Yesterday’s announcement of the discovery of gravitational waves, a phenomenon that Einstein predicted, but which he thought humans could never detect, rocked the scientific world.
In September of last year, strong gravitational waves from the collision of two black holes 1.3 billion light-years away reached the Earth squishing it and everything on it. If you didn’t notice, it’s because they only squished us 1/100,000th of a nanometer for one quarter of a second. Similar gravitational waves have probably passed through the Earth before, but this time, someone was watching.
“They had two experiments that were L-shaped. Whenever the gravitational wave passed through it, the two arms, one of them stretched and the other one compressed. And so, the lasers that were pointing and measuring the distance between these two arms, actually measured that deformation, or the compression and the stretching of each arm.”
Dr. Maria Rodriguez, a theoretical physicist and Assistant Professor in Utah State University’s Physics Department, explained how you can covert the signal from these gravitational waves into sound waves that we can hear. Here’s the gravitational wave that experimental physicists at the Laser Interferometer Gravitational-wave Observatory detected last year:
And here’s what theoretical physicists predicted such a wave should sound like:
Both waves speed up at the same rate, a property which is caused by the increasingly fast rotation of the two black holes as they approach their imminent collision.
“The theory of Einstein’s general relativity, and he had a paper 100 years ago, predicts that whenever two objects, very massive objects, collapsing or accelerating, they emit some gravitational energy or gravitational wave, and we had never seen that previously.”
These particular black holes emitted about as much gravitational energy as three of our suns. This was the most powerful explosion humans have ever detected, except for the Big Bang. In addition to confirming the existence of gravitational waves and further vindicating Einstein’s theory of general relativity, this experiment also provided us with the strongest evidence yet for the existence of black holes, which have only been observed indirectly until this point. Many scientists have predicted that this discovery is almost guaranteed to win the Nobel Prize in Physics in 2016.