Talk:Interpretations of quantum mechanics/Archive 3

References/Further reading/Weblinks
I've just copyedited the "Further reading" section by adding ISBNs and removing amazon-Links.

But I'm under the impression, that a more substantial editing is needed.

As a start I'm wondering about the distinction between the book lists in "References" and in "Further reading". Is the difference that the latter ones weren't used in writing the article. Or are the first one not recommended to be read?

Also generally speaking the lists "Further reading" and "Weblinks" look unfocused in my eyes. IMHO items dealing with one specific interpretation belong (only) in that article! And rather general books which cover a complete philosophy (of physics), like Penrose's, shouldn't be included either.

--Pjacobi (talk) 21:46, 30 April 2009 (UTC)

Interpretations in the context of Grand Unified Theories
Have seen statements that Bohm's interpretation is the most consistent with the String theories or their projected synthesis in M. In any case, the article ought I should think have some positive statement on the relation or lack thereof with Strings/M. Lycurgus (talk) 01:53, 20 May 2009 (UTC)


 * Also without some reference to GUT, the article somewhat begs the question of why there needs to be an interpretation. Lycurgus (talk) 02:49, 20 May 2009 (UTC)


 * We need good references to support the claim that "Bohm's interpretation is the most consistent with the String theories", which I find rather hard to believe.--Michael C. Price talk 06:18, 20 May 2009 (UTC)


 * This section on Bohm's interpretation of quantum mechanics is confounding this issue with Bohm's hidden variables theory. I think that reference on this page to the latter theory summons unnecessary questions.WMdeMuynck (talk) 08:11, 20 May 2009 (UTC)


 * Changed title of thread from "Bohm's interpretation and M" to current to clarify issue. Lycurgus (talk) 10:57, 20 May 2009 (UTC)

Role of Feynman and Wheeler in inspiring Transactional Interpretation.
In the section on the Transactional Interpretation, the statement: "The transactional interpretation of quantum mechanics (TIQM) by John G. Cramer [4] is an interpretation of quantum mechanics inspired by the contribution Richard Feynman made to Quantum Electrodynamics."

...is misleading at best.

The Feynman/Wheeler work on electrodynamics employing advanced/retarded waves was a classical theory of electrodynamics. As I understand it, Feynman had no success in adapting the approach to a quantum description of electrodynamics. No specific page numbers on sources, but I have seen this in the book QED and the Men Who Made It, and also in Feynman's Nobel speech, which is reprinted in his collective works. Cramer also refers to this in his The Transactional Interpretation of Quantum Mechanics:

"Although the original [Wheeler and Feynman] work dealt exclusively with classical electrodynamics, later authors (Hoyle and Narlikar, 1969, 1971; Davies 1970, 1971, 1972) have developed equivalent time-symmetric quantum-electrodynamic (QED) versions of the same approach. The predictions of these QED theories have been shown to be completely consistent with those predictions of conventional QED which can be compared with experimental observation."

I feel the entry should be changed in the following ways:

1) Wheeler should be mentioned as a collaborator with Feynman. 2) EITHER the statement should refer to Wheeler and Feynman's work on classical electrodynamics, OR the statement should reference those listed in the above quote from Cramer as sources of inspiration.

Bernerami (talk) 22:33, 11 August 2009 (UTC)
 * Instead of linking to QED it should have linked to Wheeler–Feynman absorber theory. Corrected. --Michael C. Price talk 04:12, 12 August 2009 (UTC)

Ensemble interpretation
Moved to talk page:


 * Experimental evidence favouring the ensemble interpretation is provided in a particularly clear way in Akira Tonomura's Video clip 1, presenting results of a double-slit experiment with an ensemble of individual electrons. It is evident from this experiment that, since the quantum mechanical wave function describes the final interference pattern, it must describe the ensemble rather than an individual electron, the latter being seen to yield a pointlike impact on a screen.

Seems to be original research, and rather confused. The video is a standard demonstration of the double-slit experiment (that the intensity of electrons, even when shot one-by-one, will follow an interference pattern). --Tgr (talk) 12:13, 28 September 2009 (UTC)


 * I agree. Hence I removed it again. Please address the issue here before re-inserting the passage. -- Spireguy (talk) 03:37, 29 September 2009 (UTC)


 * No original research is involved. It is sufficient to look at the video, and ask yourself at what stage the wave function comes into play. Is the wave function telling you anything about one impact (apart from the fact that the wave function does not vanish at the point of impact)? Or should we wait until a sufficient number of impacts have occurred before we can make a comparison between the pattern and the wave function (absolutely squared)? The nice thing about Tonomura's video is that it does not yield a single result ready to be compared with the quantum mechanical predictions, but that it also shows how this result comes into being, that is, by repeating the experiment many times.WMdeMuynck (talk) 22:10, 29 September 2009 (UTC)


 * The EI is not the claim that you can use the WF to calculate statistics, it is the claim that you can only do that. 1Z (talk) 23:22, 29 September 2009 (UTC)


 * I edited the previous post for readability, hope that's OK. To clarify again: the video is a demonstration of a basic result of QM, but it does not prove anything about interpretation. The claim that it does is what was identified by Tgr as original research. -- Spireguy (talk) 03:43, 30 September 2009 (UTC)


 * I only partly agree with Peterdjones's above statement. An interpretation of (the mathematical formalism of) quantum mechanics is a mapping from the mathematical formalism into reality. An EI is a mapping to an ensemble (as opposed to an individual-particle interpretation, which is a mapping to an individual particle). We evidently agree that the Tonomura experiment corroborates an EI. The question is then: does it also corroborate an individual-particle interpretation? It, at least, is not contradicting the latter interpretation as it is consistent with experimental evidence that no particle is found at a position where the wave function vanishes. So, from an observational point of view endorsing both the EI and the individual-particle interpretation is possible.


 * Since my edit was just meant as an endorsement of Ballentine's views referred to in the same paragraph, I propose to change the text so as to remove the reference to the ensemble/individual-particle controversy (which, incidentally, is dealt with in Ballentine's textbook, and therefore can hardly be seen as original research).WMdeMuynck (talk) 13:12, 30 September 2009 (UTC)


 * The current text is still misleading. All experiments are consistent all interpertations. If you could disprove an interpretation experimentally it would count as a theory. The problem is in the implication that other interpretations somehow don't pass the test. 1Z (talk) 14:17, 30 September 2009 (UTC)


 * Equating an interpretation with a theory is confounding epistemological and ontological issues. An interpretation is establishing a correspondence between theoretical terms and elements of reality, and hence is regarding both theory and physical reality; a theory is a purely epistemological object. So, which formulation is misleading? Nevertheless, I can live with the last edit, although I think it less appropriate to put relevant information in a footnote, so I will restore it to the main text.WMdeMuynck (talk) 09:22, 1 October 2009 (UTC)


 * Relevance is not a sufficient criterion for inclusion as the section is only a summary: summaries must leave out much that is relevant. 1Z (talk) 10:08, 1 October 2009 (UTC)


 * You are right. It is better to move the stuff we are discussing to the Ensemble interpretation page.WMdeMuynck (talk) 07:39, 2 October 2009 (UTC)

" Problematic status of pictures and interpretations"
Coming back to this article after a long time, I am happy to see a section on "Problematic status of pictures and interpretations" to balance the section "Obstructions to direct interpretation".

I am thinking that we need to add something like: Since classical theories such as classical mechanics and Maxwell's Electromagnetism are no longer independent theories, but only approximations to quantum mechanical theories such as field theory, any explanation that refers to classical concepts such as position or momentum (or even to classical data such as non-quantum bits) can be, at best, an approximation. The rules for applying approximations are usually very limited in accuracy and scope, while qm itself is very general and precise, so a deep understanding can only be gained through higher mathematics.

To put this in a context of the work of philosophers: There are at least two ways of taking the saying "Shut up and calculate!".

The simple way is that the philosophy of science is not important. But not thinking deeply might have lead away from things like quantum computing and maybe even super conductors, just as much as taking things like the Copenhagen Interpretation too seriously would have!

A more philosophical interpretation of this saying is that a Bertrand Russel type logical approach is needed, not a Ludwig Wittgenstein type ordinary language approach. That is, ordinary languages such as English are not capable of expressing deep philosophical aspects of quantum mechanics. To get from ordinary language to qm, one has to go through logic and higher mathematics. So one can reach a philosophical understanding while calculating, or while measuring, but not while talking or reading.

Perhaps someone who reads more philosophy can find this argument in a single source and more clearly put?

