Question

how the big bang theory happend

Answer 1

Big bang theory is a theory that tells how universe ,that space time and matter was formed in the universe this theory was derived mathematically from equation of general relatively by Belgian monk George's lemaitre that give a creation point the universe cheif features
(1) all the point that comprise our universe was confined to a single point of infinite temperature
(2)An explosion occured at that point about 13.5 billion years ago and point began to expand real time started.

Answer 2

The theory states that about 13.7 billion years ago all the matter in the Universe. was concentrated into a single incredibly tiny point. This began to enlarge rapidly in a hot explosion, and it is still expanding today. Evidence for the Big Bang includes: all the galaxies are moving away from us.

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