Big Bang

[noun]

A theory proposed by Georges Lemaitre (originally known as the "hypothesis of the primeval atom") describing the origin of the universe. It was based on the idea that if the space between galaxy clusters is continuing to increase, then there had to be a time when these same bodies were closer together. The term "Big Bang" was coined by Fred Hoyle in 1949 to describe an event 13.7 million years ago involving the rapid expansion of matter and energy from a single hot, dense point. This expansion and cooling provided a foundation for the creation of the Universe.