Gravity waves, one of Albert Einstein's most interesting predictions about the weirdness of space time, have been an elusive but accepted element of the theory of general relativity. Now it looks like a coalition of scientists from CalTech, MIT, and the LIGO Scientific Collaboration has finally found them. And it only took a century.
Researchers on Thursday likened the discovery to the difference between looking at a piece of music on paper and then hearing it in real life. "Until this moment we had our eyes on the sky and we couldn't hear the music,'' said Columbia University astrophysicist Szabolcs Marka.
Albert Einstein debuted his notions on gravitational waves almost exactly 100 years ago. Scientists have been looking for them ever since.
Gravitational waves FAQ
Gravitational waves are easy to imagine but hard to comprehend. Think of what happens when you throw a rock in a pond. Ripples spread out from the point where your rock hits the water. Now imagine space time as the surface of the pond, and something with mass as the rock. Gravitational waves, then, would be the ripples. Pretty easy right?
Sure, but what do they do? Well, they literally expand and contract space and time as they pass through a point in space.
Okay, fine, but what does that mean for you and me living on our tiny little blue ball? Not much, but each time a gravitational wave passes through earth, our planet expands or contracts as the wave goes by.
Einstein predicted that these expansions and contractions should be observable. And that's what Thursday's announcement is all about.
How did scientists find them?
Gravitational waves were discovered by a giant scientific tool called LIGO that stands for the Laser Interferometer Gravitational-Wave Observatory. Its only job was to find gravitational waves and it has been looking on and off since 2002.
LIGO is a billion-dollar project made up of two giant L-shaped observatories, one in Washington State, and one in Louisiana. They are separated by more than 3,000 kilometers and they were built so far apart for a reason. That distance is just far enough apart so they could compare the information they received and triangulate it to actually pinpoint where the wave was coming from.
And that's why this discovery is so special. For years, LIGO, CalTech and MIT scientists have been watching two black holes that were spinning around each other, getting closer and closer. When they finally merged, the scientists predicted that the collision would release some strong gravitational waves. And those are the waves that LIGO detected. They came exactly when scientists said they would, and the two observatories pinpointed them as coming from the crash of these two distant black holes.
So what's the big deal?
Scientists had already done the math that proved gravitational waves exist way back in the 1970's. But the waves had never been actually 'seen.'
"It's really comparable only to Galileo taking up the telescope and looking at the planets,'' said Penn State physics theorist Abhay Ashtekar, who wasn't part of the discovery team. "Our understanding of the heavens changed dramatically.''