Talk:De Broglie–Bohm theory/Archive 2

New Year’s Clean-up?

Deadly Nut, M. Price, et. al:

In the spirit of Bohmian Dialogue and new year's resolve, I would like to propose that we remove some of the more disputed/problematic sections of article to talk page, and either rework them from there or delete altogether.

Below are some suggestions for what I believe should be at least temporarily removed from body of the article:

“Name and Evolution.” Reasons: section needs to be tightened and recast as “history and development of the theory” or something like that. Material here can perhaps be combined with material from “History” and “FAQ” sections for a short narrative providing the historical context of the interpretation, perhaps at the end of article.

“Results.” Most of this material seems frankly superfluous. Besides, how can an interpretation have “results”? Inclination here is to delete altogether.

“Comparison with Experimental Data.” This section reads like a chat page with no references to or meaningful elucidation of the theory. No-one will be any less wise if it is deleted altogether.

“Two Slit Experiment.” Everything which is said here follows from the Principles section. Should be moved to that section or deleted.

“Measuring Spin and Polarization.” None of this is very pertinent to Bohm’s interpretation. Strong inclination to delete.

“History” Some good stuff here, but seems out of place. Probably belongs at beginning of article as “Background” or combined with “Name and Evolution section” in a larger explanatory narrative.

“Extensions.“ I would be in favor of eliminating all of these so-called extensions until there is consensus on the main body of the article. Stuff on Valenteni is very derivative. Comparison with Many Worlds is not the point of the article. Quantum Trajectory stuff is either its own article or a sub-heading of a possible “Bohmian Mechanics” article. Ditto for Quantum Chaos stuff. Regarding relativistic extensions, if we started to go in that direction there would be no end in sight!

“Frequently Asked Questions.” There are some real insights here, esp. as relating to non-locality and Bell’s influence (thank you M. Price), though the presentation needs serious work. Consider removing from body of text to talk section or perhaps incorporate in a more straightforward form into other parts of the article, or even reworking into a section on Bell/Non-locality?

Assuming the above deletions/rearrangements, that would leave the article with the following flow:

Introduction (Background?) Principles Reformulating the Schroedinger Equation One Body Formalism Many Body Formalism Indeterminism/Relation to H. Indeterminacy Relations EPR (Non-Locality) Note on Historical Development

Sfwild (talk) 08:04, 8 January 2009 (UTC)

Responding to just one of your points at the moment, “Measuring Spin and Polarization.”. I believe that this is relevant and that Bohm himself included a similar discussion in his 1952 papers. His point was that measuring spin amounts to measuring position. --Michael C. Price ^talk 01:02, 23 April 2009 (UTC)

Bohm's Wavefunction field

The wavefunction is a high dimension object, and in Bohm's interpretation it is just as high dimensional. The phrasing of the article, and many discussions of this subject, make the wavefunction sound like a three plus one dimensional field, when it is a 3N plus 1 dimensional field. This should be made clear.Likebox (talk) 15:56, 17 April 2009 (UTC)

I’m a bit dubious about this last revision, as I don’t believe it is helpful in clarifying what distinguishes the Bohmian interpretation of the S. equation from the usual one. In the initial ’52 presentation, adopting the pilot-wave approach, he is clear that the S. field corresponds to a real field with an objective physical reality. While it is true that in the case of two or more particles, the S. equation unfolds in a configuration space, Bohm himself was never happy with the formalism. As he notes in 1957: “A serious problem confronts us when we extend the theory given in Section 4 [the pilot wave theory] to the treatment of more than one electron. This difficulty arises in the circumstance that, for this case, Schroedinger’s equation (and also Dirac’s equation) does not describe a wave in ordinary three-dimensional space, but instead they describe a wave in an abstract 3N-diemensional space, when N is nth number of Particles. While our theory can be extended formally in a logically consistent way by introducing the concept of a wave in a 3N-dimentional space, it is evident that this procedure is not really acceptable in a physical theory, and at least be regarded as a artifice that one uses provisionally until one obtains a better theory in which everything is expressed once more in ordinary thee-dimensional space.” (Bohm 57, 117). It is this difficulty, among others, which leads Bohm to posit an essentially new order of physics, which he calls the “implicate order,” defined as a higher-dimensional but still real order which projects into the explicate order in ordinary 3D space.

Interesting, this contradiction between the “realist” assumptions of the theory and the abstractions of the configuration space was leveled against Bohm right away by de Broglie, who saw it as a major stumbling block.

24.130.175.188 (talk) 23:53, 22 April 2009 (UTC)

Interesting shift by Bohm between 1952-1957. Do you have a ref for de Broglie's unhappiness? I was never clear what his response was to Bohm's 1952 papers. --Michael C. Price ^talk 00:59, 23 April 2009 (UTC)

There is a rather obscure opuscule published in 1953 (La physicique quantique restera-telle-indeterministe?) which reprints some of his earlier work--no doubt to establish his priority--as well as a series of notes responding to Bohm's '52 articles. Here's a taste of de Broglie's thinking c. '52 in rough translation:

“The theory of the pilot wave could not really accomplish its intended goal, which is to return to an interpretation of wave mechanics which conforms with classical conditions, except under the assumption that the wave PSI, from which the quantum potential derives, is a “physical reality” capable of reacting on the movement of the particle or the system, because if it is just a representation of probabilities, as one generally admits today, the movement defined by the pilot wave theory would depend on possibilities which are not realized, which is paradoxical and which leads us even further astray from classical conceptions. Thus, it appears impossible to consider the wave PSI as a physical reality. It is, in effect, represented by a function which is essentially complex, and in the case of general systems, it propagates in a configuration space which is obviously abstract and fictitious" (67).

