The Big Bang [1] is dense and hot that time experienced by the universe there are about 13.7 billion years, and all cosmological models which describe, without prejudging the existence of an "initial time" or a beginning to his story.
This phase marks the beginning of the expansion of the universe, wrongly compared to an explosion, has been designated for the first time under this expressive term Big Bang by English physicist Fred Hoyle in a BBC radio program, The Nature of Things (literally "The Nature of Things"), whose text was published in 1950. Hoyle himself offered another cosmological model, then in competition with the Big Bang, but now abandoned, the theory of steady state in which the universe has not been hot and dense phase. The term Big Bang is the scientific name and became popularized in the era that had produced the universe as we know it.
The term Big Bang hot (Hot Big Bang) was sometimes used to indicate that early in this model the universe was hotter when it was denser. The adjective "hot" was added for the sake of accuracy for the fact that we can associate a notion of temperature in the universe as a whole was not yet well understood when the model was proposed, in the middle the twentieth century.
The general concept of the Big Bang, that the universe is expanding and has been denser and hotter in the past, should probably be attributed to the Russian Alexander Friedmann and the Belgian Catholic priest Georges Lemaitre, who in 1922 and 1927 respectively described it in broad expansion of the universe, before it is highlighted by Edwin Hubble in 1929. His final seat, however, was established in 1965 with the discovery of cosmic microwave background, the "luminous pale echo of the Big Bang" in the words of Georges Lemaitre, who testified definitively the reality of the times dense and hot the early universe.
2013-10-02, 11:58 من طرف 
