Black Hole

What is a black hole?

In simple terms, a black hole is a region in space where the gravity is so powerful that not even light can escape from it. They can be tiny as well as huge. A small black hole can be as little as an atom but with great mass. A type of black hole called 'stellar' black hole is said to have 20 times more mass than the sun. The largest of the black holes are known as "supermassive". NASA stated that these have masses that are more than 1 million suns together. Scientists confirm that every large galaxy has a supermassive black hole at its center. Our galaxy (Milky Way) has a supermassive black hole at the center called 'Sagittarius A'. Currently, the largest supermassive black hole known is Ton 618. This is a black hole that measures 6.6×1010?solar masses. It has a mass that equals about 66 billion times that of the Sun.

How are black holes formed?

Now that we have these interesting facts with us, let us try to understand how are these formed. Stars! A star plays an important role to give birth to such an empty space in a galaxy. Stars are a collection of enormous amount of hydrogen atoms that collapsed from gigantic gas cloud under their own gravity. Then, inside their core, a process called nuclear fusion takes place where the hydrogen atoms are crushed into helium atoms which releases tremendous amount of radiations. These radiations move against gravity. This, in turn, maintains a balance between the two forces. This stability is observed until and unless the fusion in its core continues.

But, there are stars which have greater mass than the sun and the heat and pressure at their core allow them to fuse heavier elements until they reach iron. So, many elements are fused before the star is capable enough to fuse iron. The elements that come before iron are carbon, neon, oxygen and silicon. But, we will observe a difference here. All the elements, except iron, emitted radiation. The fusion process that created iron does not generate any radiation. Iron builds up at the center of the star until it reaches a critical amount and the balance between radiation and gravity is suddenly broken. The core collapses. Within a fraction of a second, the star implodes moving at about the quarter of the speed of light, feeding even more mass into the core. It's at this very moment that all the heavier elements in the universe are created as the star dies in a super nova explosion. This either produces a neutron star or, if the star is massive enough, the entire mass of the core collapses into a black hole.

Following is an illustration of a Neutron star.

If you look at a black hole, what you will notice is the Event Horizon. Anything that crosses the event horizon needs to travel at a speed faster than light to escape. We can say that it's impossible.

What would happen if you fall into a black hole?

The experience of time is different around black holes. From the outside, it would seem that a person would be slowing down as he moves towards the Event Horizon, so time passes slower for him. At some point, he would appear to freeze in time, slowly turn red and disappear. In his perspective, he can watch the rest of the universe in fast forward like he is seeing into the future. Then, it is highly possible that the individual passing the Event Horizon may die a quick death. How soon he will die depends on the mass of the black hole. A smaller black hole might kill an individual before entering its event horizon. On the other hand, you can probably travel for quite a while inside a supermassive black hole.

Death of a black hole

Eventually, black holes start to evaporate through a process called Hawking radiation. A typical black hole will emit only one particle every year. Over time they shrink down to nothing. In other words, as a black hole continues to evaporate, it gradually reduces in size. The rate of particles escaping increases as it loses mass until all the remaining energy escapes at once. Probably, a huge flash of light and energy is visible in the final moments of a black hole.

Research from Google and YouTube. Images- Google.