The Big Bang


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 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.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
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. By now it would
strike Earth as microwave radiation. In 1965 physicists Arno Penzias and Robert
Wilson detected microwave radiation coming equally from all directions in the
sky, day and night, all year.3 And so it appears that astronomers have detected
the fireball radiation that was produced by the Big Bang. This casts serious
doubt on the Steady State model. The Steady State could not explain the
existence of this radiation, so the model cannot best explain the beginning of
the universe.
Since the Big Bang model is the better model, the existence and the future
of the universe can also be explained. Around 15 to 20 billion years ago, time
began. The points that were to become the universe exploded in the primeval
fireball called the Big Bang. The exact nature of this explosion may never be
known. However, recent theoretical breakthroughs, based on the principles of
quantum theory, have suggested that space, and the matter within it, masks an
infinitesimal realm of utter chaos, where events happen randomly, in a state
called quantum weirdness.4
Before the universe began, this chaos was all there was. At some time, a
portion of this randomness happened to form a bubble, with a temperature in
excess of 10 to the power of 34 degrees Kelvin. Being that hot, naturally it
expanded. For an extremely brief and short period, billionths of billionths of
a second, it inflated. At the end of the period of inflation, the universe may
have a diameter of a few centimetres. The temperature had cooled enough for
particles of matter and antimatter to form, and they instantly destroy each
other, producing fire and a thin haze of matter-apparently because slightly more
matter than antimatter was formed.5 The fireball, and the smoke of its burning,
was the universe at an age of trillionth of a second.
The temperature of the expanding fireball dropped rapidly,