The structure of the multiverse can be understood by analysing the ways in which information can flow in it. We may distinguish between quantum and classical information processing. In any region where the latter occurs — which includes not only classical computation but also all measurements and decoherent processes — the multiverse contains an ensemble of causally autonomous systems, each of which resembles a classical physical system. However, even in those regions, the multiverse has additional structure.
The structure of the multiverse can be understood by analysing the ways in which information can flow in it. We may distinguish between quantum and classical information processing. In any region where the latter occurs — which includes not only classical computation but also all measurements and decoherent processes — the multiverse contains an ensemble of causally autonomous systems, each of which resembles a classical physical system. However, even in those regions, the multiverse has additional structure.
The mathematical representation of the universe consists of sequences of symbols, rules and operators containing Gödel's undecidable propositions: information and its manipulation, also with Turing Machines. Classical information theory and mathematics, ideally independent from the medium used, can be interpreted realistically and objectively from their correspondence with quantum information, which is physical. Each representation of the universe and its evolution are, in any case, physical subsets of the universe, structured sets of observers and their complements in the universe made with spacetime events generated by local quantum measurements. Their description becomes a semantically closed structure without a global object-environment loss of decoherence as a von Neumann's universal constructor with a semantical abstract whose structure cannot be decided deterministically a priori from an internal observer. In a semantically closed structure, the realization of a specific event that writes the semantical abstract of the constructor is a problem of finding "which way" for the evolution of the universe as a choice of the constructor's state in a metastructure, like the many-world Everett scenario, from a specific result of any quantum measurement, corresponding to a Gödel undecidable proposition for an internal observer.
We argue that the many worlds of quantum mechanics and the many worlds of the multiverse are the same thing, and that the multiverse is necessary to give exact operational meaning to probabilistic predictions from quantum mechanics. Decoherence---the modern version of wave-function collapse---is subjective in that it depends on the choice of a set of unmonitored degrees of freedom, the environment. In fact decoherence is absent in the complete description of any region larger than the future light cone of a measurement event. However, if one restricts to the causal diamond---the largest region that can be causally probed---then the boundary of the diamond acts as a one-way membrane and thus provides a preferred choice of environment. We argue that the global multiverse is a representation of the many worlds (all possible decoherent causal diamond histories) in a single geometry. We propose that it must be possible in principle to verify quantum-mechanical predictions exactly. This requires not only the existence of exact observables but two additional postulates: a single observer within the Universe can access infinitely many identical experiments; and the outcome of each experiment must be completely definite. In causal diamonds with a finite surface area, holographic entropy bounds imply that no exact observables exist, and both postulates fail: experiments cannot be repeated infinitely many times; and decoherence is not completely irreversible, so outcomes are not definite. We argue that our postulates can be satisfied in hats (supersymmetric multiverse regions with vanishing cosmological constant). We propose a complementarity principle that relates the approximate observables associated with finite causal diamonds to exact observables in the hat.
The modern version of the wave-function collapse in quantum mechanics is based on decoherence and leads to the multiverse interpretation of quantum mechanics. The decoherence causes the universe to develop an emergent branching structure. One can interpret the branching structure either as a tree structure or as parallel different histories. Time is not continuous since there are no measurable continuous in quantum physics. Notion of continuous range of possible values of time is just an idealization. The same goes with the direction of time that is a prior assumption based on the branching structure of the multiverse. The multiverse does not exist in external space nor time since there is nothing more beside it. The observer's mind should be not in a superposition with himself. Because of this, in the Many-minds interpretations it is argued that the distinction between worlds should be made at the level of the individual observer. The human bodies are in a superposition, but the minds have definite states that are never in superposition. All possible lives, personalities that do not violate the laws of physics are facts since they represent a valid history in the multiverse. We are one of this possible personalities. Our choices are defined by our personality explained to us by our mind, our consciousness is the unchangeable part of us. It is nonphysical and it senses the world. It does not interact with the brain in the other way beside it.
A quantum theory of the universe consists of a theory of its quantum dynamics and a theory of its quantum state The theory predicts quantum multiverses in the form of decoherent sets of alternative histories describing the evolution of the universe's spacetime geometry and matter content. These consequences follow: (a) The universe generally exhibits different quantum multiverses at different levels and kinds of coarse graining. (b) Quantum multiverses are not a choice or an assumption but are consequences of the theory or not. (c) Quantum multiverses are generic for simple theories (d) Anthropic selection is automatic because observers are physical systems within the universe not somehow outside it. (e) Quantum multiverses can provide different mechanisms for the variation constants in effective theories (like the cosmological constant) enabling anthropic selection. (f) Different levels of coarse grained multiverses provide different routes to calculation as a consequence of decoherence. We support these conclusions by analyzing the quantum multiverses of a variety of quantum cosmological models aimed at the prediction of observable properties of our universe. In particular we show how the example of a multiverse consisting of a vast classical spacetime containing many pocket universes arises automatically as part of a quantum multiverse describing an eternally inflating false vacuum that decays by the quantum nucleation of true vacuum bubbles. In a FAQ we argue that the quantum multiverses of the universe are scientific, real, testable, falsifiable, and similar to those in other areas of science even if they are not directly observable on arbitrarily large scales.
Abstract Ever since its foundations were laid nearly a century ago, quantum theory has provoked questions about the very nature of reality. We address these questions by considering the universe—and the multiverse—fundamentally as complex patterns, or mathematical structures. Basic mathematical structures can be expressed more simply in terms of emergent parameters. Even simple mathematical structures can interact within their own structural environment, in a rudimentary form of self-awareness, which suggests a definition of reality in a mathematical structure as simply the complete structure. The absolute randomness of quantum outcomes is most satisfactorily explained by a multiverse of discrete, parallel universes. Some of these have to be identical to each other, but that introduces a dilemma, because each mathematical structure must be unique. The resolution is that the parallel universes must be embedded within a mathematical structure—the multiverse—which allows universes to be identical within themselves, but nevertheless distinct, as determined by their position in the structure. The multiverse needs more emergent parameters than our universe and so it can be considered to be a superstructure. Correspondingly, its reality can be called a super-reality. While every universe in the multiverse is part of the super-reality, the complete super-reality is forever beyond the horizon of any of its component universes.
Quantum Informational Geometrodynamics (QI-G) treats spacetime, matter, and interactions as emergent structures of a discrete causal network carrying quantum information. This paper investigates whether a multiplicity of effectively autonomous realities can arise within QI-G without postulating a fundamental multiverse. We formulate a kinematic space permitting superpositions of causal-network configurations, introduce coarse-grained causal histories and their decoherence functional, and define an informational causal branch through three jointly necessary conditions: suppressed interference, stable causal records, and approximate dynamical autonomy. Each branch may admit its own coarse-grained Lorentzian geometry and intrinsic causal time, so that no external simultaneity relation between branches is required. An exact sector-decomposition result is established for block-diagonal dynamics. A redundant-record model further yields the suppression law η_N = ∏_{j=1}^{N}|r_j| and the threshold ∑_j[-ln|r_j|] ≥ ln(ε^{-1}) for effective branching at tolerance ε. We also propose, as a testable but presently unproved QI-G-specific ansatz, that the decoherence rate is controlled by an informational separation functional combining quantum Jensen–Shannon divergence, causal-structure mismatch, and emergent-curvature mismatch. The resulting framework supports emergent effective multiversality but does not establish a literal or empirically distinct multiverse. Such a conclusion would require a derivation of branch-selection scales, probabilities, and residual recoherence directly from the QI-G action.