Nothing is something. It has an infinite probability to be everything.
If the universe grows, and has no boundary, that is, if you came to the boundary and tried to breach it, the universe would expand to accommodate the matter trying to go outside it.
That is the infinite hotel:
Physicists experimentally realize a quantum Hilbert hotel
The no space or “nothingness” is infinite probability. It could be anything, but it is all possible things and due to that it is “nothing”. In other words it has not collapsed into only one probability which is our spacetime universe.