He then goes on to criticize Bohm for the same reasons:

"[…] In sum, the interpretation of wave mechanics offered by the pilot wave theory, to which the work of M. Bohm redraws out attention, still seems to me to run against insurmountable difficulties, principally because of the impossibility of attributing to the wave PSI a physical reality, or of admitting that the movement of a particle could be determined by only possible movements which are not realized" (69).

De Broglie would eventually come around to endorse the interpretation offered by Bohm and Vigier in 1954 (the "causal-stochastic intepretation"). See also his '57 work on the Causal Interpretaton and his presentation of the work of "Vigier and his collaborators" (read Bohm) in 1960. Both these tomes are available in translation and give a good sense of the excitement which the revival of the causal interpretation evoked in Paris in the 50's. Sfwild (talk) 18:00, 23 April 2009 (UTC)

I'm glad de Broglie lived to see a resurrection of his pilot wave theory, and was enthused about it. I always felt he was rather shabbily treated by Pauli, despite making possibly the greatest advance in physics of all time with $p=h/\lambda$.

The translation you're quoting, is that the material that appears in the de Broglie article, namely:

• Introduction à la nouvelle théorie des particules de M. Jean-Pierre Vigier et de ses collaborateurs. Paris: Gauthier-Villars, 1961. Paris: Albin Michel, 1960.
  • English translation: Introduction to the Vigier Theory of elementary particles. Amsterdam: Elsevier, 1963.
• Étude critique des bases de l'interprétation actuelle de la mécanique ondulatoire. Paris: Gauthier-Villars, 1963.
  • English translation: The Current Interpretation of Wave Mechanics: A Critical Study. Amsterdam, Elsevier, 1964.

?--Michael C. Price ^talk 23:01, 23 April 2009 (UTC)

Reference is from "Remarques sur la theorie de l'onde pliote" in C.R. Acad. Sc. t.233, 17 septembre 1951, p. 641-644, reprinted in La physique quantique restera-t-elle indeterministe (Paris: Gauthier-Villars, 1953, pp. 67-69. Rough translation mine. De Broglie is responding to the manuscript version of the '52 articles which Bohm sent around to all the grand all men of physics in '51. I'm not sure the reference is of much use for the purposes of the present article, but it does show that in his original conceptions, Bohm clearly thought of the wave fuction as representing an objectively real field and not merely a mathematical symbol evolving in an abstract configuration space, as the usual interpretation of QM has it. The latest revision of the principles section does not make that very clear, and I believe obfuscates the issues, which is my only gripe here. Sfwild (talk) 00:09, 25 April 2009 (UTC)

I agree that Bohm's '52 articles make it clear that he treats the wave function as an objectively real field (he often compares it with the electromagnetic field). If the article isn't clear about that it should be. --Michael C. Price ^talk 11:05, 25 April 2009 (UTC)

There is a distinction between whether the wave function is objectively real and the fact that it is defined in configuration space (as opposed to "phase space" or "state space"). The latter was very important in my own understanding of the de-Broglie Bohm theory, and I have adjusted the article to include this point. Hopefully, the result will be a bit friendlier to the layman (less explicit mathematical terminology, and a reference to a page that explains the "configuration space" concept in more detail). --Dataweaver (talk) 21:44, 2 October 2009 (UTC)

Principles

I have been editing the Principles section in order to reduce the explicit references to mathematics and instead emphasize in layman's terms what the math means. I'm not happy with the current phrasing of some of this: in particular, I've rewritten it to say that a particle's momentum depends on how the wavefunction is changing; what I was trying to get at was that because a particle's momentum is the gradient of the field at the particle's location, the momentum depends not on the value of the wavefunction at the particle's location, but on how that value may differ in the particle's immediate neighborhood. Is there an easy way to say this, or am I trying to say too much? --Dataweaver (talk) 06:19, 5 October 2009 (UTC)

