Inside a Black Hole

Shawon Sarowar
5 min readApr 9, 2021

Nebulae to supernovae -the stellar black hole to the supermassive black hole- the gravitational singularity and the mystery of a black hole

A supermassive black hole with a mass of hundreds of millions to billions of times the mass of our Sun (Image credit: NASA/JPL-Caltech)

If you want to know about the black hole first of all you have to understand the life cycle of a star. What is mean by that?

Nebulae, a large amount of air mainly hydrogen compressed by their own gravitational attraction and form a star. This compressed-air creates a huge amount of mutual collision that makes the atomic shell heated. Atoms become so heated that joint them to each other and create Helium-4. This is called a fusion reaction. A hydrogen bomb works this way. So, this extra heat keeps increasing the pressure of compressed air. Star to be stable when it has a hydrostatic equilibrium which is the balance of compressed air pressure and gravitational attraction. This is how Stars are born.

When a star finished its life cycle (Basically its fuel finished), it collapses because of its own catastrophic gravitational force. It collapses and collapses, then explodes. We call it a supernovae.

A supernova explosion (Image credit: NASA Visualization Explorer)

After the explosion what happens next?

Chandrashekhar Raman, an Indian physicist first showed the calculation about the formation of exploded stars. If the mass of the sun is M, then

i. mass of a star < 1.4M, it turns into a stable white dwarf

ii. mass of a star > 1.4M and < 3M, it turns into a Neutron star

iii. mass of a star > 3M, it turns into a black hole

Bigger than 3 times the mass of our sun every star ending their life cycle turn into a black hole. We called this stellar black hole. Scientists discover three types of black holes. The stellar black hole, the supermassive, and the intermediate black hole. In the case of a stellar black hole, a mass of 5 to 10 times the mass of our sun. There are billions of stellar black holes in our galaxy alone. But a supermassive black hole’s mass hundreds of millions to billions of times the mass of our sun. Every galaxy center has a supermassive black hole. In our galaxy, we call it Sagittarius A*. There is also another type of intermediate black hole between the mass of the stellar black hole and the mass of the supermassive black hole.

According to the result of Oppenheimer recharge, it is clear that light always does not pass through a straight line. The Gravitational field of a star changes the direction of light in space-time. Light bends slightly When light travels near the surface of the star. The more the star collapses, the stronger the gravitational field has. More light bends. In collapsed star with a critical radius, the gravitational field is so strong. Light totally bends inward the star. Light can’t escape from this heavy gravitational field. If light can’t escape, nothing can escape. In this area of space-time, wherefrom nothing can escape we call it the black hole. And we call its boundaries event horizon.

Bending of light(Image credit: Science woke)

A question is how a supermassive black hole formed?

Astronomers are still not sure how these supermassive black holes form. It remains an open field recharge. Most astrophysicists believe supermassive black holes create from the ‘seed’ black holes. They say seed black holes are so big or not big, thousands to several tens of thousands of times the mass of the sun or not heavier than a hundred times the mass of the sun. Other astrophysicists believe that before the first star the giant clouds of gas could collapse to form a quasi star, a black hole star. A quasi star was formed by dark matter. A quasi star is unstable because of its core, and its collapses directly into a black hole without a supernova explosion. The core of this extremely large value of the matter density.

The Gravitational singularity(Image credit: A Black Hole Give Birth To Our Universe)

The space-time singularity of the black hole

Singularity is a location inside of a black hole with a large amount of matter density where the gravitational field is infinite and does not depend on the coordinate system. According to Einstien's special theory of relativity, nothing can go faster than light in space-time. But in the general theory space, itself goes faster than light. It happens inside a black hole. Space moves faster than light because of singularity. There is also a naked singularity in outer space, which can be seen with the naked eye.

According to Stephen W. Hawking black hole ain’t so black

Hawking discovers that the black hole ain’t completely black. According to Hawking, a black hole may connect to another universe. And the information is not lost forever inside a black hole. Information may emerge in another universe.

What happens to you if you fall into a black hole?

Inside the event horizon, all physics rules break down. If you were to fall into a black hole, the pull of its gravity rises sharply. You would be stretched out until just your atom remains. It is called spaghettification. If somehow you survive, you will see you’ve moved faster than light. From the outside of the event horizon, your friend would watch you downwards and becomes flushed. At the event horizon, theoretically, your image would freeze. But in practice, you would disappear. And the point of singularity you'd die. And if you want to send some information to your friend outside of the event horizon, your friend can see the time of the sending information is infinitely extensive.