This observation marks the first time we have evidence that the spins of the black holes might not be aligned. But it's not just applied physics and astronomy that has an interest in this event. Researchers have also used the observation to test general relativity in a new way.
"This time a further test of General Relativity has been done, to see if there was any dispersion of the gravitational waves as they traveled over this long distance from the source to us," Professor Rowan, from the University of Glasgow, added. "No dispersion was seen – which is consistent with the predictions of General Relativity – so Einstein's predictions are still holding up!"
With these observations, we are getting a clearer picture of the properties of binary black holes. Three examples is still too little data to draw unbreakable conclusions from, but more detections could soon exclude certain theoretical scenarios.
"I am particularly impressed by all the redundancies built into the LIGO data analysis that found GW170104: Two independent data analysis methods found the signal buried in the noise of the two LIGO detectors, source parameters are inferred from two independent model waveform families, and even the spin is measured in two different ways," said Dr Chiara Mingarelli, a gravitational wave astrophysicist from the Max Planck Institute for Radio Astronomy, who didn't work on the paper. "With all these redundancies and cross-checks, one feels as though the authors are daring us not to believe them. It is delightful!"
Gravitational wave observations slowly but surely continue to advance our understanding of both theoretical physics and astronomy. What else will they tell us in the future?