‘We are going to see things that we never knew existed’ say scientists announcing the detection of gravitational waves
On 14 September 2015 at 9:50 GMT, the two detectors of the newly upgraded Laser Interferometer Gravitational Wave Observatory (LIGO) detected a signal.
It was unambiguously a gravitational wave signal because it matched the predictions from Einstein’s general theory of relativity almost precisely.
A gravitational wave is a ripple in the invisible fabric of the universe, called the spacetime continuum. The particular ripple moved the LIGO detectors by about one-thousandth the width of a proton (the tiny particle found at the heart of a hydrogen atom).
It was generated by two black holes that collided 1.3 billion light years away. The masses of the individual black holes were large, at around 36 and 29 times the mass of the Sun each. They were just 150km across each and collided at half the speed of light.
The merger formed a single black hole of 62 solar masses. The missing three solar masses of matter were transformed into the energy that powered the gravitational waves detected by LIGO.
This transforms the way in which we can observe the Universe, and is expected to lead to the discovery of unanticipated celestial objects.