Term Paper on Big Bang

This essay has a total of 1137 words and 5 pages.

Big Bang

The Big Bang Theory

It is always a mystery about how the universe began, whether if and when it will end.
Astronomers construct hypotheses called cosmological models that try to find the answer.
There are two types of models: Big Bang and Steady State. However, through many
observational evidences, the Big Bang theory can best explain the creation of the

The Big Bang model postulates that about 15 to 20 billion years ago, the universe
violently exploded into being, in an event called the Big Bang. Before the Big Bang, all
of the matter and radiation of our present universe were packed together in the primeval
fireball-an extremely hot dense state from which the universe rapidly expanded. The Big
Bang was the start of time and space. The matter and radiation of that early stage rapidly
expanded and cooled. Several million years later, it condensed into galaxies. The universe
has continued to expand, and the galaxies have continued moving away from each other ever
since. Today the universe is still expanding, as astronomers have observed.

The Steady State model says that the universe does not evolve or change in time. There was
no beginning in the past, nor will there be change in the future. This model assumes the
perfect cosmological principle. This principle says that the universe is the same
everywhere on the large scale, at all times. It maintains the same average density of
matter forever.

There are observational evidences found that can prove the Big Bang model is more
reasonable than the Steady State model. First, the redshifts of distant galaxies. Redshift
is a Doppler effect which states that if a galaxy is moving away, the spectral line of
that galaxy observed will have a shift to the red end. The faster the galaxy moves, the
more shift it has. If the galaxy is moving closer, the spectral line will show a blue
shift. If the galaxy is not moving, there is no shift at all. However, as astronomers
observed, the more distance a galaxy is located from Earth, the more redshift it shows on
the spectrum. This means the further a galaxy is, the faster it moves. Therefore, the
universe is expanding, and the Big Bang model seems more reasonable than the Steady State

The second observational evidence is the radiation produced by the Big Bang. The Big Bang
model predicts that the universe should still be filled with a small remnant of radiation
left over from the original violent explosion of the primeval fireball in the past. The
primeval fireball would have sent strong shortwave radiation in all directions into space.
In time, that radiation would spread out, cool, and fill the expanding universe uniformly.
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