The Big Bang


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The Big Bang Essay, Research Paper

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, 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.

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