About Black Holes
Physicists knew that there is something in space
whose size is small and mass is very high as compared to its size. Due to which
its density becomes very high and due to all this, its gravitational field
becomes so much that even the light cannot come from it. As humans began to
develop their interest in space, he invented the telescope and saw something
that could be possible only when something like black holes existed. Like the
stars orbiting in our Milky Way Galaxy, as they are circling something which is
tying these stars with the help of its gravitational force. Like our sun has
tied all the planets of our solar system due to its gravitational force. In the
same way, these visible stars from telescope have also been gravitationally
locked by a big body. But if it’s a normal object, it would be visible to us
with the help of telescope. But we did not see that and this can only happen if
that body is a black hole.
In this post I am going to tell you all about black
holes. This post will cover everything about black holes.
Everything about Black Holes
1. What are Black holes ?
There are some places in space where the gravity is
so much that they swallow every object that comes near them. Even the light
cannot return from there. This is why we cannot see them. We call such places
as black holes. They are very dense bodies with very heavy mass in such a small
area that its gravitational field becomes almost infinite. Thus it swallows
everything.
2. How Black Holes are formed ?
As we know that all the stars in space are almost
made up of hydrogen gas and as the amount of hydrogen in these stars decreases,
the brightness of that star decreases and the star gets older. Larger the star,
greater its gravitational force. This force keeps pulling the contents of the
star continuously towards its center. The hydrogen present in the star spreads
due to the intense heat of the star. The pressure generated due to its spread
is resistant to the gravitational force of the star. Therefore, the star never
taps completely inside. But there comes a time when the hydrogen gas present in
the star is exhausted and there is no pressure of the hydrogen gas preventing
the star from sinking inwards. Because of which the star shrinks.
If the star is shaped like our sun, then it shrinks and turns into a body of about 100 km diameter. In order to suppress it in a smaller size, that star does not have enough gravitational force and now that star is called white dwarf or neutron star.
But if the size of the star is much larger than our sun, then its gravitational force is so powerful that the process of sinking inside that star continues and there comes a time when the size of star become so small. The star reached in such a state is called a black hole. If the size of star is more than thousand times greater than our sun then it will form a much bigger black hole.
This was all about one of the most asked question about black holes ‘how black holes are formed’?
If the star is shaped like our sun, then it shrinks and turns into a body of about 100 km diameter. In order to suppress it in a smaller size, that star does not have enough gravitational force and now that star is called white dwarf or neutron star.
But if the size of the star is much larger than our sun, then its gravitational force is so powerful that the process of sinking inside that star continues and there comes a time when the size of star become so small. The star reached in such a state is called a black hole. If the size of star is more than thousand times greater than our sun then it will form a much bigger black hole.
This was all about one of the most asked question about black holes ‘how black holes are formed’?
3. Types of Black Holes
According to the size and mass, the black holes are
divided into three categories. The smallest size black holes are called
Primordial Black Holes. The size of these black holes is equal to the size of
an atom and their mass is equal to the mass of a huge mountain. The most
commonly found black holes are of medium size and are called Stellar Mass Black
Holes. The mass of such black holes is up to 20 times the mass of our Sun and
this mass is compressed to a small sphere with a diameter of only 10 miles.
Some black holes are very large in size and these types of black holes are
called Supermassive Black Hole. The mass of these black holes is equal to the
mass of more than a million stars like our sun and their size is reduced to
only the size of our solar system. It is believed that every Galaxy has a
Supermassive Black Hole at its center.
4. Anything can be a Black hole
Black holes can be formed from everything present
in this universe. As we know that every object in this universe has its own
mass and if that mass is compressed in the sphere of his Schwarzschild Radius,
then that object will become a black hole.
Schwarzschild Radius is the radius from which if we compress the mass of an object in the sphere formed, that object will become a black hole. Each object has a different Schwarzschild Radius. For example, Schwarzschild Radius of our sun is about 3 kilometres. This means that if we compress the Sun and confine it to a sphere whose radius is 3 km, then it will become a black hole. Similarly, to make the Earth a black hole, we have to limit it to a sphere of about 9 millimetres of radius.
