The most persistent question to be asked is as to the creation of the universe in which we live. Once it was thought by many that there was no end to the universe or beginning and it was indeed endless. But the universe is considered infinite with the beginning of the Theory of Big Bang. The property of a finite phenomenon was forced on universe, holding a beginning and a history.
The expansion of the universe was started by a tremendous explosion around 15 billion years in the past. The blast is termed as the Big Bang. Entire energy and matter of galaxy at the point of this event was limited at only one specific point. Before the occurrence of this event what existed is regarded as true assumption and is completely unknown. This occurrence was an occasion filling entire space with all of the atoms of the embryonic universe hastening away from one another and was not a conventional blast. Unlike an explosion of a bomb in which the wreckages are outwardly thrown, the Big Bang actually consisted of a blast of space in itself. The basic for the universe is laid by the Big Bang and not the fact that a cluster was formed of all the galaxies.