School #10

Multiverse Theory

Everett, Tegmark

Multiverse Theory holds that our universe is one among many — possibly infinitely many — parallel realities, each potentially governed by different physical laws and constants. Hugh Everett III's doctoral thesis 'Relative State Formulation of Quantum Mechanics' (1957) launched the many-worlds interpretation: every quantum measurement causes the universe to branch, with each possible outcome realized in a separate, equally real branch of reality, eliminating the need for wave function collapse. Max Tegmark's 'Our Mathematical Universe' (2014) extends this into a four-level multiverse taxonomy, culminating in the radical claim that every self-consistent mathematical structure is a physically existing universe — making mathematics not a description of reality but identical with it. Together, these proposals transform the question "why these laws?" into "why not all possible laws?" — reframing fine-tuning as a selection effect within an incomprehensibly vast landscape of realized possibilities.

Worldview

The multiverse adherent lives in a reality of incomprehensible vastness, in which every possibility is not merely conceivable but actual. Every quantum event splits the universe into divergent branches, each as real as the one the observer happens to inhabit. This produces a distinctive mixture of cosmic wonder and existential vertigo: the life one is living is only one thread in an infinite tapestry of alternative histories, alternate selves, and parallel worlds governed by different physical constants. The question "why this universe?" dissolves into the answer "all universes" — fine-tuning is a selection effect, not a mystery. The multiverse adherent trades the comfort of a unique, meaningful cosmos for the awe of limitless plenitude. The framework classifies this as None: the multiverse runs on physical law alone; no personal deity or cosmic ordering principle is required beyond the branching dynamics. The framework reads this as None for moral authority: the multiverse picture is a descriptive physical hypothesis and recognizes no source — Scripture, Tradition, Reason, or Experience — as normatively final over how to act across or within branches.

Moral Implications

The multiverse poses a distinctive challenge to moral reasoning: if every possible outcome is realized somewhere, does any particular choice matter? The multiverse ethicist typically argues that moral significance is indexed to one's own branch — the suffering one causes here is real suffering, regardless of what happens in other branches. However, the framework does erode certain kinds of moral luck: in some branch, every accident was averted and every crime was committed, which complicates the assignment of blame and credit. The multiverse can also motivate a form of cosmic humility, since one's apparently unique moral situation is replicated, with variations, across infinitely many worlds.

Practical Implications

The multiverse framework has practical consequences for risk assessment, quantum computing, and the philosophy of science. If many-worlds is correct, then quantum computers exploit the computational resources of parallel branches, and the development of quantum technology becomes a way of harnessing the multiverse. In policy and planning, the multiverse perspective encourages scenario thinking — taking seriously the full range of possible outcomes rather than betting on a single predicted future. Environmentally, the multiverse does not diminish the importance of stewardship in one's own branch; ecological catastrophe here is real regardless of whether other branches fare better.

I. Time

Time is substantival and infinite — it extends across an infinite ensemble of parallel universes. Time's traversability is branching: at every quantum event, the timeline splits into divergent branches, each equally real. Direction is multi-directional across the multiverse as a whole, even if each individual branch experiences uni-directional flow. Time is continuous and N-dimensional when the full landscape of branching timelines is considered.

Attributes
Extent: Infinite Ontological Status: Substantival Grain: Continuous Freedom: Non-Deterministic Traversability: Branching Dimensionality: N Direction: Multi-directional

II. Space

Space is substantival, infinite, and curved — it encompasses the totality of parallel universes, each potentially with different spatial geometries and physical constants. Space is non-local: quantum entanglement connects spatially separated regions, and the multiverse itself may have extra spatial dimensions beyond the three we observe.

Attributes
Extent: Infinite Ontological Status: Substantival Curvature: Curved Dimensionality: N Locality: Non-local

III. Matter

Matter is substantival and infinite across the multiverse — each branch contains its own material configuration, and the total amount of matter across all branches is unlimited. Conservation holds within each branch but need not hold across the multiverse as a whole. Matter is non-local: entanglement and branching connect material states across separated regions of the multiverse.

