Here we will see three diferent theories the big bang theory the esteday state theory and the pulsating theory
but first of all let’s understand what is the universe the universe can be defined as the totality of everything
that exists that includes all mather
The Big Bang Theory - The big bang
theory was proposed by Le Maitre and
Gammow. This theory says that the
whole matter of the universe was once
concentrated in an extremely dense and
hot fireball at the beginning of the
universe.
And then very big explosion occurred nearly 20
billion years ago. This big explosion was named "the
Big Bang". This big explosion caused the matter to
break into pieces. The highly concentrated matter
was thrown out with high speed in all the directions
that later formed stars and galaxies. These stars and
Galaxies are still moving away from each other. Our
Universe is expanding
Steady State Theory of Universe - The steady state theory was
developed by Bondi, Thomas, Gold German and Fred hoyle.
According to this theory, the number of galaxies in the observable
universe is constant and new galaxies are being created
continuously out of the empty space, which fill up the gaps caused
by those galaxies which have crossed the boundary of the
observable universe. So by this theory it can be concluded that the
overall size of mass of the observable universe is constant
therefore the steady state of the universe is not disturbed at all.
Therefore this theory is named as steady state theory.
Pulsating Theory of Universe - Pulsating theory gives another
explanation for the evolution of the universe. This theory states
that the universe is pulsating, which means that our universe is
supposed to be expanding and contracting alternatively. As now
we know that our universe is expanding at present. This theory
also accepts this fact that at the present time our universe is
expanding but it will not keep on expanding all the time.
According to this theory, at certain time it is possible that this
expansion of the universe will be stopped and then it will start
contracting due to the gravitational pull. With the time this
contraction will come to a point where the explosion of the
universe again take place and again the expansion of the universe
will start. So in this way this alternate expansion and contraction
will be continued in the pulsating universe.