Explanation of the Big Bang Theory - Succeed in Physical Science. Also refer to physics, astronomy, astronomer, universe, galaxy, nebula, explosion, matter, space, time, red-shift, Doppler effect, Ron Kurtus, School for Champions. Copyright © Restrictions
Big Bang Theory
by Ron Kurtus (12 November 2006)
The Big Bang theory is the major explanation of how the universe began. Observations show that the universe is expanding, and the galaxies seem to be moving out from a specific point. By interpolating backward, it is estimated that all of the galaxies in the universe started with an explosion some 13.7 billion light years ago. An opposing theory states that the Universe is oscillating. Also, there are other questions concerning the beginning of the universe.
Questions you may have include:
- How can astronomers tell the galaxies are moving away?
- How does the explosion explain things?
- What are some other ideas?
This lesson will answer those questions. There is a mini-quiz near the end of the lesson.
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Galaxies moving away
The whole idea of the Big Bang theory came when astronomers noticed that distant nebulas and galaxies were all moving away from us. It was also seen that they were moving away at speeds proportional to their distance from us. Since it is assumed that our galaxy is also moving in some direction, it was calculated that all of the galaxies in the universe were moving away from some given point in space.
Estimating speed
The way astronomers were able to estimate the speed of the galaxies is by what is called the "red-shift" of their light. The red-shift is a form of Doppler effect with light, such that when an object is moving away from you at high speeds, the light shifts towards lower frequencies.
Calculating point
Knowing the velocities of the galaxies and their distances from this given point in space, the astronomers were able to calculate backwards to the time when all these galaxies were at a single point. Thus it was assumed that some sort of explosion blew all of the material apart.
Explains formation of stars
The turbulence of this explosion of pure matter would later result in the spinning galaxies as the matter collected together into stars and other objects. In fact, scientists have even made a scenario of what happened within fractions of a second after the explosion. This was extended to explain how various elements were formed and then the stars, planets and galaxies in the millions and billions of years afterwards.
The theory also predicts the existence of a cosmic background radiation, which is radiation or light left over from the explosion. This radiation was discovered in 1964.
Opposing theories
Although it is accepted that the universe is expanding at an accelerated rate, it is not completely accepted that it started from a large explosion. One theory is that the universe is oscillating, such that it will expand for awhile and then contract and then start expanding again.
Some questions
A problem with the Big Bang theory concerns whether the universe will continue to expand forever. Will the galaxies spread further and further apart until infinity?
Another problem is that the belief that all motion is relative. If there was a big bang, that means there is a distinct reference point for all motion. One interesting thought is that if all matter was compressed to a single point, were space and time also compressed?
Finally, there is the question concerning what existed before this Big Bang? These theories—including that of the Big Bang—can never be proven for sure.
Summary
The Big Bang theory explains how the universe began. The universe is expanding, moving out from a specific point. By interpolating backward, it is estimated that all of the galaxies in the universe started at one point. The theory states a great explosion was the start of the universe. There are opposing theories and questions concerning the beginning of the universe.
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Resources
The following resources provide information on this subject:
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Books
Top-rated books on the Big Bang
Mini-quiz to check your understanding
1. How can astronomers tell the galaxies are moving away from us?
2. How were stars formed after the Big Bang?
3. Can the Big Bang theory ever be proven?
If you got all three correct, you are on your way to becoming a Champion in Physical Science. If you had problems, you had better look over the material again.
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Big Bang Theory