Dataweaver: It's nice to have someone around who seems to know what they're doing. As for the part you mentioned, it might be easier just to scrap talk about momentum entirely (at least in the principles section, which should be basic and introductory in tone). It's correct to say that the velocity of a particle at a time depends on the value of the gradient of the WF at its location (if we're talking systems of one particle). Because Bohmian mechanics is a first-order dynamical theory, the particle's velocity at one point doesn't tell us squat about what its velocity will be once it moves somewhere else. It might be better to not gloss this as the momentum of a particle depending on the value of the wavefunction "in the particle's immediate neighborhood" but as something in terms of the velocity of a particle at an instant (and then abstract away from there).
I'm not sure if that was helpful. This whole article is a mess and really needs a full rewrite(I had been trying to help here and there while unregistered and have finally given in and signed up). It will be nice to have some new input, since many of the problems facing this article are due to a very weird historical slant/bias that some of the earlier editors had (e.g. One of the most striking and well-known features of Bohmian mechanics is that it is deterministic. However, because Bohm, sometime later in his life, recanted and presented a theory that was indeterministic, this article is full of claims that Bohmian Mechanics isn't deterministic).
((Tangent): What is the general consensus with regard to a renaming of the article? The "Bohm Interpretation" name is kind of unusual. Most discussions of this interpretation in the current foundations of QM literature are about "Bohmian Mechanics" (The name "Bohm Interpretation" doesn't really get thrown around anywhere, how did this name get picked anyway?)) ZRPerry (talk) 19:26, 9 October 2009 (UTC)

isomorphism to many worlds? Also historical bias and article namechange

I really don't like the section about the Isomorphism to the many worlds interpretation. It sounds more like an objection than an "extension" My main problem is that the suggestion sounds more like a one-way reduction than a true isomorphism. Something should be added about the possibility of reduction in the other direction. J.S. Bell said (in his Quantum Mechanics for Cosmologists, I believe) that many-worlds would be a much better theory if understood as one where there were a multitude of universes in which every particle has a definite position (So, for any configuration, there would be some world, with the distribution of configurations to world corresponding to |Ψ|²). Bell then said that the multitude of worlds other than the one we were in was unnecessary: "it seems to me that this multiplication of universes is extravagant, and serves no real purpose in the theory, and can simply be dropped without repercussions"

I think we should add a statement along these lines to the section about the "isomorphism to many worlds" showing that there is a case to be made for reduction in BOTH directions. (Of course, there actually ISN'T much of a case for the reduction in the many-worlds direction, since the wavefunction alone DOESN'T get you all the predictions/experiences we actually have. What is wikipedia policy on claims that are demonstrably false but have been made by famous and smart people?)

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 see below. @harej 04:34, 31 October 2009 (UTC)

---

Bohm interpretation → Bohmian Mechanics — Relisted for further input. --RegentsPark (sticks and stones) 21:14, 23 October 2009 (UTC)

The theory is primarily called "Bohmian Mechanics" in the physics and philosophy of science literature. The name "Bohm interpretation" has misleading historical connotations. ZRPerry (talk) 18:34, 15 October 2009 (UTC)

The reason I'm talking about it here before going ahead and making the change is that I want there to be some communication and agreement among the editors still interested in this page so that, with luck, we will be able to produce a full rewrite that will be devoid of any misinformation, historical bias, unfounded points, or obscure language. One of the advantages of Bohmian mechanics is that it is elegant, simple, and unambiguous. The wikipedia article should reflect this.
That being said, I would like to make a suggestion: I propose that the wikipedia article currently titled "Bohm Interpretation" be renamed to "Bohmian Mechanics" for two reasons:
1 - In terms of actual usage, there very little, if any, use of the phrase "Bohm Interpretation" to refer to the theory described in this wikipedia article. This is not a baseless claim, here is my evidence:
From the SEP article (titled Bohmian Mechanics): "Bohmian mechanics... is also called the de Broglie-Bohm theory, the pilot-wave model, and the causal interpretation of quantum mechanics" These are the only names of the interpretation that are mentioned.
Also, if you look at the references and notes at the bottom of the wikipedia article, "Bohmian Mechanics" appears 5-6 times, "de Broglie-Bohm interpretation" and "causal interpretation" occur a bit less than that. The words "Bohm" and "Interpretation" never appear next to each other in the titles of ANY of the articles in the references/notes section. The closest you get are two uses of the phrase "Bohmian interpretation" but there's good reason (in the Barbosa article (Second reference from the top)) to think that this isn't meant to refer to the THEORY, but to refer to an interpretation that is suggested by Bohmian mechanics!

2- The use of "Bohm Interpretation" brings with it a certain degree of connection to the beliefs of the actual guy, David Bohm. This wouldn't normally be a problem, but there are a decent number of editors that seem to think that, if it's an interpretation of QM and Bohm thought it up (and/or agreed with it), then it should be mentioned/incorporated into the article. This is a very bad stance to take. Bohm changed his mind about these issues a few times over the course of his life, but the theory itself has always been the same, regardless of what Bohm said about it. I've even seen it said that "The Bohm Interpretation" isn't deterministic because Bohm apparently supported an indeterministic theory later in his life. This is patently absurd! Bohmian mechanics is explicitly deterministic, which is one of the reasons it's so special.
If people would like to keep the article's title the same and keep its focus on some strange amalgam of the different theories Bohm held over the course of his life, then I motion to remove it for lack of notability (who cares what Bohm's actual opinions over the course of his entire life were), and I motion that we start an article about Bohmian Mechanics since it is very important for historical reasons and for modern philosophers and physicists working in foundations of Quantum Mechanics.
Also, I think it would be better to rewrite the article using the terminology and formalism in Bell's presentation of Bohmian Mechanics or Goldstein's article on it in the SEP. (Also, why the heck does Quantum Consciousness show up in the related links? Is it because Bohmian Mechanics gives no special status to consciousness/observation/measurement and is unusual in the world of QM interpretations because of it?)
ZRPerry (talk) 18:24, 15 October 2009 (UTC)

