So think of it like this…
Each galaxy has a theoretical super massive blackhole who’s job it is to suck in as much matter and energy as possible. Over time, it sucks in it’s surrounding galaxy and inevitably becomes ingested by a nearby black hole that is much more massive than itself until there are 2 black holes left in the universe. We are talking scales of time that dwarf multiple billions of years.
This final ingestion comes and the largest black hole in the universe is ate and causes instability within the blackhole system that just engulfed it; causing an inversion system where the black hole instantaneously inter-converts to a white hole and blasts out every last quark of matter in the blink of an eye. The universe is born, or should I say, the newest universe is born.
This is a theory to explain how one single quantum point in space time can infinitely contain all the material in the universe at one point and slingshot it out just as fast as it entered.
The next question is, how did the first universe occur?
andyburrells 