Editing Reality (section)

=== Multiverse ===
The [[multiverse]] is the [[hypothetical]] set of multiple possible [[universe]]s (including the historical universe we consistently experience) that together comprise everything that exists: the entirety of [[space]], time, [[matter]], and energy as well as the [[physical law]]s and [[physical constant|constants]] that describe them. The term was coined in 1895 by the American philosopher and psychologist [[William James]].<ref>James, William, ''The Will to Believe'', 1895; and earlier in 1895, as cited in [[OED]]'s new 2003 entry for "multiverse": "1895 W. JAMES in Internat. Jrnl. Ethics 6 10 Visible nature is all plasticity and indifference, a multiverse, as one might call it, and not a universe."</ref> In the [[many-worlds interpretation]] (MWI), one of the mainstream [[interpretations of quantum mechanics]], there are an infinite number of universes and every possible quantum outcome occurs in at least one universe, albeit there is [[Many-worlds interpretation#Debate whether the other worlds are real|a debate as to how real the (other) worlds are]].

The structure of the multiverse, the nature of each universe within it and the relationship between the various constituent universes, depend on the specific multiverse hypothesis considered. Multiverses have been hypothesized in [[cosmology]], physics, [[astronomy]], religion, philosophy, [[transpersonal psychology]] and fiction, particularly in science fiction and fantasy. In these contexts, parallel universes are also called "alternative universes", "quantum universes", "interpenetrating dimensions", "parallel dimensions", "parallel worlds", "alternative realities", "alternative timelines", and "dimensional planes", among others.

{{Excerpt|Multiverse#Cyclic theories|hat=no}}