Schwarzschild Radius is the radius from which if we compress the mass of an object in the sphere formed, that object will become a black hole. Each object has a different Schwarzschild Radius. For example, Schwarzschild Radius of our sun is about 3 kilometres. This means that if we compress the Sun and confine it to a sphere whose radius is 3 km, then it will become a black hole. Similarly, to make the Earth a black hole, we have to limit it to a sphere of about 9 millimetres of radius.
5. How are the Black Holes Discovered ?
This question about black holes also confuses many
people. If we cannot see the black holes even with telescopes so how are the
black holes discovered?
Just like we cannot see the wind, but seeing the trees shaking due to wind, we understand that the wind is blowing. Similarly, by looking at the inequalities in the motion of the celestial bodies around the black holes, we can infer that there is a black hole nearby.
Telescopes like Hubble have sent us some such views of the universe, in which it is seen that many stars and bodies are moving towards an invisible point. This can only happen due to the gravitational force of the black holes and this is how black holes are predicted to occur.
Just like we cannot see the wind, but seeing the trees shaking due to wind, we understand that the wind is blowing. Similarly, by looking at the inequalities in the motion of the celestial bodies around the black holes, we can infer that there is a black hole nearby.
Telescopes like Hubble have sent us some such views of the universe, in which it is seen that many stars and bodies are moving towards an invisible point. This can only happen due to the gravitational force of the black holes and this is how black holes are predicted to occur.
6. Gravitational Singularity at the center of Black Holes
Gravitational Singularity also called Space Time
Singularity is the point in black holes where the entire mass is concentrated
at a single point. Gravitational singularity lies at the center of black holes.
Due to concentration of very large mass at one point, the gravitational field
in the center of black holes becomes almost infinite. This breaks the Space
Time Relation. In non-rotating black holes, gravitational singularity is like a
single point while in rotating black holes, singularity is like a ring.
 |
| Space Time Curve |
For some time it was believed that black holes are
never destroyed. But a great scientist, Stephen Hawkings said that black holes
also perish over time. Although it takes millions of years to destroy them but
they also have an end.
Some Mathematicians of today believe that there is no any singularity or point of infinity in black holes. They say that it is physically not possible for the singularity to exist in the center of black holes. Lack of singularity in the center of black holes means nothing in the black holes.
Some Mathematicians of today believe that there is no any singularity or point of infinity in black holes. They say that it is physically not possible for the singularity to exist in the center of black holes. Lack of singularity in the center of black holes means nothing in the black holes.
7. Event Horizon in the Black Holes
Gravitational force or gravity is a force between
two bodies that attracts a body with less mass towards the body with higher
mass. Due to the excessive mass inside the black holes, their gravity becomes
almost infinite, so that it pulls every other body into itself. Due to the
gravitational pull of black holes, whenever a body is attracted towards its
center then it passes through a point whose gravitational pull is so high that
even light cannot come back from there and that point or boundary is called Event
Horizon.
For your information, let me tell you that light shows two type of nature. The first is wave nature and second is particle nature. Light is attracted to black holes due to its particle nature. That is, if the light does not go inside the event horizon of black holes, then it can easily come out of the black holes.
If a body crosses the event horizon then it will not be visible to us because after that the light from that body will never come to our eyes. In this way, that body will suddenly disappear.
For your information, let me tell you that light shows two type of nature. The first is wave nature and second is particle nature. Light is attracted to black holes due to its particle nature. That is, if the light does not go inside the event horizon of black holes, then it can easily come out of the black holes.
If a body crosses the event horizon then it will not be visible to us because after that the light from that body will never come to our eyes. In this way, that body will suddenly disappear.