Attributes
Extent: Infinite Ontological Status: Substantival Conservation: Conserved Dimensionality: N Locality: Non-local

IV. Observer

Across parallel universes, different versions of the observer exist simultaneously — each inhabiting a different branch of reality, occupying different locations, living out different histories. Within any single branch, the observer's knowledge is limited to that branch's accessible phenomena; it cannot perceive or communicate with its other selves. Each version retains only the knowledge accumulated in its own particular timeline. The observer is embodied and passive — branching happens to it, not because of it. The plurality of observers is doubled: not only do many observers share each branch, but each individual observer is multiplied across the multiverse into countless divergent copies.

Attributes
Time Instance: Multiple Space Instance: Multiple Extent of Knowledge: Mediated Retainment of Knowledge: Immediate Physicality: Embodied Agency: Passive Number: Plural Metaphysical Agency: None Moral Authority: None Theological Method: N/A

V. Energy

Energy is substantival and infinite across the multiverse — each quantum branching event creates new branches with their own energy budgets. Conservation is non-conserved globally because new branches continuously come into existence. Dispersibility is reversible in the sense that every possible energy configuration is realized somewhere in the multiverse.

Attributes
Extent: Infinite Ontological Status: Substantival Conservation: Non-conserved Dispersibility: Reversible

VI. Information

Information is conserved across the multiverse — every quantum branching preserves all information. It is discrete because quantum events create distinct branches, each encoding a definite informational outcome. The framework places this as conserved at both scales: cosmic information is preserved because every quantum branch retains the full informational state, and personal-identity information is conserved in that some branch always continues a given pattern — the self never fully ends, only some of its branches do.

Attributes
Ontological Status: Substantival Cosmic Conservation: Conserved Personal Conservation: Conserved Granularity: Discrete

Experiments This School Responds To (19)

The Double-Slit Experiment
1801 / 1927 · Reframes the question
Everettian/many-worlds: there is no collapse. Each detection outcome is realised on a separate branch; interference is between amplitudes of branches in which the particle "took" …
Bell Test Experiments
1964 / 1982 (loophole-free, 2015) · Reframes the question
Everettian: there is no faster-than-light influence because there is no single outcome to influence. Locality is preserved at the level of the branching wavefunction; "non-locality" …
The Delayed-Choice Quantum Eraser
1978 / 1999 · Reframes the question
Everettian readings dissolve the paradox: nothing is "set" at D0 until decoherence selects a branch. There is no retrocausation, only branching correlations; the sorting after …
Schrödinger's Cat
1935 · Reframes the question
Everettian: both outcomes are real on different branches. There is no collapse, no paradox, and no special role for the experimenter — only the appearance …
Wigner's Friend
1961 · Reframes the question
Everettian: the friend exists on multiple branches simultaneously; Wigner, before correlation, has not yet entered any branch and so describes the joint state correctly. No …
Boltzmann Brains
1895 / 2004 · Reframes the question
Most multiverse cosmologists treat the Boltzmann brain count as a *constraint* on viable models: any vacuum or measure that predicts BB dominance is presumed wrong. …
The Cosmic Microwave Background
1964 (detection); 1948 (prediction) · Reframes the question
Inflationary cosmology, which predicts the CMB's angular spectrum, generically implies eternal inflation and a multiverse of bubble universes. The CMB is the strongest indirect evidence …
The Sleeping Beauty Problem
2000 · Affirms / takes the bait
Anthropic reasoning in cosmology (Boltzmann brains, Doomsday argument) inherits the same self-locating structure; the Sleeping Beauty debate is the formal core of those disputes.
Hubble's Redshift Law
1929 · Reframes the question
Hubble expansion plus inflationary cosmology generically predicts eternal inflation and a multiverse of bubble universes — though the inference from Hubble alone is much weaker …
Neutrino Oscillations
1998 / 2001 · Reframes the question
The smallness of neutrino masses is one of many parameters in the SM whose values are unexplained; anthropic readings (within multiverse frameworks) have been advanced …
Quantum Teleportation
1997 (first experiment); 1993 (theory) · Reframes the question
Everettian: the "teleportation" is a particular correlation between branches, achieved by decoherence and selection. The classical bits identify which branch Bob is in.
Tegmark's Mathematical Universe Hypothesis
1998 · Affirms / takes the bait
The most expansive multiverse: not just Everettian branches or inflationary bubbles, but every consistent mathematical structure as a universe.
The Doomsday Argument
1983 · Affirms / takes the bait
Compatible with broader anthropic reasoning: the same self-sampling assumption that handles multiverse priors yields the doomsday verdict.
Tonomura's Single-Electron Interference
1989 · Reframes the question
Everettian: each electron lands somewhere on each branch; the build-up pattern reflects the Born-rule weighting of branches. No collapse needed.
JWST's Surprisingly Mature Early Galaxies
2022– · Reframes the question
If anomalies persist, anthropic readings of cosmological parameters within multiverse frameworks gain additional motivation; but the inference is theoretically heavy.
The Hubble Deep Fields
1995 (HDF); 2004 (HUDF); 2023 (JWST) · Reframes the question
The observable universe is vast but finite; multiverse frameworks place it within a much larger structure that deep fields only sample.
Pascal's Mugging
2009 · Reframes the question
Anthropic and multiverse reasoning often involves astronomical-utility considerations; the Pascal's mugging structure may already infect them.
Olbers' Paradox
1823 · Reframes the question
Bears on multiverse readings: our observable universe is finite-age, but the multiverse may be infinite and eternal; the paradox applies only to causally accessible regions.
WMAP and Planck CMB Anisotropy Maps
2003 / 2013–2018 · Reframes the question
Inflationary cosmology (which CMB confirms) generically predicts eternal inflation and a multiverse; the CMB is the strongest indirect evidence for that framework.

