Questions tagged [multiverse]

A hypothetical group of multiple universes, each of which would comprise everything that is experimentally accessible by a connected community of observers. DO NOT USE the 'multiverse' tag for the many-worlds interpretation, use the 'quantum-interpretations' tag instead.

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Can anyone correct me about these paradoxical multiverse scenarios? [closed]

If the universe is in superposition with other universes and if parallel universes really exist then I'm confused about the kind where all are the same, where I exist in every universes in different ...
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Multiple (Non-Interacting) Universes?

Before anything, I would like to clarify that I am aware that this is speculative physics more than established mainstream physics (and Smoot is not claiming that his ideas are true). However I think ...
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Quantum choices and Universe splitting

Multiverse theory says that when a choice is made between two quantum states, the Universe splits. What happens if there are 3 or more choices that need to be made? Will that state make the Universe ...
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How does eternal inflation (from a possibly finite space-time region) produce infinitely large pocket universes?

The title almost already completely captures my question: In reviews and summaries of eternal inflation models, it is typically stated that the arising pocket universes (to be precise: the space-time ...
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Probability in the Multiverse Interpretation of Quantum Mechanics [duplicate]

The Multiverse Interpretation of Quantum Mechanics interprets a quantum decision as different universes, each with each outcome. I was wondering how probability plays into this. For example, if we ...
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Does the Multiverse Theory rely on Superposition?

Note: I'm not asking if the Multiverse Theory and the MWI are the same thing, cf. e.g. this Phys.SE post. If I understand it correctly, the Multiverse Theory doesn't rely on the Many Worlds ...
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Karen Barad's theory of agential realism - does it stand on solid scientific ground or is it quantum quackery? [closed]

Before you vote to close this question as off-topic, please note that while my interest in the topic lies on the metaphysical guesswork, my question here is specifically about Karen Barad's scientific ...
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Branes with any number $n$ of dimensions and their relation to the laws of physics?

I had a few questions about this paper by Nima Arkani-Hamed, Georgi Dvali and Savas Dimopoulos (https://arxiv.org/abs/hep-th/9907209) which is closely related to the concept of branes (https://en....
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Fabric of reality shadow photon partitioned off into parallel universes among themselves?

In fabric of reality interpretation of QM chapter 2 how does David Deutsch conclude that the "shadow photons" in the one-particle-at-a-time double slit experiments are themselves ...
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Black Hole Singularity Other Universe

It is thought that there is another universe beyond the singularities of black holes. Is it because width of the light cones become zero at the singularity, meaning that you can cross infinite ...
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Other Side of an Einstein Rosen Bridge

We get an ERB when we replace $u^2$ by $r - 2M$ in Schwartzchild Metric, therefore the metric becomes symmetric along the horizon $(r = 2M)$. Why should it mean that crossing the horizon leads you to ...
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Wigner friend experiment with qbits

Suppose that in his isolated box, Wigner's friend measures a qbit in state $|→⟩=\dfrac{|↑⟩+|↓⟩}{\sqrt{2}}$ along the vertical axe. Then, he sends Wigner (who remains outside the box) a qbit in the ...
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Why are inflationary bubble universes spatially infinite from the inside but finite from the outside?

In The Hidden Reality, Brian Greene describes the bubble universes that would arise from inflation as being spatially infinite as observed by a viewer on the inside of the universe, yet spatially ...
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Does multiverse theory obviate the need for fine tuning?

I recently read the book by Max Tegmark, The mathematical Universe, where he expounds upon the multiverse and how if ANYTHING can happen, will happen, because of all the ways things can be arranged. I ...
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Multiverse theory VS Conformal Cyclic Cosmology (CCC)

Multiverse theory describes that there are many singularities taking birth and then based on their properties (like dark matter content), these may pop in and out of existence. While on the other hand,...
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What does the standard claim that detecting a closed universe would rule out the multiverse mean?

