Talk:Bell's theorem/Archive 9

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Hidden Assumptions published references

Further repetitive remarks from now-blocked IP. XOR'easter (talk) 18:44, 28 April 2022 (UTC)
The following discussion has been closed. Please do not modify it.
These published references should be written into the text of this wikipedia article. https://arxiv.org/abs/1108.3583 Karl Hess https://bayes.wustl.edu/etj/articles/cmystery.pdf E.T. Jaynes No, they shouldn't. See above for explanations of this point at considerable length. I would reiterate and try to find yet another phrasing, but I'd like an apology first. XOR'easter (talk) 22:12, 27 April 2022 (UTC) OK I apologize that I had stressed you out. Now, I take you up on your offer to rephrase what I had inserted into the article, although I thought my entry into the article was phrased very well. So shall I rephrase what I had written or shall you do it. Let's get started on it now because those two excellent published sources must be included in this wikipedia article. Go ahead, do it, I'll give you first shot at it. Let's go. 47.205.198.247 (talk) 01:33, 28 April 2022 (UTC) I'm not stressed out; that's not what you need to apologize for. Saying that I pulled Jaynes out of the text but stupidly forgot to remove the footnote to him is not just a personal attack but also is completely disconnected from the facts and suggests that you didn't read the article that you keep complaining about. That's completely unwarranted. In addition, you repeatedly claim that I requested that you rephrase your addition; I have done no such thing. As Tercer says, that's quite disingenuous. So, I'd like an apology for that, too. You are continuing your habit of making demands rather than arguments. This will get you exactly as far as it got you before: nowhere. XOR'easter (talk) 13:41, 28 April 2022 (UTC) It is dishonest for XOR'easter and Tercer to ignore Karl Hess' article and hide Jaynes in a footnote. Jaynes and Hess should be by name in the text of the article. There should be at least one sentence in the article about them both and not brush them off. 47.205.198.247 (talk) 13:32, 28 April 2022 (UTC) You are just repeating the same thing over and over again. Three different editors already disagreed with you. It's over. Stop flogging this WP:DEADHORSE. Tercer (talk) 14:06, 28 April 2022 (UTC) Wikipedia has a serious credibility problem, just like the New York FAKE NEWS mass media does. It's a shame indeed. 47.205.198.247 (talk) 14:46, 28 April 2022 (UTC) Why not include Hess et al. in Note 5 along with Jaynes ? Why Not ? Hess' article is published by the Royal Swedish Academy of Sciences. Do not censor it ! 47.205.198.247 (talk) 15:24, 28 April 2022 (UTC) As I have already explained, but you refuse to listen, Hess' article is published in Physica Scripta, which is not a reliable source, and has been ignored by the scientific community. In Wikipedia we cover papers published in reliable sources that have received the attention of the scientific community. Tercer (talk) 16:27, 28 April 2022 (UTC) Oh, I didn't know that the Royal Swedish Academy of Sciences is just a bunch of Crackpots. Wikipedia is a bunch of Crackpots as you will soon see when James Webb soon destroys all your big bang nonsense. Also, I am glad Jaynes is still in wikipedia even though you do everything to bury him because he casts doubt on Bell's nonsense. 47.205.198.247 (talk) 16:50, 28 April 2022 (UTC) I'm curious about what are you going to do when James Webb does not "destroy all your big bang nonsense", as will certainly happen. Are you going to admit that you were wrong and the Big Bang happened after all, or are you going to decide that James Webb is part of a pro-Big Bang conspiracy? Tercer (talk) 17:53, 28 April 2022 (UTC) You really do believe in it don't you. The universe once fit in a nutshell. hahaha. How gullible! And you believe in Bell's fairy tales of instantaneous action-at-a-distance too. ha ha ha. 47.205.198.247 (talk) 18:00, 28 April 2022 (UTC)

Statement of theorem

It's a bit unfortunate that a page about a theorem does not clearly state what the theorem itself actually is. The current opening statement, "Bell's theorem proves that quantum physics is incompatible with certain types of local hidden-variable theories", is about the consequences of the theorem and does not say what the theorem states. Vegard (talk) 13:26, 22 November 2021 (UTC)

Part of the problem is that there are many ways to extract a formal mathematical "theorem" from Bell's arguments. And Bell himself did not help: he once wrote that his "theorem" was just his inequality. I would say: there exists a mathematical theorem saying that one certain mathematical-physical framework is a special case of another. "Local realism" is strictly contained in "Quantum mechanics". I also think there are mathematically interesting ways to state something looking like the Bell-CHSH inequality. I will add some references later to my own work in this area. Feynman did not help either by saying that Bell's theorem was a triviality which everyone who was familiar with quantum mechanics already knew. Bell merely wrote out "a proof" but it was not particularly interesting to a physicist who was already familiar with quantum mechanics. Yet another point is that Bell's arguments also showed that *reality* (results of laboratory experiments) is incompatible with local realism (under certain assumptions, again).

How about just rewriting as "Bell's theorem states that quantum physics is incompatible with certain types of local hidden-variable theories. Richard Gill (talk) 15:27, 22 November 2021 (UTC)

Thank you for the response. I can't contribute much, as I was reading the page to build my understanding in the first place. Having looked at "On the Einstein Podolsky Rosen Paradox" (from the references in the article), probably the closest thing you can get to a proper statement of the theorem by Bell himself is: "the statistical predictions of quantum mechanics are incompatible with separable predetermination", which is close enough both to the original sentence and your proposed rewrite -- in other words, for what it's worth, I agree with your proposed rewrite.

However, one question: Why "certain types" and not simply all local hidden-variable theories? Vegard (talk) 13:02, 27 November 2021 (UTC)

"What Bell Did" by Tim Maudlin (https://arxiv.org/pdf/1408.1826.pdf) seems to offer an even stronger statement: "What Bell proved, and what theoretical physics has not yet properly absorbed, is that the physical world itself is non-­‐local." Vegard (talk) 14:48, 27 November 2021 (UTC)

Few experts actually agree with Maudlin. See the reply by Reinhard Werner, for example. XOR'easter (talk) 15:33, 27 November 2021 (UTC)

Great, another rabbit hole; I wasn't even finished with the first few! (Thanks ;-)) Vegard (talk) 15:41, 27 November 2021 (UTC)

Ugh, having read both these now, I really find Maudlin much more persuasive. Not to mention this disgusting footnote in Werner's reply: "Readers might be puzzled as to why Maudlin puts “measurement” in scare quotes. He does not explain why in his paper, but this is just what good Bohmian boys do." Vegard (talk) 19:10, 27 November 2021 (UTC)

Tone aside, there's no consensus that the impossibility of local hidden-variable models must mean that quantum theory itself is nonlocal in any meaningful way. The standard text by Nielsen and Chuang says that "most physicists" keep locality and abandon something else, "although others have argued that the assumption of locality should be dropped instead" (p. 117). Advocates of interpretations ranging from Many Worlds (e.g., Sidney Coleman [1]) to consistent histories (e.g., Pierre Hohenberg [2]), to informational (e.g., Brukner [3]), to relational (Rovelli [4]), to neo-Copenhagen (e.g., Englert [5], Streater [6], or Haag [7]), to QBist (Mermin, Fuchs [8]) all endorse locality. In their own various ways, they don't see the EPR criterion as "analytically" true, as Maudlin does. (They certainly don't all agree with each other about everything else, of course.) To be policy-compliant, a Wikipedia article should avoid giving the impression of more consensus than actually exists, which means sticking with a modest statement overall and then detailing the various reactions in the appropriate subsections. XOR'easter (talk) 20:11, 27 November 2021 (UTC)

