The Big Bang theory is today's dominant scientific theory about the origin of the universe. It states that the universe was created from an infinitely hot and dense subatomic ball, which once exploded not only created energy and matter, but space and time itself. This is estimated to have happened around 14 billion years ago. 300,000 years after the big bang took place the plasma of elementary particles had cooled to 3000K, during which atoms began to …showed first 75 words of 478 total…

…showed last 75 words of 478 total…stretched slightly due to the expansion of the universe. In recent years the Big Bang theory has faced some critism as problems have arisen which question the validity of the theory. Examples of these are the fact that the theory contradicts the law of conservation of angular momentum (in the form of retrograde motion of planets, moons etc), and the fact that it has been discovered that matter is not spread evenly throughout the universe.