If it can expand it must be finite. If it’s finite what’s around it making it finite? Nothingness? How can nothingness contain (surround) somethingness?
Is a puzzlement.
There is an old adage about a campfire.
The bigger the fire the further you can see into the darkness.
That is where we are right now—learning enough to realize we really have no clue what is going on...
“If it can expand it must be finite. If it’s finite what’s around it making it finite? Nothingness? How can nothingness contain (surround) somethingness?”
Empty space is not nothing. It has properties. It is a container that can hold matter and energy, and it is intertwined with the dimension of time.
Einstein’s finite but unbounded model of the universe, as represented by a closed, positively curved spacetime, can be conceptually reconciled with the observed expansion of the universe within the framework of a black hole cosmology. This framework proposes that our observable universe resides within the event horizon of a massive black hole, where the expansion we observe is a consequence of the black hole’s spacetime curvature and the inherent properties of the universe within its event horizon.
Einstein’s model describes a finite universe with a closed, positively curved spatial geometry. This means that if you were to travel in a straight line in any direction, you would eventually return to your starting point, similar to traveling around the surface of a sphere.
Despite being finite, this model does not have a boundary or edge, as the universe is “wrapped around” itself.
Black hole cosmology proposes that our observable universe is confined within the event horizon of a massive black hole. The event horizon is the boundary beyond which nothing, not even light, can escape the black hole’s gravitational pull.
Within the event horizon, the spacetime curvature caused by the black hole’s immense mass would manifest as the expansion we observe. The expansion is not a movement into a pre-existing space but rather a stretching of spacetime itself, akin to the stretching of the surface of a balloon as it is inflated.
This model provides a way to reconcile the observed expansion of the universe with Einstein’s finite but unbounded model. The expansion is not a consequence of the universe expanding into something else, but rather a consequence of the curvature of spacetime within the black hole’s event horizon.