David R. Ingham (talk) 18:31, 25 November 2009 (UTC)


 * Sounds rather like Roland Omnès's position to me. Unfortunately I don't have the time to find it and put it in. -- Spireguy (talk) 21:01, 25 November 2009 (UTC)


 * Thanks Spireguy. I will try to have a look.  David R. Ingham (talk) 04:46, 27 November 2009 (UTC)
 * Yes, glancing at Roland Omnès, that seems to be my point of view. He seems to understand what Schrödinger said in his Cat article about wave function collapse being a mental process caused by making a classical approximation.  David R. Ingham (talk) 20:06, 27 November 2009 (UTC)


 * I put in a sentence on the inadequacy of language. I think there is still something missing about Omnès's approach of starting inside qm and working outwards, unless I missed it somewhere else in the article.  That leads to another point, which I am putting in a different section here.David R. Ingham (talk) 23:33, 1 December 2009 (UTC)

The distinction between the mathematical core and the probabilistic rules
To me, quantum mechanics usually means the mathematical theory itself, but it is clear that some people also include the "usual probabilistic rules". That is a crucial distinction when discussing the philosophy and interpretation. Core qm is deterministic (in the sense of a state vector) and has no probabilities in it, while the rules contain most of the problems like wave function collapse and probabilities. Some sections here assume that the probabilities are inside qm, while others have them in the interpretations. So I am thinking there should be some effort put into making the distinction clearer in this article. David R. Ingham (talk) 05:27, 2 December 2009 (UTC)

Copenhagen interpretation / Consciousness causes collapse
From Consciousness_causes_collapse: "Consciousness causes collapse is the theory that observation by a conscious observer is responsible for the wavefunction collapse in quantum mechanics."

From Copenhagen_interpretation: "The act of measurement causes an instantaneous "collapse of the wave function"."

I guess the consciousness part makes the difference between this and (part of) the Copenhagen interpretation. However, is it not so that a conscious observer is necessary to do the measurement? The question I pose is: why is the 'Consciousness causes collapse' interpretation regarded as separated from the Copenhagen interpretation? Seems to be part of it... Info D 10:12, 29 October 2006 (UTC)


 * It can be regarded as part of it, I believe. The distinction (I think) is that Copenhagen (some variants) says the wavefunction collapses somewhere along the measurement chain (observed microsystem at one end, conscious observer at the other) whereas the  'Consciousness causes collapse' POV says collapse happens only at the conscious endpoint of the chain.  Other CI variants says it happens at the first irreversible interaction in the measurement chain -- consciousness is presumed to be irreversible, but is not necessarily the first such step encountered in the chain.  So CI is a somewhat broad umbrella.  --Michael C. Price talk 11:48, 29 October 2006 (UTC)


 * According to Bohr we need to describe the experiments we perform in purely classical terms, i.e., according to classical physics, as our measuring apparatus are of necessity "macroscopic." What he didn't explain was where exactly the boundary between "macroscopic" and "microscopic" should be drawn. Thus, this is a problem in itself within the Copenhagen interpretation. One of the proposed solutions to this sub-problem is to say that it's our "consiousness" that causes the collapse. As this twist of the problem never was what Bohr had in mind (for him the collapse was caused by the macroscopic instruments) it's separated from the Copenhagen interpretation in the literature. INic 12:06, 29 October 2006 (UTC)


 * However, you are absolutely right that the "cosiousness interpretation" shouldn't be treated as an interpretation of QM standing on its own. It's just a twist on the Copenhagen interpretation. Oddly enough this isn't usually stressed in the literature. In fact, most of the different "interpretations" are just different twists on the Copenhagen interpretation. I'm not sure, however, if the wikipedia article should stress this logical point of view or stick to how this is commonly treated in the literature. I personally think it's such a simple observation as it shouldn't qualify as "original research" even if we can't support this with an explicit reference. INic 12:06, 29 October 2006 (UTC)

Many Worlds vs. Copenhagen, which one is this?
I read the definitions of Many Worlds and the Copenhagen interpretation, and I still fail to understand the difference. Let's take this interpretation: every possible state of every possible element in the universe is true at the same time in all the combinations possible. When an observer measures some factor, it does so in all the universes where such event can happen, with different values on each universe. The observer obviously only sees one value in each universe, making the variable seem to "collapse". That would seem to fit both Copenhagen (since the observer makes the variable collapse in its own universe) and the Many Worlds, so what's the difference between them? Should this be clear from the article? Or is it just that Copenhagen dismisses the possibility of multiple universes?

Herbys (talk) 08:58, 4 April 2010 (UTC)


 * User Herbys, I think your analysis is pretty good. Maybe your analysis of the many worlds interpretation could be made a bit more specific by changing ``every possible state of every possible element in the universe is true at the same time in all the combinations possible into ``the possible states of the universes allowed by the wave function are true at the same time in all possible universes. The Copenhagen interpretation indeed does not contemplate parallel universes, before a measurement the state of each universe being either unknown or undetermined (depending on whether the Copenhagen author thinks about quantum mechanics in a more epistemological or an ontological way), and measurement reducing either `latitude of knowledge' or `indeterminateness' to the value measured in each particular universe.WMdeMuynck (talk) 09:07, 5 April 2010 (UTC)
 * every possible combination of each possible state of every possible element in the universe is true at the same time would be clearer. --Michael C. Price talk 09:18, 5 April 2010 (UTC)


 * It depends on what you mean by `possible'. For me it implies nonzero probability. Probabilities are described by the wave function.WMdeMuynck (talk) 15:53, 5 April 2010 (UTC)
 * Means that to me as well. I don't quite get your point. --Michael C. Price talk 16:17, 5 April 2010 (UTC)

Comparison
The comparison table might be misleading and needs an overhaul or could be removed. E.g., waveform is never defined in the article; is it equivalent to wave function? Waveform is used in telecommunication and electronic engineering to denote the shape of a signal. Any opinion?

Yes, waveform=wavefunction. And I vote for ovehaul.1Z (talk) 11:27, 19 November 2007 (UTC)

I'm all in favour of this comparison table as it provides a way to distinguish between interpretations at a glance. However I think the accompanying text has got out of phase, as it says "For example, it is difficult to get a precise definition of the Copenhagen interpretation. The table below gives two variants". However, there is only one entry for the CI? Possibly the other one is what I labelled as "Consciousness causes collapse" since the previous label (von Neumann Interpretation) didn't exist as a main page. N.B. This is essentially the same as Wheeler's PAP which could be an alternative label? Aarghdvaark (talk) 20:51, 5 April 2010 (UTC)
 * Much better solution to table label - found section to link to von Neumann with von Neumann interpretation. However that still leaves the missing 2nd variant of the CI? Aarghdvaark (talk) 21:17, 5 April 2010 (UTC)

Order of interpretations in article
Is there any rhyme or reason to the order in which the interpretations are given? Typically, Copenhagen is listed first, as being historically the first and the interpretation that every other is compared to. I also find it bizarre, for example, that "consciousness causes collapse" is listed well before the relational interpretation, given that compelling quantum-gravity theories are being formulated based on the latter. I suggest that the order be something like: (followed by everything else)
 * Copenhagen
 * Many worlds
 * Consistent histories
 * Ensemble
 * de Broglie/Bohm
 * Relational
 * Transactional
 * Objective collapse

If no one objects, I'd like to reorder the sections in this way. -Jordgette (talk) 01:06, 30 December 2009 (UTC)

Why not just put them in alphabetical order. Palindromatic (talk) 17:41, 10 January 2010 (UTC)


 * Alphabetical would be appropriate for giving all of the interpretations equal weight -- but there are far more reliable sources reporting on Many Worlds than Many Minds, for example. I've reordered them as above. If anyone wants to do a survey of G-hits and put them in an even more representative order, that'd be great. -Jordgette (talk) 21:02, 18 January 2010 (UTC)

Opening statement in article
An interpretation of quantum mechanics is a statement which attempts to explain how quantum mechanics informs our understanding of nature. Although quantum mechanics has received thorough experimental testing, many of these experiments are open to different interpretations. There exist a number of contending schools of thought, differing over whether quantum mechanics can be understood to be deterministic, which elements of quantum mechanics can be considered "real", and other matters. Although today this question is of special interest to philosophers of physics, many physicists continue to show a strong interest in the subject.[weasel words] Physicists usually consider an interpretation of quantum mechanics as an interpretation of the mathematical formalism of quantum mechanics, specifying the physical meaning of the mathematical entities of the theory.

Maybe the "weasel words" is not the right flag to use, but there is contradiction, and misleading ideas here. Much of this has been discussed in general already. The fact is, QM already is a "philosophy", based on the various authors specification of the physical parameters or mathematical entities when they submitted their papers. It is not possible to write, or get accepted, a "theory" of only numbers.

