomy that have been silent up until now. I mean, nobody actually could detect directly the collision of two black holes before. So the universe is suddenly much richer because we have this technique, this technology to detect these. And LIGO was just the first. There's another one that just started operating called Virgo. There's others that are going to be coming online. And so suddenly - and this is the great thing - there's a new device that's going to be able to make detections of things in the universe that nobody knows.
MARTIN: So we can ask more questions.
PALCA: You can have me back and I'll tell you, gosh, we never knew this was here, but there it is. So it's one of those crazy things where it's just going to change - it's going to change our world, which is - you can't say that about many discoveries, but this is really one of the more - one of these inventions which they did.
MARTIN: All right. NPR's Joe Palca talking about the three American physicists who are awarded this year's Nobel Prize in Physics for detecting gravitational waves. Hey, Joe, thanks so much for the physics lesson.
PALCA: You're welcome. Transcript provided by NPR, Copyright NPR.