Talk:Many-minds interpretation

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However Everett's work was incomplete. He was attempting to show how the seemingly non-random "real world" leads from the indeterminancy of the quantum world, but he left this last crutial step unexplained. You see only one measure, and no hint of these other values or other "yous" measuring the other values, how is this to be explained?

The many-worlds interpretation assumes that the states of an observer correspond to separate world states, so each should be unaware of the others. This may be considered a problem, since it predict entities that can't be verified by observation, but is not generally considered an incompleteness that needs to be patched. Also, the many-worlds explains how the indeterminancy of experiments leads from determinate physical laws, not the other way around. As such, I think it is best to remove this entire paragraph. I've also removed:

This interpretation thus has the added advantage of being "local" in the general relativity sense of the term, because all of the decision making takes place in your mind.

because Everett's interpretation is local in the general relativistic sense, having abandoned collapse, which is the only non-local feature of other interpretations.

This is not correct. It is the quantum state itself which is nonlocal (without any dynamical nonlocality, such as spurious action at a distance).

In general, I think the text here is fairly suspect and could do with revision by someone more familiar with what this interpretation is supposed to be about. In particular, I think this page has overstated its benefits and understated its flaws, given the mistakes above and that one of its authors has since disavowed it.

The Everett interpretation is now very popular, since it is the only dynamically consistent quantum theory.

Do we really agree on observations?

The article says: "However Albert and Loewer suggest that the mental does not supervene on the physical, because individual minds have trans-temporal identity of their own. The mind selects one of these identities to be its non-random reality, while the universe itself is unaffected. The process for selection of a single state remains unexplained. This is particularly problematic because it is not clear how different observers would thus end up agreeing on measurements, which happens all the time here in the real world. There is assumed to be a sort of feedback between the mental process that leads to selection and the universal wavefunction, thereby effecting other mental states as a matter of course. In order to make the system work, the "mind" must be separate from the body, an old duality of philosophy to replace the new one of quantum mechanics. In general this interpretation has received little attention, largely for this last reason."

I challenge the objection that "different observers ... end up agreeing on measurements ... all the time here in the real world"! It seems that, in contrast to the most basic predefined facts which are agreed to in advance, many practical observations (and interpretations of observations) differ from each other somewhat and are not perfectly repeatable. Some inconsistency seems to be the rule. We tend to dismiss this as the result of randomness, noise, measurement errors, etc. Those things seem real enough, but may not be the whole story. Possibly a component of the inconsistency is more fundamental, a result of different minds (and bodies, and measurement devices, and measured systems) interacting and themselves changing over time, further confounding agreement. The many minds interpretation may suggest why "observer bias" or "differences of opinion" seem inevitable in so many areas. Can we actually completely agree on anything, even just with ourselves over time? This question also applies to the many minds interpretation itself, which might just offer the only way out. --Parsiferon 01:44, 17 February 2007 (UTC)

(Excuse the heretical thought, but "reality" in this Wikipedia laboratory changes over time, based upon the introduction of new authors' preexisting beliefs and the addition or destruction of citations which seem more reliable than they are. My mind changes similarly: whatever I thought I knew before forces my interpretation of the world now, and influences the future directions I can take in gathering information. But new observations modify the impact of the earlier "facts," often increasing our overall degree of doubt & disagreement, if we are honest.) --Parsiferon 02:34, 17 February 2007 (UTC)

More random?

Isn't this a bit misleading:

For the majority of time, systems will evolve according to the Schrödinger equation, evolving in a way that makes the system more and more indeterminate, becoming more "random" in the sense that its physical qualities can take on a greater range of values.

The time evolution of a state governed by the Schrödinger equation is totally deterministic. The last half sentence is more in sync facts (in the sense that...). Volunteers for a better formulation?

Pjacobi 22:18, 2005 Jun 9 (UTC)

The correct statement I think would be that for all time, systems will evolve according to a Master equation such as the Lindblad equation. Many-worlds is a rather improvished form of this.--CSTAR 22:48, 9 Jun 2005 (UTC)

Yuck. This article is need of major debogusification. What the hell does this mean?

The central problem of quantum theory is that it involves an unexplained duality in nature. For the majority of time, systems will evolve according to the Schrödinger equation, evolving in a way that makes the system more and more indeterminate, becoming more "random" in the sense that its physical qualities can take on a greater range of values.

Well I assume this means that vonNeumann entropy increases.--CSTAR 22:57, 9 Jun 2005 (UTC)

Hermeneutics and the central problems

The following statement from The central problems section is definitely out of place here.