The new article "Lorentzian Vacuum Transitions: Open or Closed Universes?" On page 41 reads: "We believe that the possibility that the geometry of the bubble after nucleation ...
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Are the different fields in multi-field inflation described by different Lagrangians?

The most simple models of cosmological inflation consider only one scalar field. However, there are more complex models (like hybrid inflation or multi-field inflation) which consider more than one ...
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Why can a "wave of differentiation" be thought of as a "sphere of differentiation"?

Below is a paragraph from chapter 11 of David Deutsch's book The Beginning of Infinity (emphasis mine). The context he is referring to is the quantum "multiverse" - his conjecture about how ...
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Different symmetries or no symmetries in string theory?

I was reading the book "A Fortunate Universe" by Geraint Lewis and Luke Barnes and something caught my attention: At page 195 the authors say that universes with different symmetries could ...
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In Eternal Inflation Theory, what is the average distance between bubble universes?

Patches of normal space randomly condense out of the false vacuum of inflating space. What is the average distance between these patches? Another words, what is the average number of bubble patches ...
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If there is an infinite number of universes doesn't that mean there is a universe where there is not an infinite number of parallel universes? [closed]

Hi i'm not clever enough to think outside of my finite existence. Can someone explain the bounds of my logical thinking that infinity is a paradox like the question: "are you lying?". Is my ...
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Tegmark's level 1 universe: how many universes?

In "Our Mathematical Universe" Tegmark claims that inflation theory implies the existence of an infinite set of universes. My simple question is: what kind of infinity, and why that kind ? I ...
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Randomness in parallel universes [closed]

Suppose we have two completely identical universes (for instance in Tegmark's type III multiverse). In both of them, two identical men are sitting behind identical random number generators (RAN1 and ...
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Could the basic fundamental laws of physics change between universes in cosmological inflationary models?

According to cosmological inflationary models, different universes governed by different effective/low-energy laws of physics could exist, but the most fundamental laws of nature would remain the same....
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Is it possible that a black hole has a universe in itself? [duplicate]

Every black hole has a singularity. But the singularity is covered by a thing called 'Event horizon'or ' Schwarzchild Radius'. Our universe is originated from a naked singularity. By naked singularity,...
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Is there any model in theoretical physics combining Wheeler's "Principle of mutability" and multiverses?

Physicist John A Wheeler proposed the "Principle of mutability" which said that it could be the case that the universe would eventually shrink in a "Big Crunch" and the be re-born ...
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Theory of multiverse - it is really scientific theory? [closed]

In book Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos Brian Green shows that many current physical theories (e.g. quantum mechanics - many world interpretation of QM, superstring ...
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Does the Many worlds interpretation of quantum mechanics imply the existence of all conceivable worlds? [closed]

what I mean by this is, does every universe conceivable exist? would any universe i think of exist? could there be a universe of nothingness? are there universes of TV shows? are there universes with ...
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In the string theory multiverse, is every universe fated to collapse in a Big Crunch?

This is what I understand of the multiverse of the string landscape: the "laws of physics" reside in a 100-dimensional string landscape, which has ~$10^{500}$ minima. Each of the minima corresponds to ...
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Are the twentyish constants that have to fall in-between certain ranges to make conditions for live to exist necessary? [closed]

I have been listening to an audiobook about what we cannot know (although I have heard about 20 constants somewhere before that, just can't recall where) and in chapter 9, author talks about twenty ...
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The "Many Worlds" description of quantum mechamics and the "Multiverse"

I see a Phys.SE question, asking if the "Many Worlds" and the "Multiverse" ideas are essentially equivalent. This question was quickly squashed with a no answer. I would like to rephrase the question. ...
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Gravity in the multiverse

Consider Tegmark's multiverse theory, and single out a level. My question is: is each of the sub-universes endowed with gravity ? What about gravity between the sub-universes: does the multiverse ...
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Did Wheeler propose some kind of variation of MWI where universes would have different laws of physics?

