Misplaced Pages

Revision as of 16:59, 5 September 2011

This is the talk page for discussing improvements to the Many-worlds interpretation article. This is not a forum for general discussion of the article's subject.

Put new text under old text. Click here to start a new topic. New to Misplaced Pages? Welcome! Learn to edit; get help. Assume good faith Be polite and avoid personal attacks Be welcoming to newcomers Seek dispute resolution if needed Article policies Neutral point of view No original research Verifiability

Find sources: Google (books · news · scholar · free images · WP refs) · FENS · JSTOR · TWL

Archives: 1, 2, 3, 4, 5, 6, 7, 8Auto-archiving period: 3 months

	Many-worlds interpretation is a former featured article candidate. Please view the links under Article milestones below to see why the nomination was archived. For older candidates, please check the archive.
Article milestones Date Process Result August 1, 2005 Featured article candidate Not promoted

Physics B‑class Mid‑importance

This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Misplaced Pages. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.PhysicsWikipedia:WikiProject PhysicsTemplate:WikiProject Physicsphysics B This article has been rated as B-class on Misplaced Pages's content assessment scale. Mid This article has been rated as Mid-importance on the project's importance scale.

Archives

1 2 3 4 5

This page has archives. Sections older than 90 days may be automatically archived by Lowercase sigmabot III when more than 5 sections are present.

Many-minds: Not as irrelevant as its single-sentence section suggests.

I don't like the current sentence about the Many-minds interpretation. Here's my beef: The many-minds interpretation was originally presented as an "interpretation" of the many worlds interpretation (in Loewer and Albert's "Interpreting the Many Worlds Interpretation"). Basically it was an attempt to make sense of the Everettian picture in a way that didn't open you up to certain really bad-looking objections. Standard many-worlds, as a deterministic theory, has no obvious way of accounting for the quantum mechanical probabilities, even though it is through experimentation suggesting that the world obeys these probabilities that we came to accept the quantum mechanical picture in the first place. The Many-minds interpretation adds an explicitly indeterministic feature to many-worlds, which allows it to avoid this problem. In the many-minds picture, (in addition to the wavefunction) there are non-physical minds which evolve stochastically over time in a way that (by design) corresponds to the probabilistic predictions of QM (minds don't enter superpositions, even when the brains they are associated with do). The many-minds view shares the advantages of MWI and can account for the probabilities. The only problem with the many-minds view is that it's totally, unforgivably insane.

I would prefer if the article (1) mentioned the trouble that MWI has accounting for the probabilities which are a central part of QM and (2) mentioned that, rather than merely having a similar-sounding name, the many-minds interpretation is very relevant to the MWI, since it factors into an argument against MWI: if the only way of getting the right results from MWI is to interpret it as many-minds, then, since many-minds is utterly preposterous, MWI is either false or equally preposterous.

The article, as it stands, is structured so bizarrely that I'm at a loss as to where an addition of this sort could even fit in. I'm also not sure whether such an edit would last, since it involves a non-scarcrowified objection to the MWI, something conspicuously absent from the article as it stands. ZRPerry (talk) 21:55, 13 August 2010 (UTC)

1. The article already mentions probability within MWI in some detail.
2. Many-minds has been abandoned by one or both of its founders. The theory is essentially "dead".
3. There is ambiguity about what many-minds means (it exists in two distinct forms).

For these reasons it is better discussed in its own article, with just a short non-judgemental summary here. --Michael C. Price 05:07, 14 August 2010 (UTC)

PS I agree that this article has a bizarre structure. Some of the sections don't really help the reader. I tried to remove them, but the consensus was "keep". --Michael C. Price 05:10, 14 August 2010 (UTC)

My bad timing, as the issue had just been sorted... But actually, I was hoping you might (a) clarify whether Many–Worlds is a meta–interpretation, an interpretation, or a number of different meta–interpretations and/or interpretations... and (b) comment if a suitably abstract "MWMI" would be Physics or Metaphysics or ? (in terms of Instrumentalism/Entity realism). Thanks—Machine Elf 1735 (talk) 15:51, 14 August 2010 (UTC) (φύσις amateur)

According to Everett, with whom I agree, MWI is a meta-theory and a theory. Whether you want to call that an interpretation is debatable. To be an interpretation suggests that we have some freedom to adopt other viewpoints, but I don't think we have - although all adherents to other interpretations would disagree, of course. --Michael C. Price 18:01, 14 August 2010 (UTC)

Could someone clarify for me, isn't Many Worlds a meta–interpretation? Apart from the many franchises, isn't there a version abstract enough to permit probabilities to be calculated with whatever run of the mill math is accompanied by a straight face? If MWI is untestable (?) but addresses the paradoxes in a more logically salubrious way than alternatives, is it Physics?