At the primary pragmatic level orthodox QT deals with the problem of causation by using the facts that: choices are causally efficacious in the physical world independently of their causal roots and that those causal roots are, in principle, untracible solely in the physical world. Hence we are both entitled to, and required to, take these choices as primary variables, whose physical effects are specified, but whose origins must, to the extent that they can be traced, involve also non-physical variables. If this pragmatic structure is imbeded in an objective one-mind-per-person ontology then the rules must be specified that fix the particularness of each person's choices.

I am removing it, because regardless of whether it means anything or not, doesn't address what is the central problem addressd by many-worlds or many minds. --CSTAR 16:20, 15 October 2005 (UTC)

• I put in a quote by Zeh that says the same thing as the passage you pulled (which I do admit was a bit obscure); this one I think will be a bit easer to understand. DV8 2XL 19:58, 15 October 2005 (UTC)

Indeed the quote is meaningful, and regardless whether one agrees with it or not, proposes as an empirical problem the connetcion between observation and mind. Clear. I made some minor copyedits with the introductory sentence. --CSTAR 22:05, 15 October 2005 (UTC)

Zeh dates

The concept was first introduced in 1970 by H. Dieter Zeh

The idea of many minds was suggested early on by Zeh in 1995.

The article is completely inconsistent about the date at which Zeh started many minds. A reference would help -- even one!!!

--Michael C Price 10:43, 15 June 2006 (UTC)

Clarification required

I've temporarily moved some text here for clarification:

One problem with [Everett's] approach is that it is not clear how one is to maintain a constant view of the universe given that macrorealm selection has to be random in order to maintain the statistical nature of QM. That is, if the macrorealm selection is entirely random, no consistent history should exist, the outcomes of past actions would have only minor influence on current ones. Everett never addressed this problem in any depth, although there have been a number of attempts since. Many-minds is one such attempt.

First, wouldn't a criticism of Everett's theory be better placed in its own article? Second, I am not clear what the alleged deficiency of Everett's MWI refers to. Is that we see subjective indeterminancy whilst the equations are deterministic, or is it that you don't see how the Born probability law emerges, or is it how come we have a consistent memory of the past? All of these issues were addressed by Everett and elaborated on by his sucessors. Of course not everyone is happy with the answers he gives, but that is true of most aspects of most interpretations of quantum theory. --Michael C. Price ^talk 21:46, 26 January 2007 (UTC)

The basic reason for mentioning this here is that the reader is otherwise left without any reason for many-minds even existing.The argument is one of the primary ones from the Stanford Encyclopedia of Philosophy, you can read it here, under 6. There are other problems that could be mentioned as well, but this one is the most "focused" because one proposed solution is to move the problem out of physics and into evolutionary theory -- weak IMHO. You're right, these objections have been addressed, but it definitely wasn't Everett who did it, most of the explanations date into the 1980s, which is the same time frame as many-minds. Maury 13:24, 27 January 2007 (UTC)

Hi Maury, thanks for removing my duplicated paragraph (more tired than I realised!). Everett definitely did address the three issues outlined above in his original 1957 paper; whether and how much elaboration it requires, within the MWI framework, is a matter of opinion. Thanks for the Stanford Encyclopedia of Philosophy link (still digesting it); they make the interesting point that there are really two, quite different MMI versions, which is the impression I get as well. --Michael C. Price ^talk 15:30, 27 January 2007 (UTC)

Zeh, eh?

Is there a source I could see for the claim that Zeh "first introduced the concept" of the many-minds interpretation? This part of the article is kind of ambiguous. It's not clear whether we should take this to mean that the interpretation was first introduced by Zeh or simply the idea that there are multiple minds that, in some way, factor into the MWI. I did some snooping around the internet but all I could find was this line: "There are two very different approaches with the same name "The Many-Minds Interpretation (MMI)". The Albert and Loewer 1988 MMI mentioned above should not be confused with Lockwood’[s] 1996 MMI (which resembles the approach of Zeh 1981)." (http://plato.stanford.edu/entries/qm-manyworlds/)

If these approaches are relevantly different, the article should explain how this is so. Also, the Zeh work cited in the above quote is from 1981, not 1970. What happened in 1970? ZRPerry (talk) 23:41, 24 October 2009 (UTC)

I'm guessing that the source is

• H. Dieter Zeh, On the Interpretation of Measurement in Quantum Theory, Foundation of Physics, vol. 1, pp. 69-76, (1970).

