big bang theory

noun

, Astronomy.

1. a theory that deduces a cataclysmic birth of the universe big bang from the observed expansion of the universe, cosmic background radiation, abundance of the elements, and the laws of physics.

big-bang theory

noun

1. See steady-state theory
   a cosmological theory postulating that approximately 12 billion years ago all the matter of the universe, packed into a small superdense mass, was hurled in all directions by a cataclysmic explosion. As the fragments slowed down, the galaxies and stars evolved but the universe is still expanding Compare steady-state theory

Big Bang theory

1. In astronomy , a theory according to which the universe began billions of years ago in a single event, similar to an explosion. There is evidence for the Big Bang theory in the observed red shift of distant galaxies , which indicates that they are moving away from the Earth , in the existence of cosmic microwave background , and from other data. The Big Bang theory of the origin of the universe is accepted by most astronomers today.

Notes

Scientists have recently found that the expansion of the universe is actually speeding up. This effect is attributed to the presence of dark energy .

Word History and Origins

Origin of big bang theory¹

First recorded in 1950–55

Example Sentences

In 1996, John Paul II called the Big Bang theory “more than a hypothesis.”

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Eight seasons in, The Big Bang Theory is one of the funniest shows on TV.

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Calvin astronomer Howard Van Till was for years the leading evangelical champion of the Big Bang Theory.

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