Multiverse

The multiverse, also known as creation is a group of multiple universes. Together, these universes comprise everything that exists: the entirety of space, time, matter, energy, and the physical laws and constants that describe them. The different universes within the multiverse are called "parallel universes", "other universes", or "alternate universes".

History of the concept
In Dublin in 1952, Erwin Schrödinger gave a lecture in which he jocularly warned his audience that what he was about to say might "seem lunatic". He said that when his equations seemed to describe several different histories, these were "not alternatives, but all really happen simultaneously". The American philosopher and psychologist William James used the term "multiverse" in 1895, but in a different context. The term was first used in fiction and in its current Physics context by Michael Moorcock in his 1963 SF Adventures novella The Sundered Worlds.

Brief explanation
Multiple universes have been hypothesized in cosmology, physics, astronomy, religion, philosophy, transpersonal psychology, and literature, particularly in science fiction and fantasy. In these contexts, parallel universes are also called "alternate universes", "quantum universes", "interpenetrating dimensions", "parallel universes", "parallel dimensions", "parallel worlds", "parallel realities", "quantum realities", "alternate realities", "alternate timelines", "alternate dimensions" and "dimensional planes". The physics community has debated the various multiverse theories over time. Prominent physicists are divided about whether any other universes exist outside of our own.