Question

what is big bang theory with explanation​

Answer 1

$\tt{\Blue{\huge{\fbox{Big Bang Theory}}}}$

The big bang theory is a leading explanation how the Universe begins. at its simplest it says the universe we know it starting with simple singularity then inflated over the next13.8 billion years to the cosmos we know today.

$\huge{Hope It Helps}$

Answer 2

The Big Bang is a scientific theory about how the universe started, and then made the stars and galaxies we see today. ... The universe began as a very hot, small, and dense superforce (the mix of the four fundamental forces), with no stars, atoms, form, or structure (called a "singularity").