Bell test currently has this (unsourced) definition of the theorem: "According to Bell's theorem, if nature actually operates in accord with any theory of local hidden variables, then the results of a Bell test will be constrained in a particular, quantifiable way." Later, the article also states: "In 1964, John Stewart Bell proposed his now famous theorem, which states that no physical theory of hidden local variables can ever reproduce all the predictions of quantum mechanics. Implicit in the theorem is the proposition that the determinism of classical physics is fundamentally incapable of describing quantum mechanics. Bell expanded on the theorem to provide what would become the conceptual foundation of the Bell test experiments." Vegard (talk) 15:52, 27 November 2021 (UTC)

as I see "Bell's theorem" mostly used, it is not about quantum mechanics at all. It states that all "local-realistic theories" (="local hidden variable theories") must satisfy certain constraints on the correlations of measurement outcomes of space-like separated measurements. Some of these constraints are not obeyed by QM, thus, as a corollary of Bell's theorem, QM cannot be local-realistic. I find it important that Bell's theorem is a theorem about a whole class of theories, not just about the properties of a single one (QM). However, if there were no such corollary (an actually relevant theory outside the setting of local realism), then the "theorem" would have received little attention. Hence maybe including "...and QM does not obey all of them." in the statement of the theorem makes sense? --Qcomp (talk) 16:56, 27 November 2021 (UTC)

There are several versions of Bell's theorem. The most popular one is the version proved in by Clauser, Horne, Shimony, and Holt in their 1969 paper. It's the one use in Nielsen and Chuang's textbook, for example. It's not philosophically deep, but at least it is very clear cut. Bell himself proved two versions (see [9]), one in 1964 and another in 1976. The 1964 version is an informal mess, we should never use that. The 1976 theorem is my personal favourite, but I think for the purposes of this article it's better to stick with the version by CHSH. Which is what the article is doing now anyway, down to copying Nielsen's and Chuang terrible notation. Tercer (talk) 13:35, 19 April 2022 (UTC)

I'd be amenable to improved notation. XOR'easter (talk) 03:51, 24 April 2022 (UTC)

Ok, I gave it a go. Tercer (talk) 13:17, 29 April 2022 (UTC)

Looks good to me; thanks. XOR'easter (talk) 13:46, 29 April 2022 (UTC)

• I tweaked the lead several times; the biggest issue was the phrasing "Bell's theorem proves..." which cannot be correct. A theorem doesn't prove anything; a theorem is a statement which can be proven itself. Theorems state things, mathematics and experimentation may prove a theorem, but the theorem is not itself a proof of anything. Bell's theorem in its most basic form is that there are no "hidden variables" that are compatible with the mathematics of quantum mechanics. --Jayron32 14:54, 29 April 2022 (UTC)

I think you're just being pedantic. Nevertheless, I think your phrasing was an improvement over the previous version. Tercer (talk) 15:02, 29 April 2022 (UTC)

I think the revisions are a move in a good direction, yes. This isn't a hill I want to die on, but in my experience, saying that a theorem proves something is common and fine. Google Scholar finds over 20,000 hits for the exact phrase "theorem proves", very few of which look to be false positives. For example, Will someone say exactly what the H-theorem proves? Or, But it is not true that Goedel's theorem proves this. Or, The following theorem proves that the condition on the quotient groups is not necessary. An article in Nature begins, Bell's theorem proves the existence of entangled quantum states with no classical counterpart [10]. I am reluctant to impose a prescriptive rule that the literature we summarize apparently does not care about.

I'm a bit concerned about the phrase "mathematical rigor", which might not put its finger quite on what varies across the theorems in question. To me, that carries the connotation that some of them use epsilon-delta proofs while others make handwaves about tiny intervals, you know? XOR'easter (talk) 15:11, 29 April 2022 (UTC)

 Fixed. --Jayron32 15:14, 29 April 2022 (UTC)

Also, regarding "prove" versus "state", using the "proof" phrasing is awkward in an opening sentence, which should describe what a concept is and not what it does. Perhaps I was a bit too harsh on proscribing the usage, but just because one can in many contexts say "Such and such a theorem proves that..." doesn't mean this is one of those contexts. As the first sentence of an article, it is awkward IMHO, which is why I think the "states" phrasing works better here. --Jayron32 15:16, 29 April 2022 (UTC)

To explain where I'm coming from: I'd say that an opening sentence should get across the most important thing, which in this case is more of a does than an is. The is of any of these theorems is a statement about correlations or expectation values, an inequality that will necessarily be satisfied given some assumptions. That's much more detailed, esoteric, and opaque than the import of the theorem. One might forget the proof of a particular Bell inequality, but remember the inequality; then one might forget the inequality but remember the meaning of it, and that meaning is the big primary message to convey. This doesn't have to be done with the phrase "Bell's theorem proves", but it makes the use of the verb "proves" sound natural to me. "Bell's theorem states" sounds just a little off, because the statement of a Bell inequality doesn't itself include quantum theory. The sum of these expectation values for these combinations of binary measurements lies within this interval — that's not a statement within or relying upon the language of quantum mechanics. Now, the reason why we care about such an inequality is that, when you bring in quantum mechanics, you can get a violation of that inequality. The important thing is that consequence. XOR'easter (talk) 15:46, 29 April 2022 (UTC)

I have tried to further elaborate, using language which is both accessible and as accurate as possible, what Bell's theorem means and why it is important, clarifying where necessary. This has necessitated breaking of the basic explanation into it's own lead paragraph, and leaving the more esoteric details in later paragraphs. Fundamentally, Bell's theorem is a means to disprove hidden variable theories; which is to say that any "quantum weirdness" introduced by quantum experiments cannot be explained by unmeasurable variables. The manner in which it does this is less important, for a non-physicist trying to understand what it's all about, than the fact that it does so disprove local hidden variable theories, and I hope the opening paragraph does capture that in as clear of a language as possible. The following paragraphs in the lead are now more about the specifics of the theorem, mainly the history of its development (response to the EPR paradox) and the manner in which it does what it says on the label (Bell inequalities and all that), and finally the lead section goes into variations on, and experiments testing, the theorem. I think this gives a better narrative flow than the prior lead. I welcome further improvements, but in general I stand by my changes as an overall improvement to what was previously a hard-to-follow lead section. --Jayron32 15:55, 29 April 2022 (UTC)

I think we share a view of what is important to convey, details of verb choice aside. Huzzah! :-) I have two remaining concerns, neither of which I know how to resolve. First, I worry a bit about how the first paragraph treats "Bell's theorem" as a single result. Compare with how the Stanford Encyclopedia article begins: Bell’s Theorem is the collective name for a family of results.... There isn't just one theorem inequality with multiple derivations, the way there are hundreds of proofs of the Pythagorean theorem or the law of quadratic reciprocity; there are actually multiple different inequalities (Bell '64, CHSH, etc.). Maybe there's some small tweak that can address this. (I tried "umbrella term" but am not wedded to that.) My other concern about the first paragraph as it currently stands is how it drops in the "local realism" term of art so quickly. My guess is that anyone who has a clue what "local realism" might mean already knows a lot about Bell's theorem. It doesn't really elucidate the meaning of "local hidden-variable theory" used in the previous sentence, being a term of equal or greater technicality. XOR'easter (talk) 16:38, 29 April 2022 (UTC)

WOuld it make more sense to move the article to "Bell's theorems"; since it would be awkward to use the singular but still refer to multiple independent inequalities? --Jayron32 16:41, 29 April 2022 (UTC)

I have also added a bit of an elaboration on the "local realism" issue as you suggested. --Jayron32 16:50, 29 April 2022 (UTC)

I went ahead and also tried to introduce wording that closer mirrors the Stanford Encyclopedia introduction. --Jayron32 16:53, 29 April 2022 (UTC)

Thanks!

