24 October, 2016 - 15:54 (Research Matters)
Scientists at the Laser Interferometer Gravitational-waves Observatory (LIGO) recently announced the detection of gravitational waves. This comes exactly 100 years after Einstein had predicted their existence in 1916. This discovery has caused huge ripples of enthusiasm in the arena of astronomy. But what are gravitational waves?
We all know about “gravity”, the force that made an apple fall on Isaac Newton’s head. While Newton explained why an apple, or any other thing, falls on the ground, he did not answer one important question - how do other objects notice a change in the gravitational force when an object changes its position? Einstein then answered this through his theory of General Relativity.
To understand Einstein’s model of space-time, imagine the Universe to be a huge stretched tarpaulin sheet. If we drop a ball on the sheet, it sags due to the weight of the ball and a valley is created around it. If we then place a smaller ball on the same sheet, it is attracted towards the bigger ball because the tarpaulin is curved in that direction due to its mass. Now, if the balls start accelerating, ripples are formed on the tarpaulin. These ripples in the fabric of the space-time are called gravitational waves.
The detection of gravitational waves is a revolutionary step. Until recently, scientists have been using light to study objects in our Universe. But objects in between the observer and the light source can block light. It is thought that objects in their path do not obstruct the gravitational waves. Thus, they can help us 'look' at regions in the Universe that are invisible to telescopes. They can increase our understanding about the Big Bang, the early Universe, black holes, neutron stars, pulsars and others. Their discovery thus heralds a new and unprecedented era of studying the Cosmos!