“It turned out that nature was very kind, and there appear to be many of these black holes in the Universe and we were lucky enough to see one.” -Dave Reitze, executive director of LIGO
On September 14th, 2015, just days after turning on, the twin Advanced LIGO detectors detected the first gravitational wave signature: a merger between two black holes, of 36 and 29 solar masses. They inspiraled, they merged, and they lost 5% of their rest mass to gravitational radiation, sending ripples through the fabric of space due to Einstein’s E = mc^2. It raised a whole slew of questions: were these typical black holes? Where were the lighter ones? How many other events would LIGO see? And was this a fluke?
Today, a second gravitational wave event was announced: GW151226, occurring the day after Christmas, saw a 14 and an 8 solar mass black hole merger together from 1.4 billion light years away. The Universe has always been speaking to us, and thanks to the power of gravitational wave observatories, we’re finally learning how to listen in a whole new way.