By Vandya Rai
JUNE 11, 2022
No light can escape from a black hole. So, it’s impossible for us to sense the hole directly, no matter which instrument you use. The only way to recognise a black hole is to notice the effect it has on everything around it.
Image Source: NASA
Black holes are of at least 3 types. Primordial black holes range from the size of an atom to a mountain’s mass. Stellar black holes are 20 times more massive than our Sun. Supermassive black holes live in the centres of galaxies and are a million times bigger than the sun.
Image Source: NASA
There might be 100 billion galaxies out there, with millions of black holes living inside each. 1 out of every 1000 stars is massive enough to become a black hole. So, with over 100 billion stars in the Milky Way alone, there might be a billion stellar black holes in our galaxy.
Image Source: Unsplash
The extreme gravitational pull of a black hole slows down time and warps space around it. They create such deep curves in space that nothing has enough energy to climb back out, not even light. As you move faster towards the centre, time moves slower, where space-time curves infinitely.
Image Source: NASA
When you’re near a black hole, you spiral inward and your feet get stretched by gravity’s greater pull towards the centre. Since the top half of your body is farther away, it does not move towards the centre as fast. The result: You get stretched thin!
Image Source: Wikimedia Commons
A black hole can generate energy more efficiently than the Sun. Materials orbiting its event horizon move so rapidly that the heat can form blackbody radiation. To compare, Nuclear Fusion converts 0.7% of mass into energy, whereas a black hole converts 10% of mass into energy!
Image Source: NASA
Supermassive black holes occasionally expel enough material to form whole new stars. They also control the number of stars a galaxy can have by deciding how quickly the process of star formation turns off. Sometimes, these stars land in deep space, far beyond their origin galaxy.
Image Source: NASA
There is a supermassive black hole at the heart of every galaxy; even ours! The Sagittarius A lives in the centre of the Milky Way, 30,000 lightyears away, and is four million times more massive than our sun. It is dormant for now, but scientists believe it may have erupted 2 million years ago!
Image Source: Wikimedia Commons
This phenomenon was discovered by Stephen Hawking, and is known as the Hawking radiation. It disperses a black hole’s mass into space over time, until there is nothing left. Every black hole dies by slowly evaporating.
Image Source: Wikimedia Commons
If our Sun shrank down to a size of 6 km across, then its mass would be compressed into an incredibly small space, making it dense enough to be a black hole. The same theory can be applied to Earth or your own body. But, in reality, only the gravitational collapse of an extremely massive star can form a black hole.
Image Source: NASA