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Sample essay topic, essay writing: Big Bang Theory - 1148 words
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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 manyobservational 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 universeviolently exploded into being, in an event called the Big Bang. Before the Big Bang, all ofthe matter and radiation of our present universe were packed together in the primevalfireball--an extremely hot dense state from which the universe rapidly expanded. The BigBang was the start of time and space.
The matter and radiation of that early stage rapidlyexpanded and cooled. Several million years later, it condensed into galaxies. The universehas continued to expand, and the galaxies have continued moving away from each otherever 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 modelassumes the perfect cosmological principle. This principle says that the universe is thesame everywhere on the large scale, at all times. It maintains the same average density ofmatter forever.There are observational evidences found that can prove the Big Bang model is morereasonable than the Steady State model. First, the redshifts of distant galaxies. Redshift isa Doppler effect which states that if a galaxy is moving away, the spectral line of thatgalaxy observed will have a shift to the red end. The faster the galaxy moves, the moreshift it has.
If the galaxy is moving closer, the spectral line will show a blue shift. If thegalaxy is not moving, there is no shift at all. However, as astronomers observed, the moredistance a galaxy is located from Earth, the more redshift it shows on the spectrum. Thismeans 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 BigBang model predicts that the universe should still be filled with a small remnant ofradiation left over from the original violent explosion of the primeval fireballin the past. The primeval fireball would have sent strong shortwave radiation in alldirections into space. In time, that radiation would spread out, cool, and fill the expandinguniverse uniformly. By now it would strike Earth as microwave radiation. In 1965physicists Arno Penzias and Robert Wilson detected microwave radiation coming equallyfrom all directions in the sky, day and night, all year. And so it appears thatastronomers have detected the fireball radiation that was produced by the Big Bang.
Thiscasts serious doubt on the Steady State model. The Steady State could not explain theexistence 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 theuniverse can also be explained. Around 15 to 20 billion years ago, time began. The pointsthat were to become the universe exploded in the primeval fireball called theBig 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 utterchaos, where events happen randomly, in a state called quantum weirdness.Before the universe began, this chaos was all there was. At some time, a portion ofthis randomness happened to form a bubble, with a temperature in excess of 10 to thepower of 34 degrees Kelvin. Being that hot, naturally it expanded. For an extremely briefand short period, billionths of billionths of a second, it inflated. At the end of the period ofinflation, the universe may have a diameter of a few centimetres.
The temperature hadcooled enough for particles of matter and antimatter to form, and they instantly destroyeach other, producing fire and a thin haze of matter-apparently because slightly morematter than antimatter was formed. The fireball, and the smoke of its burning, was theuniverse at an age of trillionth of a second.The temperature of the expanding fireball dropped rapidly, cooling to a few billiondegrees in few minutes. Matter continued to condense out of energy, first protons andneutrons, then electrons, and finally neutrinos. After about an hour, the temperature haddropped below a billion degrees, and protons and neutrons combined and formedhydrogen, deuterium, helium. In a billion years, this cloud of energy, atoms, and neutrinoshad cooled enough for galaxies to form. The expanding cloud cooled still further untiltoday, 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 BigBang, the universe attained a speed of expansion.
If that speed is greater than theuniverse's own escape velocity, then the universe will not stop its expansion. Such auniverse 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 inthe air comes to the top of its arc, slows, stops, and starts to fall. The crash of the longfall may be the Big Bang to the beginning of another universe, as the fireball formed at theend of the contraction leaps outward in another great expansion. Such a universe is saidto be closed, and pulsating.If the universe has achieved escape velocity, it will continue to expand forever. Thestars will redden and die, the universe will be like a limitless empty haze, expandinginfinitely into the darkness.
This space will become even emptier, as the fundamentalparticles 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 beorbiting each other at distances of hundreds of astronomical units. These particles willspiral slowly toward each other until touching, and they will vanish in the last flash oflight. After all, the Big Bang model is only an assumption.
No one knows for sure thatexactly how the universe began and how it will end. However, the Big Bang model is themost logical and reasonable theory to explain the universe in modern science.BIBLIOGRAPHYBoslough, 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.
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