Using "Bell's theorem" in the singular as a collective label is pretty standard. "Bell's theorems" is awkward in its own way, because they weren't all proved by Bell, and some people say "Bell's theorems" to mean the two different results of Bell '64 and Bell '66 [11]. Bell inequalities is a title that sounds natural to me in the plural. XOR'easter (talk) 17:02, 29 April 2022 (UTC)

All this reminds me that we have a heap of overlapping articles on this general topic. In addition to the current article, we've got Bell test, Hidden-variable theory, Local hidden-variable theory, EPR paradox, quantum nonlocality, principle of locality, etc. Some of that is probably fine. There's enough historical material specific to EPR paradox that I'm comfortable dedicating a page to it. But Local hidden-variable theory sounds like it should be a section within Hidden-variable theory, while its content actually reads like a fork of Bell's theorem. XOR'easter (talk) 17:15, 29 April 2022 (UTC)

I'd like to clarify that the multiple versions of Bell's theorem do not refer to the multiple Bell inequalities. Rather they refer to the different assumptions use to derive the factorizability condition, i.e., $p(ab|xy)=\sum _{\lambda }p(\lambda )p(a|x,\lambda )p(b|y,\lambda )$. This is what you to need to derive whatever Bell inequality in whatever scenario you want. Now deriving the Bell inequalities is a well-understood and uncontroversial technique, when papers discuss the versions of Bell's theorem they are discussion the assumptions you can use to obtain factorizability.

Also, we should avoid the term "local realism". Sometimes it still appears in the literature, but usually people talk about local hidden-variable theories (LHVs) instead. The problem is that the informal interpretation of "realism" is having an objective reality, and people do often misunderstand the result as implying that to have locality we have to give up on having an objective reality. This is nonsense, of course. The assumption of "realism" in the proof simply means determinism. Tercer (talk) 17:44, 29 April 2022 (UTC)

How about starting the second sentence, The "local" in this case refers to the idea that a particle can only be influenced by its immediate surroundings? Or maybe we should explain "hidden variables" first, and then say that in a local HV theory, interactions are restricted. XOR'easter (talk) 18:30, 29 April 2022 (UTC)

Per your suggestion, I took out the "realism" and replaced it with Principle of locality, which seems more relevant here. I do think the following clause is necessary, because what "influenced by" means here is "field-mediated interactions" which are governed by speed of light concerns; the very notion that an interaction could occur faster than the speed of light, "spooky action at a distance", is at the heart of the EPR paradox and of Bell's response to it; the invocation of "hidden variables" was only done to resolve this paradox. The idea of interacting with one's local environment requires such a discussion to make sence. --Jayron32 18:35, 29 April 2022 (UTC)

I think that's a good solution. I also removed the last mention of "local realism" that was done in Wikivoice from the text. Tercer (talk) 18:59, 29 April 2022 (UTC)

Makes sense to me. I noticed and removed an instance of "local realist" and tweaked a quote [12]; I'd be fine in principle with quoting someone saying "local realism", but since we don't define it, a verbatim quote is less than clear. Perhaps there's a better way to handle that — I don't have strong feelings on the matter. XOR'easter (talk) 19:03, 29 April 2022 (UTC)

I know we're not really supposed to edit this archived page, I just wanted to add my thanks to XOR'easter, Tercer, Jayron, and Qcomp for a very nice discussion, good points, and a good resolution. Vegard (talk) 07:28, 10 October 2022 (UTC)

Remove specious and unnecessary claim about MWI that measurement causes alice and bob to 'split'

I would like to point out that the appeals to splitting and copying remove clarity by adding too much detail and thereby creating a functional fixedness effect for the reader. MWI does not require that any kind of splitting or copying take place. Things are waves and this is part of wave motion. I have made this edit boldly, and it has been reversed. The edit does not add material or substantially change it to disagree with the source. It improves the material by helping readers get a correct sense about how physicists consider this problem.

Thanks. --71.32.81.195 (talk) 12:41, 6 May 2022 (UTC)

I don't see what's all that unclear about the text as it stands (after Tercer's latest partial revert). Splits or branches or copies are derived from unitary evolution as approximations or emergent phenomena, in a manner that depends upon which particular version of MWI is being considered. As Lev Vaidman writes, In the framework of the many-worlds interpretation we need splitting of worlds. The moment of splitting does not have a rigorous definition, but a standard definition ... is that macroscopic objects must have macroscopically different states [13]. XOR'easter (talk) 14:40, 6 May 2022 (UTC)

Another correct interpretation is that both branches of bob existed before, and each one observed a different outcome. This does not involve splitting. The bobs are not copies, they are *similar*. Upon further consideration, the cited text does not at all support the claim or interpretation that bob is split by the measurement. It would be more appropriate to say that they are *polarized*. It is a subtractive operation at best, not an additive one. Please consider emphasizing the 'branch' nomenclature to reflect the concurrent existence of various alices and bobs prior to the measurement.

71.32.81.195 (talk) 14:44, 6 May 2022 (UTC)

Adding,

> Unitary processes of decoherence

lead to effective non-interaction between the different terms in this superposition, and lead to effective classicality for their future evolution over time.

I have said this before as "the experimenter is a wave, and when the experiment wave hits the experimenter wave, each part evolves mostly clasically". MWI needs to be open to this interpretation.

The problem with your edit is that the following sentence is unintelligible, and only true under this particular "overlaping branches" interpretation: The explanation it provides for the Bell correlations is that different local branches of Alice and Bob make the various measurements. From the point of view of each branch of Alice, there are multiple branches of Bob experiencing different results, so Bob cannot have a definite result, and the same is true from the point of view of each branch of Bob. The formulation with splitting and copying is both easier for the lay reader to understand and has more support in the literature. Tercer (talk) 07:13, 7 May 2022 (UTC)

Hidden Assumptions in Bell's Theorem

This article needs to be inserted into Wikipedia. https://www.researchgate.net/publication/51931411_Hidden_assumptions_in_the_derivation_of_the_Theorem_of_Bell — Preceding unsigned comment added by 47.205.198.247 (talk) 14:08, 6 April 2022 (UTC)

quod grātīs asseritur, grātīs negātur. XOR'easter (talk) 16:31, 6 April 2022 (UTC)

The source is reputably published in Physica Scripta, and so must be accepted into wikipedia. 47.205.198.247 (talk) 04:12, 7 April 2022 (UTC)

No, it doesn't. The mere fact of publication in a journal doesn't by itself merit inclusion anywhere here. Plenty of papers are published in journals and then forgotten, or ignored outside the tiny niche of their original authors and a few friends. Sometimes papers get published and turn out to be total garbage. Wikipedia's job is to be a reference for mainstream science, not to provide publicity for obscure challenges to established material. Also, making uncivil comments is not going to be any more productive than it was when you tried it on this page last summer or at the quantum entanglement article last spring. XOR'easter (talk) 04:45, 7 April 2022 (UTC)

Dr. Hess, who has 600 publications, is not the only physicist to publish an article critical of John Bell's work. You are not allowing any of them.47.205.198.247 (talk) 13:08, 18 April 2022 (UTC)

A total number of "publications" is meaningless, except that a very big number might raise a physicist's eyebrow and suggest that not very much work went into each one. Policy requires that we not make viewpoints look more influential or more highly regarded than they actually are. The article includes a mention of Jaynes' skepticism and a lengthy section on possible loopholes, because that is all justifiable. XOR'easter (talk) 14:44, 18 April 2022 (UTC)

You are mistaken. That section "Other Criticism" where Jaynes was mentioned was deleted by someone, probably you. Put it back and add the Hess article to it. 47.205.198.247 (talk) 18:56, 18 April 2022 (UTC)