Films Reading Through This School (5)

← #9 Eternalism All Schools #11 Simulation Theory →

Works that name Multiverse Theory in their embodiments

Foundational texts that draw on this school, with each work's declared weight.

45%
"Relative State" Formulation of Quantum Mechanics
Hugh Everett III · 1957
40%
On the Plurality of Worlds (Late (Lewis's mature systematic statement of the modal-realist programme))
David Lewis · 1986
25%
Exposition du système du monde (Mid)
Pierre-Simon Laplace · 1796 (revised through 1824)
25%
The Fabric of Reality (Mid)
David Deutsch · 1997
15%
Relative State Formulation of Quantum Mechanics (Early)
Hugh Everett III · 1957 (Reviews of Modern Physics)
15%
Traité de mécanique céleste (Mid-to-late)
Pierre-Simon Laplace · 1799-1825 (5 vols)
10%
Counterfactuals (Early)
David Lewis · 1973
10%
On the Infinite Universe and Worlds (De l'Infinito Universo e Mondi) (Late)
Giordano Bruno · 1584
10%
Ficciones (Mid)
Jorge Luis Borges · 1944
10%
Our Mathematical Universe (Late)
Max Tegmark · 2014
10%
An Example of a New Type of Cosmological Solution to Einstein's Field Equations (Mature (the Princeton period — Gödel's only published paper in general relativity))
Kurt Gödel · 1949 (Reviews of Modern Physics 21, in the Einstein 70th-birthday Festschrift)
10%
Quantum theory, the Church-Turing principle and the universal quantum computer (Early)
David Deutsch · 1985
5%
Ways of Worldmaking (Late)
Nelson Goodman · 1978
5%
Speakable and Unspeakable in Quantum Mechanics (Late)
John S. Bell · 1987 (papers 1964-86)
5%
Invisible Cities (Le città invisibili) (Mid)
Italo Calvino · 1972
5%
Superintelligence: Paths, Dangers, Strategies (Late)
Nick Bostrom · 2014
5%
A Brief History of Time (Late)
Stephen Hawking · 1988

Personas with Multiverse Theory as a declared influence

50%  David Deutsch 40%  Hugh Everett III 30%  David Lewis 20%  Stephen Hawking 15%  John Archibald Wheeler 15%  Democritus of Abdera 10%  Saul Kripke

How Multiverse Theory resolves each dilemma

57 resolved positions across 4 dimensions, including 30 distinctive where the majority of schools go the other way.

Each dimension is sorted so minority positions come first. Mainstream positions are folded into an expandable list.

Time · 9 dilemmas · 5 distinctive

Persistence, the future, and the direction of becoming.