Of course, the ontology is always sensationalized, (Multiverse makes a four course meal of that though). I think adding even one mini mind is much more extravagant when, "by design", why not have magic QM corresponding eyeballs collapse your wave function? Besides, we'll want that mind busy jumping from world to world finding our lotto numbers.

Is there anything useful about MWI that isn't ruined by mini minds?—Machine Elf 1735 (talk) 05:12, 14 August 2010 (UTC)

Unmentioned Thought Experiment.

I don't know if this is original, but a quantum random bit generator's ASCII output would appear intelligent in some world-lines. Could there be religious objections to the many-worlds interpretation? —Preceding unsigned comment added by Mister Mormon (talk • contribs) 02:05, 14 November 2010 (UTC)

Criticism Section

This article appears to be heavily biased towards the MWI; there exists only a section addressing common objections to the MWI based on misconceptions. Perhaps the article would benefit from a return to neutrality in the form of a 'Criticism' section, which mentions some of the main objections to the MWI which aren't ill founded. 220.235.96.106 (talk) 03:20, 21 March 2011 (UTC)

Can you think of any? (And can you source them?) -- cheers, Michael C. Price 07:42, 21 March 2011 (UTC)

I strongly agree that the article is heavily biased towards MWI, and in particular the "Criticism" section does not accurately represent the whole range of published views on the subject. Just doing a random review of six books on quantum mechanics and its interpretations, I find that all six of them are decidedly NOT favorable toward MWI, and some of them are outright derisive. These books are by recognized scholars and experts in the field, so they ought to be accurately reflected in this article, regardless of whether we agree with them.AIMW32 (talk) 14:07, 31 August 2011 (UTC)

There isn't a section called criticism. 1Z (talk) 14:35, 31 August 2011 (UTC)

Right, the section is called "Reception", and the point is that the section (as presently written) is preposterously biased in favor of MWI. According to Misplaced Pages policy, the section needs to be evenly representative of the reputable sources and literature on this subject. Most of the reputable sources are decidedly not favorable to the MWI interpretation, but a reader of this Misplaced Pages article, as presently written, would never suspect this. So the section needs to be re-written to be more balanced and representative.AIMW32 (talk) 04:43, 2 September 2011 (UTC)

I do not call having informative responses to criticisms "preposterously biased". However, if in the interests of "balance" you wish to include quotations from the six books that "are are decidedly NOT favorable toward MWI, and some of them are outright derisive.", go ahead; it is true that many "experts" are derisive - and the fact of their derision is worth reporting - although whether they still form a majority is not so clear. -- cheers, Michael C. Price 07:15, 2 September 2011 (UTC)

Welcome to Misplaced Pages, I hope you like it here and decide to stay. Here are some guidelines:

1. WP:CITE your sources, don't just make it up.
2. Or at least, make it is plausible. You did not find that most "scholarly literature on quantum mechanics and its interpretations" WP:DONTLIKE MWI from your "cursory" survey.
3. And see WP:OR before embarking on an extensive survey. It won't get any traction either. Cite one from an WP:RS.
4. Try to resist editorializing, but honestly, if you want to say MW-haters talk a lot of smack, I don't think that's likely to be challenged.—Machine Elf  09:50, 2 September 2011 (UTC)

Specific conditions of time travel.

Regardless of artificial or natural time travel claims, if time travel (wormholes) exists then parallel realities precisely make sense period. —Preceding unsigned comment added by 196.20.160.72 (talk) 09:13, 31 March 2011 (UTC)

The "Reception" Section

As mentioned above, I think the section on "Reception" needs to more accurately reflect the available reputable sources. Here is the kind of section that I think would be appropriate and representative of the views of the scientific community.

