Glossary of Astronomical Terms/big bang model

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Big Bang is the popular name for a hypothetical model of the universe in which all matter and energy were once concentrated into an unimaginably dense point from which it has since expanded. The dating of the initial expansion has been estimated as being between 13 and 20 billion years ago. The main evidence supporting this model is the redshift of galaxies as they speed away from us, and the microwave background radiation which the model accurately predicted to exist as an artifact of the original explosive event.