The gravitational wave proposed by Albert Einstein centuries ago has been detected by 1000 Physicists for the first time, marking one of the biggest astrophysical discoveries in ages.
This discovery not only improved the understanding of how the universe works, it paved ways for further study and possibly, new inventions.
The historic announcement was made at a press conference yesterday February 11. Experts are already saying the discovery is a shoo-in for a Nobel Prize.
According to Einstein’s theory, the fabric of space-time can become curved by anything massive in the Universe. When cataclysmic events happen, such as black holes merging or stars exploding, these curves can ripple out elsewhere as gravitational waves, just like if someone had dropped a stone in a pond.
The Gravitational wave is described as Two black holes circling one another, locked in an orbital dance a kilometer or more away from each other and at the same time accelerating rapidly to within a whisker of the speed of light. Both are about 100km across. One contains 36 times as much mass as the sun; the other, 29. Their event horizons—the spheres defining their points-of-no-return—touch. There is a violent wobble as, for an instant, quintillion upon quintillion of kilograms redistribute themselves. Then there is calm. In under a second, a larger black hole has been born.
Gravitational researcher, David Blair, from the University of Western Australia said:
“Gravitational waves are akin to sound waves that travelled through space at the speed of light.”
“Up to now humanity has been deaf to the universe. Suddenly we know how to listen. The Universe has spoken and we have understood.”
It is, however, a hole that is less than the sum of its parts. Three suns’ worth of mass has been turned into energy, in the form of gravitational waves: travelling ripples that stretch and compress space, and thereby all in their path. During the merger’s final fifth of a second, envisaged in an artist’s impression above, the coalescing holes pumped 50 times more energy into space this way than the whole of the rest of the universe emitted in light, radio waves, X-rays and gamma rays combined.
And then, 1.3 billion years later, in September 2015, on a small planet orbiting an unregarded yellow sun, at facilities known to the planet’s inhabitants as the Advanced Laser Interferometer Gravitational-wave Observatory (LIGO), the faintest slice of those waves was caught. That slice, called GW150914 by LIGO’s masters and announced to the world on February 11th, is the first gravitational wave to be detected directly by human scientists. It is a triumph that has been a century in the making, opening a new window onto the universe and giving researchers a means to peer at hitherto inaccessible happenings, perhaps as far back in time as the Big Bang.
The Story So Far (Finger on the Pulsar)
The idea of gravitational waves emerged from the general theory of relativity, Albert Einstein’s fundamental exposition of gravity, unveiled almost exactly 100 years before GW150914’s discovery. Mass, Einstein realised, deforms the space and time around itself. Gravity is the effect of this, the behaviour of objects dutifully moving along the curves of mass-warped spacetime. It is a simple idea, but the equations that give it mathematical heft are damnably hard to solve. Only by making certain approximations can solutions be found. And one such approximation led Einstein to an odd prediction: Any accelerating mass should make ripples in spacetime.
Einstein was not happy with this idea. He would, himself, oscillate like a wave on the topic—rescinding and remaking his case, arguing for such waves and then, after redoing the sums, against them. But, while he and others stretched and squeezed the maths, experimentalists set about trying to catch the putative waves in the act of stretching and squeezing matter.
Their problem was that the expected effect was a transient change in dimensions equivalent to perhaps a thousandth of the width of a proton in an apparatus several kilometres across. Indirect proof of gravitational waves’ existence has been found over the years, most notably by measuring radio emissions from pairs of dead stars called pulsars that are orbiting one another, and deducing from this how the distance between them is shrinking as they broadcast gravitational waves into the cosmos. But the waves themselves proved elusive until the construction of LIGO.