Hi

Big Big Bang Theory is a theory which explains how universe came into existence or how it was formed.

It says that ,

our universe started with a small singularity i.e it started with a small single point which then keep on expanding for the next 13.8 billion years to the the universe that we know today .

• Time had no meaning before Big Bang

• There was no Universe before Big Bang

I hope that you find this helpful

Thank you