Gravitational Waves made easy

Time for another "Made easy" article! Gravitational waves! It is all over the news. What are they? What is the big deal? What is the brouhaha all about? I am offering an easy to read, layman version of the news and the Physics involved.

Firstly, think of the size of our universe. Universe is SO SO SO SO ENORMOUSLY, dazzlingly, bamboozlingly, mind bendingly BIG. It is huge, like really majestic. I mean seriously really really huge. Even if we go super duper fast in rockets we will need 1 lakh years just to cross our Galaxy. When one satellite went far away and took the photo of the earth, earth looked like a pale blue dot. Just a blue dot! A Pale blue dot!! If Bengalooreans have a hard time understanding what happens near Manglooru how will we ever understand anything happening in other parts of our galaxy if it is that big? Keep that question in mind for a while.

Let us talk about Gravitation first. We will keep it short. Let me just say that Newton's idea of gravitation cannot explain many things. It is incomplete. Einstein solved this problem with many brilliant ideas. He changed the concept of gravity.

Imagine a bed sheet streched and held by Digvijay Singh and Mani Shankar Iyer. Now say Sonia enters and keeps a basketball in the middle. This ball will press the bedsheet down and it will sink it down a bit. That is sort of how gravity works.

Gravity is not like a magnet that attracts things placed away(Newton's idea).
Gravity is like the basketball on the bed sheet that presses it down(Einstein's idea)
It creates one depression type thing, it creates a dimple on the bed sheet. It creates a warp. Now if you keep one lemon on the bed sheet it will roll towards the dimple.

Bed sheet = Space and time.
Basketball = Mass

With this in mind let us talk about Black Hole: Take a Star. Let us call it Ashwini Nakshatra. Say, it is 20 times heavier than Sun. What happens when the petrol tank of this star is empty? What happens when this Ashwini Nakshatra runs out of fuel? What happens is this:

Ask Tiger prabhakar and Sunny Deol to Crush that star. Really hard. Now the size reduces to the size of a house. Now ask Arnold Shivaji Nagara to to crush it further. Crush like crazy. It now reduces to the size of a football.Now call Rajni and ask him to crush it. It reduces to the size of an atom. Now ask Telugu film directors to crush it. What do you get? Something with almost zero volume. But the weight still is 20 times more than Sun. This version of Ashwini Nakshatra is called as Black Hole. Imagine the weight of an elephant condensed into the size of a rice grain. It will have the strength and power of the elephant but it will look like a rice grain. Black holes are like that rice grain.

Some hifi sounding terms:

Event Horizon: This is just a fancy term for the outer part of Black hole.

Singularity: Another sophisticated term for the innermost part of the black hole.

We had Tiger Prabhakar, Sunny paaji, Rajni, Arnold and all crushing the Star, right? In reality it is the Gravity which crushes it.

Remember Singularity? A flashy term for the innermost part of blackhole? Gravity there is really crazy. You take your bike and go inside a blackhole. It will suck you in like a toilet flush. If you go near the singularity, you will never come back. Gravity is so very high. Forget you, even light cannot escape such crazy gravity. Not even Rajnikanth can escape from a Singularity.

Now, what if two basketballs are dropped into that stretched bed sheet? That will create some ripples/waves in the bed sheet. Right? Something similar happened in the universe in a far far away place. 2 Blackholes collided like two trains crashing. And that created some ripples/waves in the bedsheet(Space). And we detected those ripples! We did it! YAY!!!!! So,"scientists are doing Gangnam style dance for something as silly as that" you ask?

If Shreya Ghoshal sings a song in Africa, will you be able to hear it in Bengalooru? No. Similarly if something happens in a far away place(Remember how big the universe is?) we will find it difficult to detect. These 2 blackholes collided 1 billion light year away. Meaning, light will take some 100 crore years to reach from there to Bengalooru. Not 1, not 10, 100 crore years! Also, We detected something that happened 100 crore years ago. And that is not the exciting part! Some 100 years ago Einstein said that stars and planets and stuff should make ripples/waves in space, and he used some really cool math to explain why he thought that. Lots of scientists checked the math and agreed that Einstein rocks.

But we've never been able to see those ripples before. By the time those ripples travel that long long long distance and get to us on Earth, they're extremely weak and tiny(Like how we cannot hear a song sung in Africa). Scientists have now built a hi fi 4 Km long equipment. This equipment detected the ripples/waves/Gravitational waves. We can now detect them because we have such a ridiculously precise detector. It is like if a pin is dropped in Europe we can detect it sitting in Mumbai. In short, Einstein said, you will detect these ripples and now we have detected them after 100 years! And we know that only singularities could have created such ripples/waves.

One last thing. We hear about the size of universe, stuff about other galaxies and all that, right? As I already told they are so so so so far away,nobody has actually been there. If we have never been there, how do we know what we know? Isn't it like sitting in Bengalooru and talking about Africa? We know things indirectly because of electromagnetic waves(Visible light, X-rays, radio waves etc.) Light, X Rays, Radio waves etc. are like cousins belonging to the same family. These EM waves are the eyes through which we are seeing things. Now alongwith the eyes we have an ear called Gravitational waves! And this Gravitational wave dude is not the cousin of electromagnetic waves. So, basically we have a new way of understanding what is happening in far away places of galaxies. We also have new ways to understand how our universe was formed and things like that. We had eyes, now we have an ear also. That calls for a tappanguchchi dance. Doesn't it?