What are gravitational waves and why are they important?

Finally, the gravitational waves have been detected and with this the last major prediction by Einstein has been confirmed. But what are these gravitational waves and why are they so important? First, you will be disappointed to know that such waves can not be used by you for surfing in space like you can surf on sea waves. But these are still very important as they open up an entire new chapter in the field of physics. Predicted by Albert Einstein on the basis of his theory of general relativity, gravitational waves are ripples caused in the spacetime fabric. Now, if some of you clever people are thinking that why don't we use them for mobile communication to get faster internet just like RF waves, you may be right, but the only problem is that to produce such waves you need a black hole or neutron star in your cellphone. For those who can't arrange a black hole, good news is that your bodies can also produce these waves but such waves are very very tiny to say the least.This is because gravity is a weak force and we need massive bodies to produce any significant gravitational waves. Binary neutron stars in-spiraling, colliding black holes and supernova explosions qualify as valid candidates.

Gravitational waves visualized- When a mass is correctly accelerated through space, these waves travel outward from the source. To visualize it, suppose there is a stretched rubber sheet and you put a billiards ball at the center. Now, the sheet would obviously depress in the middle due to the weight of the ball. If you put a marble anywhere on that sheet, it will roll down towards the ball due to depression in the sheet at center. This is gravity. Now if we put one more billiards ball near the first ball, it will also produce a depression on the sheet. If the balls are close enough, then their depressions will merge slowly and the balls will start moving towards each other. Imagine that they do not move quickly but are rather caught up in a spiral motion on the sheet, like in-spiraling stars. Such motion will produce waves on the rubber sheet and these waves can be called as gravitational waves.

Why we couldn't detect them before? Why it took us a hundred years after Einstein's prediction to detect them directly? This is because gravitational waves produced by distant sources can lengthen or shorten our space only by a factor of 10^-21 or less. This is less than a millionth billionth of the width of a human hair. Such detection can only be done with lasers.This unbelievable task was attempted by LIGO starting in 2002.

LIGO stands for  Laser Interferometer Gravitational-Wave Observatory. It used lasers to measure the changes in distance between ends of  4 km long tunnels. But from 2002 to 2010, it detected nothing. After this it was upgraded into what is known as Advanced LIGO. This was 10 times more sensitive. It started operating in September 2015 and has already achieved success. The gravitational waves detected by LIGO have come from a black hole merger about 1.3 billion light years away from earth.

So, gravitational waves can make you taller and thinner for an instant but such minuscule improvement in your appearance will impress your girl friend only if she uses lasers to measure you. In my opinion, exercise will be a much better option.

This detection has opened up an exciting new field of gravitational wave astronomy. Studying these waves will give us more information about the cosmic events which produce them. And yes, we know now that with this great feat we have found a key in the universe to open a box which is full of mysteries.

References-
http://www.ligo.org/
https://en.wikipedia.org/wiki/Gravitational_wave
https://en.wikipedia.org/wiki/LIGO
https://www.youtube.com/watch?v=gw-i_VKd6Wo
https://openclipart.org/detail/240758/Gravitational-waves-confirmed