1244 GMT November 19, 2019
The impact was so powerful that it shook not only space but also time, sending a ripple through the very fabric of the Universe with 50 times more energy than all the stars combined, the Telegraph reported.
The shockwave rolled out in all directions and entered our own galaxy, the Milky Way, just as modern humans began to expand throughout the world some 40,000 years ago.
On September. 14, 2015, that ripple finally arrived on Earth and was picked up as a chirp by the world’s most powerful detector, a discovery hailed as significant as Galileo pointing his telescope to the heavens.
It has been a long time coming. One hundred years ago, Albert Einstein predicted that such gravitational shockwaves must exist, as part of his General Theory of Relativity, but it remained his unfinished symphony, and scientists have been searching for proof ever since.
"It's monumental ― like Galileo using the telescope for the first time. It's been a very long road, but this is just the beginning," Gaby Gonzalez, professor of physics and astronomy at Louisiana State University told a press conference in Washington.
"It happened when life on Earth was just beginning to spread and it took a billion years to come to Earth."
Einstein’s genius was in suggesting that space should not be seen as a vacuum but rather a four dimensional fabric which could be warped by huge bodies, like planets, in the same way that a heavy ball would distort a rubber sheet.
He expected that violent collisions in the Universe would produce ripples in that fabric but even he did not believe that they would be detectable, and twice declared that they did not exist. The problem was building an instrument that was sensitive enough to catch the dying shockwaves.
Decades after Einstein’s prediction, scientists began to consider how to create such an instrument. The first attempt was by Joe Webber, an engineering professor at the University of Maryland, who believed that waves could be detected using an aluminum cylinder. Webber announced that he found the waves, but his experiments could never be replicated.
It was Raine Weiss of MIT who first suggested building the Laser Interferometer Gravitational-Wave Observatory (LIGO) in 1972 and by the early 1980s he had constructed the first prototype with Kip Thorne of the California Institute of Technology and Scottish physicist Ronald Drever, formally of Glasgow University.
Drever is suffering from Alzheimer's and could not celebrate the proof of the discovery with his friends.
In 1990, the trio persuaded the National Science Foundation to fund the construction of LIGO at a cost of more than $272 million and it finally became operational in 2001. A five year $200 million upgrade took the detector offline in 2010 and it was not switched back on until last September, just in time to pick up the chirp.
David Reitze, executive director of LIGO and professor of physics at the University of Florida, said: "We did it. This was truly a scientific moonshot, and we did it. We landed on the moon.
“What's really exciting is what comes next. 400 years ago, Galileo turned a telescope to the sky. I think we're doing something equally important, I think we're opening a window on the Universe and an era of gravitational astronomy. It's mind boggling.
“It's the first time the Universe has spoken to us through gravitational waves. Until now, we have been deaf to gravitational waves, but now we can hear.”
LIGO is actually two observatories, separated by nearly nineteen hundred miles, one in the swamplands of Louisiana and one in Washington. The 'L-shaped' device splits a single laser beam into two and sends both beams shooting off at right angles to each other. The beams bounce of mirrors in a tunnel and should travel equal distances. But a passing gravitational wave can change the distance that each bends relative to the other.
Astrophysicist Professor Kip Thorne of California Institute of Technology added: “Until now, we have only seen warped space time when it's very calm. We had never seen the ocean in a storm with crashing waves. All changed on Sept. 14. They created a violent storm in the fabric of space time. A storm in which the shape of space was bent.
“The storm is brief, 20 milliseconds but very powerful. The total power output was 50 times greater than all of the power of all of the stars in the universe.”
The chirp was first picked up by Marco Draco, 32, a postdoctoral student who was working with the LIGO team at the Albert Einstein Institute, in Hannover, Germany. A squiggle on the screen which usually pulsated up and down with background noise suddenly gave a little jump.
Scientists said the discovery ushered in a new era of gravitational astronomy and new window with which to view the Universe.