I think I'm against a change to Bohmian mechanics - particularly because Bohm himself hated that title, but also because it is unfair to de Broglie, whose idea the whole thing was. I essentially agree with what Towler says in his lectures referenced at the end of the article (lecture 7, slide 21):

Strictly speaking, the main thing done by Bohm not done before by de Broglie - other than stating the matter more clearly - was adding proper measurement theory (effectively inventing the 'decoherence' concept). Thus calling the theory 'Bohmian mechanics', the 'Bohm interpretation', the 'Bohm theory', and its adherents 'Bohmians' is unfair to our French friend, and the practice should be stopped - in favour of 'de Broglie-Bohm theory', or better 'pilot-wave theory' (since no-one born outside France can pronounce de Broglie's surname). It is not an interpretation either, but effectively a new theory.

According to his biographer [F. David Peat, Infinite Potential], Bohm 'was horrified when his own hidden variable theory was later called Bohmian mechanics by some physicists'.

Zicovich (talk) 21:49, 23 October 2009 (UTC)

I should also add that according to Towler, Bohm actively lied about what de Broglie's contribution had been (or at least couldn't be bothered to find out, which was almost worse):

The idea of a 'pilot wave' that guides the movement of the electron was first suggested by de Broglie in 1927, but only in connection with the one-body system. De Broglie presented this idea at the 1927 Solvay Congress where it was strongly criticised by Pauli. His most important criticism was that, in a two-body scattering process, the model could not be applied coherently. In consequence de Broglie abandoned his suggestion. The idea of a pilot wave was proposed again in 1952 by Bohm in which an interpretation for the many-body system was given. This latter made it possible to answer Pauli's criticism. [quote from Bohm and Hiley's 1993 'Undivided Universe']

and Bohm also wrote:

Thus, Pauli's objection is seen to be based on the use of the excessively abstract model of an infinite plane wave.

In fact (I cherry pick and slightly edit remarks from the Cambridge course):

- De Broglie published the 1 particle theory in May 1927 in Le Journal de Physique et le Radium, 8, 225 (1927):

One will assume the existence, as distinct realities, of the material point and of the continuous wave represented by the function psi and one will take it as a postulate that the motion of the point is determined as a function of the phase of the wave by the equation v = grad S / m + e/c A. One then conceives the continuous wave as guiding the motion of the particle. It is a pilot wave.

- de Broglie then presented the full N-particle theory at the Solvay conference in October 1927. The theory was applied to a nonrelativistic system of N particles guided by a wave function in configuration space that determines the particle velocities according to de Broglie's law of motion. The theory published in the Proceedings is absolutely pilot-wave dynamics/Bohmian mechanics as we know it today (though without properly extending it to macroscopic measuring devices).

- Pauli's objection was that the theory didn't give a unique result for inelastic scattering. If Bohm was correct that Pauli's problem was in using an infinite plane wave, then the same objection could made about elastic scattering (which Pauli explicitly states is correctly treated in de Broglie's work). So Bohm was wrong about this. In fact Pauli's objection was incorrect for another reason (his use of Fermi's misleading optical analogy which could not be applied in this context). De Broglie's reply quoted in the Proceedings did actually contain more or less the right answer, but he was misled by Pauli's use of the optical analogy and phrased his answer in terms of it.

- Note also the irony that Pauli was [incorrectly] complaining about the pilot-wave theory not producing a unique result, when the orthodox quantum theory of the time had exactly the same problem (which was only 'solved' by introducing the idea of 'wave collapse' i.e. effectively just stating that it gave a unique result when it didn't).

- de Broglie didn't abandon his idea for another three years (and then not specifically because of Pauli's objection).

So the paragraph in Bohm and Hiley - while 'accepted history' to some extent - is clearly wrong on essentially all of its substantive points - which is unfortunate to say the least.

I'm not making this up - this is discussed extensively in Valentini and Bacciagaluppi's recent book 'Quantum Theory at the Crossroads: Reconsidering the 1927 Solvay Conference' - they also give the first full translation in English of the Proceedings in the last third of the book.

In short, de Broglie's priority is now clearly established. We cannot continue to call it either the 'Bohm interpretation' or 'Bohmian mechanics'.

Zicovich (talk) 22:19, 23 October 2009 (UTC)

We can because we just follow the literature and report it. What we do not do in Wikipedia is to decide on priority disputes ourselves.

Also your logic is flawed; de Broglie's theory was less developed than Bohm's, particularly in the area of measurement which, as we all know, is a pretty big deal in quantum mechanics.

That said, I wouldn't really object to it being called "deBroglie-Bohm" or some such, since that usage occurs in the literature.--Michael C. Price ^talk 23:23, 23 October 2009 (UTC)

Sorry, did you not read my post? Valentini and Baccigaluppi is a non-controversial highly scholarly 553 page book in which the priority dispute is forensically examined, and which comes down heavily in favour of de Broglie. I am not deciding on a priority dipute myself - I am following the literature and reporting it. Are you? Have you even read this book?