My main complaint here, is the separation of "physicists" and "philosophers" - there is no difference in the context of QM. The fact that "interpretation" is even possible is due to the fact that this theory is not finished yet. There are still problems being worked out, especially in the area of relativity. So these pursuits have the goal of laying the fundamental foundations for the theory that will be. This needs to be explained as to "why" physicists (and philosophers of physics) are still showing strong interest. Also a good idea, is to "date" the term "philosophers of physics" - it is a relatively new area, and its growth can be attributed to the above reasons. 100 years ago, ALL scientists were formally trained in Philosophy; today the near opposite is true. Guevara&#39;s Revenge (talk) 15:45, 19 January 2010 (UTC)


 * I don't understand why you "re-weaseled" the above paragraph. How is that better than the edit that I made? Do you have any suggestions for wording? -Jordgette (talk) 20:10, 19 January 2010 (UTC)

Because I flagged one sentence, and you deleted another. That made the problem worse, not better. There probably are some good ways to say it, but perhaps the easiest, and clearest, is to delete " Although today this question is of special interest to philosophers of physics, many physicists continue to show a strong interest in the subject", entirely, because it is self evident, and does not give more explanation to the topic. Guevara&#39;s Revenge (talk) 02:49, 23 January 2010 (UTC)


 * Thank you for the input; I have made that change. I think it's better to be bold and just make a change rather than put in a weasel tag -- especially if you have a definite opinion about the wording. -Jordgette (talk) 21:25, 23 January 2010 (UTC)

Smith interpretation
There has been an addition of Wolfgang Smith's interpretation of QM. I am removing it, but if it can be reworked with better sourcing, perhaps it can be replaced. My problem with the addition is that "Smith interpretation" appears not to be a recognized concept in the field of quantum mechanics. Googling ["Wolfgang Smith" "Smith interpretation"] yields three results, one of which is this article, neither of the other two being a reliable source. It seems the physics community hasn't noticed this interpretation, and no science writers have reported on it (that I can find). So, the addition does not seem appropriate for this article, citing WP:RS and WP:OR. However, thank you to the editor for working on the article. -Jordgette (talk) 20:25, 20 March 2010 (UTC)

Wolfgang Smith is a Cornell, Purdue and Columbia graduate and a professional mathematician whose works have been published in PNAS, and American Journal of Mathematics. His interpretation can be found in his book Quantum Enigma, available on Amazon (http://www.amazon.com/Quantum-Enigma-Finding-Hidden-Key/dp/1597310077). I restored my additions and hope that you will respect my decision to do so. -ryan.vilbig (talk) 21:08, 20 March 2010 (UTC)

Yet it remains that there are no reliable independent sources for this interpretation. The fact that he invokes God suggests to me that this is not science and that it will not be noticed by the physics community. I support removing it until reliable independent sources are available, but I will wait for further discussion. -- Bduke   (Discussion)  21:40, 20 March 2010 (UTC)


 * ryan.vilbig, I'm glad you're participating in Wikipedia. We need more editors. However, please know that reverting a content removal without (1) directly addressing the reasons for the removal and (2) awaiting further discussion from others, is not considered good form. Please read WP:RS and WP:OR to familiarize yourself with the guidelines for what is and isn't appropriate on Wikipedia. It doesn't matter how distinguished someone's credentials are, or whether he has published a book; if his idea is not present in the scientific literature and is not written on by peers in the field, which this isn't (please prove me wrong), then that idea should not be in Wikipedia, period. It's really quite simple. -Jordgette (talk) 22:04, 20 March 2010 (UTC)


 * Jordgette is right. As of current time, the so-called Smith Interpretation is simply not notable.  In due course, it will be picked up by the scientific community and studied (assuming it is considered valuable), but this appears yet to happen.  That Smith is a graduate of particular schools is irrelevant here.  His interpretation needs to be picked up by the scientific community for it to be included here as a notable idea in its own right.  This will happen if it is valuable.  Patience may be required, however.  Cheers, --P LUMBAGO  17:17, 22 March 2010 (UTC)


 * Here's another link to Smith's interpretation, (http://www.thomist.org/jour/1999/Jan%20A%20Smith.htm) in a peer reviewed philosophy journal. Furthermore, a similar interpretation has been put forth by Robert John Russell: “My central thesis is that God acts objectively and directly in and through quantum events to actualize one of several potential outcomes; in short, the collapse of the wave function occurs because of divine and natural causality working together even while God's action remains ontologically different from natural agency" (The Oxford Handbook of Religion and Science, page 586). (http://www.amazon.com/Handbook-Religion-Science-Handbooks-Theology/dp/0199543658/ref=sr_1_1?ie=UTF8&s=books&qid=1269311362&sr=8-1). I'm restoring my additions. Thank you for your cooperation. --Ryan.vilbig (talk) 02:32, 23 March 2010 (UTC)
 * You keep giving us links to Smith on Smith's interpretation. We need links from independent sources that show that scientists are taking this interpretation seriously. I am not seeing that. It remains simply not notable. You need to convince people here before it can be included. Not just finding an other link and then restoring it. You are breaching WP policies by keeping on restoring it. -- Bduke   (Discussion)  06:56, 23 March 2010 (UTC)
 * Re-read my previous post. Robert John Russell has discussed a similar interpretation. These are notable ideas. I mean, seriously, the many-minds interpretation is on this site. I think you guys are being ridiculous. --70.238.174.104 (talk) 13:28, 23 March 2010 (UTC)


 * Many Minds has attracted a degree of attention in the scientific literature (see the article), but it is unclear that this has happened for Smith's interpretation. Possibly, as suggested by another editor above, because it invokes supernatural elements.  If this is a notable scientific viewpoint on this scientific topic, then the place to go looking is the scientific literature.  If there's nothing there right now, wait.  Valuable, and thus demonstrably notable, ideas will be discussed there eventually.  Adding early would likely violate WP:UNDUE and WP:RS.  --P LUMBAGO  13:50, 23 March 2010 (UTC)

Hydrodynamic interpretation?
One of the "interpretations" listed is the hydrodynamic interpretation, linked to Madelung equations. As far as I can see, this isn't really an interpretation of QM, but a formulation (much as matrix mechanics and wave mechanics are different formulations of the equations which govern QM, but don't say anything about how the mathematical objects that they describe are to be interpreted). In the interests of keeping this article focused on the different interpretations, I propose removing "hydrodynamic interpretation" from the article. Djr32 (talk) 17:46, 27 March 2010 (UTC)
 * I agree. This page needs to be "weeded" every so often by a knowlegeable editor to remove the theories that do no qualify as legitimate "interpretations". -- Chetvorno TALK 18:16, 27 March 2010 (UTC)
 * Done. Hopefully nobody will revert it this time!  Djr32 (talk) 21:05, 7 April 2010 (UTC)

Requested move

 * The following discussion is an archived discussion of a requested move. Please do not modify it. Subsequent comments should be made in a new section on the talk page. No further edits should be made to this section. 

The result of the move request was: page moved, no comments. billinghurst  sDrewth  13:21, 6 July 2010 (UTC) billinghurst  sDrewth  13:21, 6 July 2010 (UTC)

Interpretation of quantum mechanics → — This should be plural to match the navigation template.--Brazmyth (talk) 07:19, 28 June 2010 (UTC)


 * The above discussion is preserved as an archive of a requested move. Please do not modify it. Subsequent comments should be made in a new section on this talk page. No further edits should be made to this section.

Meaning of NA?
On January 27, 2007 in the table of Interpretations an entry Yes has been changed into NA. Although there was no explanation of the meaning of this NA it has survived untill the present day. Can someone tell what its meaning is, and, perhaps, add it as a note?WMdeMuynck (talk) 09:54, 21 March 2010 (UTC)
 * I think it's that Copenhagen doesn't take a position (?) on either wavefunction collapse or observer role, that both are considered unknowable, something we just need to deal with. Copenhagen seems to have its own interpretations, depending on who you ask -- so perhaps someone else can weigh in on whether "NA" is generally accurate, and perhaps add a footnote to the chart. -Jordgette (talk) 20:08, 21 March 2010 (UTC)


 * OK. So `NA' stands for `not applicable'? If this is a standard expression, then, if correct, it does not need an explanation.


 * However, I think that the answer to `Collapsing wavefunctions? should be `Yes' since this is consistent with an interpretation of the wave function as a description of an individual particle (rather than an ensemble), which seems to me to be shared by all Copenhageners. Also `Observer role?' could be answered `Yes', even though there are considerable differences between different Copenhageners; however, with all of them the observer seems to play some (subjective) role, be it that measurement may have objective features stemming from the physical interaction between the microscopic object and the measuring instrument.


 * On the other hand, it is not evident what is meant by `Observer role?' If this is taken in an ontic sense (in which the observer is supposed to be able to change the object in a physical sense), then `NA' might be applicable because not all Copenhageners will be able to answer `Yes' in this sense. However, if it is taken in an epistemic sense, then also in the ensemble interpretation there is reason to answer `Yes' (rather than the present `None') because in this interpretation the observer may play a role by selecting a subensemble.WMdeMuynck (talk) 23:25, 21 March 2010 (UTC)


 * Or could the meaning of NA be `not axiomatic' (as suggested in a recent edit by User:Plumbago)?WMdeMuynck (talk) 17:54, 22 March 2010 (UTC)

The article apparently differentiates between von Neumann interpretation on one side and the Bohr / Heisenberg variants of the Copenhagen interpretation on the other side. Bohr, I think, did not believe in the collapse. Thats what the SEP-article says:
 * “Bohr's view was, to phrase it in a modern philosophical jargon, that the truth conditions of sentences ascribing a certain kinematic or dynamic value to an atomic object are dependent on the apparatus involved, in such a way that these truth conditions have to include reference to the experimental setup as well as the actual outcome of the experiment. This claim is called Bohr's indefinability thesis (Murdoch 1987; Faye 1991). Hence, those physicists who accuse this interpretation of operating with a mysterious collapse of the wave function during measurements haven't got it right. Bohr accepted the Born statistical interpretation because he believed that the ψ-function has only a symbolic meaning and does not represent anything real. It makes sense to talk about a collapse of the wave function only if, as Bohr put it, the ψ-function can be given a pictorial representation, something he strongly denied.”