Reception

From the beginning, the response to the many worlds interpretation of quantum has been quite varied. Hugh Everett’s thesis advisor, John Wheeler, originally looked favorably on the idea, but in later years withdrew his endorsement. In an interview in 1986 Wheeler said “I supported this to begin with, because it seemed to represent the logical follow-up of the formalism of quantum theory. I have changed my view on it today because there's too much metaphysical baggage being carried along with it, in the sense that every time you see this or that happening you have to envisage other universes in which I see something else happening. This is to make science into a kind of mysticism.” Also, when (at Wheeler’s urging) Everett visited Neils Bohr in Copenhagen in 1959, hoping to convince Bohr of the soundness of the idea, Bohr and his circle reacted very negatively, even derisively. (This may have contributed to Wheeler’s loss of confidence, since he was a great admirer of Bohr.) Bohr's close colleague, Leon Rosenfeld, wrote in 1959 after meeting with Everett “This work suffers from the fundamental misunderstanding which affects all attempts at ‘axiomatizing’ any part of physics. The ‘axiomatizers’ do not realize that every physical theory must necessarily make use of concepts which cannot in principle be further analyzed. … The fact, emphasized by Everett, that it is actually possible to set-up a wave function for the experimental apparatus and a Hamiltonian for the interaction between system and apparatus is perfectly trivial, but also terribly treacherous; in fact, it did mislead Everett to the conception that it might be possible to describe apparatus + atomic object as a closed system. … This, however, is an illusion.”

In his book "Particles and Paradoxes, The Limits of Quantum Logic" Peter Gibbins remarks that the MWI "is taken very seriously by a few physicists and philosophers, and not at all by most others", and he follows this with a review of the range of criticisms.

Similarly in “The Structure and Interpretation of Quantum Mechanics”, R. Hughes says the MWI has been subjected to each of four types of criticisms: "(1) the internal consistency of MWI can be challenged, (2) it's philosophical coherence can be doubted, (3) one can object to the lack of fit between MWI and other physical theories, and (4) one can critize it on general methodological grounds." In particular Huges discusses what he regards as a problem concerning the lack of a valid probability measure for the outcomes of events. He says that those who contend MWI solves the measurement problem typically imagine that the probability distribution for the various possible outcomes of a sequence of quantum events can be associated with the relative number of future “worlds” that contain one set of outcomes versus another, but according to Huges there is no suitable principle of individuation to distinguish “worlds” in such a way that their relative numbers can be "counted" in any statistically meaningful sense. He concludes that the MWI does not provide us with any new understanding of the measurement process, because each observer is still faced with the dualism that the interpretation sought to eliminate. The only difference is that any "apparent" transition not governed by the Schrodinger equation "is now accompanied by an ontological cloudburst beside which the original modest dualism of von Newmann looks unremarkable, if not pusillanimous".

Euan Squires has written that "the general view of the theoretical physics community has been to reject the many-worlds interpretation... has become more fashionable in recent years". After reviewing again the problem of a lack of a suitable probability measure, Squires sums up his view as follows: "The many worlds interpretation of quantum theory only makes sense if some notion of selection, generally at random and probably associated with consciousness, is added to the theory."

Likewise, Roger Penrose comments : "It seems to me a theory of consciousness would be needed before the many worlds interpretation can be squared with what one actually observes... Claims have been made that the 'illusion' of can, in some sense, be effectively deduced in this picture, but I do not think that these claims hold up. At the very least, one needs further ingredients to make the scheme work. It seems to me that the many worlds view introduces a multitude of problems of its own without really touching upon the REAL puzzles of quantum mechanics."

Alistaire Rae’s response to the MWI was also negative. He wrote : "The idea of a near-infinite number of universes which can never interact with each other and whose existence can therefore never be verified seems to most scientists to be an extreme breach of this principle and certainly greater than that implied by the de Broglie-Bohm hidden-variable theory." Rae goes on to say "In recent years a combination of “many worlds” and subjectivism has been suggested. This proposes that there is no collapse, the wave function evolves according to the time-dependent Schrodinger equation, and that is all there is in the physical universe. However, we conscious observers are incapable of seeing the world this way; it is in our nature that we can be aware of only one result of any measurement process so, although the others are still out there, we are unaware of them. One of the problems that this approach gives rise to is to explain how different conscious observers always see the same results, and indeed it has been suggested that this points to all our consciousnesses being linked to some 'universal consciousness', one of whose jobs is to see that this agreement occurs!"