Distinctive · only 2% of schools agree (5/208)
How much weight do future people deserve?
If a billion people will exist in the 25th century, do their interests count for as much as the interests of a billion people alive now? The answer turns on what kind of reality the future has.
The future branches — what we owe depends on which branch we create.
On these views, time is not a single line stretching forward but a tree of possibilities, at each moment opening into alternatives. Future people are real in some sense, but which future people exist depends on which branches get actualized — and that is the …
Roads not taken Future people are as real as you are — and their interests count for as much. (47%) · Time arises from events or from a deeper substrate — the future is not yet. (31%) · Past, present, and future are bound in cycles — duties span generations as a matter of course. (18%)
Distinctive · only 2% of schools agree (5/208)
Is regret rational?
If the past is fixed and unchangeable, what kind of mental act is regret? An error, a duty, a lesson, a perspective on a moment that is still in some sense present?
Other branches exist; regret tracks roads not taken that are nonetheless real.
On branching views, what you regret not doing is, in some sense, what you did do — in another branch. The regret tracks the difference between the branch you are in and the branches you might have been. Whether this makes regret weightier or lighter …
Roads not taken The past is as real as the present; regret is a real attitude toward a real thing. (47%) · The past is not a thing now; regret is the present holding what is no longer. (31%) · The past is part of a cycle one keeps returning to; regret is one of the gates of the cycle. (18%)
Distinctive · only 2% of schools agree (5/208)
Do we owe extinct species something we cannot give them?
A species that no longer exists cannot be helped, cannot be consulted, cannot benefit. Whether anything is owed to it anyway turns on what kind of reality past beings have.
Extinction is path-dependent; the species exists in branches we didn't take.
On branching views, an extinct species exists in branches where its decisive moments went differently. Whether we owe the species something depends on whether we identify with this branch alone, with all branches, or with the multiverse as a whole. De-extinction research, on this view, …
Roads not taken Extinct species are as real as we are; they have standing. (47%) · Past species no longer exist; what we owe is to the present and the future. (31%) · Past beings are part of the cycle; we owe them what we owe ancestors. (18%)
Distinctive · only 6% of schools agree (12/208)
Do you really choose?
If the brain is a physical system and physical systems are governed by laws, then every choice is also a chain of causes — which raises the question of what was really left to choose.
Even if the universe is undetermined, you are not the chooser.
On this view, the indeterminacy of the universe — whether from quantum mechanics, sheer contingency, or something else — does nothing to recover meaningful choice. A coin-flipping brain is not a deliberating brain; randomness in the underlying physics doesn't translate into power for the observer. …
Roads not taken The future is open and you are a genuine origin of it. (69%) · Choice is structural illusion — every event is fixed by the prior state. (10%) · Choice is real within a determined order — agency and determinism aren’t opposites. (10%)
Distinctive · only 6% of schools agree (12/208)
Are addicts responsible for their addiction?
Addiction looks from one angle like the textbook case of agency failing — a person doing what they don't, in any meaningful sense, want to do. From another angle it looks like agency at work in hard conditions. Which it is depends on what agency is.
Even if the universe is undetermined, the addict isn't the chooser.
On this view, the indeterminacy of the universe does nothing to convert an addict's brain into a responsible chooser. Randomness is not freedom. The addict is being acted on by neurochemistry, by environment, by craving; the appearance of agency is downstream of these. Compassion is …
Roads not taken The addict could have chosen otherwise — that's why recovery is real. (69%) · The addict's behaviour is the outcome of causes; 'responsibility' is a useful fiction, not a metaphysical fact. (10%) · The addict is genuinely responsible within a determined order. (10%)
4 mainstream positions
Matter · 7 dilemmas, all mainstream

Observer · 37 dilemmas · 5 distinctive

Mind, agency, and the knower's relation to the known.