On the other hand, Heisenberg in his 1927 article on the uncertainty relation, explains the Stern-Gerlach-experiment in terms of a state transition:
 * “Wenn wir experimentell feststellen, daß das Atom eben in den Zustand m wirklich übergegangen sei, so werden wir ihm zur Berechnung alles Folgenden nicht die Funktion sum(Cnm S_n ), sondern eben die Funktion S_m mit unbestimmter Phase zuzuordnen haben; durch die experimentelle Feststellung: "Zustand m" wählen wir aus der Fülle der verschiedenen Möglichkeiten (Cnm) eine bestimmte: m aus, zerstören aber gleichzeitig, wie nachher erläutert wird, alles, was an Phasenbeziehungen noch in den Größen Cnm enthalten war.”

(Sorry, I have the quote only in the original german language). So perhaps the article should separate the Copenhagen row in two rows, one with Copenhagen (Bohr) and one with Copenhagen (Heisenberg).-- Belsazar (talk) 19:46, 22 March 2010 (UTC) Addendum: Later, in the 1950s, he come up with a "hybrid" interpretetation: When unobserved, the wavefunction refers to a objective physical property he called "potentia" (Möglichkeitsfeld). When observed, the wavefunction refers to "our knowledge of the systems, which of course has to be subjective". The collapse corresponds then to "our" gain of information due to the measurement.-- Belsazar (talk) 06:00, 23 March 2010 (UTC)

NA definitely means "not applicable" which is usually rendered "N/A" However I would also dispute whether the ones listed in the Copenhagen Interpretation entry are correct. Wavefunctions do collapse in the CI (attend any undergrad course on QM), and this requires a role for the observer/measurement - it's what this means that is unclear.

Upon reflection I also updated the ensemble NA to "agnostic", since it seemed a bit more informative and accurate. -- cheers, Michael C. Price talk 16:35, 20 January 2011 (UTC)

Since the CI is agnostic about the ontological status of the WF, it can hardly fail to be agnostic about the ontology of collapse. It is certainly less of a "collapse interpretation" than Objectie Collapse (OrchoR/GRW) theories, even if it is still more than MWI. 1Z (talk) 18:42, 21 January 2011 (UTC)

Just above the table it says "it is difficult to get a precise definition of the Copenhagen interpretation. The table below gives two variants". However there is only one entry for CI. In the course of changes made, possibly about this topic (NA), did the text and the table get out of sync? Also for the CI to have wavefunction real? No, and Collapsing wavefunctions? Yes, is a little odd, but that's QM :) Aarghdvaark (talk) 19:33, 21 January 2011 (UTC)
 * But why shouldn't an agnostic wavefunction collapse? I'm not saying it should, but it isn't clear to me that it can't, either. -- cheers, Michael C. Price talk 23:15, 21 January 2011 (UTC)
 * I quite agree an agnostic wavefunction could collapse, but the current table entry says the wavefunction for CI is not real. Re-reading these posts, it seems to me the consensus is that for CI the entries should read 'wavefunction real? agnostic', and 'Collapsing wavefunctions? Yes'. And remove the bit in the text about there being two variants of CI (which I think referred to one row with 'wavefunction real? No' and one with 'wavefunction real? Yes'. I've implemented these changes on the main article - feel free to change back Aarghdvaark (talk) 12:46, 22 January 2011 (UTC)
 * Good changes, I agree. -- cheers, Michael C. Price talk 13:26, 22 January 2011 (UTC)
 * I doubt that the CI entry and the footnotes 11 and 12 are correct:
 * Which CI proponent claims / claimed that the wave function corresponds to an element of reality? Source? The CI is usually formulated as a "shut-up and calculate" stance, i.e. as an instrumentalistic interpretation.
 * Bohr did not believe in the collapse (see my SEP citation above), he was an instrumentalist with respect to the meaning of the wavefunction (for him the complementarity principle was primary).
 * The entry "Observer role: Yes" is mistakable. Is this the "what the bleep do we know" kind of mystical ideas about the meaning of QM? Neither Bohr nor Heisenberg emphasized such reading of QM. In any case this entry on the observer role should be supported with references.
 * The entry "wavefunction real: Agnostic" is also questionable. Bohr, or Heisenberg, were hardly "agnostic" with respect to the interpretation of the wavefunction. On the contrary, they had specific -albeit quite different- ways of thinking about the wavefunction.-- Belsazar (talk) 14:20, 22 January 2011 (UTC)
 * Hi Belsazer, but you say above '(Heisenberg) ... came up with a "hybrid" interpretetation: When unobserved, the wavefunction refers to a objective physical property'. I take that as meaning something real? Aarghdvaark (talk) 15:37, 22 January 2011 (UTC)
 * Also I think we should not debate about what Bohr or Heisenberg "actually" believed (which is open to debate), but instead look at how these interpretations are taught. CI is normally taught in undergrad courses as involving wavefunction collapse, but what the wavefunction actually is is usually left rather vague. -- cheers, Michael C. Price talk 18:23, 22 January 2011 (UTC)
 * @Aarghdvaark: Yes, I think Heisenbergs variant of the CI interpretation contained some realistic elements. However, it has been severely criticised as being inconsistent (it is unlogical to ascribe the wavefunction to something existing out there but to relate the collapse of the wavefunction to "our knowledge"). Thus, neither Bohrs complementarity principle nor Heisenbergs "potentia" are part of modern textbook explications of the CI. Modern texbooks -like Audretsch "Entangled Systems"- rather put it on a level with the "minimal interpretation" ( see here), avoiding metaphysical statements as much as possible. I think this is not an "agnostic" point of view, but a deliberately minimalistic stance. I agree with Michael C Price that the article should focus primarily on current explications of the CI.-- Belsazar (talk) 19:04, 22 January 2011 (UTC)
 * We should stick to Yes, No or Agnostic as table entries, otherwise the table loses its ability to show things at a glance. I think 'Agnostic' for Wavefunction real? is the most appropriate choice, and this would tie in with Michael's quote above: "what the wavefunction actually is is usually left rather vague". Also, loosely, agnostic is sometimes taken as 'don't care' which would seem to fit the minimalist interpretation? BTW whether Heisenberg's variant has been severely criticised or not is something we could highlight, but that does not mean we should write it out of history, but anyway criticising anything in QM for being inconsistent or unlogical is more likely to mean the criticism is wrong! There's a quote much to that effect from Bohr I think. Aarghdvaark (talk) 11:34, 23 January 2011 (UTC)
 * I read Audretschs writing on the minimal interpretation, and also Bohrs citations, as a clear negation of the assumption of reality of the wavefunction:
 * „The minimal interpretation of quantum mechanics ascribes reality only to preparations, transformations and measurement devices. [...] All other elements of the mathematical component of the quantum theory are only computational aids. This attitude can be accurately characterized by the intentionally exaggerated formulation of Niels Bohr: "There is no quantum world".“
 * This is not an agnostic position. It clearly states that -according to this interpretation- the wavefunction does not exist, so for this position the entry on the reality of the wavefunction should be "no".
 * Moreover I doubt that an agnostic position can be called an interpretation at all, since it is a main purpose of an interpretation to assign a semantic meaning to the mathematical symbols of the theory. If "agnostic" is the main characteristic of the current-day CI reading, this claim should be supported by references.
 * As to Heisenberg, I thought we agreed to use actual teaching. Which textbook uses Heisenbergs concept of potentia? I am not aware of any. Moreover, it certainly is not an agnostic position, it is just different to Bohrs.-- Belsazar (talk) 12:48, 23 January 2011 (UTC)


 * Hi Belsazar, we were discussing the CI entry for the table, so whatever the minimal interpretation says is irrelevant here. We are not discussing the reality of the wavefunction per se, but what the CI says about that reality. We can use current teaching of the CI if it is clear, which is why we have put 'Yes' for 'Collapsing wavefunctions?'. But current textbooks on CI do not give a clear line on the reality of the wavefunction, which is why I think 'Agnostic' is the correct entry for 'Wavefunction real?' (out of the choices Yes/No/Agnostic). We can also legitimately use what Bohr and Heisenberg thought, and I think we can best sum up what they thought for 'Wavefunction real?' as Bohr - No, Heisenberg - No, Yes. And I did not say that Heisenberg was agnostic, only that trying to resolve Bohr and Heisenberg's position can best be put in one word as agnostic. Aarghdvaark (talk) 13:22, 23 January 2011 (UTC)
 * Which current textbook on CI does not give a clear line on the reality of the wavefunction? Of course, there are many QM textbooks diving as fast as possible into the mathematics, which are mute concerning metaphysical reflections about interpretation. But such books are hardly a good reference for this article, which is focusing on interpretation. We obviously should use books explicitly speaking about interpretation. Audretsch is one, and many more books dealing with this matter are available.
 * Concerning the relationship of minimal interpretation to the CI Audretsch writes
 * „There are no unified statements in the literature concerning what precisely is contained in the Copenhagen Interpretation of the quantum theory. The minimal interpretation however certainly reflects the characteristic features of that interpretation.“
 * So Audretsch makes a clear claim that he sees CI close to the minimal interpretation.
 * Concerning Heisenberg and Bohr, I dont really understand your proposal. Is this kind of an averaging procedure ("realistic" + "not realistic" = "agnostic")? I am not convinced of this idea.-- Belsazar (talk) 14:15, 23 January 2011 (UTC)


