This essay The Universe has a total of 1252 words and 9 pages.
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 universe.
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.1 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
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.2 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 model.
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 pri
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