I don’t really have any opinion on this. Its unlikely to be proven true of false any time soon (if ever) so until there is good reason to believe it exists I’ll probably remain a non-believer.
Its a cool idea though…
There are some theories of physics that predict parallel universes, although we don’t know if they are correct theories yet!We certainly haven’t seen any signs of a parallel universe yet.
But the important thing is not whether I believe in parallel universe or not, but whether we can do an experiment to prove whether or not they exist.