Question

What is Universe? what is Big Bang theory?​

Answer 1

Answer:

there are millions of such galaxies that make the universe

Answer 2

All the matter and the space in the cosmos is called as Universe.

* Universe is made up of Matter, dark matter and dark energy.

Big Bang is the theory which explains how these existing universe got created and then how it expand.

These all happened 13 billion years ago.

hope it helps...