Hawking Radiation: End of Black Holes?

 Learn about Black Holes: Part 3

Black holes are one of the most fascinating things found in the Universe. They have an extremely strong gravitational field and most of them are located at the center of galaxies. Black holes are formed as a result of the death of Gaint stars, having masses that are 20-30 times that of the sun. In the previous post, we talked about 'event horizon' and the concept of spaghettification. Here, we'll get to know more about Singularity; also we'll discuss the question, "Can Black holes die?"

Singularity is present at the center of every black hole; it's a point in space where all the mass of a black hole is concentrated. Anything that falls in the black hole travels till the Singularity. The space-time curvature at this point is infinite and so is the density. We can basically call it a 'divided by zero' error. Some singularities spin in a small ring; these are called 'ring singularities' or 'ringularities'. Theoretically, all black holes must be spinning because of the inertia provided by a dying star's core (which is spinning as well). A few scientists say that black holes can spin at up to 90% the speed of light. That's super fast!

But the real mystery here is about the death of black holes. There is a theory proposed by the scientist 'Stephen Hawking' which says that Black holes are actually losing mass but it's a very slow process and we probably wouldn't notice it. The sheet of space-time is boiling with quantum fluctuations. These fluctuations create matter and anti-matter. However, these particles exist for a very short time before annihilating each other. When this happens near the event horizon, one of the particles falls inside the black hole while the other is repelled outside. The particle that escapes is called 'Hawking Radiation' and it's a constant process that happens at the event horizon. As a black hole shrinks, hawking radiation gets stronger and faster until the hole evaporates. Unfortunately, it's a very slow process: a black hole the mass of our sun will take 10^67 years to completely evaporate. So it is unlikely that the Universe would be able to survive the catastrophe of being sucked into a black hole. 

There are 2 main types of Black holes: Stellar-mass and Supermassive black holes. It is so interesting to learn about their origins. Stellar-mass black holes are created from stars that are 10-20 times as massive as our sun, then the supernova causes it to convert into a black hole. It's the size of an asteroid. On the other hand, Supermassive black holes have a mass that's billions of times the mass of our sun. They are usually found at the heart of galaxies. The Milky Way galaxy has a black hole at its center called 'Sagittarius A'.