Jaynes is reference 91. I actually looked for material to justify expanding what is said about him now, but I did not find much in the way of specifics published in reliable sources. XOR'easter (talk) 19:40, 18 April 2022 (UTC)

It is ridiculous to have a footnote 91 to Jaynes when there is no footnote 91 anywhere in the text. Jaynes should be in the text and so should also be Dr.Hess along with him. 47.205.198.247 (talk) 13:05, 19 April 2022 (UTC)

Hess is a crackpot, and Physica Scripta is a crackpot journal. He resorted to outright lying in another of his "disproofs" of Bell's theorem. Tercer (talk) 13:45, 19 April 2022 (UTC)

It is against Wikipedia rules to call each other crackpots and your post must be deleted for it. Also, if you can refute Dr.Hess' above article on hidden assumptions, then let's hear it. You cannot. 47.205.198.247 (talk) 02:10, 20 April 2022 (UTC)

"Each other" being the relevant part. This only applies to Wikipedia editors, we can speak freely about other people. Also, I have better things to do than reading Hess' drivel. Reorganizing my sock drawer comes to mind. In general, editors are not supposed to referee any paper here, what is relevant is whether they are published in reputable journals and have attracted the attention of the scientific community. Hess' paper fulfils neither criterion. Tercer (talk) 06:07, 20 April 2022 (UTC)

Jaynes' reference should be restored to the text in the Wikipedia article, and Dr.Hess' article should be there with it. See Jaynes here https://en.wikipedia.org/w/index.php?title=Bell%27s_theorem&oldid=1074285206#Other_criticism

I've reverted your addition. On top of violating WP:RS and ignoring WP:UNDUE, the text in question was completely disorganized; the article already introduced the Conway–Kochen free will theorem elsewhere, in a way that actually integrated it with its historical and conceptual context, and without going overboard about it in an article that is not devoted to it. When everyone else disagrees with you about doing something, it's probably a bad idea to go ahead and do it after making literally zero policy-based arguments for it. XOR'easter (talk) 15:07, 23 April 2022 (UTC)

XOR'easter is Wrong to delete that entire section entitled Other Criticism which applies directly to Bell's Theorem. XOR'easter is Wrong to not allow any criticism of Bell's Theorem, which definitely belongs right here. That section has been in wikipedia since last year and XOR'easter comes along and deletes the entire section. I add that most physicists are skeptical of Bell's Theorem and Bell's wild claims and this must be expressed here in wikipedia. Restore the section. 47.205.198.247 (talk) 17:19, 23 April 2022 (UTC)

Longevity of content is not a guarantee that it is good; outright hoaxes have survived for over sixteen years. This is particularly true in subject areas that accumulate cruft and that have few editors willing to put in the work to clean them up. Quantum foundations is a prototypical example of such an area. The claim that most physicists are skeptical of Bell's Theorem is wildly, yet unsurprisingly, untrue.XOR'easter (talk) 17:46, 23 April 2022 (UTC)

Karl Hess' article is published by the Swedish Royal Academy of Sciences and XOR'easter wants it censored, and he wants no mention of Jaynes in the text of the article. That is all blatant censorship. 47.205.198.247 (talk) 17:56, 23 April 2022 (UTC)

What you call censorship, we call WP:DUE. Headbomb {t · c · p · b} 18:06, 23 April 2022 (UTC)

Your reference says there can be See Also sections in wikipedia. The section that XOR'easter wants censored should at least remain in wikipedia as See Also. — Preceding unsigned comment added by 47.205.198.247 (talk) 18:31, 23 April 2022 (UTC)

That's not what a "see also" section is. Like, at all. XOR'easter (talk) 18:40, 23 April 2022 (UTC)

Jaynes must actually be mentioned right in the text here because he is shown as a footnote to nowhere in the text. Karl Hess should be there too, with Jaynes, right in the text. Best way to do that is to restore the Other Criticism section as I had done earlier today.47.205.198.247 (talk) 18:46, 23 April 2022 (UTC)

This still violates WP:RS and WP:DUE. The article is in no way improved by adding a crackpot who has spent the last twenty years failing to take criticism to heart. XOR'easter (talk) 03:03, 24 April 2022 (UTC)

Crackpot? XOR'easter is the one who first pulled Jaynes out of the text but stupidly forgot to remove the footnote to him. It is now a hanging footnote to nothing in the text. 47.205.198.247 (talk) 03:14, 24 April 2022 (UTC)

No, it isn't. It is plainly and evidently cited in Note 5.

At this point, on top of making personal attacks upon other editors, you're doing very little to convince anyone that you're here to build an encyclopedia. XOR'easter (talk) 03:20, 24 April 2022 (UTC)

Bell's mysticism is not physics. In Note 5, I see that Gill listed a good number of physicists who think Bell's work is wrong. They should all be cited in this wikipedia article in a section regarding Criticism, so wikipedia readers will see that not all physicists believe Bell's nonsense. 47.205.198.247 (talk) 03:34, 24 April 2022 (UTC)

Bell was the furthest thing from being a mystic, and brief "this is why these are not persuasive" discussions of incredibly marginal views in a conference proceeding do not amount to significant coverage.

If anyone is curious, there's a brief dismissal of this aspect of Jaynes' thinking here, but the passage is mostly about other writers and says very little about Jaynes specifically: Fuchs, Christopher A. (2011). Coming of Age with Quantum Information: Notes on a Paulian Idea. Cambridge, UK: Cambridge University Press. pp. 268–271. ISBN 978-0-511-76278-9. OCLC 712621692. Jaynes' metaphor about the omelette has probably been more influential than his thoughts on Bell's theorem. XOR'easter (talk) 03:46, 24 April 2022 (UTC)

Your Note 5 says Jaynes was one exception which is false. Gill lists many physicists who question the validity of Bell's work. They should all be mentioned here in wikipedia. Controversial subjects like Bell's theorem and Big Bang nonsense should not be presented by Wikipedia as facts. — Preceding unsigned comment added by 47.205.198.247 (talk • contribs)

Somewhere below, this degenerated into argumenta ad hominem et ad populum, and unconstructive bickering. Please stick to content and sourcing. —David Eppstein (talk) 19:03, 10 April 2022 (UTC)
The following discussion has been closed. Please do not modify it.
Wikipedia should not present wild theories like instantaneous action-at-a-distance, or big bang nonsense, without allowing expression of most physicists that such things are nonsense. Wikipedia is misleading the public and making fools of themselves. 47.205.198.247 (talk) 12:45, 7 April 2022 (UTC) The comment by 47.205.198.247 might confuse some Wikipedia readers. What the IP editor calls "Wild theories" are published in peer-reviewed journals according to the long tradition in physics and science in general, backed up by a long consensus of other papers, the equivalent of meta-analysis in Medicine. Although there is a general policy against removing talk comments, I suggest, in this special case, deleting such a post. Calling these theories "nonsense" is just not acceptable. Limit-theorem (talk) 13:18, 7 April 2022 (UTC) Hess has nearly 600 published articles and he should be included here in Wikipedia. His article must be included. Also, there is mainstream skepticism over big bang theory and also over magical instantaneous action-at-a-distance. Wikipedia should not present such things as facts.47.205.198.247 (talk) 13:35, 7 April 2022 (UTC) You are following the same fruitless path as before. No, physicists don't all agree with you in secret, there is not "mainstream skepticism over big bang theory", and as we tried to explain to you before, that's not what entanglement is. XOR'easter (talk) 15:37, 7 April 2022 (UTC) I am a physicist and know many physicists. None of them believe in instantaneous action-at-a-distance nor in the big bang nonsense. 47.205.198.247 (talk) 16:44, 7 April 2022 (UTC) You mischaracterize the phenomenon of entanglement, the meaning of Bell's theorem, and what is known about the Big Bang. Furthermore, it is apparent that you mischaracterize your own training in physics. It is not appreciated when contributors pretend to more expertise than they actually exhibit. Prokaryotic Caspase Homolog (talk) 22:18, 7 April 2022 (UTC) James Webb Telescope will destroy your ridiculous big bang theory and you will eat your ignorant words. 47.205.198.247 (talk) 12:57, 10 April 2022 (UTC) Do you know that you get permanently blocked for insulting editors? Wikipedia is a professional space. Limit-theorem (talk) 13:16, 10 April 2022 (UTC) and Who is insulting whom? 47.205.198.247 (talk) 13:18, 10 April 2022 (UTC)

I think it could be a good idea to write a Wikipedia article on the ongoing debates about the interpretations and assumptions of Bell's theorem. I made a start in an own sandbox, anyone is welcome to build further on this. https://en.wikipedia.org/wiki/User:Gill110951/Bell_theorem_opposition. Here follow the thoughts on this which I wrote on that page. You can also find many links and further names there.

