Among ⊍̻Ɲ͇͍⎪̘͎ⱽ̦̫͇Ȝ̭̮̘̭̥̯̦Ɽ͕̙̤̭̼Ƨ̫̺̞̣̙ͅ⋿̭̠̖͕̘L͈⦿̺̫͚̤̟̻ͅg̖̳̫̘̩̰̳ist there are two main interpretations about what it is the Multiverse.
The first one is the concept that the Multiverse its a physical space with unknow dimensionality containing a immense or infinite set of universes indirectly connected to each other.
The second one is that the consciousness itself its a multiverse, or atleast a gate or/and transmitter to the multiverse. That hypothesis its part of the multiversalist paradigm, and imply that the brain is a computer,analogically speaking, and the consciousness its a internet-like thing, a network that connect us with everything beyond the barriers of what is called reality. All myths, stories, concepts, lies and half truths exist in a alternate universe as a brick from a different objective reality. That multiverse is called mental multiverse and while some ⊍̻Ɲ͇͍⎪̘͎ⱽ̦̫͇Ȝ̭̮̘̭̥̯̦Ɽ͕̙̤̭̼Ƨ̫̺̞̣̙ͅ⋿̭̠̖͕̘L͈⦿̺̫͚̤̟̻ͅg̖̳̫̘̩̰̳ist make categorizations of universes,multiverses and meta-multiverses inside the mental multiverse, the most correct assumption(or not,since it is ⊍̻Ɲ͇͍⎪̘͎ⱽ̦̫͇Ȝ̭̮̘̭̥̯̦Ɽ͕̙̤̭̼Ƨ̫̺̞̣̙ͅ⋿̭̠̖͕̘L͈⦿̺̫͚̤̟̻ͅg̖̳̫̘̩̰̳y̥͍ ) is that each one of these universes are part of a single structure, and the different categorizations exist only to decrease the difficulty of our studies about these worlds, since a complete understanding is impossible to us, with the limited perception we have.
The first interpretation is based in the idea of a infinite set of physical universes with possible vague similarities with our own universe and with varied physical laws and dimensionality.
The second interpretation claim that there is a infinite set of universes made by intangible,ficticious and unknowable things, and ourselves are creators and beings of that infinite set trapped in a three dimensional body in a physical universe.
While in the second interpretation apophenic gnose is welcome and even required, in the first, since it is a physical multiverse, speculations, with luck, can only achieve a close or symbolic knowledge.
All the not physically verified theories about what exist outside our universe are a mental-universe creation, even when that isn't the purpose of the theorist
The mental multiverse have the imagination as its core, so any made up world already exist in that far(and close) plane of reality.