“We can now hear the universe,” a LIGO physicist exclaimed! “The detection is the beginning of a new era: The field of gravitational astronomy is now a reality.” Gravitational waves have always been washing through our planet and will continue to do so for years to come, but only now have we seen its proof. We’ve now opened our eyes and ears to a different kind of cosmic signal such as that of a‘re-birthing’ black hole that happened about 1.3 billion years ago. The vibrations caused by the most energetic event known to us were witnessed recently which is now paving way for the birth of a brand new field of astronomy.
Gravitational waves are ripples in spacetime which propagate as waves, a bit like ripples on a pond that travel out at the speed of light. According to Einstein’s general theory of relativity, spacetime isn’t a void, but rather a four-dimensional “fabric” that can be pushed or pulled as objects like planets and stars move through it. These waves cause distortions which is also why the Earth and other planets orbit around the Sun – there’s no force pulling them towards the Sun, just a big distortion in the space around it. These waves are known to be generated from the occurrence of gravitational interactions of the league of cosmic events such as colliding of two black holes, merging of pulsars among others. These relic gravitational waves travel outwards from its source and emanate Herculean energy in the form of radiations.
These waves have been observed much later in time after they were predicted to be existing in the cosmos. The year 1961 saw Albert Einstein prognosticate the presence of gravitational waves in his General Theory of Relativity which had left the scientist community bewildered until recently when they were observed. The calculations further revealed that accelerating objects would cause disturbances in spacetime in such a way that ‘waves’ of distorted space would travel with the speed of light in the universe, carrying along vital information about their nature and origins. Physicists have concluded that the so found gravitational waves were produced during the final second of the merging of two black holes to produce one massive black hole. This collision of two black holes had been predicted but never observed, until now. This quivering energy is the remains of gravitational waves from the early evolution of the universe much like the leftover light from the Big Bang phenomenon. If this was to be believed, then these waves would have been stretched as the universe expanded and they can tell us about the very beginning of the universe!
Gravitational waves interact with matter by squeezing objects in one direction while stretching them perpendicularly, much like how LIGO worked to make this discovery. LIGO (Laser Interferometer Gravitational-wave Observatory) is the collective name given to two wave detectors located in USA-one in Hanford, Washington and the other in Louisiana. Both Interferometers inclusively make one state-of-the-art detector consisting of L-shaped interferometer arms, carefully looking over the interference patterns produced by the combination of two sources of light, making it hundred folds stronger than a telescope. LIGO uses a special mirror to spot a signal and splits the beam of laser light. It is then sent down to the two interferometer arms placed at a right angle. After oscillating back and forth about 400 times, each beam takes a 1,600 kilometre long round-trip, ending with the recombination of light near its source. The experiment is tactfully designed so that the light waves cancel each other out during recombination so that no light signal is sent to the nearby detector. But a gravitational wave stretches one tube while squeezing the other, changing the relative distance of the two beams. Due to this difference, the alignment of the recombining waves is lost and they no longer cancel out. The detector is structured to pick up even the weakest signal, signalling a passing wave. Being located far enough apart so that they stay away from tapping on to one another’s local disturbances (like earthquakes); it’s only when both of them pick up on the change of values that notifies the researchers that those cosmic ripples are occurring.
The question that still remains with the masses is that, what good will this discovery bring us? Apart from being the last missing puzzle piece of one of the greatest theory, Einstein’s Theory of Relativity now stands as a symbol of greater understanding of the universe. “We were deaf till the point we actually ‘heard’ the universe” says once scientist at the observatory. Scientists across the globe are chuffed to have not only found the proof that black holes and gravitational waves do exist but also that we have the right technology at present to have discovered them. Ultimately, this discovery is another medallion for humanity and will prove to be a gift from us to our descendants. This monumental event can only be described in the words of Neil Armstrong himself, ‘One small step for man, one giant leap for mankind’.