Using Gravitational Waves to Pinpoint Colliding Black Holes

Imagine watching birds in your backyard. You love birds and want to know when certain birds are there. Sure, you have your favorite binoculars to look for these birds—but what if you also listen for birds? Better yet, what if you use several microphones to determine the location and type of bird in your yard? This is what gravitational wave observatories add to the field of astronomy. Instead of just detecting electromagnetic waves (infrared, radio, visible, UV, X-ray), we can also detect gravitational waves.

In the recent announcement from LIGO, physicists have detected a gravitational wave event. Not only does this reveal the existence of gravitational waves (as predicted by Einstein), it provides some details about the event: a collision, some 1.3 billion years ago, between two black holes with masses of 29 and 36 times that of our sun.