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   «¬¬¬¬|   |:  |   |:   |        |¬¬¬¬«     [Big Bang Model               ]
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ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>Chop Here>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ>ÄÄÄÄÄÄÄÄÄ
     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, cooling to
a few billion degrees in few minutes.  Matter continued to condense out of
energy, first protons and neutrons, then electrons, and finally neutrinos.
After about an hour, the temperature had dropped below a billion degrees,
and protons and neutrons combined and formed hydrogen, deuterium, helium.
In a billion years, this cloud of energy, atoms, and neutrinos had cooled
enough for galaxies to form.  The expanding cloud cooled still further
until today, its temperature is a couple of degrees above absolute zero.

     In the future, the universe may end up in two possible situations.
From the initial Big Bang, the universe attained a speed of expansion.  If
that speed is greater than the universe's own escape velocity, then the
universe will not stop its expansion.  Such a universe is said to be open.
If the velocity of expansion is slower than the escape velocity, the
universe will eventually reach the limit of its outward thrust, just like a
ball thrown in the air comes to the top of its arc, slows, stops, and
starts to fall.  The crash of the long fall may be the Big Bang to the
beginning of another universe, as the fireball formed at the end of the
contraction leaps outward in another great expansion.6  Such a universe is
said to be closed, and pulsating.

     If the universe has achieved escape velocity, it will continue to
expand forever.  The stars will redden and die, the universe will be like a
limitless empty haze, expanding infinitely into the darkness.  This space
will become even emptier, as the fundamental particles of matter age, and
decay through time.  As the years stretch on into infinity, nothing will
remain.  A few primitive atoms such as positrons and electrons will be
orbiting each other at distances of hundreds of astronomical units.7  These
particles will spiral slowly toward each other until touching, and they
will vanish in the last flash of light.  After all, the Big Bang model is
only an assumption. No one knows for sure that exactly how the universe
began and how it will end.  However, the Big Bang model is the most logical
and reasonable theory to explain the universe in modern science.

                              ENDNOTES

     1. Dinah L. Mache, Astronomy, New York: John Wiley & Sons,
Inc., 1987. p. 128.

     2. Ibid., p. 130.

     3. Joseph Silk, The Big Bang, New York: W.H. Freeman and    
Company, 1989. p. 60.

     4. Terry Holt, The Universe Next Door, New York: Charles
Scribner's Sons, 1985. p. 326.

     5. Ibid., p. 327.

     6. Charles J. Caes, Cosmology, The Search For The Order Of
The Universe, USA: Tab Books Inc., 1986. p. 72.

     7. John Gribbin, In Search Of The Big Bang, New York: Bantam
Books, 1986.  p. 273.
                          BIBLIOGRAPHY

Boslough, John.  Stephen Hawking's Universe.  New York: Cambridge 
     University Press, 1980.

Caes, J. Charles.  Cosmology, The Search For The Order Of The     
     Universe.  USA: Tab Books Inc., 1986.

Gribbin, John.  In Search Of The Big Bang.  New York: Bantam      
     Books, 1986.

Holt, Terry.  The Universe Next Door.  New York: Charles          
     Scribner's Sons, 1985.

Kaufmann, J. William III.  Astronomy: The Structure Of The        
     Universe.  New York: Macmillan Publishing Co., Inc., 1977.

Mache, L. Dinah.  Astronomy.  New York: John Wiley & Sons, Inc.,  
     1987.

Silk, Joseph.  The Big Bang.  New York: W.H. Freeman and Company, 
     1989.