 * Hi Belsazar, I think the the minimal interpretation is the same as the ensemble interpretation, which explicitly excludes making any conclusions from a single experimental result and so is totally at odds with the CI. I do not know what Audretsch means in the quote you give above - perhaps just that any valid interpretation of QM must predict the same result as CI for any experiment? I note from your link to Audretsch above that there seem to be only two passing references to 'Copenhagen' in the whole book - hence this would not be a good book on the CI. As to your last question: does ("realistic" + "not realistic" = "agnostic"), exactly! Aarghdvaark (talk) 10:03, 24 January 2011 (UTC)

I think the minimal interpretation is the "shut up and calculate" interpretation, which is distinct from the ensemble interpretation. At least this is how New Scientist presents it (see last section on this page) and it makes sense to me. I suggest we standardise on the New Scientist article. -- cheers, Michael C. Price talk 13:11, 24 January 2011 (UTC)
 * If the New Scientist Article explicitely describes CI -or variants of CI-, it certainly is one possible source. Unfortunately I I dont have access to the New Scientist, so I cannot tell anything about it. But I dont expect much news, the bare facts are AFAICS not controversial: There are many variants of CI, there is one major instrumentalistic / pragmatic strand, there is also the partially realistic variant of Heisenberg, and presumably there are some other subvariants. The discussion is about how to put this diversity into one table row. One possible solution would be to split up the one line into two, an "instrumentalistic/pragmatic variant" and a "partially realistic (=Heisenberg) line", and eventually write a little comment. You also may sum up to "agnostic", I dont bother and wont insist further, but I dont really take this solution serious.-- Belsazar (talk) 19:37, 24 January 2011 (UTC)


 * I'll post a summary of the NS article in a day or two, and we can take it from there. -- cheers, Michael C. Price talk 00:38, 25 January 2011 (UTC)


 * The New Scientist article is a good read, and may be good for one liners, but it doesn't mention a minimal solution, and all it says about the "shut up and calculate" position is that "unquestioning use of the Copenhagen interpretation is sometimes known as the 'shut up and calculate' interpretation". Semantics perhaps, but "shut up and calculate" by definition is not an interpretation. When you say above: "I think the minimal interpretation is the "shut up and calculate" interpretation, which is distinct from the ensemble interpretation. At least this is how New Scientist presents it", I agree "shut up and calculate" is not the same as the ensemble interpretation, but I don't see how from the article you got the idea that the minimal interpretation is "shut up and calculate"?


 * Also, I found this on the minimal interpretation "Here we only describe a point of view, which we call the ‘minimal interpretation’, that seems to be shared by both the adherents of the Copenhagen interpretation and of other views". So that suggests it is not identical with the CI, but an attempt to synthesize something which several interpretations could agree on. It goes on to say "More precisely, one imagines a great number of copies of the system under consideration, all prepared in the same way. On each copy the momentum, say, is measured". Well, I think that's a clear description of the ensemble interpretation! Aarghdvaark (talk) 00:00, 26 January 2011 (UTC)
 * I think this question about the minimal interpretation has a simple solution, the term simply is not defined uniquely among different authors. Again citing Audretsch :
 * „We should also point out that the concept 'minimal interpretation' is used in different senses in the literature.“
 * In his book he defines "minimal interpretation" -and thus by reference also the CI- as an instrumentalistic (=antirealistic) interpretation.. But I dont have to stick to Audretsch, it is easy enough to find other books on this issue: google books with "Copenhagen instrumentalist interpretation" gives ~6000 book hits. Take away 99% bad or mediocre books, there are still enough good books to source the claim that CI is presented by a huge number of authors as an instrumentalisc interpretation. Question: Is this accepted as a fact, or should we try to get a more comprehensive picture of the literature? Im asking because a serious, more comprehensive study of the available literature and collecting relevant citations requires quite some effort.-- Belsazar (talk) 18:18, 26 January 2011 (UTC)


 * Ok, so we've established the minimal interpretation is not uniquely defined so I guess that means we shouldn't mention it (unless to say just that) - it just gets too confusing. But about the CI and the instrumentalist interpretation (aka "shut up and calculate") I think we are talking about a difference of emphasis. I see the instrumentalist interpretation as using the CI, but not being identical to it. The New Scientist article tends to suggest this too I think when it says "unquestioning use of the Copenhagen interpretation is sometimes known as the 'shut up and calculate' interpretation". The instrumentalist interpretation really is agnostic as to the question 'Wavefunction real?', as it would not seek to engage with either Bohr or Heisenberg on their speculations. But precisely because it doesn't seek to engage in speculation, it isn't the same as the CI. This Wikipedia article itself describes the Instrumentalist interpretation and says "By abuse of language, the bare instrumentalist description can be referred to as an interpretation". I think we should therefore be careful and avoid saying Instrumentalist interpretation in the article, rather using position or description. The reason the instrumentalist position uses the CI is that the mathematical underpinnings of the CI have never been disproved and it was the first most complete theory, so effectively every other valid interpretation has to have the same math Aarghdvaark (talk) 11:51, 27 January 2011 (UTC)
 * Instrumentalism is not regarded as neutral with respect to the realism question, it is on the contrary a position explicitly opposing scientific realism. SEP entry
 * So, coming back to the CI table entry ("agnostic" vs. "not real"), the problem I see with the "agnostic" entry is the following: "Agnostic" is neutral with respect to the realism question. The wavefunction may or may not be real, who knows, who cares? But this is not the position the majority of CI adherents were putting forward. Remember e.g. the famous Bohr-Einstein debates on the realism question. Or read chapter 11.2.1 "The relevance for scientific realism" in Cushings book "Quantum mechanics: historical contingency and the Copenhagen hegemony". Some citations:
 * "To begin with, the almost universally accepted Copenhagen interpretation has traditionally been a serious (almost an insurmountable) challenge to a realistic construal of quantum mechanics." Next page: "Realism is in double jeopardy here: Copenhagen can be seen as anathema to realism [...]"
 * So, according to Cushing, CI is certainly not neutral to the realism question. I posted here now quite a number of references showing the non-realist reading of CI. But contrariwise, I have not seen here one single reference calling the "agnostic". -- Belsazar (talk) 20:18, 27 January 2011 (UTC)

Is the de Broglie-Bohm theory incorrect?
Although in my view it is preferable to look upon the de Broglie-Bohm theory as an interpretation of quantum mechanics rather than a separate theory, there is no incorrectness in considering it a theory. Its empirically verifiable predictions are not different from those of quantum mechanics.WMdeMuynck (talk) 09:54, 12 August 2010 (UTC)

Does that not also apply to any other interpretation of quantum mechanics? Karl (talk) 12:09, 12 August 2010 (UTC)


 * Unfortunately, there is no consensus about the use of the word `interpretation'. Thus, within physics it is mostly used as `a mapping from the mathematical formalism of a theory into physical reality', physical meaning being given to the mathematical entities of the theory by referring to the corresponding physical objects or processes. Within philosophy of science an `interpretation of a theory' is usually seen, conversely, as `a mapping from reality into a theory' in which the meaning of a word like `electron' is thought to be provided by the information contained on it by the theory.WMdeMuynck (talk) 08:51, 13 August 2010 (UTC)


 * At first glance, it probably would make more sense to label it as an "interpretation" rather than a theory. The article doesn't label most of the other interpretations as theories, although the specific article that deals with de Broglie-Bohm labels it a theory and an interpretation in the opening sentence.  That said, we should follow convention, and use the most popular wording from the scientific literature.  A quick Google trawl suggests "theory" wins out over "interpretation", but this may well not reflect use within the scientific community.  Anyway, before changing it here (and in the main article) I'd suggest a more systematic survey of the literature.  Cheers, --P LUMBAGO  12:29, 12 August 2010 (UTC)
 * Everybody prefers to call their preferred interpretation a "theory". What's new? -- cheers, Michael C. Price talk 16:28, 20 January 2011 (UTC)

2011 status
The latest New Scientist has a survey of the main interpretations with, amongst other things, a one word summary status. I suggest we add this to the table. Any objections? -- cheers, Michael C. Price talk 16:36, 20 January 2011 (UTC)


 * Good one liners especially about current status, but I would hesitate to use this New Scientist article to try and change anything else. e.g. it says "Adherents of the Copenhagen interpretation ... see quantum systems as carriers of information ... This new focus on information ...". We would need a lot more to justify updating the CI to try and include information as the CI is an old interpretation. Certainly you can add to it, but then it becomes a new interpretation. Aarghdvaark (talk) 00:10, 26 January 2011 (UTC)


 * I think that's because the CI is a very broad, umbrella term. -- cheers, Michael C. Price talk 17:43, 28 January 2011 (UTC)

I would like to add 2 more columns to the table, for nonlocality and counterfactual definiteness. These seem to be features that are just as important as the existing columns. But I am not sure about some of the interpretations. Does anyone want to help me? It seems to me that CI and von Neumann would be (local:no,CFD:no), Bohm would be (local:no,CFD:yes), and many worlds and consistent histories would be (local:yes,CFD:no). Roger (talk) 20:51, 9 March 2011 (UTC)

Contradiction between the comparison table and the text
The de Broglie Bohm interpretation section contains the statement: "It has been shown to be empirically equivalent to the Copenhagen interpretation, which retains locality but gives up counter factual definiteness." But the comparison table shows the Copenhagen interpretation as not local. One of them is in error. Ross Fraser (talk) 07:06, 5 May 2011 (UTC)


