What is Black Hole? Albert Einstein Theory of Black Hole

What is the Black hole?

The history of black holes isn't very long. 100 years ago, no one knew about black holes Because of Einstein’s Theory of Relativity, black holes were later discovered. There are two parts to the theory. The Special Theory of Relativity, and the general theory of Relativity.

Black Hole 

Black Hole

The discovery of black holes is one of the few major discoveries in human history. Albert Einstein, who is one of the few great scientists in the field of physics in human history, was born in 1879 and died in 1921.  In the field of physics, he also received the Nobel Prize. He mathematically proved that if a lot of mass is concentrated in a place in the universe and it is almost zero, negligible, then the gravitational force inside it will be very high.

Albert Einstein Theory

Albert Einstein

The General Theory of Relativity published by Einstein in 1905, tells us how speed influences time. If you are in a spaceship that is going very fast or the speed is too high, time will slow down for you. Compared to those back on Earth who weren't on the spaceship. In a spaceship, where time does not seem to slow down, the word "relative" is crucial. You might assume that time is passing as it usually does.

 

Space Ship

Imagine a fabric of space-time the mesh of the way that all planetary objects are placed. The more mass they have, the more they bend the mesh of space-time.  Not only physical objects are getting more attracted towards it, but time is also starting to dilate due to it, such as sound, heat, and light, gravitation has an effect on all of them.  Everything is affected by the force of gravity, not only physical objects are attracted, but heat, sound, and light are also attracted, so This means that there can be objects in the universe in which the gravitational force is so high that they Absorb the light completely and if there are such objects it means that they will be completely black and we will not see them because the light will not be able to escape from them.

The theoretical concept of Einstein

This is exactly what black holes are, but when Einstein proposed his theory of general relativity, the concept of black holes was only theoretical. Einstein knew that gravity influences light and theoretically, there could be objects that could influence light.  But Einstein did not know that black holes exist in reality.

In fact, when Einstein was alive, he found the concept of black holes very strange.  He did not believe that such objects exist in reality, so the word black hole was not invented until his death.  It is not that the force of gravity is instantly felt by us everywhere, its upper limit is the speed of light. 

Light Speed in Black Holes

Example:

Suppose, the sun suddenly disappeared, you all know that we will know only after eight minutes that the sun on the earth has disappeared because light takes eight minutes to reach the earth, but according to Einstein, the sun disappears.  We will feel the gravitational impact on the earth after eight minutes.

Solar System Without Sun

Black holes in space are made of stars

Then there is no hole in space. Black holes in space are made of stars, so there must be some material in their center. Nuclear fusion reactions are taking place in their center. Due to these reactions, heat and light are produced.

Black holes in space are made of stars

Scientists Research on Black Hole

By the 1960s, researchers and scientists finally believed that not only theoretically, but also realistically, one day we would be able to see black holes because they actually exist in space. Then there is no hole in space. Black holes in space are made of stars, so there must be some material in their center. Nuclear fusion reactions are taking place in their center. Due to these reactions, heat and light are produced.

The life cycle of Star

 If the star is not massive enough to turn into a red joint, it can then become a planetary nebula or a white dwarf, but if it is a massive star, it is a massive star when it runs out of fuel.  It cools down to form a red supergiant and then the supergiant explodes and becomes a supernova, leaving behind a very small core.  If the core is large, we call it a black hole.  The material is compressed if a star as big as our Sun forms a black hole, the diameter of the black hole will be only 50 km, so the volume decreases. Recognize what a black hole looks like.

                                                  Life cycle of Star

Stage	Description
Nebula	A large cloud of gas and dust in space.
Protostar	A dense core of gas and dust that collapses under its own gravity.
T-Tauri star	A young star that is still contracting and accreting mass.
Main sequence star	A stable star that is fusing hydrogen into helium in its core.
Red giant	A star that has exhausted its hydrogen fuel and is expanding and cooling.
Asymptotic giant branch (AGB) star	A red giant that is further evolving and shedding its outer layers of gas.
Planetary nebula	The shell of gas that is expelled by an AGB star.
White dwarf	The hot, dense core of a star that has exhausted its fuel.
Neutron star	The collapsed core of a massive star that has exploded as a supernova.
Black hole	The collapsed core of a very massive star that has exploded as a supernova.

There are three or four types of black holes:

Type	Description
Stellar Black Holes	Formed from the gravitational collapse of massive stars.
Primordial BHs	Hypothetical black holes that could have formed in the early universe due to high density fluctuations
Supermassive BHs	Found at the centers of galaxies, with masses ranging from millions to billions of solar masses
Non-Rotating Charged BHs	No angular momentum but electric charge present.

 

Ø     Stellar black hole

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Stellar Black Hole

   The first is the stellar black hole, which is the most common type of black hole. Those black holes that form from stars are estimated by scientists to be our Milky Way Galaxy.     There are at least Ten million to one billion such black holes.

Ø       Primordial black holes

Primordial Black Holes

 They are as small as an atom but their weight is as big as a mountain, so it is also an assumption that their size is as small as an atom. These black holes are only theoretical and hypothetical about them.

Ø       Supermassive Black Holes

Primordial Black Holes

These are supermassive black holes so massive that they have a mass greater than the combined mass of one million suns and they fit into a ball so large that the ball's diameter is ours As big as the solar system is, scientists believe that the center of every major galaxy, there is a supermassive black hole. Sagittarius A is the name of the supermassive black hole in the center of our Milky Way galaxy.

 

A fourth variety of black holes may also exist, according to scientists. The fourth form of a black hole the intermediate black hole will be somewhere between the sizes of stellar and supermassive black holes, however, it is impossible to say for sure.

Observed Mass Ranger of Compact Objects

First Photo of a Black Hole

The first image of a black hole was captured in 2019. Even in this yellowish-orange colour was used to represent the accretion disk. One thing that is clearly noticed in the actual photo, is that particles on one side are brighter than the other side.

First Photo of A black Hole

There’s a simple reason for that the particles spinning towards us seem bright to us, and those that are spinning away from us, seem dimmer. This is due to the Doppler beaming effect. If you look at the hole from the top, it will look like a normal, round disk. Only when we look at the black hole from the sides do we receive this illusion.

What is Photosphere?

Apart from this, when you enter the black hole, you will see the last circle of light it is the photosphere. Because of the region's intense gravity, light begins to orbit the black hole. The photons start orbiting the black hole. The light is going in a circle, forming a ring, thus hypothetically, if you make it to this region of a black hole alive, you might be able to see your own head.

Photosphere in Black Hole

Event Horizon

After this point, is the boundary of the black hole this is known as the Event Horizon It is regarded as a border since, beyond this point, even light cannot escape due to the extreme gravity. Everything is back beyond this point.

Event Horizon

 

Einstein's General Theory of Relativity:

In this theory, the center of the black hole is termed singularity. Singularity is the region of a black hole, the center where the curvature of space-time is infinite. The heavier the object, the more the mesh of space-time will bend. This is bent so far in the case of a black hole that it stretches indefinitely.

There are several intriguing hypotheses, such as the one that claims light is absorbed by black holes, preventing us from seeing within them from the outside.

 

·    One theory says that inside the event horizon, light reflects off of multiple points before reaching the singularity. So it's plausible that something might truly be seen inside the Event Horizon.

10th April, 2019 photo of Black Hole

Conclusion:

·        The thing that have seen for sure about black holes is the single photo. This photo was taken by the Event Horizon telescope, on 10^th April, 2019. This proved the existence of black holes practically.