Also my logic is not flawed. I made the same point about measurement myself, but while important, it is a small part of the overall conception and logically follows from the application of de Broglian mechanics to a macroscopic system. An important addition of course, but surely not enough to have the whole thing named after you.

Zicovich (talk) 23:41, 23 October 2009 (UTC)

I find it hard to accept your statements, given that de Broglie did abandon his theory, and then reembraced it after Bohm extended it. It demonstrates that Bohm's measurement contribution was critical.

You didn't respond to my final point: "De Broglie-Bohm"? --Michael C. Price ^talk 09:42, 24 October 2009 (UTC)

Zicovich, I see your point. We definitely should not under-represent the contribution that de Broglie made to the theory. However, I agree with Michael's point that it isn't our place to make this decision. In current foundations of QM work that is being done by physicists, mathematicians and philosophers, the most common name (as far as I have seen) has been "Bohmian mechanics" (of course, "de Broglie-Bohm theory" is also popular, and would still certainly be an improvement over "Bohm interpretation"). Maybe it's wrong that so many people who accept a theory which has its roots in the work of de Broglie call themselves "Bohmians" and call their theory "Bohmian mechanics", but Michael is right that the job of an encyclopedia article isn't to make a call about what people should call the theory, but to inform the masses about what people do call it. Of course, there is nothing stopping you from including a NPOV, well cited section about the monumental contribution de Broglie made to what would eventually become Bohmian mechanics.

I have only one issue with the "de Broglie-Bohm theory" name, which is basically the same issue I had with the "Bohm interpretation" name: misleading historical connotations. Both of these article titles might give some unsuspecting editor the idea that the goal of the article was to give a description of the theories as accepted/presented by de Broglie or Bohm. However, this has two problems: First, de Broglie and Bohm ended up rejecting these theories. As such, we don't want to include information in the article about different theories that also happened to have the honor of being supported by Bohm or de Broglie. Titles like the two above are problematic in this respect; it is conceivable that someone might think that "de Broglie-Bohm theory" is short for "de Broglie's and/or Bohm's theories" or that "Bohm interpretation" is short for "Bohm's interpretation" which would lead to confusion and lack of clarity that should be refreshingly absent from an article on Bohmian mechanics.

Second problem with the current name and the "de Broglie-Bohm theory" name: One might, again, conclude from these titles that the article should contain an exposition of the theory as the authors presented it. While this might be acceptable in some cases, there is no reason to think it should work here. It should be that, when a sufficiently intelligent person reads an article on a theory currently being debated about in wikipedia, she should be able to turn to a (relatively accessible) article on the subject and read it with something (hopefully) very close to comprehension. However, contemporary discussions of Bohmian mechanics make use of a strikingly different formulation than the one in Bohm's 1952 paper (formulations are usually closer to Bell's).

I think it should be made clear that the "Bohmian mechanics" title wouldn't rule out giving de Broglie the credit that he deserves (and we can verify). Also, it looks like de Broglie's pilot-wave picture already has a page: Pilot wave. Given that there is already an article about de Broglie's formulation of the theory, there shouldn't be any reason why this article can't focus on the theory as suggested by Bohm and defended by his followers (Bell, Goldstein, etc.). ZRPerry (talk) 21:40, 24 October 2009 (UTC)

I thought that de Broglie re-embraced his theory after Bohm extended it. Are you saying that de Broglie subsequently rejected it again, or that he never returned to it at all?

I would like to see an article just about the theory as presented in Bohm's 1952 papers. What should that be named? --Michael C. Price ^talk 21:50, 24 October 2009 (UTC)

I only meant that de Broglie spent a period of his life where he didn't accept it and (presumably) accepted some other theory in its stead.

"I would like to see an article just about the theory as presented in Bohm's 1952 papers." Why on earth would you want to see that? Look: Bohmian mechanics is a theory that is still being argued about today. Wikipedia should, then, be up to date in presenting the theory as it appears today. It might be nice to have a section devoted to discussing the way Bohm presented his theory, but the discussion of the theory itself should be in the clearest, most up to date terms available.

Historical significance or importance is not a good enough reason to use older, out of use terminology and notation when discussing a theory that is still around. If you have an independent argument for either including a separate article about Bohm's 1952 presentation of the theory, or making this the topic of the Bohmian mechanics article, I would like to hear it. Imagine if you made an analogous suggestion on the Calculus page: that they ought to phrase their exposition of the theory in terms of fluxions (an essential part of Newton's original formulation of the theory) and whatnot (The place you do see a discussion of fluxions in Calculus is on the History of Calculus page, where Newton's "idiosyncratic" notation is mentioned, but no math is done using that notation. The same should apply for Bohmian mechanics). All I'm saying is, all else being equal, use the most common and most modern formulation of a live theory as you can. If you think all else is not equal, prove it. ZRPerry (talk) 22:09, 24 October 2009 (UTC)

I just think that the 1952 presentation is the clearest. After that it all seemed to go pear-shaped and fuzzy. Implicate order and all that. Just MO, of course.

