The multiverse is a set of possible universes, including the universe in which we live. Together, these universes comprise everything that exists: the entirety of spacetime, and the physical laws that define and describe them.
They are also called bubble universes in that they appear, grow, and then pop like bubbles into nothingness over vast cosmic timelines, or pocket universes with cycles that produce habitable conditions repeatedly inside each pocket.
The various universes within the multiverse are called paraverses, "parallel universes", "other universes", or "alternative universes".
According to the Many-Worlds interpretation of quantum mechanics, the total number of possible states of every quantum particle could equal the total number of universes in the multiverse, which is about 10500 which for all intents and purposes is countless finite or transfinite.
Infinite multiverses can only be in the megaverse. Each universe in the multiverse represents one instance, whereas infinite instances are in the megaverse. A time travel paradox that is about to violate causality will naturally break out of its originating bubble universe and follow another causality line, transferring the cause/effect into another instance. Instances are linked to the quantum-gravitational (6d) fabric of reality, where virtual particles can pop in and out of existence, in a quantum foam. It is the quantum nature of this foam that can either disappear in a planck time, or grow into another universe. Travelling between universes can be via subspace, traversable wormholes, or beings with immense power with the science to manipulate the fabric of reality.
Michio Kaku has said the multiverse is an 11-dimensional "bubble bath" but for the purposes of this wiki, the omniverse is in 11d.
See also[]
Part of 6d physics[]
The multiverse is an energy based expression of the universe with time fragmenting along all plausible causality lines, making it no longer fate but choice. Mass including 4d only travels one path so the other eventualities collapse under the weight of time.
Wave particle duality[]
The double-slit experiments showed that under a quantum observation, matter acted like a particle but like a wave when unobserved. This is due to the interaction that brings both the 4d and 6d together. Instead of acting in 6d space like it should, the observer forces the 4d reaction by forcing mass down one path.