J. C. Polkinghorne has this to say : ", entities are being multiplied with incredible profusion. Such prodigality makes little appeal to professional scientists, whose instincts are to seek for a tight and economic understanding of the world. Very few of them, indeed, have espoused the Everett interpretation. It has, however, become more popular with what one might call the 'Gee-whizz' school of science popularizers, always out to stun the public with the weirdness of what they have to offer... Reality is not to be triffled with and sliced up in this way."

Huw Price has written "...quantum cosmologists have become enthusiastic supporters of the no-collapse view... Philosophers have been rather less enthusiastic, and there are a number of astute critical studies of the no-collapse proposal in the philosophical literature on quantum mechanics. One that is well-recognized by the view's proponents is... the issue as to why the many-branched reality it envisages should appear classical... but I want first to draw attention to a problem which seems not to be recognized at all by the proponents of the no-collapse view... It concerns the notion of probability in a model of this kind." Price then goes on to recount the problem discussed above, pointing out the lack of a suitable probability measure. He also comments that the task of critiquing MWI is complicated by "the fact that the interpretation is ill-defined in a number of crucial respects (among them, the issue of what, if anything, actually 'splits')."

David Wick writes: "Many-worlds go, in my opinion, beyond the reasonable and into science fiction... Contemplating all possible worlds suggests hubris but is philosophically respectable; claiming that they all co-exist is not."

In a series of interviews with prominent quantum physicists in 1986, including John Bell, John Wheeler, John Taylor, and David Deutsch, the first three spoke negatively about MWI, and even Deutsch (regarded as a well-known proponent of MWI) conceded that “I now think Everett was slightly wrong.” According to Deutsch, Everett thought that his interpretation followed directly from the formalism of quantum mechanics, but Deutsch believes that “even in his interpretation, one requires a little bit of extra structure in order to arrive at the interpretation… it is the little piece of mathematics which provides the connection between the wave function… and the concept of the many parallel universes. I don’t think one can do without this extra structure”. Deutsch agrees that this “little bit of extra structure” is needed “to tell us something about how any individual universe in this vast stack of cosmic alternatives fits into the stack”. Furthermore, Deutsch believes Everett was wrong to claim that MWI is empirically indistinguishable from the other interpretations. Deutsch contends that quantum mechanics under the MWI is not empirically equivalent to conventional quantum mechanics, because he says a sufficiently sensitive consciousness actually would perceive a superposition of universes – just as many critics of MWI have always asserted. He said “If we had fine enough senses, then we could detect or feel (whatever that would mean) the presence of the other universes”, and he suggests that it may become possible to test this with artificial intelligence devices within a few decades.

John Bell, although saying the the MWI had “some merit”, did not view it favorably. He said “I have strong feelings against it… it’s extremely bizarre, and for me that would already be enough reason to dislike it. The idea that there are all those other universes which we can't see is hard to swallow. But there are also technical problems with it which people usually gloss over or don't even realize when they study it. The actual point at which a branching occurs is supposed to be the point at which a measurement is made. But the point at which the measurement is made is totally obscure. The experiments at CERN for example take months and months, and at which particular second on which particular day the measurement is made and the branching occurs is perfectly obscure. So I believe that the many-universes interpretation is a kind of heuristic, simplified theory, which people have done on the backs of envelopes but haven't really thought through. When you do try to think it through it is not coherent.”AIMW32 (talk) 16:03, 3 September 2011 (UTC)

Thanks for doing all this. One thing that worries me here is that the Bell quote seems to be talking about something different from MWI as it is described in this article (he seems to be talking about a form of MWI in which measurements have special status and branching is instantaneous). The same may be true of some of the other quotes. (I'm not sure what to do about this - I just wanted to point out the problem.) --Zundark (talk) 12:12, 4 September 2011 (UTC)

Bell was reacting to early work by Everett. Ideas of decoherence came later. 1Z (talk) 18:10, 4 September 2011 (UTC)

