From the time of the Big Bang that took place 1377 crore years ago, the Universe is expanding incessantly and galaxies in the Universe are flying away from each other.
As per the Big Bang theory the matter
in the Universe was concentrated in a small area before the Big Bang happened. The
diameter of the Universe at the time of Big Bang was indeterminate, but the
heat and pressure in that primordial ball were immense beyond imagination.
Theoretical models suggest that the entire
matter in the Universe coalesced into a singularity. However later estimations
indicate a size as big as a few meters. What
is the state of matter at this primitive stage, we cannot even fathom. But
whatever the temperature and the pressure of the primordial ball, it is
inevitable that it had to explode given the conditions, and so it did 1377
crore years ago. In 1 year the Universe has expanded to 100,000 light years in
diameter.
But how did that happen? Einstein postulated
that nothing can travel faster than light which means that the Universe can at
best expand to only 1 light year in diameter in 1year. But it expanded 100,000
times more which is phenomenally faster than light.
Scientists say that is because space itself
stretches and the fabric of space expands faster while the objects in it do not
travel at more than the speed of light. They say that there is no limit to the
expansion of the speed of the Universe.
But that looks to be a paradox to me, and in their enthusiasm, it looks to me that the theorists seem to have gone overboard.
They claim that there is no speed limit for the expansion of space
unlike in the case of objects but obviously if the space expands so fast, then
is it not inevitable that the objects in it should also do so? How can they say that space would expand far faster
than light, while the objects within it would not? What the basis do they to
rest their theory on? How can anyone postulate such a thing when they cannot
even judge the conditions of that time and not knowing the properties of space?
The primordial ball contained not just the
matter known to us, but it also contained dark matter and dark energy to the
tune of 95% which today none of our instruments are capable of measuring. The
mass of the Universe is estimated by scientists to be 1.5* 1050
tons. The Dark energy which consists of 68% mass-energy of the Universe speeds
up its expansion continuously so that it accelerates.
We know that the Universe is constantly
expanding, and today the known Universe should have a diameter of 1377 crore
light years. However, the Hubble and James Webb space telescopes have revealed
that the expansion of the Universe is in fact accelerating and this
acceleration is on account of the Dark energy present in the Universe.
Considering this acceleration, the diameter of the Universe has now grown to
9300 crore light years. One should keep in mind that this diameter is the
diameter of the observable Universe.
That is which our instruments can allow us to
postulate on and we have no means of knowing what is beyond it. For all we know there may be other such
similar Universes outside it, and logically that have to be so. There is no reason to assume that there is only Universe just because we know of only one.
The Big Bang did not happen at a single place
in the universe. It happened everywhere at once. So each Galaxy is moving away
from another. As galaxies drift apart, new star formation would stop and older
stars would die and the Universe would become cold, dark and empty.
But most of the theory of the Universe ending
is a mere assumption. It may or may not have an end, and we can only speculate
on that. Theoretically all the Hydrogen and Helium should have been exhausted by
now given the rate of fusion in stars and the 1377 crore years age of the
Universe, yet even today 73-75% of the mass of the Universe is Hydrogen. Then Helium makes up 24-25% of the mass of
the Universe.
It is postulated that all the Hydrogen in the
Universe has formed after the big bang. That being the case, despite zillions
of stars burning Hydrogen up for 13.7 billion years would not bring down its
content?
There is no explanation as to why this is so?
New stars continue to form while the older stars die, so given the current
conditions in the Universe, it is very difficult to accept that it would finally
become cold, dark & empty. But Astronomy in some areas is like a dark
street wherein one has to venture with dark glasses. Our knowledge and
technology is too meagre to speculate about the ending of the Universe.
