Big Bang Theory
A theory that suggests that the universe started with a giant explosion. The Big Bang theory is the most accepted theory so far to describe the origin and evolution of the Universe. According to it, all the matter and energy in the Universe was originally contained in a very small 'point' - technically called a 'singularity' - at an almost infinite temperature and density. About 10 to 20 billion years ago this tiny Universe started to expand, and has not stopped expanding since.
This theory was first drafted by Russian physicist George Gamow in the late forties, although only when the cosmic microwave background was discovered in 1964 did the astronomical community start to take it seriously.
As of today, apart from the cosmic microwave background, two other pillars support the Big Bang theory: the current expansion of the Universe and the measured abundance of light elements.
- Recombination Era (300 000 years after the Big Bang)
- The time when matter and radiation first separated.