The Big Bang is the theory that the universe was suddently born. The Big Bang wasn’t a explosion, it was a expansion of the universe! The universe started very, very small and grew very big: In just one second it became 100B km long and it continued its expansion. In this time, particles formed which create protons and formed the first atom: hydrogen. When these atoms collapsed each other because of the gravitational force stars and galaxies start to form. Finally there was light!
We don’t know what was before the Big Bang. All we know now is that than was no time and the natural laws did ‘t make any sense.
The multiverse theory says that there are many universes, but we don’t know sure!
That’s all for today! See you next time!