8. Spaghettification in the Black Holes
If a body goes into a black hole, it will have to
go through the event horizon of that black hole and in such a situation it will
become part of a process which we call Spaghettification. Suppose you fell into
a black hole. After entering the black hole, your body will pull from your
feet. This is because the gravity of that black hole will have more effect on
your feet and less on your head. Even though there is not much distance between
your legs and head, but when there is so much gravity, then this attraction
force works like this. Due to the stretch on the side of the feet, your body
will start to compress from both the left and right sides, so that you will
start looking like a noodle. That is why it is also called noodle effect. This
entire process is called spaghettification.
9. Fire Wall in the Black Holes
It was believed that black holes cannot break the
rules of quantum physics. The rule of quantum physics says that information can
never be destroyed. For example, every word uttered by man is present somewhere
in the atmosphere which can never be destroyed. But it was believed that if the
information went inside the black holes, then even though that information
could not come outside the black holes, but it would be present inside the
black holes. Some people said that when the black holes end, the information
inside them starts coming out. But it was difficult for some physicist to
believe, because in real it is impossible to find evidence of its occurrence.
Then a new theory came out which says that whenever information goes through an
event horizon of black holes, then it collides with a large energy wall and
that information gets spoiled. That energy wall is called fire wall.
10. Origin of Gravity
As we know, gravity is a force that acts between
two bodies which have some mass. However, despite working on the largest scale,
out of the four fundamental forces, Gravitational force is the weakest force.
And no one knows the reason behind this. Some scientists say that the
gravitational force is so weak because it is not made in our Three Dimension Space
in which we live. Gravity came from another dimension. It is believed that this
force is leaking in small amounts from any other dimension, due to which it is
such a weak force. But inside black holes, any different dimension can be
experienced. May be from where gravity came. Because space time is not normal
inside black holes.
The great scientist Stephen Hawkings gave a theory. In which he said that we can make a small black hole and find out is there any gravity being created in it?
The great scientist Stephen Hawkings gave a theory. In which he said that we can make a small black hole and find out is there any gravity being created in it?
11. Time slows down near Black Holes
For your information, let me tell you that time is
relative rather than absolute. That is, the speed at which time is going on for
you, it is not necessary that for every object
present in the universe, it should run the same way. To put it in clear words,
time can run at different speeds for different objects present in this
universe.
There are many factors that affect time, one of which is gravity. Gravity affects time and as we know that the gravity of black holes is very high, so time around black holes runs at very slow speed.
Suppose somehow a man went to the edge of a black hole. As compared to you, the time will run slower for that man. Maybe your one hour is equal to one minute of that man or maybe your 10 years is equal to 1 day of that man.
There are many factors that affect time, one of which is gravity. Gravity affects time and as we know that the gravity of black holes is very high, so time around black holes runs at very slow speed.
Suppose somehow a man went to the edge of a black hole. As compared to you, the time will run slower for that man. Maybe your one hour is equal to one minute of that man or maybe your 10 years is equal to 1 day of that man.
12. Black Holes as Gravastar
As we told you that there is either singularity
inside the black holes or there is nothing inside it. But another alternative
theory suggests that black holes are actually Gravastars.
Gravastar is an imaginary structure that lags behind when a star bursts. But instead of making hole in space time, it becomes like a bubble. A famous Physicist said that black hole is a strange bubble. The biggest reason for accepting this theory is that seeing the behavior of black holes, it does not require as much evidence and explanation to prove the black holes to be a bubble as require to prove the singularity.
Gravastar is an imaginary structure that lags behind when a star bursts. But instead of making hole in space time, it becomes like a bubble. A famous Physicist said that black hole is a strange bubble. The biggest reason for accepting this theory is that seeing the behavior of black holes, it does not require as much evidence and explanation to prove the black holes to be a bubble as require to prove the singularity.