Possibly reprinted in the Wheeler-Zurek Quantum Measurement tome. I'll have to check.--Michael C. Price ^talk 01:03, 25 October 2009 (UTC)

Zeh presumed in his 1970 paper that consciousness supervenes on the world-components of the universal wavefunction. He attributed this interpretation to Everett:

Such a dynamical decoupling of components is even more extreme if phi_R and phi_L represent two states of a pointer corresponding to different positions. Each state will now produce macroscopically correlated states: different images on the retina, different events in the brain, and different reactions of the observer. The different components represent two completely decoupled worlds. This decoupling describes exactly the "reduction of the wave function." As the "other" component cannot be observed any more, it serves only to save the consistency of quantum theory. Omitting this component is justified pragmatically, but leads to the discrepancies discussed above.

This interpretation, corresponding to a "localization of consciousness" not only in space and time, but also in certain Hilbert-space components, has been suggested by Everett) in connection with the quantization of general relativity, and called the "relative state interpretation" of quantum theory. It amounts to a reformulation of the "psychophysical parallelism" which has in any case become necessary as a consequence of the above discussion of dynamical correlations between states of macroscopic systems) A theory of measurement must necessarily be empty if it does not have a substitute for psychophysical parallelism. Everett's relative state interpretation is ambiguous, however, since the dynamical stability conditions z are not considered. This ambiguity is present in the orthodox interpretation of quantum theory as well, where it has always been left to intuition which property of a system is measured "automatically" (e.g., handedness for the sugar, but parity for the ammonia molecule). The dynamical stability appears also to be the cause why microscopic oscillators are observed in energy eigenstates, whereas macroscopic ones occur in "coherent states."

According to the twofold localization of consciousness, there are two kinds of subjectivity: The result of a measurement is subjective in that it depends on the world component of the observer; it is objective in the sense that all observers of this world component observe the same result.

In contrast, other variants of the many-minds-interpretation (e.g. Albert & Lower) do not rely on physicalism, they assume an explicit dualist approach. -- Belsazar (talk) 14:54, 25 October 2009 (UTC)

I do not read that quote as implying "that consciousness supervenes on the world-components of the universal wavefunction"; Zeh says "localization" which something else entirely.--Michael C. Price ^talk 17:12, 25 October 2009 (UTC)

So how do you read Zehs "localization of consciousness [...] in certain Hilbert-space components" without implying supervenience?-- Belsazar (talk) 20:00, 25 October 2009 (UTC)

I read: localisation = splitting. Supervenience, in my dictionary, implies something unexpected, which could mean anything and nothing.--Michael C. Price ^talk 23:14, 25 October 2009 (UTC)

Okay, I'm having trouble making sense of that quote. Here's my problem: I can see that Zeh was offering some kind of interpretation of the MWI on which there are a bunch of minds. However, this isn't enough to show that Zeh actually pre-empted Loewer and Albert's Many-Minds theory. What was important about the Many-minds theory is that the minds weren't governed by the Schrodinger equation, but instead evolved stochastically with probabilities given by |$\psi$|². I can see how saying that the minds supervene on the physical, if that means supervenes on the product states (that is, the individual terms of the superposition), would make it look alot like the Many-minds theory. However, unless there was some further rule for the evolution of these minds which wasn't specified in the Everettian picture to begin with, I can't see how Zeh's theory is a version of the Many-minds theory.

Of course, I could be completely wrong. I don't know the content of Zeh's theory and I'm not sure what I'm supposed to take from the quote you gave. However, it seems to me that saying that the minds supervene on the "world-components of the universal wavefunction" only gets you as far as many-minds if you have something further to say about which mind is which after a splitting occurs. ZRPerry (talk) 19:44, 16 November 2009 (UTC)

Zehs paper from year 2000 (which is basically a revised version of an earlier paper written in 1981) provides perhaps a more mature description of his variant of the many-minds interpretation. There he is explicitely claiming that he was the first author proposing the many-minds idea.-- Belsazar (talk) 19:10, 1 December 2009 (UTC)

Good find! --Michael C. Price ^talk 22:54, 1 December 2009 (UTC)

So I only skimmed the paper you linked, but it looks interesting. So Zeh actually accepts his version of the many-minds picture? This certainly puts him in a league of his own, as far as I'm aware. The Loewer/Albert Many-minds picture was (as I understand it) an obvious way of interpreting Everett's core proposal, which has a whole lot of trouble saying anything remotely close to satisfactory about probabilities, so that you would get a clear and sensible account of probabilities, and the moral of their story was not that such a theory was true, but that incorporating probabilities into the Everettian picture in a straightforward way had, apparently, very steep costs. Here's an amusing quote from David Albert from which you should be able to infer his degree of commitment to many-minds:

"[If you accept the many-minds theory] then you have something for the probabilities to apply to in an absolutely familiar and conventional way, and so on and so forth. The only trouble with such a proposal is that it is preposterous."

ZRPerry (talk) 20:28, 14 December 2009 (UTC)