“Einstein’s gravitational theory, which is said to be the greatest single achievement of theoretical physics, resulted in beautiful relations connecting gravitational phenomena with the geometry of space; this was an exciting idea.” -Richard Feynman
Gazing out in the sky, into the vastness of the universe, we usually obtain information about it by spectral emission from light of various wavelengths. However, there are other possibilities for astronomy, including by looking for the neutrinos emitted by astrophysical sources — first detected in the supernova explosion of 1987 — and in the gravitational waves emitted by accelerating masses. However, the study of gravitational wave is as elusive as the end of a rainbow.
Few days ago though, the universe is trumpeting a yet again another signal for mankind. This time, it’s the elusive gravitational wave, a previously theorised model to explain the perturbations of spacetime which is propagated as waves, travelling outward from the source, at a rate similar to the speed of light. The existence of gravitational waves is a possible consequence of the Lorentz invariance of general relativity as it brings the concept of a finite speed of propagation of the physical interactions with it.
LIGO(Laser Interferometer Gravitational Wave Observatory) in Luisiana and Washington demonstrated its proof-of-concept from 2002-2010, and then operations suddenly gets decommissioned while undergoing upgrade. In September of 2015 though, it was reprised, this time with the promised upgrade, and thus came the Advanced LIGO. Advanced LIGO announced the discovery of this gravitational wave which is a result of a merging of two black holes, close to the size of Quezon City.
But what does this mean to us? Why make a huge fuss abut it?
For one, gravitational wave is a piece of the puzzle. It is a a form of information, and by detecting them we could get information from previously unobservable parts of the universe.
Take these two black holes, for instance. Both are less than 150 kilometres but located 1.3 billion light-years away. We have no other instruments in existence that could detect information from objects so small and far away.
Second, we can now closely say that gravitons, a hypothetical particle of gravity, is massless, hence able to travel at speed of light.
Third, this will pave way to a yet another form of astronomy, a Gravitational Wave Astronomy.