Slightly under a 100 years after Albert Einstein propounded his famous General Theory of Relativity (GTR), evidence supporting a rather elusive implication of the theory was found. The US-based Laser Interferometer Gravitational-wave Observatory (LIGO) has published data on the recording of the first observed gravitational wave. A bare-basic understanding of the GTR tells us that the motion of black-hole size masses creates ripples, or gravitational waves, in the stiff fabric of space-time. However, any such wave remained undetected till September 14 last year—when LIGO, one of the most sophisticated “ears” of Earth to have ever existed, registered the vibration caused by the wave that emanated 1.3 billion years ago as two black holes collided. This near- imperceptibility of the waves is because gravity is the weakest of the four fundamental forces. For perspective, The Guardian notes that a gravitational wave from even as close as 4.24 light years away—where the nearest star to Earth, outside the solar system, is—will move space-time by just a fraction of the width of an atom. In fact, this caused so much doubt to Einstein regarding the prospect of gravitational waves being ever detected that he twice declared them “non-existent” before reverting to his original position.
This discovery, apart from vindicating Einstein, is the first proof that binary black-hole systems—the existence of which was always treated as a theoretical probability—are materially real. Also, with a spectrum of gravitational waves theoretically possible, it means it could potentially allow us to reach back in time to attempt a more informed understanding of “big bang” or the primordial universe, given it could be perhaps the single-largest generator of gravitational waves, many of which could still be reverberating around us.