Distinctive · only 2% of schools agree (5/208)
Is environmental damage ever truly permanent?
Extinction is forever; soil erosion takes centuries to repair; the carbon we emit will warm the climate for millennia. But whether 'forever' or 'millennia' means what they say depends on what kind of process the universe is.
What is irreversible in this branch is reversible in another.
On branching views, the universe contains branches where the damage didn't happen, where the species didn't go extinct, where the ecology held. Whether the damage is 'permanent' depends on whether you identify with this branch or with the wider branching structure. The same physical fact …
Roads not taken Damage is real and permanent on the relevant timescales. There is no recovery; there is only limitation. (66%) · Loss is part of cycles; what disappears returns in another form. (18%) · From the standpoint of the One, the categories of permanence and loss are conventional. (8%)
Distinctive · only 2% of schools agree (5/208)
Can a civilization recover from collapse?
Rome fell; Maya cities emptied; Bronze Age trade networks collapsed in a single generation. Whether what was lost can be recovered — or whether collapse is structurally final — depends on what kind of process civilization is.
In one branch the civilization collapses; in another it doesn't. Recovery depends on which branch you're in.
On branching views, the civilization that collapsed in this branch persists in others. Recovery in this branch is engineering work on a specific trajectory; the lost is not lost everywhere. The metaphysical question of cross-branch identity is open, but the framing matters for how to …
Roads not taken Civilizational complexity is hard to build and easy to lose; recovery is at best partial. (66%) · Civilization rises and falls in cycles; recovery is structural to history. (18%) · From the One's vantage, civilizational categories are themselves conventional. (8%)
Distinctive · only 2% of schools agree (5/208)
Does the second law of thermodynamics mean something morally?
The universe trends from order to disorder. Whether that physical pattern carries moral weight — making the preservation of order, beauty, complexity a kind of cosmic duty — depends on whether time has the kind of structure morality could lean on.
Entropy looks different from different branches; the moral reading is branch-relative.
On branching views, the appearance of irreversibility is partly an artifact of which branch one occupies. Across the whole tree of branches, configurations are perpetually being instantiated. The moral reading of the second law has to take seriously the multiplicity of branches before treating any …
Roads not taken Entropy is what time is. The moral weight, if any, is the weight of working against the current. (66%) · Local entropy increase is part of a cycle; the moral category is participation in the cycle. (18%) · From the One's vantage, the second law is itself a feature of the conventional, not the ultimate. (8%)
Distinctive · only 2% of schools agree (5/208)
Could causation work backwards?
If the laws of physics are time-symmetric, what makes causes precede their effects? And if the asymmetry isn't metaphysical, could retroactive causation be coherent?
Time branches; 'forward' picks out the branch you're in, not the only available direction.
On branching views, time is a tree of possibilities. Causation within a branch runs in the ordinary way, but the larger structure of branches embraces possibilities that this branch's forward arrow doesn't capture. Quantum-mechanical retrocausation, in the delayed-choice sense, finds natural framing here.
Roads not taken Causation runs one way — the arrow of time is real and structural. (68%) · Time is structured as return; 'forward' and 'backward' are local features of the cycle. (18%) · From the One's vantage, causation itself is a conventional category. (8%)
Distinctive · only 2% of schools agree (5/208)
Is the asymmetry between memory and anticipation a real feature of time, or just of us?
You remember the past but anticipate the future. Whether that asymmetry tracks something deep about time, or just something contingent about how minds happen to be wired, depends on what direction time has.
Memory is of the branch behind you; what would 'remembering' another branch even mean?
On branching views, memory tracks the path through the tree of branches that the observer has taken. Anticipation is about which downstream branches are possible. The asymmetry tracks the tree structure: backwards is one definite path, forward is many possibilities. Remembering the future would have …
Roads not taken The asymmetry is real because time itself has a real direction. (68%) · Memory and anticipation are phases of a cycle that visits both directions. (18%) · From the One's vantage, memory and anticipation are themselves conventional. (8%)