 * I favor deleting the sentence. Copenhagen uses a non-local collapse of the wave function. Roger (talk) 21:44, 5 May 2011 (UTC)


 * I think the sentence is supposed to mean the de Broglie Bohm interpretation gives the same experimental predictions as the CI (empirically equivalent?), as indeed it would have to do to be a successful interpretation. But both CI and the de Broglie Bohm interpretation are non-local, so the sentence is wrong. I've deleted it. Aarghdvaark (talk) 05:24, 7 May 2011 (UTC)

Instrumentalist interpretation vs. Ensemble Interpretation
It is unclear to me, what the difference between these two interpretations is. — Preceding unsigned comment added by 93.128.10.62 (talk) 17:15, 13 July 2011 (UTC)

What is the purpose of Akira Tonomura's Video clip? This is a well known experiment, consistent with most interpretations listed? — Preceding unsigned comment added by 93.128.10.62 (talk) 17:51, 13 July 2011 (UTC)


 * I suggest getting rid of the instrumentalist interpretation as well as this video. Roger (talk) 05:13, 14 July 2011 (UTC)

Time symmetric
What does
 * Several theories have been proposed which modify the equations of quantum mechanics to be symmetric with respect to time reversal

mean? The Schrodinger equation is already time symmetric.-- cheers, Michael C. Price talk 09:01, 9 July 2011 (UTC)

Buckyballs as waves
As a new Scientific American article points out, large molecules like Buckminsterfullerene have been shown to produce a macroscopic interference pattern at temperatures of roughly 1000 degrees Kelvin, thus demonstrating the wave-function of molecular particles. This would seem to create a preference for some interpretations over others. This link goes into greater detail. Should there be any changes in the article or the comparative chart to reflect these results? -- TheLastWordSword (talk) 00:20, 23 May 2011 (UTC)


 * So I'm having trouble finding where they did this at 1000 degrees Kelvin. Could you point that out? You don't mean the degrees of freedom maybe? Sean Egan (talk) 07:01, 21 June 2012 (UTC)

Wave function real?
What is meant by this column? It can't be a field in space like an EM field if you look at the wave function of multiple particles (in all interpretations). It is an abstract vector describing the state of a system. When would you say such a vector is real? In relational QM this wavefunction is highly depending on the observer (it only makes sense with a reference to an observer). Nevertheless in relational QM, we have a YES in that column? Jephire (talk) 20:15, 15 July 2011 (UTC)

Confusing wording
I believe the following sentence should be re-written.


 * What interpretations are interpretations of is a formalism — a set of equations and formulae for generating results and predictions — and a phenomenology, a set of observations, including both those obtained by empirical research, and more informal subjective ones (the fact that humans invariably observe an unequivocal world is important in the interpretation of quantum mechanics).

I understand the point being made and think it is very important to stress the meanings of these two words, but I think the sentence as a whole is a bit convoluted. Especially "What interpretations are interpretations of is a formalism". It could be stated "We make interpretations of reality through our interpretation of a formalism" or "Our interpretation of a formalism provides us with a framework for interpreting reality." Or something of that nature. And maybe the sentence can be reworded. I had a past student come to me today just to ask what this sentence meant.

As a whole, I think it's a great section that lends incredible meaning to the profound statements made in the article. It would serve more good if some parts were reworded. Sean Egan (talk) 06:46, 21 June 2012 (UTC)


 * You're right, it was an awkward and confusing sentence. I took a shot at improving it.  -Jord gette  [talk]  19:23, 21 June 2012 (UTC)

Should there be a section on Schrodinger's cat?
I'm wondering if there should be a section on Schrodinger's cat as the standard thought experiment used to illustrate the differences between interpretations (at least for the general public). Although they raise many other philosophical issues, the one issue that all interpretations have to address is wavefunction collapse: how long superpositions last, or whether they exist at all. I believe some authors differentiate the interpretations based on how long the superposed wavefunction is presumed to last: It seems to me that this could serve as a concrete illustration for nontechnical readers in what is otherwise a very abstract, esoteric article. -- Chetvorno TALK 05:19, 2 September 2012 (UTC)
 * A few interpretations (Ensemble interpretation?) postulate that superpositions are an illusion in some sense, or (de Broglie-Bohm theory?) that there is additional information about particle trajectories (hidden variables). So in the Schodinger experiment, neither the radioactive atoms nor the cat are ever "actually" in a superposition, collapse doesn't occur, and the cat is unambiguously alive or dead.
 * Others (Objective collapse theory) say that superpositions exist, but collapse stochastically or when a specific (usually small) threshold of energy or time is reached. Thus in the Schrodinger experiment the radioactive atom is in a superposition, but it collapses before it affects the cat, so the cat is never in a superposition but is unambiguously alive or dead.
 * A few (Conciousness causes collapse, Many minds interpretation?) require that the superposition does not collapse until it is observed by a mind.  In the Schrodinger experiment, if the cat can act as an observer, the superposition collapses when the poison does or does not kill it.   If the theory requires a human mind, the superposition collapses when a human being opens the box and observes it.
 * Others (Many worlds interpretation) say that the wavefunction never collapses at all, but causes a splitting of the wavefunction of the universe. In Schodinger's experiment the cat in the box is in a superposition, and opening the box initiates a superposition or splitting of the rest of the universe.
 * I'm in favor of it. We could also add the relational interpretation, in which the appearance of superposition (to a generic observer) is due to the observer's lack of information, and the appearance of wavefunction collapse is due to the observer's sudden gain of information. In Schrödinger's experiment, the atom appears to be in superposition in relation to the cat, until the atom probablistically decays; meanwhile, both the cat and atom appear to be in superposition in relation to the human, until the box is opened.  -Jord gette  [talk]  19:52, 3 September 2012 (UTC)
 * Wow, I hadn't heard of that one. That's interesting. I don't know much about QM so I don't know where many of the other interpretations say wavefunction collapse occurs in the Cat experiment - particularly the Copenhagen Interpretation.  Schro seemed to think it implied collapse occurs when the box is opened and the "external world" observes it.  Quotes by Heisenberg and Weinberg in the CI article imply that CI says that collapse occurs when "measurement" occurs, and doesn't require a human observer, but that because "measurement" is defined classically it is ambiguous.  It seems to me that it could be interpreted to occur when the radiation hits the geiger counter, when the geiger counter amplifies the signal to a macroscopic level, or any number of other points.  Perhaps it should be said that CI simply doesn't prescribe where collapse occurs in the Cat experiment?  -- Chetvorno TALK 00:33, 4 September 2012 (UTC)
 * Yes, Copenhagen has splintered somewhat and the interpretation of the cat expt will vary depending on who you ask. That's as good a start as any; the wording will be ironed out here eventually. As for RQM, it's a great interpretation. It basically says that nothing in the universe has properties except with respect to something else (the generic "observer"), and depending on what that something else is at the moment, the properties themselves can seem to change. It explains an awful lot if you ask me.  -Jord gette  [talk]  18:46, 4 September 2012 (UTC)

Elementary cycles - does not seem notable at present
I appreciate the revision of the Elementary Cycles addition; it reads better now. However, this appears to be (presently) a minor interpretation and belongs in Minority interpretations of quantum mechanics, if anywhere. Four of the five references provided are written by the originator, and the t'Hooft article predates the interpretation. Have any notable third parties discussed the Elementary Cycles interpretation alongside the others, as an indication of its importance? In Wikipedia, that, and only that, would qualify its inclusion in this article. Please note that "Other interpretations (e.g. time-symmetry) have less reviewed publications than this" does not fly; see the "other stuff" argument. As an editor it's better to remove the other material that shouldn't be here than add new material. In fact, I've taken care of it; you're right, and other listings may need to be reviewed as well.

Readers of this article expect to see a selection of interpretations that the physics community at large has deemed of lasting significance in the literature. If no such source can be produced that supports this status, then I encourage another editor to move the entry to the minor interpretations article or remove it altogether.  -Jord gette  [talk]  22:12, 7 January 2013 (UTC)

Recent addition
This edit I also found suspicious. It seems it's a direct quote from Wheeler, but I didn't get around to dig out a proper reference yet. &mdash;&thinsp; H HHIPPO  07:22, 15 January 2013 (UTC)

Rewrite by IP editor
I don't believe it's "being bold" for IP editor/writer 72.89.40.204 to completely rewrite this highly technical article that has an eight-year history of contributions. I support the reversion of the lede, obviously. Does someone now have to go through the body of the article line by line and revert the non-improvements? One new sentence reads, "Although the Copenhagen interpretation was originally most popular, quantum decoherence has gained popularity." This is fallacious and misleading. Quantum decoherence is an experimentally demonstrated mechanism, not an interpretation. Copenhagen is still arguably the most popular QM interpretation.  -Jord gette  [talk]  01:55, 3 September 2013 (UTC)
 * I tried going through the article. The organization and rewrite was too extensive and complex, with sections moved around, etc., to attempt a line-by-line comparison. This is the problem -- when someone rewrites and reorganizes an article with years of contributions, it then requires years of further fact-checking and editing before anyone can once again say the article is factually accurate and arrived at through consensus. As it stands, there are now large sections of the article, written (in some places terribly) by one IP contributor, which no one has checked for accuracy or clarity. This is not good for the article or for the encyclopedia in general. I'm giving up on this article and unwatching it.  -Jord gette  [talk]  22:56, 6 September 2013 (UTC)

