Answer:
According to big bang model, the universe was born during a period of inflation that began about 13.8 billions years ago. Like a rapidly expanding balloon, it swelled from a size smaller than an electron to nearly its current size.
Initially the universe was permeated only by energy, some of the energy congealed into particles, which assembled into light atoms like hydrogen and helium.
At first the atoms turned into galaxies, then stars and then other elements were forged.
Explanation:
These are what happened when the universe was forming.
Hope it helps.
