The Creation of the Big Bang Theory
A consequence of the universe expansion discovery was reformation of universe-creation theories. If you go back in time and reverse the expansion, you will find that the galaxies move closer together, and the universe becomes smaller, hotter, and more dense. If you go back in time far enough, you will find that all the galaxies, and in fact, all of the matter in the universe, is compacted into a small, infinitely hot and dense point called a singularity.
Cosmologists tried to formulate new theories on how the universe began. In the 1930's, soon after Edwin Hubble's discovery, cosmologists first established what is now known as the big-bang theory. The theory states that the universe began with a significant explosion at the singularity that caused all the matter in the universe, in the form of hot gas, to expand evenly throughout space. The gas moved away from the center of the universe much like debris from an explosion. As the gas expanded, it cooled, allowing structures like stars and galaxies to form.
The big bang theory made some predictions about the universe, and these were confirmed by observations. The theory predicted that galaxies should be moving apart, and this was confirmed by Edwin Hubble in 1929. The theory also predicted that as a result of the hot gases expanding after the big bang, microwave background radiation of a particular frequency should be present throughout the universe. This was confirmed in 1964 by Bell Laboratory radio astronomers Arno Penzias and Robert Wilson. Finally, the the big bang should have produced an abundance of hydrogen, deuterium, helium, and lithium. The predicted abundances are consistent with what is observed today. Not surprisingly, the theory soon became popularized and was generally accepted as the " standard" universe-creation theory.
The Big Bang Theory Busts
There are some aspects of the universe which the big bang theory is unable to explain.
The big bang theory moved people from away the idea that the universe was static and unchanging. In this sense, science and the prevailing attitudes of the people made a step "in the right direction." The theory made some predictions that more closely corresponded with observations of the universe, than did any of the previous universe-creation theories. However, the big bang theory still left something to be desired; some observations remained to be explained. Because of this, new theories, or modifications of old ones would once again be necessary.
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