Question

how did big bang happend

Answer 1

It was believed that the universe was a matter of particles, and was size of a golf ball, with intense heat, gravity, and mass. But once the gravity broke down and the it started expanding.

Answer 2

We know the Universe is now expanding due to gravitational force of dark matter.But before the big bang it was opposite, I mean that the world was contracting.And when everything contracted,everything came closer to each other fastly and striked each other with a very greater impact.This lead to The Big Bang.Till then the universe is expanding.
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