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. 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

But Gran didn’t tolerate ideas like evolution or the big bang theory, despite the evidence.

From Literature

Tyler referenced those assaults during Saturday’s show, recalling them as “the big bang theory” before Perry shushed him.

From Seattle Times

We now possess an excellent description of how it all started: the big bang theory has successfully explained the features of our universe.

From Scientific American

For a time, big bang theory and steady-state theory lived side by side, alternatives that astronomers chose between depending on their philosophy.

From Literature

He says the big bang theory is a “paradigm-smashing concept to end all paradigm-smashing concepts” because it demonstrates that the universe had a beginning.

From Washington Times