Big Bang

Prevailing theory and model for how the universe came in to being. It is thought that in the beginning all the matter in the universe was condensed in to a single miniscule point in time and space. At a specific time in history ( some 13 - 20 billion years ago ) the density of matter became greater than that of the surrounding radiation resulting in the beginning of the universe's expansion. The galaxies would have started to form some 2 billion years later.

The science behind the Big Bang is extensive and complex however scientists generally agree that it is the best supported model for the expansion of the universe and the observations made with modern day telescopes and observatories of objects at the furthest edges of observable space.