32 mainstream positions
Is the arrow of time a real feature of the cosmos, or only of how we describe it? The arrow is the path through the branches; reality has many arrows pointing many ways. 2% What makes someone the same person over time? You span moments — identity is a pattern that need not be located at a single now. 9% Is the late-stage dementia patient still the person their spouse married? The person is the pattern across moments — diminished pattern, diminished person. 9% If a teleporter copied and destroyed you, would you have survived? You are the pattern; the pattern survives the substrate change. You arrive. 9% Who is the moral primary — the individual, the community, the cosmos, the class, or the species? The species or biosphere is the moral primary. 11% What is our place in nature? Subject to a real natural order we did not make. 12% Should we colonize space? Nature includes its limits; colonisation is bounded by what the cosmos allows. 12% Is genetic engineering of food stewardship or domination? Biology is what it is; we modify it within real biological constraints. 12% Does environmental harm in another country bind me morally? Distance doesn't dilute obligation; what is real is the connection, not its length. 12% Are the dead morally present to the living? Observers span moments; the dead are present in a real (not merely metaphorical) way. 12% Is divine omniscience compatible with human freedom? An observer can occupy multiple times at once; foreknowledge is not foreordering. 12% Does meditation reveal something genuinely timeless? Meditation accesses a trans-temporal level the ordinary observer doesn't ordinarily reach. 12% Does prayer change God's mind? Prayer participates in a trans-temporal liturgy or communion; the question of 'changing the mind' misses the trans-temporal mode. 12% Is reality fundamentally digital? Yes — bits, quanta, computational substrate. 13% Are there indivisible units of experience? Yes — naturalist quanta of experience. 13% Is memory stored or reconstructed? Stored — discrete engrams, traces, weights. 13% Is truth universal, tradition-bound, situated, or constructed? Truth is mind-independent, universal, accessible in principle to all. 66% When does a person begin? A person exists from conception — when a new being comes into existence. 55% What is marriage? Marriage has a given form — it’s a kind of thing we recognize, not make. 55% Can prayer for someone far away affect them? Prayer changes the pray-er, not the prayed-for. 47% Are coincidences ever more than coincidence? Coincidence is exactly what the math says it is. The pattern is in the noticer. 47% What kind of religious-theological authority does the tradition recognize? The category does not apply — the school is non-religious. 42% Does history have a direction or meaning? History is not where the deepest truth lives. 36% Do animals have moral standing comparable to humans? Animal minds are real because biology is the substrate of mind. 31% Could a fetal brain organoid in a petri dish be conscious? Brain tissue can in principle do what brains do; the question is integration. 31% What happens to "you" when you die? Death is genuinely the end. 29% How is knowledge of reality produced? Through controlled empirical investigation. 17% Is salvation, liberation, or fulfillment individual or communal? Liberation is the realization of cosmic or species self. 14% Could an AI have a mind that matters? Yes — mind is a pattern, not a substrate. 9% Should we trust expert testimony when we can't verify it? Trust the method, not the institutions or the persons — and remain wary. 8% Is religious revelation a real source of knowledge? Revelation is not knowledge in the descriptive-empirical sense. 8% Does an LLM 'know' the things it correctly produces? An LLM produces tokens; calling that 'knowledge' is a measurement choice. 8%
Information · 4 dilemmas, all mainstream
Jump to school (208)
#1 #2 #3 #4 #5 #6 #7 #8 #9 #10 #11 #12 #13 #14 #15 #16 #17 #18 #19 #20 #21 #22 #23 #24 #25 #26 #27 #28 #29 #30 #31 #32 #33 #34 #35 #36 #37 #38 #39 #40 #41 #42 #43 #44 #45 #46 #47 #48 #49 #50 #51 #52 #53 #54 #55 #56 #57 #58 #59 #60 #61 #62 #63 #64 #65 #66 #67 #68 #69 #70 #71 #72 #73 #74 #75 #76 #77 #78 #79 #80 #81 #82 #83 #84 #85 #86 #87 #88 #89 #90 #91 #92 #93 #94 #95 #96 #97 #98 #99 #100 #101 #102 #103 #104 #105 #106 #107 #108 #109 #110 #111 #112 #113 #114 #115 #116 #117 #118 #119 #120 #121 #122 #123 #124 #125 #126 #127 #128 #129 #130 #131 #132 #133 #134 #135 #136 #137 #138 #139 #140 #141 #142 #143 #144 #145 #146 #147 #148 #149 #150 #151 #152 #153 #154 #155 #156 #157 #158 #159 #160 #161 #162 #163 #164 #165 #166 #167 #168 #169 #170 #171 #172 #173 #174 #175 #176 #177 #178 #179 #180 #181 #182 #183 #184 #185 #186 #187 #188 #189 #190 #191 #192 #193 #194 #195 #196 #197 #198 #199 #200 #201 #202 #203 #204 #205 #206 #207 #208