Black holes: Two become one
In the research paper, the team deduces that the signal came from two massive black holes – about 29 and 36 times the mass of our sun – merging approximately 1.3 billion light years away.
As the two black holes circled each other, the resultant energies began to radiate out as small gravitational waves. But when they collided at about half the speed of light and merged, there was an explosion of energy that – for a tiny moment – produced a peak power output about 50 times that of the whole visible universe.
The gravitational waves created by this merging process rippled out through spacetime, losing power as they went. 1.3 billion years later, they caused a minute ripple to pass through the earth and it was this that the LIGO instruments picked up.
"The description of this observation is beautifully described in the Einstein theory of general relativity formulated 100 years ago, and comprises the first test of the theory in strong gravitation. It would have been wonderful to watch Einstein's face had we been able to tell him," said Weiss.
No one was at the detector at the time and the signal was first seen by a European researcher monitoring the feeds remotely. The news spread through the team like wildfire but everyone kept their mouths shut publicly because the signal had to be checked very, very carefully.
The signal was processed again and again to see what else could have caused it. As part of their jobs, four members of the team have to try and introduce faults into the signal, and all four said they weren't responsible for the signal. Finally the decision to publish was made.
It's a whole new world out there
For the last few millennia, mankind has been limited to exploring the universe visually. This has huge disadvantages, since so much of the universe is dark, particularly black holes. But now boffins have a whole new way of examining the universe and its mysteries by using gravitational forces. In doing so, it will open up an entirely new field of astronomy.
"With this discovery, we humans are embarking on a marvelous new quest: the quest to explore the warped side of the universe – objects and phenomena that are made from warped spacetime. Colliding black holes and gravitational waves are our first beautiful examples," said Thorne.
Light has some real limitations as a method of exploration. It's easy to block, can be warped or lensed by large masses, and has a limited spectrum on which to operate. Gravity, on the other hand, passes though the universe unobstructed and contains a wealth of data.
Plans are now afoot for a third LIGO detector to be built in India, to extract yet more information from newly detected gravitational waves; more – and better – designs will come along as engineering progresses.
"This discovery is akin to Galileo first looking through his telescope and seeing the moons of Jupiter," said Sean McWilliams, assistant professor of physics and astronomy in the Eberly College of Arts and Sciences and a LIGO team member.
"We are 'hearing' the Universe now for the first time, and given how much we have learned by seeing the Universe since Galileo's time, it's a genuine thrill to imagine how much we will now be able to learn by listening to gravitational waves."
The discovery will also almost certainly mean Nobel Prizes for team members, with Weiss, Thorne and Drever all being mooted for the award. But, tragically, Drever may never understand that his work has led to so much good science, since he is reportedly in a Scots nursing home with advanced dementia.
Nevertheless, his work – and that of 1,000 other scientists who have worked on the project – will live on as long as humanity survives, and should tell us a phenomenal amount about the workings of the universe around us and how to tap into its secrets. Provided it isn't another false positive, that is. ®