What Are Gravitational Waves | Q And A | Episode 3 | The Secrets of the Universe

Everyday, we see different types of waves. We see waves on strings, waves in lakes and ponds and the water waves on the beach. Apart from these, we even feel the sound waves when we
hear something and the seismic waves during an earthquake. In 2015, mankind detected a new form of waves: The Gravitational waves. But where did these waves come
from? What was the magnitude of these waves and why were they so important to us? This is Q and A and here is the answer to the question, What are gravitational waves.

Modern day physics stands on two main pillars: One is Quantum mechanics that deals with the matter at the atomic and sub atomic level and the other General Relativity that explains the phenomoneon at
larger scales of the universe. Time dilation, black holes, wormholes, bending of light due to gravity are all outcomes of General Relativity. But this theory given by Einstein also predicted a new form of waves,
known as the gravitational waves. Basically, Einstein assumed that mass distorts space and time as shown. Heavier the mass, more is the distortion. As the mass acceleraters, the ripples in spacetime
propage outwards at the speed of light and these waves are known as gravitational waves.

Now the math says that by the time these waves reach us, they become very weak. In 2015, the LIGO detector detected the first gravitational waves from a black hole merger that was 1.3
billion light years away. This also means that the merger actually took 1.3 billion years ago and the waves travelling at the speed of light reached us in 2015. As these waves pass by anything,
they will stretech it and compress it. So our Earth is constantly being stretched and compressed by these waves. But this stretch and comression is extremely small? How small? A few millimeters?
Micromaters? Nanometers? no! It is Equivalent to the thousandth part of the diameter of a proton! And this is what we detected using state of
the art scientific equipments.

Detecting these waves is a very challenging task. Imagine you have a scale that is a billion trillion meters long and you had to tell if it shrunk by 5 mm. That's the level of precisiion we are
talking about. The LIGO detector consists of two 4 km long tunnels with laser beams travelling inside them. Known as an interferometer, this type of equipment was
being used even 100 years ago by experimentalists. Currently LIGO is operating in 2 observatories and now it will build its 3rd observatory in India in collaboration with MIT (Cambridge), RRCAT (Indore), IUCAA
(Pune), IPR (Ahmedabad). This will further strengthen its network around the world and help in extracting the best information about the gravitational waves.

Lastly, why are these waves important for us? Well, with gravitatonal waves we can study unique properties of black holes, stellar explosions, neutron stars and even white dwarfs. These waves can even
tell us a lot about the early universe. Gravitational wave Astronomy has just begun and there is a lot to explore in this field. Share this with your friends and do ask questions for the next episode of Q and A.

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