Pocket universe
From Tardis Wiki, the free Doctor Who reference
Pocket universes were functionally discrete continua which nevertheless constituted a subset of a larger universe. They were usually artificial in origin, created by powerful beings.
- E-Space, though smaller than our N-Space, was a separate continnum and therefore is not a pocket universe.
- The Matrix was described as a "micro-universe", not a pocket universe, though whether it can be considered one or not is unknown.
Possible Pocket Universes