Black Holes
Black Holes
Hello friends, black holes are
such dead stars which had mass at least 1.44 times greater than the sun. We
should know about a star’s lifecycle, if we want to know about black hole. We
have already published a blog on a star’s lifecycle. If you have not read, click here. In this blog we will discuss on advance properties of a black hole.
So let’s start-
Chandrashekhar, an Indian
scientist, had shown that exclusion principle could not halt the collapse of a
star more massive than the Chandrashekhar limit, but the problem of
understanding what would happen to such a star, according to general
relativity, was first solved by Robert Oppenheimer. His result suggested that
there would be no observational consequences that could be detected by the
telescopes of the day. Then the second world war started and Oppenheimer
involved in atom bomb project. The picture that we know from Oppenheimer’s work
is as follows:
The gravitational field of a star
changes the path of light rays in space-time from what they would have been had
the star not been present. The light cones, which indicate the paths followed
in space and time by flashes of light emitted from their tips, are bent
slightly near the surface of the star. This can be seen the bending of light
from distant stars observed during an eclipse of the sun. As the star
contracts, the gravitational force of its surface gets stronger and the light
cones get bent inward more. This makes it more difficult for light from the
star to escape, and the light appears dimmer and redder to an observer at a
distance. When the star has shrunk t a certain critical radius, the
gravitational field at the surface becomes so strong that even the light can’t
escape from its surface. Theory of relativity says that nothing can travel
faster than light. It means nothing can escape from a black hole. The boundary
of a black hole is called event horizon. 
The black holes are the point
of infinite density. They curve space-time too much. There must be a point of singularity inside a black hole
like at the time of big bang. Black holes are good medium of time travelling.
You are not to go inside this, you are to stay in its event horizon. We should
remember whatever we study about black hole is on the basis of theories. None
has seen a black hole yet because light can’t escape from its surface. But in
2015, LIGO detected the gravitational waves, caused by the collapsing of two
black holes about one million years ago. It is an evidence of black holes
existence. But there some scientists are against the black hole’s existence. We
will discuss on such theories in another blog.
If you are interested in
astrophysics or in black holes, always visit here because we want you to learn
the best.
-Thank You
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