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This question applies to any type of multiverse or many worlds that translates or actualizes each of a set of potentials into a separate universe. These potentials may come from quantum randomness or cosmological fine-tuning or something similar.

The “desperate” adjective is deliberate. I am asking if taking a multiverse approach to randomness implies science has given up on finding an explanation for the randomness, that is, there is a suspicion that an explanation cannot exist and the multiverse offers no other help in explaining the original randomness.

The “agency” is deliberate. A random event could be viewed as some type of agent making a choice. I am aware of theistic arguments for God using fine-tuning, but the agents I am concerned with are more general. They need not be divine, but could be, say, a system of electrons or what Whitehead might describe as organisms.

To limit scope, I am not concerned about a multiverse that is posited to get an infinite number of universes because ours appears finite in some way. That idea of a multiverse is not a translation of potentialities into actualized universes to remove the potentialities from consideration. It is just the idea that given the existence of our universe there may be many other universes similar to our own.

Also, I am not concerned with the more general principle of plenitude although in this case all possibilities are also actualized. The multiverse ideas I am interested in seem to be offered to eliminate the possibility for agents to be actualized. They seem to me motivated more by a principle of parsimony at least with regards to possible agents.

My suspicion is the answer is “yes”. I am looking for references to those who have already developed this idea or to “no” answers that would counter my suspicions. If the answer is “no”, what does a multiverse explain besides an interest in removing agency?

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    If we are talking about true rather than apparent randomness then (predictive) "explanation" can not exist by definition, it is not a suspicion. And MWI does make some people more comfortable because it "restores" determinism in some sense, illusory though it might be (see e.g. Does True Randomness actually exist?). But what exactly does such psychoanalysis accomplish? Isn't the issue whether it is a good model rather than what psychology motivates it?
    – Conifold
    Feb 19 '18 at 19:54
  • @Conifold In the case of QM no explanation exists as you say. Previously I thought the reason for MWI was to restore determinism, but now I think the reason to restore determinism is really to avoid agency at the quantum level. But if there is something else that makes this a "good model" I wonder what is it? At the moment I see no motivation for it but psychology. Given MWI physics stops since everything is actualized. The fact that our world is so orderly given this new randomness is evidence that MWI is false. Why did we luck out being in this world? Why do our computers still work?
    – Frank Hubeny
    Feb 20 '18 at 3:12
  • "Everything is actualized" is not MWI, it might be some pop-sci misconception of it based on superficial phrasing. The laws of QM still hold in every branch, it is after all only an interpretation, which means that what is "actualized" is severely constrained. And emergence of order from stochastic behavior is a well known phenomenon even under classical laws anyway. One theoretical motivation offered by supporters is that MWI is parsimonious on formalism (not ontology), it removes the additional collapse postulate while still obtaining equivalent empirical results.
    – Conifold
    Feb 20 '18 at 18:33
  • @Conifold I am aware that MWI supporters claim their position is "parsimonious on formalism (not ontology)". What I wonder is why do they even bother with this interpretation? Is there something besides determinism or blocking agency that motivates it? At the moment, as far as I can see, the only people benefiting from it are pop-sci and sci-fi writers.
    – Frank Hubeny
    Feb 20 '18 at 19:18
  • People working in decoherence, quantum computation and cosmology (Zeh, Deutsch, Carroll, etc.) find MWI language to be more natural for phrasing their work, most of them do not care about determinism or agency. I am not a fan of MWI due to its inflated ontology of unobservable entities, but if it is fruitful for doing physics let a thousand flowers bloom.
    – Conifold
    Feb 20 '18 at 20:27
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Agency is about the fact that you can make decisions by considering different possible options and selecting among them. A random event doesn't involve any agency.

The many worlds interpretation (MWI) involves taking quantum mechanics seriously as a description of how the world works. The MWI explains the results of experiments. This includes cases in which the results involve numbers that obey the rules of probability.

The short version of the explanation is that in interference experiments, and some other experiments, a system is set up so it can down more than one possible path. For example, you pass a laser through a set of filters so it is very dim and there will be only one photon in your experiment at a time. You shine the resulting laser beam on a pair of slits and observe what happens to the light that passes through the slits. You see a pattern of light and dark stripes parallel to the slits. If you cut more slits, or you block slits then you change the pattern of light and dark stripes. Places that previously were lit may become dark. So something is passing through the experiment that you don't see. The thing you don't see acts like the photons you do see, except that they don't trigger measurement instruments. If you place a measuring instrument in font of a slit and block it, then the invisible photons will act as if they were blocked by a measuring instrument of the kind you out in front of the slit. So the invisible photons are interacting with a measuring instrument you can't see. It was placed there by an experimenter you can't see, it is attached to a computer you can't see and so on. There is an entire universe you can't see. And there is more than universe you can't see.

This is a short version of the argument. For the longer version, see "The Fabric of Reality" by David Deutsch, Chapter 2. See also "The Beginning of Infinity" by the same author. In any case, the MWI is about explaining the results of experiments, it's not about agency or anything like that.

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  • +1 For providing a thoughtful answer. If I understand, you are saying the value of MWI is that is provides a "description of how the world works". Shimon Malin ("Nature Loves to Hide", page 259-60) gives three problems with this description of how things work: (1) a position measurement splits a single experiment into a non-well-defined infinite number of universes, (2) the instantaneous split is not relativistic and (3) the ambiguities of the collapse are not resolved but transformed into world splitting. I'm trying to see what explanatory benefits MWI provide.
    – Frank Hubeny
    Feb 20 '18 at 3:05
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    If that is Shomon Malin's description, then he is mistaken. Each system exists in multiple versions that can interfere with one another under suitable circumstances. Thoser versions gradually become different over time as a result of local processes. When information is copied from a system it can no longer undergo interference, this, too, is local. As information about different versions of system 1 spreads systems that pick up that information differentiate into different versions corresponding to the results of that interaction. A world is an emergent result of lots of those interactions.
    – alanf
    Feb 20 '18 at 5:53
  • What benefits does MWI offer besides guaranteeing determinism which blocks assuming there is agency at the quantum level? What does it explain that other interpretations do not besides this? I suspect there are many different versions that could be called MWI. There must be a reason that people like this interpretation. I offered my views why, but I don't know what they might be.
    – Frank Hubeny
    Feb 20 '18 at 19:23
  • An explanation is an account of what is happening in reality to bring about some event. Saying "somehow interacting with a system over here produces the following measurement somewhere else" is not an explanation, but that is all other theories have to offer as far as entanglement is concerned. By contrast, the MWI has an explanation of exactly how information flows in entanglement experiments arxiv.org/abs/quant-ph/9906007 arxiv.org/abs/1109.6223. For single particle interference, there is a similar issue.
    – alanf
    Feb 20 '18 at 21:29
  • The paper on locality looks interesting. Here would be a difference between the non-locality one gets from the Bell inequality and MWI. That MWI is a local theory also raises the question of whether the splitting of worlds occurs at a speed less than that of light even if that split is only information transferal.
    – Frank Hubeny
    Feb 20 '18 at 22:06

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