WHAT ARE GRAVITATIONAL WAVES? | LIGO AND IT'S WORKING?

In this mystical universe there are some entities which we can observe and understand, but beyond this fact some entities are also there which we could not observe and understand but yet they exist and can be predicted through mathematical equations.

From this undefined amount of treasury I present you the concept of Gravitational Waves :

In 1916 Albert Einstein first predicted the gravitational waves on the basis of his General Relativity.

On 14 september 2015 LIGO detected the Presence of gravitational waves which were radiated by merging of two black holes situated Billions of Light years away from Earth.

This discovery has created revolution in the history of science or more specifically provided another Pillar to Modern physics.

In 1915 Einstein published his general relativity in which he talked about 4-dimensional space-time concept which completely changed the meaning of Gravity. According to him every type of mass Distorts the space-time fabric.

If an object has huge mass It will distort the space-time fabric more and small mass object cause less distortion and this results to attraction of low mass objects towards huge mass objects; this attraction is what we call GRAVITY.

If that huge mass object start moving from its place, It produces ripples(disturbance) in space-time and this disturbance propagate around the UNIVERSE, which we call Gravitational Waves.

Above Example was just introduction. Let us know how Gravitational Waves are actually formed

When Two Neutron stars or black holes are nearby; they firstly revolve around each other and then merges to form single entity.

From the very moment they start revolving around each other repels also start forming in space-time and when they merges to form single entity, a huge amount of energy is released.

NOTE : Gravitational waves are created by two ways -

1. Merging of two massive objects.
2. Motion of a massive object.

These Gravitational waves travel around UNIVERSE at the speed if LIGHT.

Let us know how Gravitational waves were detected :

In 1974 two Astronomers discovered an Binary Pulsar  in which extremely dense and heavy stars were revolving around each other and this was the perfect system to test the theory of Gravitational waves.

After observing till 40 years It was found that both the stars were really attracting each other. Thus Einstein was correct and it means they have also created Gravitational waves bit till 2015 we were not able to detect them.

On the day of 14 september 2015, LIGO detected the distortion in space time field which was caused by merging of two Black holes situated BILLIONS of light years away from Earth(as mentioned earlier). After then we have detected them TWICE.

FACT : As Gravitational waves are ripples produced in space-time. If any source of  Gravitational waves is present near Earth we would have died years ago.

But as they emerge from very very distant source, before reaching earth their effect is very small that it effect earth as same as it's effect on 1000th part of nucleus present in an ATOM. That's why we can't feel this Effect.

WHAT IS LIGO AND HOW DOES IT WORKS  ?

LIGO : It is the Biggest Gravitational waves observatory in the world. In Technical terms it work as same as INTERFEROMETERS.

WORKING : From the central building a laser beam is fired which at base splits into two long perpendicular tubes and these tubes have same length and at the end of them a mirror is placed. when laser beam meets at base after reflecting from the mirrors. The light waves are aligned in such a manner that they cancel out each other which causes no detection at the Photo Detector(placed in central Building). Normally LIGO don't detect anything but when Gravitational waves arrives the earth, It distorts the space and because of that Length of both perpendicular tubes alters for some time.

Sometimes 1st tube gets expanded and 2nd one gets contracted and vice-versa, This happens till Gravitational waves completely passes the earth.

Instruments of LIGO are so powerful and accurate that if 1000th part of proton get effected they could detect it. Because of this the alignments of light waves are not same as before and they can't completely gets cancel out and thus same light reaches to photo detectors and the intensity of  light depends upon difference caused in the length of tubes.Measurement of this intensity provides measurement of Gravitational Waves.

NOTE : LIGO can only detect the Gravitational waves of massive events like merging of black holes or big bang itself.

Gravitational waves not only help us to understand gravity but also to understand the behaviour of unknown entities like WHITE HOLES, WORM HOLES, etc.