The Big Bang (Comparisive Of Two Major Theories) Essay, Research Paper

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. 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. 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. 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 know. However, recent

theoretical breakthroughs, based on the principles of quantum theory, have suggested that

space, and the matter within it, masks an infinitesimal realm or utter chaos, 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 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 exploded. For an extremely brief and

short period, billionths and billionths of a second, it inflated. At the end of this 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 destroyed

each other, producing fire and a thin haze of matter apparently because slightly more

matter than antimatter was formed. The fireball, and the smoke of its buring, was the

universe at an age of a trillionth a second.

The temperature of the expanding fireball dropped rapidly, cooling to a few billion

degrees in a 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, and 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. 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. 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. Man will never know the exact truth

about the roots of our universe, however, the Big Bang model is the most logical and

reasonable theory to explain the universe in modern science.