There continues to be lively debate on the meaning and the correctness of Bell’s theorem. To some extent, this debate continues outside of “establishment science”; but also within established academia, there exists a vocal minority who disagree with the general consensus in the physics community that the early debates between Einstein and Bohr were concluded in Bohr’s favour. Unfortunately, the disagreements inside this minority are extremely large, too [cite Karl Hess on this: he noted sadly that though many people seem to believe that Bell was badly wrong, none of hem agree with one another; they each have their own pet "refutation" and pet "alternative" but none of them adopts the solutions of the others].

There are two main ways to “get around” Bell’s theorem. The most radical is to suggest that there are mistakes in common proofs of the theorem, or even that the violation of Bell’s inequality in experiments actually points to failings in usually accepted mathematics or logic [e.g. Itamar Pitowski]. Less radical is to exploit some alternatives which were already explicitly discussed by Bell in his many papers over the years: “superdeterminism”, and “retrocausality”. Superdeterminism is presently (2020) being championed by Sabine Hossenfelder, Tim Palmer, and for quite a few years has been supported by Gerard ‘t Hooft. Retrocausality has champions in Leifer and Pusey, Jarek Duda, and others.

The theorem is commonly supposed to say that quantum mechanics is incompatible with locality and realism, but a third condition, sometimes denoted freedom, sometimes no-conspiracy, is often added by many writers. Superdeterminism, and retrocausality, imply that experimenters do *not* have the freedom to choose experimental parameters freely. Other scientists reject locality. Finally, there is a possibility to reject realism. According to the many-worlds interpretation of quantum mechanics, the branching of possibilities allegedly occurring when quantum measurements are made is an illusion. All possibilities co-exist. Another radical way to avoid realism is QBism, according to which physics merely tells an agent what the probabilities will be of future experiences, when they make various possible different future interventions. The question of whether or not there is an objective reality out there is thought to be irrelevant.

The terminology itself is also hotly debated. The word “conspiracy” is objectionable, since pejorative. Example: QBism is solipsistic, but solipsism is itself a pejorative word. Recently the term "convivial solipsism" has been invented, to point out that even if you only have your own sensory impressions to depend on, you do become aware through those impressions that other beings seem to be around you, who already know useful stuff. You are not entirely on your own. I would add that evolution has also put the memories of our ancestors at our disposal.

A fundamental question is what is meant by “understand”. For some, to understand just means to be able to calculate and predict. To others, it means having expressed something in terms of fundamental intuitive concepts. Neurolinguistics has the notion of “systems of core knowledge”, standing for knowledge in our brains about the world which has been built-in by evolution, and which needs to be there in order to interpret experience and acquire knowledge. I have written about this myself in one paper. I suggest that the reason "nobody understands quantum mechanics" is quite simply that our human brains cannot understand it, because it contradicts the basic modules of understanding the world which are built into our brains by evolution. All one can do is become familiar with the mathematics, and indeed, gain intuition and be creative with it. Richard Gill (talk) 11:01, 20 May 2022 (UTC)

Indicate subtleties in reasoning

I added the qualifier "apparently" (to collapses) and replaced "this means" by "this suggests" in the early sentence in the article describing collapse of the state. After all, we have interpretations of quantum mechanics which deny the physicaal reality of the quantum state and see the "collapse" as a computational device for updating predictions about future measurement results. When an agent's knowledge changes, their predictions about the future might well change too. But physical reality around them has not changed. Richard Gill (talk) 10:21, 20 May 2022 (UTC)

This is the sentence I am referring to, my new words in bold: "When they choose a measurement and obtain a result, the quantum state of the other particle apparently collapses instantaneously into a new state depending upon that result, no matter how far away the other particle is. This suggests that either the measurement of the first particle somehow also interacted with the second particle at faster than the speed of light, or that the entangled particles had some unmeasured property which pre-determined their final quantum states before they were separated." Richard Gill (talk) 11:07, 20 May 2022 (UTC)

Notice that Alice's idea of Bob's particle's state has changed after Alice does her measurement and sees her result, but Bob does not know anything yet. As long as no message from Alice reaches him, he is perfectly right to use the original joint state for his own local prediction purposes. In fact, he can also conveniently reduce the joint density matrix to the reduced state of his subsystem by tracing out the other. So what did collapse? Nothing. Alice's knowledge about the world changed because something happened close by, which she saw. Richard Gill (talk) 11:12, 20 May 2022 (UTC)

The result of Bob's measurement will still be correlated with Alice's in a manner that cannot be explained by a local influence. Talking about quantum states being subjective and people having the right to assign any state they want doesn't explain anything. It's just idle talk by people that insist in denying Bell's 1976 theorem. Tercer (talk) 11:52, 20 May 2022 (UTC)

I agree. I am not denying Bell’s theorem. Richard Gill (talk) 12:17, 20 May 2022 (UTC)

You wrote “ Talking about quantum states being subjective and people having the right to assign any state they want doesn't explain anything.” I never said quantum states are subjective and people have the right to use any state they like. They are objective. But they are not “real” in the sense of being located in space time. Richard Gill (talk) 12:20, 20 May 2022 (UTC)

So quantum states are not subjective, but at the same time they are not located in spacetime. What are they, then? Magical fairies that have any property you need in order to deny the existence of nonlocality? Tercer (talk) 12:27, 20 May 2022 (UTC)

No. Read the Wikipedia article on QBism. “both QBism and RQM [Rovelli’s relational QM] insist that quantum mechanics is a fundamentally local theory. MWI people say so, too. People are emotional about the words “local”, “locality”. I’m a mathematician who also works in Quantum Information and in Quantun Foundations. I try to keep an open mind. There is a central core to QM which everyone does agree on, and many interpretations, which seem to me to be optional extras , since they don’t influence the work of a physicist. Richard Gill (talk) 12:35, 20 May 2022 (UTC)

I'm familiar with QBism and RQM. I know that they claim to be local. It's just not true. They are just throwing up a smokescreen to hide the obvious fact that quantum mechanics is not local, as proven by Bell in 1976. MWI, on the other hand, is actually local, as Bell needs to assume that measurements have a single outcome in order to derive nonlocality. Tercer (talk) 13:23, 20 May 2022 (UTC)

In my opinion, MWI is the big smokescreen! Anyway, I suppose we agree that Bell's theorem is a true theorem. Bell defined a hidden variables model as an essentially deterministic model, and he defined "local hidden variables model" as a special case of "hidden variables model". Quantum mechanics is not a hidden variables model. There are good reasons that one may describe it as a local model, though you may not like Rovelli's reasons or the qBists' reasons. "What's in a name? A rose by any name would smell as sweet". I don't have an axe to grind on this (as I probably said, I'm a mathematician). Anyway: I hope we agree that there are QM predictions which cannot even be approximated by an LHV model, and more importantly, there are real experimental results which cannot be modelled by an LHV model. Richard Gill (talk) 13:40, 20 May 2022 (UTC)