Oh! I certainly agree that the theory presented in the 1952 paper should be the focus of the article. Much of what Bohm says after that isn't really about Bohmian mechanics at all, or, if it is, it's about certain philosophical and interpretation foundations for it. As far as a physical theory which describes the motion of particles, what he says in the 1952 paper is where all the action's at. I was only saying that we needn't focus on the way that Bohm presented these ideas, if the idiosyncrasies of his presentation aren't involved in the theory as it's talked about today.

The sort of theory I'm talking about is one that can be gleaned from the 1952 paper alone, but is easier to understand if you look at J.S. Bell's presentation, or Goldstein's article in the SEP. The theory is first-order, only needs the Schrodinger equation and the Guidance equation, is demonstrably deterministic, non-local, and solves the measurement problem with ease. Most of the other proclamations of Bohm (the stuff that Bohm was getting on about later in his life) are just excess baggage. Of course, some of this baggage might have historical importance (like the fact that Bohm's original (1952) presentation was of a second order theory of particle motion, with a quantum potential playing an important role), and thus deserve mention; but most of the historical peculiarities won't be worth mentioning or explaining in full in the main article.

I think the article here should be close to the SEP article in its historical focus (http://plato.stanford.edu/entries/qm-bohm/). It should point out that Bohm originally presented the theory as a second-order theory with particles being acted on by forces stemming from a Quantum Potential, but that the theory can be formulated using just the Schrodinger equation and the Guidance equation without any fundamental inclusion of notions like force or acceleration. It should spell out the theory in the simplest formulation (the first-order one) and mention that this is the one which is receiving the most attention currently (with citations galore). Would this come at all close to fulfilling your desire to see an article just about the 1952 theory? ZRPerry (talk) 23:22, 24 October 2009 (UTC)

I'm too tired to read the full SEP entry right now, but the introduction looks spot on with regards to the history and theory content. The identification of Bohmian mechanics = Bohm1952 = de Broglie-Bohm = pilot-wave model is one that I'm very happy with.--Michael C. Price ^talk 01:20, 25 October 2009 (UTC)

I think it’s fine that there’s a mathematician from New Jersey and a couple academics from Germany who go around promoting something they call “Bohmian Mechanics.” That the theory in the form they present it has anything to do with the theory Bohm was about in the ‘52 articles, or that “Bohmian Mechanics” should be seen as the legitimate successor and incarnation of the “de-Broglie-Bohm theory” are highly questionable assumptions. Since there is no definitive “appellation controlee” for the theory, for Wikipedia purposes it’s probably better to keep the rather generic “Bohm Interpretation,” and then reference these other labels. The problem with calling the article the De Broglie-Bohm Interpretation is that someone would have to present the development of the pilot wave theory and what de Broglie calls “the theory of the double solution.” These papers are collected in Une tentative d'interprétation causale et non linéaire de la mécanique ondulatoire: la théorie de la double solution, Gauthier-Villars, Paris, 1956. Holland provides a good historical summary. Main caveats are: while Bohm in a sense “rediscovered” the pilot wave solution, they approach the problem in very different ways. De Broglie is working from the idea of a “Fuerungsfeld” and wave mechanics. Bohm comes to similar results from a hidden variable approach with an emphasis on what he calls the quantum potential as an additional force. Then there is the question of nonlocality. De Broglie never accepted non-locality, and conceived of the motions of particles in the microscopic domain in strictly local and deterministic ways; Bohm’s presentation, on the other hand, is clearly non-local, implicit in the 1952 papers (eg discussion of EPR) and then explicitly after digesting the work of Bell.

In terms of the content of the article, there are still a lot of very questionable passages, such as the “Results” section (superfluous) and the section entitled “Comparison with Experimental Delta” (tangential at best). Rather than worrying overmuch about what the article is called, it would be better to try to improve the article so that it is useful for someone (the gentle Wikipedia reader) who simply wants to find out what this alternative Bohmian approach is all about. Focusing on the ‘52 articles still seems to me to be the right approach.Sfwild (talk) —Preceding undated comment added 17:16, 25 October 2009 (UTC).

Hey Sfwild, welcome to the discussion. I think my answer to you is going to be similar to the answer that was given to Zicovich. You may think that the claims made by the proponents of Bohmian Mechanics that the theory they defend is a version of the theory suggested by Bohm's '52 paper, is a load of hooey, but it's not Wikipedia's job to reflect your view as fact. The reason I suggested "Bohmian mechanics" as the new name is because, of the people still working in foundations of QM (both on the physics and on the philosophy sides of the field), almost all of them are using the name "Bohmian mechanics" and far far fewer (if any) researchers currently working on these questions call it the "Bohm interpretation"

If you think this is wrong, that's fine, but I'd like to see some evidence. Particularly, I'd like to see evidence that a significant enough amount of the work (that is: articles by respectable physicists, mathematical physicists, or philosophers of physics) currently being done on this theory is being done in terms of the 1952 presentation. It would be even better if there were any such articles that also made mention of the "Bohmian Mechanical" formulation used by Bell, Goldstein, etc. and gave reasons why they chose to stick to the 1952 presentation.