13. Black Holes as Wormholes
According to the Physicist, there is a path in the
center of black holes that opens to another part of the universe. We call this
path as the wormhole. The theory of worm holes was first introduced by
physicist Ludwig Flamm in 1916. Giving the solution of equation of Einstein's
theory of relativity, he said that there can be something like a white hole inside
black holes.
After this, Einstein himself worked on it and told that this white hole can be part of a bridge which connects any two parts of the universe inside black holes. This bridge’s concept given by Albert Einstein and Nathan Rosen is called Einstein-Rosen Bridge. With the help of which you can easily go from one part of universe to another. This bridge exists according to the equation of Einstein but no evidence has been found yet for this.
Read also : All about Wormholes explained in detail
Read also : All about Wormholes explained in detail
14.
Real Picture of Black Hole
Earlier we had no strong evidence of black holes
being present. But now we have a real picture of a black hole. This photo of
Black has been taken with the help of International Telescope Collaboration.
04 April 2019, the two largest telescopes of the
earth were doing their work. These two telescopes were observing the radio
waves emanating from the center of our Milky Way Galaxy and Messier 87 (M87) Galaxy.
Together with these two, 6 more Telescopes formed an Event Horizon Telescope (EST)
with the help of International Collaboration who took the first photo of black
hole in the history till date.
In the picture, we see a glowing material around the black hole. Due to friction these materials are warmer than several million tons of degree centigrade, and when anything gets so hot like this, it starts emitting X-rays which can be seen with the help of telescope and this is why this picture of black hole has been possible.
There should be many favorable conditions for taking photograph of any black hole. For example, the wavelength of some light emanating from the outer pheriphery of that black hole should be so high that without absorbing or without being scattered by the gases and dust clouds coming on the way, without reflecting or refracting from the atmosphere of our earth, it can reach to lenses of superstrong telescopes on earth.
The wavelength of the light of the black hole seen in the picture was 1.3 mm, which is very large wavelength and it comes in the category of radio waves. Now such a large wavelength light and 8 observatory telescopes were installed at the place where the weather is always clear and they are much higher than the sea level. Because of this the light of that black hole was able to travel such a distance and our telescopes could record its information. This black hole is about 5 crore 35 lakh (53 million) light years away from our Earth. Its mass is about 6 arab 50 crore (6 billion 500 million) times more than our sun.
The maximum information of this photo could be taken only when the orientation of our earth is such that the eight telescopes can see it together and this happens only once a year. The information of the eight telescopes was collected and filtered. The information of all telescopes was calculated and analyzed by a specialized team. After this, four groups were formed, in which there were highly specialized people. Those four groups worked with these informations for months and brought this photo as best of best to all of us.
In the picture, we see a glowing material around the black hole. Due to friction these materials are warmer than several million tons of degree centigrade, and when anything gets so hot like this, it starts emitting X-rays which can be seen with the help of telescope and this is why this picture of black hole has been possible.
There should be many favorable conditions for taking photograph of any black hole. For example, the wavelength of some light emanating from the outer pheriphery of that black hole should be so high that without absorbing or without being scattered by the gases and dust clouds coming on the way, without reflecting or refracting from the atmosphere of our earth, it can reach to lenses of superstrong telescopes on earth.
The wavelength of the light of the black hole seen in the picture was 1.3 mm, which is very large wavelength and it comes in the category of radio waves. Now such a large wavelength light and 8 observatory telescopes were installed at the place where the weather is always clear and they are much higher than the sea level. Because of this the light of that black hole was able to travel such a distance and our telescopes could record its information. This black hole is about 5 crore 35 lakh (53 million) light years away from our Earth. Its mass is about 6 arab 50 crore (6 billion 500 million) times more than our sun.
The maximum information of this photo could be taken only when the orientation of our earth is such that the eight telescopes can see it together and this happens only once a year. The information of the eight telescopes was collected and filtered. The information of all telescopes was calculated and analyzed by a specialized team. After this, four groups were formed, in which there were highly specialized people. Those four groups worked with these informations for months and brought this photo as best of best to all of us.
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