Scientists have observed a stunning discovery in their quest to fully understand gravity. They have observed the warping of space time generated by the collision of two black holes more than a billion light-years from Earth. The scientist team says the first detection of these gravitational waves will usher in a new era for astronomy. But the gravitational waves were predicted by Albert Einstein in his general theory of relativity 100 years ago in 1915. The gravitational waves were detected on September 14, 2015 by LIGO detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.
So the Question arise what are gravitational waves ?
Gravitational waves are ripples in the curvature of space-time which propagate as waves, travelling outward from the source. These are believed to travel across the universe at the speed of light.
What is Space-time?
In physics, space-time is any mathematical model that combines space and time into a single interwoven continuum. The space-time of our universe is “usually” interpreted from a Euclidean space perspective, which regards space as consisting of three dimensions, and time as consisting of one dimension, the “fourth dimension”. So the universe can be viewed as having three space dimensions — up/down, left/right, forward/backward and one time dimension. This 4 dimensional space is referred to as the space-time continuum.
What do Gravitational Waves look like?
A century ago, Einstein predicted that big things like planets bend the fabric of space-time. Albert Einstein believed that when any object accelerates in space, it creates simple ripples in space-time known as Gravitational waves and gravity happens when other bodies follow these curves produced. These waves radiate out and compress & stretch the fabric of Space-time similar to how sound waves vibrate the air.
The earth & other planets, as they approach the sun, would revolve around the sun along these ripples only. As they accelerate, they also create their own ripples or Gravitational Waves. Now when two celestial bodies like Black Holes orbit around each other, they create these ripples called Gravitational Waves. But these are too weak for us to measure them. However, when two large black holes or neutron stars slam into each other, they create measurable Gravitational waves like an earthquake in space.
What is LIGO ?
The Laser Interferometer Gravitational-Wave Observatory is a large-scale physics experiment aiming to directly detect gravitational waves. LIGO operates two gravitational wave observatories in unison: the LIGO Livingston Observatory in Livingston, Louisiana, and the LIGO Hanford Observatory, on the DOE Hanford Site, located near Richland, Washington. These sites are separated by 3,002 kilometers. Since gravitational waves are expected to travel at the speed of light, this distance corresponds to a difference in gravitational wave arrival times of up to ten milliseconds.
Why is this discovery important?
Discovery of gravitational waves would represent a scientific landmark, opening the door to an entirely new way to observe the cosmos and unlock secrets about the early universe and mysterious objects like black holes and neutron stars. Til now, we were looking at the Universe through telescopes measuring light and other forms of electromagnetic waves. But through Gravitational Waves we can now study space by listening to gravity itself. Its simply “Hearing the universe”. It enables the astronomers to look back in time as well as space.