I agree that there is some difficulty here, due to the fact that, at various times, various people have expounded various concepts, all of which are commonly grouped under the header of "the many worlds interpretation", and it's difficult to talk about the "reception" of all those ideas in a single article. This goes back to the very beginning, because one could say DeWitt (after his brief initial opposition) quickly became a supporter of Everett's interpretation, and yet, as many people have pointed out, the interpretation that DeWitt described was not identical to what Everett described. Likewise the people who regard themselves as proponents of "many worlds" today usually have in mind some particular vairant that is different from both the Everett and the DeWitt conceptions. For example, as noted above, Deutsch says Everett was wrong to believe that a viable interpretation arises purely from the formalism of quantum mechanics, and he (Deutsch) now agrees with many of the critics of Everett who always insisted that some additional feature was needed to even have a coherent interpretation. Furthermore Deutsch believes a sufficiently sensitive observer actually WOULD sense the superposition of worlds, which Everett (and many current proponents of "many worlds") would vociferously deny. So is it correct to count Deutsch as a supporter of Everett's interpretation, or as a critic and debunker of it?

Despite the fact that many of the scientists I quoted above were addressing variants of "many worlds" that differ from the variant that is espoused by the "owners" of this Wiki article, all these scientists were giving their reaction to what had been presented to them as the "many worlds" interpretation, so I think this is legitimately part of the "reception" of many worlds. Maybe the best that can be done in this article would be to preface the "Reception" section with an explanation that a variety of ideas related to "many worlds" have been proposed, some differing from each other in significant ways, and this section surveys the reception of this whole class of ideas. In many cases, those who espouse one particular variant of "many worlds" actually agree with the criticisms of the other variants, even though (of course) they believe the criticisms do not apply to their own preferred variant.AIMW32 (talk) 15:38, 4 September 2011 (UTC)

If a notable source says "many Worlds", that should count for Wikipedian purposes. WP should not filter, although it may contextualise (see below) 1Z (talk) 18:10, 4 September 2011 (UTC)

I think it would be better to "stick to physics" and don't give too much weight to opinions of people, and instead explain the detailed mathematical arguments that have been published in physics journals. E.g. we can explain Deutsch's thought experiment that demonstrates how exactly one could in principle experimentally falsify the Copenhagen interpretation. Count Iblis (talk) 15:49, 4 September 2011 (UTC)

I disagree: There is endless complaint about physics articles being too dry and technical here.1Z (talk) 18:10, 4 September 2011 (UTC)

Agree with 1Z, we are not here "just" to report the science, but also to report on the response to the theory, place it in context etc etc. -- cheers, Michael C. Price 21:48, 4 September 2011 (UTC)

Hmmm... a "reception" section (which is fairly standard to be included in an article of this kind) is basically intended to report the views, expressed in reputable published sources, of scientists, giving a representative indication of how the subject theory has been received within the scientific community. This consists of reporting and/or summarizing the published views of a representative sampling of recognized experts in the field. I don't think it would be appropriate to suppress this information in the present article, even if some editors here don't agree with how the scientific community has viewed the subject. We have to guard against constructing a novel narrative, i.e., cherry picking published claims with which we (certain Wiki editors) agree, and suppressing the published reaction to those claims within the scientific community. For example, when you say above that Deutsch's thought experiment "demonstrates" how one could in principle falsify Cophenhagen, you seem to think this is somehow definitive and nothing more need to be said, whereas in fact there is nothing like universal assent to Deutsch's claims within the overall scientific community (nor even within the many-worlds community). The criticisms expressed by many scientists are precisely aimed at the claims of people like Deutsch. So, although I agree with you that the article should explain Deutsch's claims (noting that they contradict the views of Everett, et al), I don't think this obviates the Reception section.AIMW32 (talk) 16:18, 4 September 2011 (UTC)

My apologies for not suggesting WP:NPOV as well. It's difficult to be objective, sometimes it's only possible collectively, and that can look a lot like mistakes from a subjective point of view (WP:AGF). Still, your version would be the obvious example of "cherry picking" (even flippant remarks) with no real effort to represent a competing point of view. It self-consciously repeats purported faults needlessly, hanging a lantern on the disproportionate number of negative assessments given (vs. zero positive) which must seem absurd.