John Wheeler proposed along with Hugh Everett and Bryce DeWitt the 'Many Worlds' Interpretation of Quantum Mechanics (although he expressed some doubts about its validity) I have read, from an ...
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Why is the measure problem an issue if the universe is always finite?

As a follow-up from this question, I was wondering how the measure problem applies to the idea of eternal inflation. First, why is it even a problem? As time progresses, more universes are created in ...
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Is it possible that the acceleration of the growth of our universe is driven by the overall gravitational pull of neighboring universes [closed]

I am painfully unequipped when I think about my my knowledge of physics. Still, I am enthralled, as many of us are, by the mysteries and complexity of the universe, both known and unknown. I was ...
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Multiverse and the anthropic principle? [closed]

In this paper (https://arxiv.org/abs/hep-th/0211048) by physicist Andrei Linde, the multiverse concept, the anthropic principle, quantum cosmology and inflationary cosmology are analyzed. In the ...
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Are there other theories (apart from string theory) that combined with inflation, would produce universes with different laws?

In chaotic inflation, space would stop expanding in some points, creating hubble volumes that could experience different spontaneous symmetry breaking, which would result in different properties, such ...
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Examples of theories that assume the existence of an "External Reality"?

In this paper written by physicist Max Tegmark (https://arxiv.org/pdf/0704.0646.pdf) it talks about "External Reality Hypothesis". Specifically, he says: Although many physicists subscribe to the ...
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Is the universe a closed system?

Most places say it is. But according to the multiverse hypothesis, gravitons and other quantum particles could travel from one universe to another. Wouldn't matter-energy then be transferred and thus ...
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Could micro-states not have equal probability as assumed? [closed]

How could micro-states have uniform distribution in a 3D space unless there was 0 Gravity? Gravity violates the assumption of equal probability as it makes matter move in a predictable direction. ...
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What are the laws of physics of the Multiverse ? What is the multiversal constant? [closed]

What are the laws of physics outside our Universe ? Can a Multiverse constant exist ? And what is the Multiverse constant if it exists ?
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Tegmark's level 1 multiverse - why does infinite set of universes imply existence of a universe almost identical to ours?

In "Our Mathematical Universe" Tegmark claims that inflation theory implies existence of (countably, it seems to me) infinite set of universes. He says that from this follows existence of a universe ...
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Charge of multiverse

The charge of the universe is said to be zero. The most general argument I hear about this is that: since there was no net charge before the universe there must not be any after. Hence the universe is ...
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Could information in a boundary be modified once encoded in holographic principle?

There are models of universes where holographic principle has a different correspondence (there is absolutely no reason to assume that this would hold true for all possible universes. You could have a ...
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Can holography be applied to every model?

Can all models have a holographic representation? I was talking with a physicist and he told me: "Holography is not a property you can just apply to any model of the universe willy-nilly. It either ...
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Have string theory and brane cosmology the same landscape?

Has any of these hypothetical theories a "higher" number of possible universes or has string theory landscape the same type of possible universes than brane cosmology?
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Heat death in eternal inflation

Heat death is the predicted fate of the universe. Eternal inflation theory states that new hydrogen atoms are created in each pocket universe so that means new hydrogen atoms are still being created ...
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How is the multiverse possible with the law of conservation of energy? [closed]

So I am not a physicist or have any background in physics but I enjoy thought experiments and thinking about the nature of our universe and I was thinking about the idea that we live in a multiverse ...
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Time and the Multiverse [closed]

Is a clock in one universe of any use to someone in a different universe? Supposing the multiverse model is correct, it posits the existence of several distinct universes that exist independently of ...
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If Hawking's last paper is correct, is it valid to assume that we live in a 5 dimensional universe?

If I understand Hawking's last paper, "A smooth exit from eternal inflation?" (2018-04-27), correctly it implies that the Big Bang generated more universes than our own. This means that to locate a ...