What is a black hole and how it is formed?

    I am pretty sure you might have heard a lot about black holes. Have you ever wondered what they are? You might have initially thought that black holes are objects in a fantasy story that is narrated to kids. Didn't you? Well, it’s actually a beautiful space phenomenon that I'll be explaining to you in this post. So let's begin!  

What is a black hole?

Credit: NASA

Black holes are regions of space-time. Till now we have seen objects which are three-dimensional but in our space there is no restriction, an event can occur at any point in time and space, so they are interdependent, causing a four-dimensional space called "space-time", which Einstein first discovered in his " Theory of Relativity ".
 
  Black holes are simply points (singularity - an infinity point in space-time) in space. They are so dense and have such a strong gravitational force that no particles or even electromagnetic radiations can escape.

The next question will be: can we escape a black hole?

    It’s impossible to escape a black hole, to escape a person or anything should travel faster than the speed of light which is impossible.

How are they formed?

Life cycle of a star.

If a star has a sufficiently compact mass approximately 10 to 20 times the mass of the sun, it can turn into a black hole (depending on their mass there are different types of black holes which we will be learning about it in the next post. So keep following!). When the star dies out of its fuel it starts contracting to make the gravitational force high and it starts bending the light cones (figure 1.1). 

   In space-time, a light cone marks out the possible directions light rays can travel through an event. It stops contracting after reaching a certain radius, causing a large explosion known as a supernova.

fig 1.1- light cones

Have you ever heard of a supernova? 

   

It's nothing but the explosion of a dying star. It's the largest explosion ever witnessed in space. A supernova burns for only a short period, but it can tell scientists /astronomers a lot about the universe. 

  For example, it has shown the world that we live in an expanding universe and it helps us to know more about space for example if there is a supernova burst it shoots debris of the star or elements into the space and these particles are the one which is falling towards the earth in name of asteroids. After this huge explosion the gravitational force of that star would be so high and also the light cones will completely turn inward which causes no light to escape and now a fully-fledged black hole is formed! 

Additional information:

Gravity:  Newton discovered a law to describe the force of gravity, which states that everybody attracts every other object with a force proportional to the mass of each body.

Have you ever wondered how all objects fall at the same rate?
It’s because of the reason that the gravitational force is proportional to the mass of each body. If an object A had twice it's mass and another object B had thrice it's mass the gravitational force would be 6 times as strong .according to Newton's second law these two effects will cancel each other so the acceleration will be the same in all cases, Interesting isn’t.

Comment your opinion and also share your thoughts on Black holes. See you in my next post!!