I could not find any evidence that Von Neumann believed that consciousness collapses the wave function.
The only source that is sited is 'Mathematical Foundations of Quantum Mechanics', but it doesn't say where. I have a pdf copy of the book, and could not find any reference to consciousness in the book. — Preceding unsigned comment added by Asdfjasdjkfl (talk • contribs) 07:19, 25 December 2012 (UTC)
 * it's discussed at the beginning of the last chapter "The Measuring Process", e.g., "But in any case, no matter how far we calculate to the mercury vessel, to the scale of the thermometer, to the retina, or into the brain, at some time we must say: and this is perceived by the observer. That is, we must always divide the world into two parts, the one being the observed system, the other the observer." (p419/20 in the Princeton University Press edition of 1955, translation of R. Breyer) --Qcomp (talk) 17:30, 12 October 2013 (UTC)

Consciousness causes collapse
Editors here may be interested that the Consciousness causes collapse article is up for deletion under the title Articles for deletion/Quantum mind–body problem.—Machine Elf 1735  08:20, 17 December 2013 (UTC)

Superdeterminism
What about Superdeterminism as another interpretation of Quantum theory? It says that the universe is like a giant clockwork, where each step is pre-determined. So there's nothing random and about quantum probabilities (only pseudo-randomness), and non-locality dissolves, too.

Doesn't this qualify as a QM interpretation? --91.42.91.8 (talk) 11:52, 24 January 2014 (UTC)


 * Some interpretations are deterministic, and some are not. Superdeterminism is a way of rationalizing the apparent contradiction between determinism and randomness. I don't see it as a separate interpretation. Roger (talk) 05:24, 25 January 2014 (UTC)

Prune the list
I suggest pruning the list to just those interpretations that either have a nontrivial following today or have some historical significance. Others can go in Minority interpretations of quantum mechanics. Recent proposals do not belong here unless there is some significant published criticism.

I favor dropping Cosmological interpretation (maybe a good idea, but no publication takes it seriously), Popper's interpretation (just a way of thinking of entanglement, not a coherent interpretation), Time-symmetric theories (just a property of other interpretations, and not a separate interpretation), Stochastic interpretation (never caught on or fleshed out, afaik), and Teichmuller (if it reappears). Roger (talk) 17:41, 14 March 2014 (UTC)


 * I agree in general; I think 17 interpretations is too many, and I'm sure that Teichmuller doesn't belong on the same list with such mainstream interpretations as Many-Worlds or Bohm. I don't know enough about the other interpretations you mention to have an opinion.  Another idea: do you think  some of the related theories could be combined under broader categories?   People tend to add their favorite theory to the list without looking to see if it belongs under one of the existing headings.  For example the "Transactional interpretation" seems to me to belong under "Time-symmetric theories". -- Chetvorno TALK 20:21, 14 March 2014 (UTC)

Copenhagen and Ensemble are Nonlocal?
I noticed both the Copenhagen and Ensemble interpretations are described as nonlocal interpretations in the "Comparison of interpretations" table. I believe both these interpretations assert that quantum mechanics is a local theory, as all correlations emerge from local action, and the wavefunction is a subjective tool in the mainstream version of both interpretations ( http://arxiv.org/pdf/1308.5290v2.pdf ). The correlations themselves are nonlocal, but that is unremarkable, and exists even in classical physics. Kelso psi (talk) 16:01, 29 May 2014 (UTC)

dead citation link
this citation is dead. how about replacing it with an archive.org link? the version at scientific american seems to costs money to view, so i don't know whether linking to the archive.org version will incite scientific american to tell archive.org to remove the archive, which would be counter-productive, in my opinion. — Preceding unsigned comment added by Sudozero (talk • contribs) 00:16, 18 June 2014 (UTC)

Ensemble Interpretation
Removed John Gribbon's comment on the Ensemble Interpretation alleged refutation. Gribbon comment has no relevance whatsoever as despite the same name "Ensemble", Gribbon's comment was about another interpretation entirely, not the interpretation as put forward by L. Ballentine. If an editor desires to re-insert such a comment, please provide a source that clearly shows that he was referring to the Ballentine Ensemble Interpretation. The EI is mathematically identically to the CI, hence cannot be refuted experimentally. Thats a point of an interpretation to the mathematics. Kevin Aylward 18:16, 22 June 2014 (UTC) — Preceding unsigned comment added by Kevin aylward (talk • contribs)

Does String theory contain an interpretation of quantum mechanics
Does string theory contain an interpretation of quantum mechanics. If so some knowledgeable person might like to add a section.

Does the addition of extra dimensions and the particles string/brane provide a gateway or connection between quantum interactions.

I picture this as a particle/string/brane extending from the last interaction and then connecting up to the next interaction, attracted by the strength of the wave function, leading to the collapse of the wave function (implemented by a reverse phase wave function sent from the last interaction to cancel the original wave function), and then a forward in time transfer of the collapse energy to be used in the new wave function originating at the next interaction point.

There is a little bit of backwards in time causality implicit in this description.

I was just thinking about this and it seemed to make sense to my limited understanding. But I could be completely wrong.

Thepigdog (talk) 14:51, 18 July 2014 (UTC)


 * String theory is under the umbrella of quantum mechanics, but it does not AFAIK provide an interpretation of QM. You would need a reliable source (see WP:RS) for your interpretation before it could be put into the article, otherwise it is OR (Original Research) which is not allowed here. JRSpriggs (talk) 15:39, 18 July 2014 (UTC)


 * Sure, I do not want my guess added. My description was just given in the hopes of prompting some expert to explain things in simple terms.  Thepigdog (talk) 23:23, 18 July 2014 (UTC)

new edit on Copenhagen and coherence and Whitehead
I have made the edit for the following reason.

The task of the editor includes expressing material in ways that are apprehensible to general readers, not just to specialists. Neither Bohr nor the coherence people are top experts on the difference between the ontic and the epistemic. Indeed, they are beginners in that area. It takes a physicist's expertise to work out that they do not radically differ in their views, though they may seem to if their language is read naively. On the other hand, Whitehead is one of the top experts in the difference between the ontic and the epistemic, being knowledgeable in relativity theory and mathematics, as well as in general philosophy. Whitehead provides a perspective that enables one to see the common view held by Bohr and the coherence people. This is not about the substance of physics, it is about the presentation of that substance in terms apprehensible to a general reader.Chjoaygame (talk) 11:53, 28 July 2014 (UTC)

Wishing not to overburden my edit with references, I did not offer a reference for the word 'aspect'. Here is a suitable one: "In order to avoid the mistake of supposing that [quantum mechanicslly] incompatible descriptions are mutually exclusive, it is helpful to think of them as referring to different aspects of a Quantum system." I still think it perhaps better to leave this tacit in the article, but I would not oppose putting it in.Chjoaygame (talk) 00:33, 29 July 2014 (UTC)

Adding wacky interpretations
This article is for mainstream theories. Published theories that have not achieved any mainstream acceptance can be added to Minority interpretations of quantum mechanics. Original ressarch and unpublised theories should not be added to either.

An anonymous editor keeps adding an interpretation even tho there is no published paper that even mentions it as an interpretation of quantum mechanics. Please stop. If you think that I am wrong, then please address it here. Also, please stop the personal attacks. Roger (talk) 05:24, 11 October 2013 (UTC)
 * I agree. "Teichmuller space"  does not even qualify as a "minor" interpretation; it is supported by one published paper (the unpublished Arxiv preprint is not a WP:RS).  Plus the IP pushing it plagiarized his content from the Winterburg paper's abstract.  This doesn't belong in the article.  -- Chetvorno TALK 05:20, 12 October 2013 (UTC)


 * How do you define "mainstream acceptance"? For example, on Caltech professor Sean Carrol's website, there is a graph of several physicists' "favorite" interpretations as polled at a quantum foundations meeting; according to this graph, several interpretations on this wiki page, including "consistent histories", "Ensemble interpretation, or statistical interpretation", "de Broglie-Bohm theory" and "Transactional interpretation" have a 0% favoritism. The importance of the Teichmuller space interpretation is that something which is non-local in ordinary space can be local in complex Teichmuller space, and thereby is able to explain the EPR paradox and resurrect the de Broglie-Bohm theory. — Preceding unsigned comment added by 134.197.0.21 (talk) 20:48, 22 October 2013 (UTC)


 * If the theory attracts significant interest as shown by mentions in RSs there will be plenty of time to add it. Do you have any idea how many papers on the "interpretation problem" are published every year?    Listing a theory as an "interpretation of quantum mechanics" based on one single author would be rampant UNDUE emphasis.  As a WP editor you should know that. -- Chetvorno TALK 03:29, 23 October 2013 (UTC)


 * An interpretation does not need to be popular to be on the list. As you note, some interpretations are mainly of historical or philosophical interest, and have few current subscribers. But note that the poll did not ask about the Teichmuller space interpretation. If it did, then that would be evidence that it is a noteworthy interpretation. As it is, it belongs on the page with the other esoteric interpretations that have no significant published analysis. Roger (talk) 04:36, 24 October 2013 (UTC)
 * If we let every grad student who has managed to get a paper published on his speculative interpretation of QM list it here on this page so he can get some attention, we are going to get hundreds of entries every year. A single published paper is setting far too low a bar.  The  absolute minimum should be two.  That is, to include an interpretation on this page, someone besides the author should have seen enough value in the interpretation to mention it in a published work.  -- Chetvorno <i style="color:purple; font-size:smaller;">TALK</i> 23:45, 13 February 2014 (UTC)