While it does allude to the possibility of outdated counter-examples, the backhanded concession is spoiled by inaccurately stating the reaction to MW from "the beginning" has been "quite varied". The initial reaction was emphatically negative, it was ridiculed and summarily dismissed, as was Everett: "undescribably stupid and could not understand the simplest things in quantum mechanics" .

It goes out of its way to paint MW's advocates as opponents by misrepresenting qualified merits as unqualified defects or something of a renunciation and mia culpa. (It would need to provide more citations, not fewer, when contradicting other statements in the article; generally, anything likely to challenged should be cited. Also, the citations are inadequate; consider using citation templates, Template:cite, and please provide a page number where possible).

As was noted, it fails to distinguish between the various "theories" which have been associated with MW. It characterizing them all by the earliest versions or far-fetched attempts to fix it like "many minds", presumably the proper topic of several comments. However, these are portrayed as requirements of any MW interpretation, implying some kind of unscientific mystical (or otherwise disembodied) selection must be made.

Generally, the context of remarks is omitted, in effect, making it seem like other interpretations make better predictions ("selections") or anyway, that they make them at all. Perhaps the sources in question do mistakenly believe that MW doesn't use the square of the wave function, or that it dispenses with the wave function entirely. An accurate description is presented elsewhere in the article and its reception is not about what people mistakenly say it says. On the other hand, an "ontological cloudburst" is notably florid and stunningly wrong headed vis-à-vis hidden variables. In so far as the apparently metaphysical objection would be hypocritical, it may argue that some non-metaphysicists should "shut-up and calculate", foregoing a naïve appeal to Occam's razor, (i.e., instances of "world" count but instances of "particle" do not). But though interesting, it's not so much about MW's reception per se, it's about the irrationality of an individual's reaction, despite being a physicist (presumably).

Further, as an alternative to Copenhagen's fictional "collapse" (now recognized as philosophical dogma), MW provided an objective explanation of a subjective scenario. This is mischaracterized as the introduction of subjectivism by MW, rather than its refusal to ignore the issue. In so far as the fiction is science, similar charity is denied MW, because realism is not incompatible (another amateur foul vs. the null doxa; I don't think scientists should worry too much about paradox but MW is a philosophical slam dunk).

My advice would be to focus on how sources say it's been received, including the competing point of view.—Machine Elf  23:31, 4 September 2011 (UTC)

The sampling of comments on MWI that I gave above was not cherry picked. I honestly grabbed – quite indiscriminantly - every book I could lay my hands on that said anything on the subject, and wrote down what they said. I didn’t choose the sources based on whether they were favorable or unfavorable towards the MWI. It just so happens that they were all unfavorable (with the partial exception of Deutsch’s comments, but he was arguably advocating something different from what this Wiki article describes as MWI). Nothing I can do about it, other than go hunting for more books that discuss the relative merits of various interpretations of quantum mechanics, and try to find some that view MWI favorably. It's true that some of the references I cited were from a time prior to when "decoherence" began to be cited by proponents of MWI in response to certain kinds of criticisms, but not all of them were.

By the way, the existing article doesn't seem to directly address the issue of whether MWI solves or elucidates the measurement problem. The Wiki article on decoherence says specifically that it does not, and includes external links to references defending that poition. Since this is evidently a controversial point, and a very important one, I think this article should contain an explanation of how the proponents think MWI elucidates the measurement problem, and also why critics think it does not.

One other comment/question: Is the image that appears at the top of this article, showing a little film strip of Schrodinger’s cat splitting at the point of decision into a live cat and a dead cat, really representative of how the proponents believe MWI works? If so, then they ought to accept criticisms of this version of MWI. If not, the image ought to be replaced with one that depicts an interpretation that the proponents are willing to defend.AIMW32 (talk) 16:45, 5 September 2011 (UTC)

1. Davies, Brown, “The Ghost in the Atom”
2. Squires, "The Mystery of the Quantum World"
3. Penrose, "The Emperor's New Mind"
4. Rae, "Quantum Mechanics" (3rd ed)
5. Polkinghorne, "The Quantum World"
6. Price, “Time’s Arrow and Archimedes Point”
7. Wick, "The Infamous Boundary"

• B-Class physics articles
• Mid-importance physics articles
• B-Class physics articles of Mid-importance