@peter jeffrey cobb,
Hello Peter ! How are you ? Long time no see...
Personally I don't believe "zero" is what most people tend to think it is...
"Zero" for me represents a balance of opposing forces, or opposing anything, not nothingness.
Zero is the result of opposing balance between things that exist !
The structure of space is curved by matter and HAS the PROPERTY of alloying stuff to move
in it. (At least classically thinking)
It could be argued nothing really moves and spacetime with matter in it is just a big 4D block...but then perception, detection, of what is existing works like swapping from a radio station to another. Both stations keep existing but the swapping gives you the illusion one substituted the other.
As I see it, there is no barrier to "existence", there is no outside...
"Zeros" in existence, are like the space and time took between things that replace each other in our perception of what NOW is.