The recently added "Cosmological interpretation" appears to be lacking support. There is a 2010 paper describing it, but we need a peer-reviewed published paper supporting it, or criticizing it, or even just mentioning it as a viable alternative to other interpretations. I say it should be removed, and a couple of others could be removed also. Roger (talk) 23:39, 19 February 2014 (UTC)
 * I agree, its gone. -- Chetvorno <i style="color:purple; font-size:smaller;">TALK</i> 02:19, 20 February 2014 (UTC)
 * The IP restored the Cosmological interpretation; on the strength that the Tegmark paper was published.  User:72.93.226.49, your interpretation is already listed in Minority interpretations of quantum mechanics.  That's where it belongs.  It is supported by a single published paper - you can't get any more "minority" than that.  Do you really think, as a WP editor, that it is NOTABLE enough to list alongside the Copenhagen interpretation and Many-worlds interpretation?  When nobody has mentioned it besides the author?   If proves to be of value, other WP:RSs will mention it, and then it can be moved to this article. -- Chetvorno <i style="color:purple; font-size:smaller;">TALK</i> 00:29, 24 February 2014 (UTC)

Since the interpretation of quantum mechanics is notoriously controversial, it is crucial that this page reflect what is actually happening in the peer-reviewed scientific literature, with a clear objective criterion for inclusion, and that WP editors avoid letting their personal assessments determine what gets included and what’s “wacky”. The currently stated criterion for the "Minority Interpretations" page is "Published theories that have not achieved any mainstream acceptance". Being accepted in a peer-reviewed journal with 8 external citations in a few years (see http://arxiv.org/cits/1008.1066) clearly doesn't match "not achieved any mainstream acceptance". Similarly, the "Quantum Bayesianism" approach has been peer-reviewed and generated attention at recent physics conferences, and doesn't meet this "no acceptance" or "wacky" criterion. In contrast, this page includes the ensemble interpretation, even while stating "The Ensemble interpretation is not popular, and is regarded as having been decisively refuted by some physicists." Either the criterion should be uniformly applied and appropriate interpretations included, or the criteria should be changed (perhaps to "Published theories that have not achieved significant mainstream acceptance") after a discussion here on the talk page. — Preceding unsigned comment added by 72.93.226.49 (talk) 21:36, 24 February 2014 (UTC)
 * Does anybody else have an opinion on whether this interpretation should be included? — Preceding unsigned comment added by Chetvorno (talk • contribs) 22:47, 24 February 2014‎ (UTC)
 * I think it should not be included here. This article explicitly lists common interpretations, which this one clearly isn't (at least not yet). So the right place for it is the minority interpretations article. Of course the inclusion criteria for the two pages should not have a gap between them, but I don't see such a gap. The quote "Published theories that have not achieved any mainstream acceptance" is from a user's statement on the talk page, the article itself says "...which have not made a significant scientific impact", which is pretty much what the IP suggests. &mdash;&thinsp; H HHIPPO  07:44, 25 February 2014 (UTC)

I just read both this article and the “Minority interpretations of quantum mechanics” articles. I’m a physicist, and agree that some reorganization/cleanup would be appropriate. Here are the most flagrant issues I see:

1) “Time-symmetric interpretations are currently on both pages” - it clearly only belongs on one of the two

2) It is odd that the article lists the “instrumentalist interpretation” before the interpretation list begins, even though it is clearly not an interpretation (failing to say anything coherent about Wigner’s friend paradox); the text at the end misleadingly suggests that its only drawback is not addressing “why” questions https://en.wikipedia.org/wiki/Wigner's_friend

In terms of which interpretations to include here, I don’t have any strong opinions as long as there’s a clearly applied criterion. When quantum interpretation polls have been taken at recent physics conferences I’ve attended, these five always come up and obviously need to be in the main article:


 * 5.2 The Copenhagen interpretation
 * 5.3 Many worlds
 * 5.4 Consistent histories
 * 5.6 de Broglie–Bohm theory
 * 5.11 Objective collapse theories

These have occasionally come up as well:
 * 5.7 Relational quantum mechanics
 * 5.16 Modal interpretations of quantum theory
 * 5.13 Many minds
 * QUBism
 * Cosmological interpretation (inspired by cosmological inflation)
 * Montevideo interpretation (inspired by intrinsic decoherence from the quantum gravity clock ambiguity)

They’re certainly less established than the “fab 5”, but despite the disparaging title above, there’s nothing “Wacky” about them and I see no harm in including the last three in the main article and letting WP readers learn about these relatively recent developments. An advantage of WP is that it can include Interesting recent developments (which are by definition less established). I’m happy to do some significant work on this article, but will hold off to hear what you all think, since I don’t want to ruffle anybody’s feathers. — Preceding unsigned comment added by James1831 (talk • contribs) 14:09, 25 February 2014 (UTC)


 * Those last 2 interpretations are a little wacky, and as far as I know, have not gained any significant support beyond the original proponents. To include them I think that we would need some published references that take these interpretations seriously, and have some outside criticism of them. QBism is not wacky, but it is essentially the same as Copenhagen, and there is no good reason to separate here. The Teichmuller interpretation also does not belong, but someone keeps re-inserting it without any explanation. Roger (talk) 16:55, 11 March 2014 (UTC)


 * Can someone else please remove the Teichmuller interpretation? It goes against the consensus on this talk page. Roger (talk) 22:40, 11 March 2014 (UTC)
 * Removed per WP:COPYVIO. The text is a literal copy from http://vixra.org/abs/1301.0146. Even with serious rephrasing, the material should only be re-added together with a reference to an independent, reliable source certifying that this interpretation made a significant scientific impact. Being new or brilliant is not an inclusion criterion for this page, but being mainstream excplicitly is. &mdash;&thinsp; H HHIPPO  17:56, 12 March 2014 (UTC)
 * A new IP 12.72.186.51 readded the Teichmuller interpretation. There are 4 or 5 different IP's that have been reverting, all in the Reno/Sun Valley/Univ. of Reno area.    User:12.72.186.51, are you the same as User:12.72.186.45, User:12.72.186.126, and User:134.197.31.45?  Using multiple identities on WP to pretend to be different editors is called Sockpuppetry, is prohibited and can get you blocked. -- Chetvorno <i style="color:purple; font-size:smaller;">TALK</i> 06:15, 13 March 2014 (UTC)

I am not sure about using the term "wacky" here. However, I do think that an interpretation has to be supported by rather more than the person who first put it forward. If 5 or 6 quite independent people supported the interpretation, it could be included, but that does not seem to be the case here. To the IP editor, if you are using dynamic IP addresses you may well have a different one each time you edit, but now you have been asked you should admit that they are all by the same person. If you do not you will be assumed to be doing it deliberately to give the impression that several editors have the same view. You would be better to register and use a single use name. -- Bduke   (Discussion)  06:53, 13 March 2014 (UTC)
 * This is getting too much. I asked for semi-protection to stop further insertion of copyright-violating material. 134.197.31.45: please contribute to the discussion here rather than edit-warring. It is possible that this interpretation can be included, but it needs to be done in a way that doesn't violate copyright law, and it needs to be accompanied by a secondary source verifying that this is indeed, as claimed by adding it to this article, a mainstream interpretation that has made a significant scientific impact. Note that your behavior so far is suited to damage the reputation of the authors of the primary paper, since it might appear to readers as if you're one of those authors. &mdash;&thinsp; H HHIPPO  22:51, 13 March 2014 (UTC)
 * Good idea. This edit warring has to stop.  User:134.197.31.45 and anyone else interested, we need to discuss this here and reach consensus.  My feeling is that Max Tegmark is a respected physicist and author, but that and eight citations don't make his interpretation a "mainstream" interpretation. But I'm open to being convinced otherwise.  User:134.197.31.45, if you have anything else, let's hear it. -- Chetvorno <i style="color:purple; font-size:smaller;">TALK</i> 20:44, 14 March 2014 (UTC)

Someone added Hidden-measurements interpretation. I suggest dropping it, and leaving it to Minority interpretations of quantum mechanics. There are a bunch of references by the proponents, but none by others, and none saying that it is one of the major interpretations to be considered. Roger (talk) 00:53, 9 August 2014 (UTC)
 * I agree, get rid of it. 29 references by the same 3 guys does not make it a "common interpretation". -- Chetvorno <i style="color:purple; font-size:smaller;">TALK</i> 03:23, 9 August 2014 (UTC)

General Enough ?
In 'Obstructions to direct interpretation' there is a line which reads:
 * 'Further, the process of measurement plays an essential role in the theory'.

However this is not the case. While measurement plays an essential role in the Copenhagen Interpretation of QM, it does not play an essential role in (for example) the Consistent Histories Interpretation of QM. In other words the essentiality of measurement is not a necessary attribute of 'the theory' per se. Carl Looper 202.6.86.1 (talk) 22:05, 21 December 2010 (UTC)