Note, however, that I am not objecting to including, in the article, Bohm's original presentation. I am merely saying that the article should mention that there are parts of this presentation that can be done away with without loss to the theory, and that a more streamlined version is the one that is currently held as definitive (or, at least, is the version that is receiving current attention).

You failed to mention the other reason I thought the name "Bohm interpretation" was a bad choice: the historical connotations. I agree with your last point that what we really need to do is fix the content of the article, but I think any progress in this direction will be overly difficult if the subject of the article remains ambiguous. With a title like "Bohmian mechanics" it will be much clearer that the subject of the article is a particular theory, which has been held by some and rejected by others, as opposed to the quantum mechanical worldview of one man. An article on the theory, whatever we call it, should make it clear that the theory is deterministic, realistic, equivalent with orthodox QM insofar as the latter is non-ambiguous, and non-local. It should also point out that Bohmian Mechanics is remarkably elegant, and present the theory in such a way that the average reader can tell that this claim is true (Legendary philosopher Hilary Putnam is quoted in the SEP article on Bohmian Mechanics (last section), where he takes a direct jab at the Wikipedia article for misrepresenting Bohmian Mechanics as being mathematically inelegant)

In short, we can (roughly) divide the class of people who have ever talked about a Bohm-like theory into two groups: The people who are calling it "Bohmian mechanics" and the people who aren't talking about it anymore. So, since an article about a live scientific theory should reflect the theory in its most up to date formulation, we should change this article's title.

By the way, here are two active research groups (admittedly, both located in or around Germany, which I hope you don't treat as grounds for ignoring them) I found that are working on Bohmian mechanics in its contemporary formulation.

http://www.bohmian-mechanics.net/ and http://bohm-mechanics.uibk.ac.at/

I couldn't find any that stick to the 1952 version (and I did look). ZRPerry (talk) 03:10, 26 October 2009 (UTC)

The problem with naming the article “Bohmian mechanics” is that that’s not at all what the article, in its current form, is about. Indeed, the article would have to be totally rewritten to conform to the “Bohmian Mechanics” theory as presented in Goldstein, Tumulka, Duerr usw. I also disagree that workers interested in the foundation of physics issues tend to use the term “Bohmian Mechanics.” My experience is that those who have an interest in the entstehungsgeschichten of these ideas tend to use the more accurate historical designation of the “De Broglie-Bohm Theory” or some variant thereof (as does Holland for instance). Also, while the Bohmian Mechanics proponents reference Bell quite frequently, I do not believe Bell himself ever used the term. I have no problem with the article mentioning "Bohmian Mechanics" though what is needed is some “disambiguation” to make clear the differences. This could be done, for instance, with a short section in the extensions section explicating Bohmian Mechanics, stating how the theory differs from Bohm’s original presentation, the primary importance accorded to the guiding equation (as opposed to the quantum potential), its presentation as a “primary” theory of the positions of the particles, its uncompromising determinism—all of which is very different from the way Bohm goes about things. The irony here, as has been mentioned, is that the theory promulgated under the banner of “Bohmian Mechanics” is actually much closer to De Broglie’s original presentation of la double solution than it is to Bohm’s approach. Perhaps the theory should be called “La mechanique de Brogliean” This would be a boon for all true Bohmites as it would relieve his name from a questionable legacy and, since it’s unpronounceable, would help facilitate its demise and thus clear the way for a proper recovery of Bohm’s theory. Historical bias? Not at all!Sfwild (talk) —Preceding undated comment added 18:29, 26 October 2009 (UTC).

Listen, I have no problem with the article including an explication of both the 1952 presentation and the contemporary presentation of the theory (which, I think, got its start in Bell). I also don't have much of a problem with compromising and naming the article after the de Broglie-Bohm Theory, since that's what, I believe, Bell called it. Remember, this isn't a debate about what the theory should be called, but a debate about what we should call the article about the theory. If the prevailing consensus among most philosophers and scientists currently working in this field is that the theory has this name, the Wikipedia article should have that name, regardless of whether the theory should have that name or not.

What I do have a problem with is the current inclusion of certain aspects of other theories that Bohm held at different points in his life. Bohmian Mechanics, or the de Broglie-Bohm theory, or whatever you want to call it, is a deterministic theory, plain and simple. This is a big part of what makes this theory so interesting, and if you ask someone currently engaged in the debates where this theory appears, they will attest to this fact without hesitation.

The place for Bohm's later theories are either in the article about Bohm, or in some wholly separate article. In the 1952 article, Bohm presented the framework for a complete theory. The philosophical baggage he would end up, later in his life, attaching to it, was not an extension of the theory; it was something else entirely. I will say it again: This article is about one particular influential and scientifically viable theory, not the quantum mechanical worldview of one (influential) man.

A man can accept and reject different theories over the course of his life, but the theories do not change (as a result). Bohm accepted the theory this article is about (the de-Broglie Bohm theory or Bohmian mechanics, whatever you call it) when he wrote his '52 paper, but he eventually rejected it. As such, it is not enough that some theory enjoys Bohm's approval that it should be mentioned in this article. Only the specific theory, which is still being held and argued about (though in an alternate formulation) by certain working philosophers of science and physicists, is the topic of this article.

