Over hundred years ago, Albert Einstein has anticipated about gravitational waves, today after centuries of endless research and speculations, scientists finally detected the phenomena that considered to be one of the breakthrough discovery of modern times.
“We have detected gravitational waves. We did it,” said David Reitze, executive director of the Laser Interferometer Gravitational-Wave Observatory (Ligo), at a press conference in Washington.
Long ago, even before it was detected, gravity waves has been hypothesized in Albert Einstein's general theory of relativity, which predicted that an accelerating mass would radiate gravitational waves as it lost energy. For example, it's been a belief from centuries in science that, two pulsars (celestial bodies that emit radiation in regular pulses) orbit around each other should emanate gravity waves as their orbits decay. In accordance with laws of thermodynamics, energy neither be created nor be destroyed, it can be changed from one form to other – the energy loss associated with orbit's decay is radiated as gravitational waves.
The LIGO system consists of suspended weights with mirrored surfaces that can move freely horizontally. If any gravitational wave were to pass through it, the distance between the weights (which is measured by laser beam moving back and forth between the mirrors and then recombined at photodetector) would be altered.
Over a distance about billion lightyears away from Earth, the two black holes (black hole is a region in spacetime with such high gravitational strength that even light can't escape from it) collided, and this phenomena came into the radar of the LIGO detector. The scientists listened for 20 thousandths of a second as the two giant black holes, one 35 times the mass of the sun, the other slightly smaller, circled around each other.
At first, their calculations told them how stars perish: the two objects begin by circling each other for 30 times a second. By the end of the 20 millisecond snatch of data, the two had accelerated 250 times a second before the final collision and a dark, and a rather violent merger. Following which, gravity waves emerges and has been detected on the system.
“We have detected gravitational waves. We did it,” said David Reitze, executive director of the Laser Interferometer Gravitational-Wave Observatory (Ligo), at a press conference in Washington.
1. What is Gravitational Waves?
Okay, I'm sure many of you actually confused about this term 'Gravitational wave' all around the web today. Let me define that for you, Gravitational waves are nothing but a ripples in the curvature of spacetime continuum (combination of three perceived physical space dimensions, plus fourth dimension as time) created by the movement of matter. |
| 3D visualization of Gravitational wave, Picture courtesy: LIGO Lab |
2. How they detected it?
Over the years, scientists across the world trying to construct detectors that detects gravity wave and identify their sources. In September 2015, Advance LIGO (Laser Interferometer Gravitational-Wave Observatory) began their first science observation at about four times the sensitivity of its initial attempts. That means, their new advanced instrument is four times more sharper than it was when they first introduced it in 2002. LIGO is funded by US government agency National Science Foundation (NSF), with major contributions from UK, Germany and Australian research societies.The LIGO system consists of suspended weights with mirrored surfaces that can move freely horizontally. If any gravitational wave were to pass through it, the distance between the weights (which is measured by laser beam moving back and forth between the mirrors and then recombined at photodetector) would be altered.
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| Gravity-wave detector, a picture by MIT/LIGO Lab |
At first, their calculations told them how stars perish: the two objects begin by circling each other for 30 times a second. By the end of the 20 millisecond snatch of data, the two had accelerated 250 times a second before the final collision and a dark, and a rather violent merger. Following which, gravity waves emerges and has been detected on the system.
3. Why it's important?
This discovery is a massive confirmation of Einstein's theory of General Relativity, based on which we are understanding the concept of gravity and universe till now. It validates the research that scientists has been carrying out.
And most importantly, this has also opens up a new horizon in observational astronomy. Present day astronomy works through telescopes that observes different forms of light waves - infrared, visible light, x-rays, radio waves, etc. But gravitational waves gives a new perspective to astronomers, that allows us to see things we couldn't have seen otherwise.
For example, an object that is about 30x the mass of sun is a pretty small object to see from a distance of billion light years away, and black holes which are really really small. We have detected that small object which is in actual a billion light years away in proximity of less than 100 kms. Which is an impossible thing to do with any other method of science till date.
Gravitational waves will give an incredible amount of information about the universe, which subsequently lead to many practical applications. For example, their ability to pass through matter unaltered could enable the transmission of a signal over vast distances in space.
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