Gravitational Waves and LIGO

(Last Updated On: August 6, 2019)


Gravity, for a really long time, seemed to be a mystery before Isaac Newton published a comprehensive theory of gravity in 1687. This not just paved a way for the development of the laws of motion and classical physics but also seemed to promise a complete understanding of the universe.

Everything appeared to be intelligible with physics flourishing based on Newton’s idea of gravity but this slowed down in the early twentieth century-  not just for the World wars but also for the near assumption that the universe is completely deterministic exclusively on the then known and accepted theories. Everything seemed to obey all the laws laid down.

Also Read: Physics History – The Beginning of The Physics

Einstein’s prediction

In 1916, Albert Einstein published his paper – The General Theory of Relativity. This groundbreaking theory changed the way we perceive the universe and it also demanded some major amendments in the laws of classical physics.

Einstein foresaw a special event occurring when two massive bodies like planets or stars orbit each other. He concluded that such movement in the fabric of space-time could cause ripples in it. These ripples would spread out like the ripples in a pond when a stone is tossed in. These ripples in the space were later called gravitational waves. 

What are gravitational waves?

Gravitational waves are ripples in the fabric of space-time – which is otherwise inflexible. They are produced by the most violent phenomena being staged in the ever-expanding universe – things like exploding or colliding of starts, massive objects moving with high speeds, supernova explosions, merging black holes, etc.

Gravitational Waves - LiGO
Gravitational Waves

Gravitational waves travel all over the cosmos, even though  Earth, all the time, but we weren’t able to detect them until recently as our instruments were not sensitive enough. Also, the fact that these events take place in the far spreads of the universe, the ripples gradually become weak which makes them much hard to be detected.

Gravitational waves are invisible yet incredibly fast. They travel at the speed of light (186,000 miles per second) and their most distinguished character is that they stretch and squeeze everything in their path as they pass by. This unique property is employed in the detection of gravitational waves.

Read More About Gravitational Waves: Gravitational Waves – The Final Test Of Einstein

 What is LIGO?


LIGO – the  Laser Interferometer Gravitational-Wave Observatory is made up of two observatories – one in Louisiana and one in Washington. Each observatory has two long arms that are each more than 2 miles (4 kilometers) long.

How are gravitational waves detected?

When a gravitational wave passes by Earth, it squeezes and stretches space. A passing gravitational wave causes the length of the arms to change slightly, hence the light emitted by one of the lasers takes a slightly longer time to reach the mirror. LIGO uses lasers and mirrors which are so sensitive that they can detect this infinitesimally small (few thousandths of a diameter of a proton) changes during the squeezing and stretching!

The very first time a gravitational wave was detected on 15th September 2015. These first gravitational waves originated when two black holes collided and merged into one another. This collision happened 1.3 billion years ago. This proved Einstein’s theory.

Why are they important?

Everything we know about the universe is for the electromagnetic spectrum we observed but there are dark regions in the cosmos which do not emit any radiation, like the black holes. how do we study them? Should we just give up blaming the obscure engineering of the cosmos?

Gravitational waves would help us decode the story of the universe we never have heard before. We should be able to understand gravity in a whole new way. We might be able to detect more black holes far from us. We might be able to witness neutron stars crashing into each other, the exploding supernova and many more cosmic phenomena now being phantoms to us.  Maybe the sound of the universe might take us to every beginning of the universe, to the Big Bang! If that happens, then we’d finally have a unified theory of everything.

The gravitational waves have a lot for you and me to offer. They have a glorious story, louder than the rustles and chirps of the cosmos, waiting to be heard while observatories like LIGO are being set up. One of such observatories is being set up in India promising us an exciting future for Physics and the understanding of the universe.

Read Also: Radio Astronomy – An Unseen Field

Fardeen Ahmed

Fardeen Ahmed

He is a B.Sc. graduate and preparing for his Masters in Physics. He is a physics and philosophy enthusiast passionate about teaching Physics after completing his education. He's also a poet and has written many poems in English and Urdu.

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