That's a common misconception, and why I'm insisting on Bell 1976 instead of Bell 1964 or CHSH 1969. Bell does not assume determinism. The only assumption is local causality. Read the paper. It's not about hidden variable models, it's about any (single-world) theory at all, and it evidently applies to quantum mechanics, as that was the whole point. Tercer (talk) 15:41, 20 May 2022 (UTC)

Ah, I was wondering why you kept writing 1976, thanks! Cool. But: I have read all the papers, many times. (I even wrote quite a few much cited papers on the topic, too. I'm just saying that I have been working quite intensively in this field for 25 years now, collaborating with many physicists too). Yes, in 1976 he allows local randomness. We cannot distinguish randomness from deterministic chaos. His assumption of local causality allows him to write down a deterministic model, in which the randomness of measurement outcomes derives from randomly varying initial conditions. In mathematical terms: a Kolmogorovian probability space represents "random variables" as deterministic functions of some hidden variable omega. Richard Gill (talk) 15:51, 20 May 2022 (UTC)

You seem to have forgotten or misunderstood this one, though. He is not doing a deterministic model at all. The randomness of measurement outcomes does not derive from randomly varying initial conditions, there's no explanation whatsoever for randomness, as that is not the point of the paper. What he assumes is local causality, that the probability of an event a only depends on events in its past light cone, $\psi$, and in particular does not depend on spacelike separated events $\gamma$. In symbols, $p(a|\psi ,\gamma )=p(a|\psi )$. It's really that simple. And quantum mechanics clearly violates this assumption, as the probability $p(a|\psi )$ will be 0.5 when $\psi$ is a maximally entangled state and a is the event of Alice obtaining 0 when measuring in the computational basis, but if we let $\gamma$ be the event of Bob obtaining 0 when making his measurement, $p(a|\psi ,\gamma )$ becomes either 0 or 1. Again, this is not about determinism or hidden variables. Tercer (talk) 16:19, 20 May 2022 (UTC)

Indeed, there's no *explanation* for the randomness. Why should there be? He assumes randomness. He assumes randomness exists. In other writings (Bertlmann's socks, 1981) he explains that the randomness could come from the uncontrollable initial values of the myriad fundamental constituents of all the stuff in the source and both measuring devices and the transmission lines joining them shortly before the measurement settings are introduced. And I agree, it is as simple as you say. But I would take 1981 as the definitive mature Bell statement. Richard Gill (talk) 16:34, 20 May 2022 (UTC)

I find it rather ironic that you're quoting Bertlmann's socks. In that paper Bell is complaining about how people refuse to listen, and that determinism is not an assumption in either his theorem or EPR's argument. Instead, local causality is the whole point. It doesn't really matter what Bell said, though. It's still a mathematical theorem what he proved in 1976. That will be true regardless of anyone's opinion, including his. Tercer (talk) 18:47, 20 May 2022 (UTC)

I agree, local causality is the whole point. He proved a theorem. In 1976 and in 1981. Deterministic or random is not the issue. His definition of local causality depends on a concept of probability. The interpretation of “probability” is another question. Richard Gill (talk) 03:55, 21 May 2022 (UTC)

Yes, people come up with elaborate excuses to dismiss the fact that the quantum probabilities violate local causality. Probabilities are subjective, probabilities are not real, probabilities do not exist, only relative frequencies. Take your pick. It's just denial. Quantum probabilities are obviously objective, and they do violate local causality. Tercer (talk) 09:16, 21 May 2022 (UTC)

It’s obvious to you. Fine. Richard Gill (talk) 10:44, 21 May 2022 (UTC)

Where John Bell is all wrong

Discussion obviously going nowhere.

It has been pointed out that Bell's work is based on false concepts of the Copenhagen Interpretation, those false concepts of wave function collapse and superpositions, which do not even exist in a minimalist statistical ensemble interpretation of quantum mechanics, so Bell's work is totally wrong. This should be more clearly pointed out in Wikipedia. — Preceding unsigned comment added by 47.205.188.45 (talk) 19:06, 19 September 2022 (UTC) Can you please provide citations to reliable sources that support your claims? Tayste (edits) 02:42, 20 September 2022 (UTC) Bell clearly used wavefunction collapse, and not all interpretations recognize wavefunction collapse. 47.205.188.45 (talk) 03:17, 20 September 2022 (UTC) This is an article about Bell's Theorem. The theorem has nothing to do with wavefunction collapse. I suggest that you propose your changes here on the Talk page, as I cannot figure out what you are trying to do. Roger (talk) 03:30, 20 September 2022 (UTC) Read the second paragraph of the wikipedia Intro, it is indeed about wavefunction collapse.47.205.188.45 (talk) 04:04, 20 September 2022 (UTC) That is a paragraph about Einstein's beliefs, not Bell's. Roger (talk) 04:17, 20 September 2022 (UTC) Bell test experimenters speak in those terms, superpositions and wavefunction collapse. Neither exists according to many interpretations of quantum mechanics. This belongs in Wikipedia here.47.205.188.45 (talk) 13:14, 20 September 2022 (UTC) So go write an article on the philosophical beliefs of the Bell test experimenters. It doesn't have anything to do with this article. Roger (talk) 19:23, 20 September 2022 (UTC) The Intro leaves one hanging its full implications for the interpretation of quantum mechanics remain unresolved. There is needed an additional sentence to complete the Intro. I suggest Bell used quantum entanglement which entails superpositions and wave function collapse. In some other interpretations of quantum mechanics there is no superposition and no wavefunction collapse. This explanatory note needs be in the Intro to complete the thought of the Intro. — Preceding unsigned comment added by 47.205.188.45 (talk) 13:42, 21 September 2022 (UTC)

Deriving the expectation values

The expectation values for measuring the bell state:

$$\langle A_{0}\otimes B_{0}\rangle ={\frac {1}{\sqrt {2}}},\langle A_{0}\otimes B_{1}\rangle ={\frac {1}{\sqrt {2}}},\langle A_{1}\otimes B_{0}\rangle ={\frac {1}{\sqrt {2}}},\langle A_{1}\otimes B_{1}\rangle =-{\frac {1}{\sqrt {2}}}\,.$$

are simply given without derivation. I'd love to see a calculation of at least one, because the notation is kind of dense: The measured properties are referred to quite abstractly as $A_{0}$ etc. but the Pauli matrices later on then suggest that these are spin states. Thereafter, |01> seems to refer to a two particle system with one spin up and one spin down, but written as is it could also mean a single particle with spin down. I would really appreciate the original author expanding at least one of these given expectation values into a calculation, where you can see which part of the tensor operator acts on which part of the state. — Preceding unsigned comment added by 2A02:8109:B540:7CB:798F:B853:53BD:F07D (talk) 21:37, 8 October 2022 (UTC)

I'm a little unclear as to what you're unclear about. In the first part, the derivation of the inequality, the measured quantities are "referred to quite abstractly" because the point is that they can be anything. Then, in the second part, a particular choice of quantum state and measurement combinations is shown to violate that inequality. I tweaked the sentence flow and the notation a bit just now in a way that might (or might not) be an improvement, but really, the calculations are just matrix algebra. I'm not sure how much more we can say about that without violating the rule that Wikipedia isn't a textbook. XOR'easter (talk) 15:51, 9 October 2022 (UTC)

Recent changes

@HossenfelderS: rather than repeatedly reverting in the changes you would like to make to the article, why not discuss here on the talk page, and say why you think the changes are correct (with sources)? Wikipedia has sourcing requirements that can take some getting used to. Russ Woodroofe (talk) 07:36, 10 October 2022 (UTC)

