noun 1. Physics.
any of a hypothetical collection of undetectable universes that are like our known universe but have branched off from our universe due to a quantum-level event. See also multiverse
(in cosmology) a hypothetical universe that coexists with our known universe but may operate under fundamentally different laws of physics. See also multiverse
3. Also called alternative universe.
(in science fiction, fantasy
, etc.) a separate universe or world that coexists with our known universe but is very different from it.
a realm of existence and experience that is fundamentally different from the one that most humans share; a separate reality: I don’t understand him—I think he lives in a parallel universe.