what is parallel universe

A parallel universe, also known as an alternate universe, parallel world, parallel dimension, or alternate reality, is a hypothetical self-contained plane of existence, co-existing with ones own. In science fiction, the concept of "hyperspace" often refers to a parallel universe that can be used as a faster-than-light shortcut for interstellar travel. Some scientific theories support the idea of parallel universes beyond our own, such as the multiverse theory, which suggests that there are multiple universes that are all related to ours and branch off from ours. The idea of parallel universes is often argued in the context of other major scientific concepts like the Big Bang, string theory, and quantum mechanics. Some researchers base their ideas of parallel universes on quantum mechanics, where multiple states of existence for tiny particles are all possible at the same time. However, when we actually look, we only ever observe one of the possibilities. Some physicists argue that we dont need the multiverse theory at all, as it doesnt solve any paradoxes and only creates more.