Just to note the existence of a Twitter thread about this [14]. I'm encouraging them to engage here. Thanks. Mike Peel (talk) 08:18, 10 October 2022 (UTC)

It seems that the Twitter followers have arrived. And of course, they don't want to discuss anything, just edit war. Tercer (talk) 10:32, 10 October 2022 (UTC)

It looks to me like users coming from Twitter are editing in good faith, but may be unaware of the necessity of consensus and sourcing on Wikipedia. Perhaps experienced editor Tarinth will comment? Russ Woodroofe (talk) 12:07, 10 October 2022 (UTC)

I was surprised that sourced material was simply reverted based on an opinion. If there's a dispute on accuracy then it is incumbent on the editor to add a citation of sufficient notability. Alternatively, it would probably be fine to just acknowledge that there is public disagreement amongst physicists on the topic, and cite the contrasting views. This would be more productive than reverting cited material. Tarinth (talk) 12:26, 10 October 2022 (UTC)

As I wrote when originally reverting this edit: that's WP:UNDUE. We definitely shouldn't mention in the first sentence of the article a hypothesis experts considered necessary to even do science. this would be like starting mathematics articles adding the qualifier that the result only holds under the standard axioms of set theory. This is not about sourcing, it's about Hossenfelder's insistence on advertising her pet theory in the first sentence of the article. Tercer (talk) 12:46, 10 October 2022 (UTC)

I am sure that your edit was in good faith and that you are unable to see how the wording "pet theory" suggests bias. Please refer to WP:NPOV. Tarinth (talk) 12:54, 10 October 2022 (UTC)

I already added a reference. I don't have time for more of this. HossenfelderS (talk) 16:43, 10 October 2022 (UTC)

Is there a citation contradicting that a mere "1 / 15 bits of prior correlation" is sufficient to establish a loophole, or experimental evidence showing that measurements have less correlation than that?

There appear to be multiple peer reviewed, published articles showing that correlation via either superdeterminism or retrocausality are loopholes in the current evidence supporting Bell's theorem. It seems reasonable to cite the contrasting views. LeBleu (talk) 12:51, 10 October 2022 (UTC)

I agree with LeBleu's suggestion of capturing the contrasting views with citations (ideally more than one given the apparent controversial nature). WP:UNDUE as suggested above is intended for fringe theories such as flat-Earthism, not for legitimate contrasting views amongst experts in the field.

Tarinth (talk) 12:59, 10 October 2022 (UTC)

You are missing the point. There's no controversy about the correctness of Hall's results, or that superdeterminism evades Bell's theorem. The dispute is about mentioning this in the first sentence in the article (as it was already mentioned later in the article). It's WP:UNDUE, as it's a position all experts in the field find ridiculous. Tercer (talk) 13:04, 10 October 2022 (UTC)

Hall's paper is not cited at all in the current article. But are you saying that your concern is simply that the citation and the four words it was linked to ("which fulfil measurement independence") ought to appear in the Superdeterminism section as opposed to the first paragraph? Why not move it to the section you feel more appropriate rather than revert an editor's work. That would be less disruptive. I also note that you believe that it is a "position all experts in the field find ridiculous" (emphasis on "all") -- if you believe that's the case, I suggest adding something to that effect to the section with a citation regarding this consensus. Tarinth (talk) 13:22, 10 October 2022 (UTC)

I have no problem with citing Hall's paper in the superdeterminism section. The position of experts in the field is already discussed in superdeterminism. Tercer (talk) 13:39, 10 October 2022 (UTC)

I found the citation for Wiseman & Cavalcanti in superdeterminism that provide their opinion. Extending this opinion to "all experts" is WP:OR, but perhaps you have a cituation for it? Tarinth (talk) 13:56, 10 October 2022 (UTC)

That article also quotes the opinion of Zeilinger. This article notes the opinion of Larsson, that it is necessary to even do science in the first place. What more do you want? A comprehensive survey of all experts on nonlocality? That doesn't exist. What I can assure you is that any expert will have written that it's ridiculous, or won't have wasted their time with this nonsense to start with. In any case, I don't need to provide any citation for this claim, since I'm not trying to include it in the article. Tercer (talk) 14:06, 10 October 2022 (UTC)

Got it -- so there isn't a citation, just WP:OR. Tarinth (talk) 14:13, 10 October 2022 (UTC)

It's not "just WP:OR", it's a reasonable summary of the sources that do exist on a topic of niche interest. XOR'easter (talk) 14:58, 10 October 2022 (UTC)

Just FYI, Scott Aaronson (renowned quantum-computing researcher) wrote about superdeterminism on his blog ([[15]], starting at "People also asked me to respond to Sabine Hossenfelder’s recent video..."), saying about his criticism of superdeterminism that: "It’s all come across as obvious to the majority of physicists and computer scientists who think as I do, and it’s all fallen on deaf ears to superdeterminism’s fans." I don't know if this qualifies as a citation or just hearsay. But I thought it was worth pointing out. Vegard (talk) 12:12, 11 October 2022 (UTC)

WP:UNDUE isn't just about outright nonsense like flat-Earthism. It also applies to things that legitimate experts have said. Bell inequalities have been discussed for decades, and plenty of peer-reviewed papers have been published on them that have sunk into obscurity and thus would be WP:UNDUE inclusion here. XOR'easter (talk) 15:08, 10 October 2022 (UTC)

I looked at the most recently reverted edit (not sure if there were other versions), but at first blush the proposed modifications strike me as sensible and broadly proportionate. If I understand the record, there is a possible alternative explanation of the Bell inequality experiments that was acknowledged decades ago, is still the subject of professional discussion, and is already reflected in an existing section of the article (i.e. "Superdeterminism"). There does not appear to be any argument that this alternative interpretation is disproven or impossible, just that there is no particular evidence to support it (and perhaps no clear way to acquire any). So, it appears to be a legitimate consideration among experts in the field, even if perhaps most consider it unlikely. In that context, including a small caveat in the article header, such as was proposed, seems appropriate to me. Of course, we could also entertain alternative ways to express that caveat in the lead, but in a technical article like this, I lean towards the inclusion of such caveats when they are backed (as in this case) by an apparent history of scientific discussion. Dragons flight (talk) 15:08, 10 October 2022 (UTC)

It's definitely not first-sentence material. Probably not even first-paragraph. Towards the end of the intro, we discuss loopholes, and in its last paragraph, we mention how the philosophical implications have yet to be resolved. If any caveats are to be included in the already rather long lede, that would be the most sensible place. Given the current contents of the article body, including superdeterminism in the lede without also including nonlocal hidden variables and the abandonment of counterfactual definiteness would be an outright violation of the Manual of Style. XOR'easter (talk) 15:10, 10 October 2022 (UTC)

I would agree that the lead is overly long at present. Reducing it would be a good thing. (The second paragraph, in particular, strikes me as more detailed than a summary needs to be.) At the same time, it is important that the lead not express statements as flat fact if the associated literature acknowledges that there may be meaningful exceptions / alternative interpretations. In that context, I think each of the professionally recognized potential alternatives (or "loopholes", as you put it) should be acknowledged clearly (though ideally briefly) in the lead. Dragons flight (talk) 15:35, 10 October 2022 (UTC)

When we were last involved in revising the lede, I tried and failed to find a way to express everything that the second paragraph ought to cover that was much shorter than what we have now. Eventually, the cost of shaving off a word here or there just wasn't worth the benefit, but maybe someone else can do a better job. ("Loopholes", by the bye, is the standard term; we used to have a whole article called Loopholes in Bell tests until it was merged into this one. This general subject area has accumulated a lot of little articles over the years, and perhaps they could do with even more merging and condensation, but that's a different discussion.) XOR'easter (talk) 15:47, 10 October 2022 (UTC)

