Understanding Black Holes

You would have most recently seen and heard of black hole in Christopher Nolan’s hit movie Interstellar, and felt like a nasty bouncer above the head? Well, there is a simple explanation to what black holes are and how do they exist. Imagine a massive celestial object in space, so densely packed with matter that nothing can ever escape it, not even light- that’s what black holes are. They are formed by large stars- stars that are way larger in size (20 times or more) than the sun. When such massive stars run out of fuel in its course, it can no longer sustain its heavy weight. They rapidly collapse causing colossal of explosions called supernova. The dense core of the star continues to remain bound together by the force of gravity and pressures from the star’s outer layers continue to collapse inwards because of its weight.  These particles continue to be squashed together and the star becomes smaller and smaller until all that is left is a black hole. This object is so dense that even light cannot escape it and is expected to be spinning. Due to the spinning nature and strong gravity, they drag the space around them just like honey drags along a spinning spoon. We can see an object only when light bounces from it, but since black holes don't let light escape, they appear black - hence the name.  Singularity is the name given to the tiny gravitational centre in a black hole, which is incredibly dense, think of it as the nucleus of an atom. Around the Singularity there is a region from which light is not able to escape and is sucked in. The edge of this region is called event horizon. Outside of this event horizon, matter and light will still be sucked in but they can be seen and they appear like Saturn rings spiralling in - think of water spiralling in the sink hole - instead of rings, this region is called accretion disk (accretion means gathering).  So if we cannot "see" a black hole, how do we know that they exist? Well, just like planets revolve around sun due to sun's gravity, similarly when celestial objects are seen revolving around an invisible centre, a black hole is spotted.  Many scientists from the 17th century have tried to prove the existence of black holes but it was only in 1970s when Stephen hawking proved that black holes must exist. Recent studies prove that black holes exist, generating lot of fascination and mystery around this subject matter.