Bfl
If you travel at the speed of light for a few days, and then return,
and find the friends you left behind have aged 50 years, how much
“real” time has passed?
It depends on the point of view — a few days or a few decades.
Einstein showed that time is not a constant. And that gravity affects time.
The “big bang” theory would suggest that time was massively distorted at the moment of the creation — so that matter proceeded across billions of light years but in a trillioneth of a trillioneth of a second.
So how much time passed — billions of years, or a tiny fraction of a second?
And how much time for the atoms to form into elements, and the elements into planets, etc? Hours? or billions of years? It depends...