It is confusing to put "measurement independence" in the first sentence. All scientific theories assume measurement independence. If you take superdeterminism seriously, then many thousands of WP pages need to be qualified as resting on some measurement assumptions. It is like starting the Dinosaur article with "Dinosaurs are extinct reptiles, assuming that fossils can be used as evidence for them." The fringe skepticism can go later in the article. Roger (talk) 23:48, 10 October 2022 (UTC)

The main issue here is that the statement in the lead that the violation of Bells's inequality rules out local hidden variable theories is too strong and should be changed. Now, physics is not mathematics, in physics we don't engage in mathematical pedantism. As long as superdeterminism and all other loopholes are regarded as physically unacceptable loopholes, there is not problem with making that statement. But Hossenfelder and previously 't Hooft have argued that superdeterminism cannot be dismissed as physically unacceptable. Hossenfelder and few of her colleagues have recently made these arguments more rigorous. This does not mean that we must mention superdeterminism or the assumption of statistical independence in the lead, but we must weaken the statement in the lead, because it now reads too much as a rigorously proven statement. Compare this to the lead of the Mermin–Wagner theorem article. That is about a rigorously proven theorem and the lead covers precisely what that theorem says. Count Iblis (talk) 10:08, 11 October 2022 (UTC)

Hossenfelder and her colleagues haven't made these arguments more rigorous. This has been known for decades, and was already perfectly rigorous (it's mathematically trivial, after all). The problem is that superdeterminism can be used to invalidate any probabilistic statement. For example, one could add a caveat to every article that uses radiocarbon dating that it only holds if we assume measurement independence, that is, that carbon atoms don't decay at this rate only when we want to make a dating experiment. As long as the experts don't take this seriously we don't need to weaken the lead. Of this article, or any other. Tercer (talk) 10:24, 11 October 2022 (UTC)

I agree with Tercer here. It's not like there's a mathematical subtlety that escaped attention and, when exposed, opened new avenues of investigation. (Like how the Coleman–Mandula theorem restricts the combination of spacetime and internal symmetries, but then people realized that theories could be supersymmetric.) We just have some people saying that maybe everything happens because it's fated to have always happened that way, while most everybody else either ignores them or says that that kind of attitude amounts to giving up on science. Nothing has been made "more rigorous", just more hyped for mass consumption. The place to mention this, if at all, is in the "responses to Bell's theorem" part of the discussion. XOR'easter (talk) 15:14, 11 October 2022 (UTC)

Many Worlds nonsense

There is a lot of nonsense in the many worlds section. Bell's theorem assumes that experiments have single outcomes. It does not say anything about many worlds. The section has a couple of references, but they don't really support the text. The text is a lot of fringe theorizing with no mainstream support. Roger (talk) 08:33, 9 October 2022 (UTC)

Note that this section is specifically about the Many-Worlds interpretation of Bell's theorem. It's not being presented as the mainstream interpretation. You clearly haven't read the references, because they do support the text. Tercer (talk) 09:54, 9 October 2022 (UTC)

Here is an example of the nonsense. "It can generate correlations that violate a Bell inequality because it violates an implicit assumption by Bell that measurements have a single outcome. In fact, Bell's theorem can be proven in the Many-Worlds framework from the assumption that a measurement has a single outcome." This says that in many worlds, measurements have multiple outcomes. Then it says you can have Bell's theorem if you assume a single outcome. Assuming a single outcome is contrary to many worlds! Roger (talk) 23:34, 10 October 2022 (UTC)

I seem to be once again confused about what is confusing. The article says that MWI'ers prove Bell's theorem from the assumption that a measurement has a single outcome. Then they deny that a measurement has a single outcome. Thus, Bell inequalities do not constrict the correlations found in nature. This is what they want, because they are trying to interpret a theory that violates the Bell inequalities. XOR'easter (talk) 01:39, 11 October 2022 (UTC)

It would be simpler to say that Bells Theorem is meaningless in the MWI. That is a lot of verbiage to say that nothing can be said. Roger (talk) 03:06, 11 October 2022 (UTC)

But what that paper is showing is that it's not meaningless; in Many-Worlds correlations that do not violate Bell inequalities are precisely those that are compatible with the assumption that measurements have a single outcome. Thus, in Many-Worlds, an experimental violation of a Bell inequality is a proof that measurements have multiple outcomes. Tercer (talk) 07:05, 11 October 2022 (UTC)

No, that is obviously not true, or the Nobel citation would have mentioned that the prize winning experiments prove that measurements have multiple outcomes. Roger (talk) 22:46, 12 October 2022 (UTC)

This is the Many-Worlds point of view, that is mentioned in the Many-Worlds section. If it were the mainstream view it would be mentioned in the lead, and it would be mentioned by the Nobel prize committee. In any case, it's a theorem: you either have multiple outcomes or you have nonlocality. Most physicists prefer nonlocality. The Many-Worlders prefer having multiple outcomes. Tercer (talk) 05:59, 13 October 2022 (UTC)

No, not correct. Bell's theorem and tests show that in a hidden variable theory, we must have nonlocality, multiple outcomes, or superdeterminism. But if it is not a hidden variable theory, the conclusion does not apply. So one can reject both many worlds and nonlocality. There are some physicists who disagree with me on this point, but they have a minority view, and it should be labeled as such. Roger (talk) 20:34, 13 October 2022 (UTC)

I tend to think that the "Interpretations" section, as a whole, is clear enough about who believes what, and that we can't say much beyond what we already do without new analysis and conclusions. I am also reluctant to label positions as "minority views" in the absence of much better survey data than is presently available. I mean, the majority position on many of these questions might well be, "I don't wanna think about it." XOR'easter (talk) 04:20, 14 October 2022 (UTC)

Nobel Prize in lede

Sorry, I don't buy it. I don't see why we need to step outside the ordinary way of organizing articles because an incidental feature of a topic will be in the news for ~2 weeks. For comparison, quantum electrodynamics doesn't mention the 1965 Nobel for Feynman, Schwinger, and Tomonaga in its lede. Radium doesn't mention the 1911 prize to Curie. The lede of photoelectric effect mentions Einstein but not the 1921 prize. Bose–Einstein condensate doesn't get around to mentioning the Prize until the History section. There's no hard-and-fast rule about this, and in some articles the inclusion might make sense, but the intro here is already quite long. What matters more, the actual subject matter or a particular institution's delayed recognition of its importance? XOR'easter (talk) 15:11, 9 October 2022 (UTC)

On a second thought, I think you're right. I might be suffering of short-termism myself. Tercer (talk) 15:15, 9 October 2022 (UTC)

Much ado, I think. I simply thought that noting the Nobel within the context of the paragraph on Bell tests was appropriate. I am not a physicist or a Wikipedia guru. Tachyon (talk) 15:37, 9 October 2022 (UTC)

Never visited a 'talk' page before; hope I'm doing it "right." After reading the previous paragraph, it occurs to me that the Nobel in particular seems to enjoy a sense of cultural aggrandizement above any/all other "prizes" of its ilk. Why is this so? But assuming that is, I would now agree that overzealous lede-mentions only serve to perpetuate the problem (POV pushing in disguise... or rather, plain sight). 67.185.21.25 (talk) 03:28, 21 November 2022 (UTC)

Btw @XOR'easter... did you mean to retain the cite when you reverted my edit, or was that just a happy accident?... because it does suggest a compromise solution for "Nobel lede" frenzy/mania? 67.185.21.25 (talk) 03:39, 21 November 2022 (UTC)

The citation seemed fine; the Nobel Prize people do put a fair amount of effort into writing summaries at various levels, so they're not bad sources, generally speaking. XOR'easter (talk) 05:38, 21 November 2022 (UTC)