Sfwild, I beg of you. I can see that you are extremely knowledgeable about the various positions and ideas Bohm defended over his lifetime. However, this is an article about an (that is, one) alternative interpretation of quantum mechanics. This interpretation is not a dead theory, there is still work being done about it and there are still a great many people who expect that it, or something very much like it, is the correct account of the nature of the world. This is an encyclopedia article about an interpretation that plays an important role in current debates about the topic. I have provided, in this discussion, examples of research groups at large universities with a focus on this interpretation. I have also pointed out that the name I suggested for this article's title is the one that appears most often in the actual citations and footnotes in the article itself, and in the current literature on this topic.

My request is just this: either (1) give me well evidenced reasons to think that I am wrong about the formulation (and name) of this theory as it is currently being discussed, or (2) give me reasons to think that I am wrong that this Wikipedia article is about this extremely important and influential theory and that it is, in fact, about the many-staged personal interpretation of one physicist.

If you can do either of these things, I will gladly concede your point. However, if you cannot or do not, I must insist that this article's name be changed to "Bohmian mechanics" in order to reflect its discussion in the relevant literature, or, at least, it be changed to "The de Broglie-Bohm theory" ZRPerry (talk) 20:48, 26 October 2009 (UTC)

I agree with ZRPerry. But there is no reason why we can't have an "Implicite Order" / "Bohm-Hilley" article in addition to a "Bohmian mechanics" / "de Broglie(-Born?)-Bohm" article. Bohm's article could then explain how Bohm's views shifted over the years. That would seem to make everyone happy, would it not?--Michael C. Price ^talk 00:57, 27 October 2009 (UTC)

To summarize my position, I just want to add some additional points:

(1) I follow work in this field closely and have met most of the other people who do. As SfWild said or implied, It is a fact that Sheldon Goldstein, Detlef Durr, Nino Zanghi and people in their groups refer to what they work on as Bohmian mechanics (indeed you can't get a job with them unless you do - as they defend this position with great vigour and determination). Almost everyone else, including *everyone* who has ever written a book on the subject except Durr, call it something else, with the general drift being towards something like 'de Broglie-Bohm pilot-wave theory'. (I'm thinking of Valentini, Holland, Hiley, Riggs, Bell, Towler, Cushing etc. etc.). Many of the active researchers in the field (led by Valentini) are actively campaigning that the name should be changed.. Now that the actual historical course of events has become clear (which it wasn't when G, D, and Z started working on this) it is clear that the second group are 'correct', morally and historically speaking, and now that Valentini and Bacciagaluppi's book has come out, I think Wikipedia should not retitle its article to one which will inevitable become obsolete over the next few years.

(2) De Broglie's 'theory of the double solution' is a complete red herring. Although he did work on seeing if this was possible, he rejected it. What he produced for the 1927 Solvay conference was exactly 'Bohmian mechanics' for an N-particle system as it is known today (though without applying it to a macroscopic system).

(3) I agree that Bohm's later implicate order stuff should indeed not be included in this article. Again, referring to the Cambridge lecture course, this stuff is indeed mentioned, but it is split off into the final lecture and the author makes it quite clear that it is not part of physics nor of the 'de Broglie-Bohm pilot wave theory'.

So - just for amusement - I wonder if ZRPerry would confirm or deny that he is one of Goldstein, Durr, or Zanghi or that he works in one of their groups and his request to have the name of the article changed is just part of the propaganda struggle currently taking place within the field? Or is he just a disinterested observer? :-)

Zicovich (talk) 10:02, 27 October 2009 (UTC)

It is not customary on Wikipedia to have to reveal your real-life affiliations.

Incidentally, here are some google web search counts with the g-scholar count in brackets:

"Bohmian mechanics" - 17,400 (1,610)

"de broglie bohm" - 415,000 (1,470)

"pilot wave" - 15,400 (1,660)

--Michael C. Price ^talk 10:24, 27 October 2009 (UTC)

So - a clear win for 'de Broglie Bohm' then? :-)

I'm aware that we don't reveal who we are. I just think it's important that as disinterested encyclopedia writers, we are sure that our motivations for changing the title of an article are pure, and this is not just another partisan shot in some internal physics propaganda war..

Zicovich (talk) 10:45, 27 October 2009 (UTC)

Seriously though, I think it is now clear that simply counting the numbers of times some term is used in the literature will not produce a definitive result, since the theory is referred to in many different ways by many different people. Wikipedia must therefore use some other criterion to choose between the various alternatives. My humble suggestion is that we refer to the most recent scholarly work in this field (namely Valentini and Bacciagaluppi's 2009 book) which makes the historical context clear (including the fact that Bohm's 1952 work was done almost in its entirety by de Broglie 30 years previously, and that Bohm actively produced misinformation about this). Just to state my affiliations - note that I am neither Valentini nor Bacciagaluppi, nor one of their friends. :-)

Zicovich (talk) 10:56, 27 October 2009 (UTC)

Just passing through. As I was doing a Web of Knowledge search anyway, I plugged "Bohmian interpretation" and "Bohmian mechanics" into it. The former returns 19 hits, while the latter manages 209. "Pilot wave" only polls 109, and "de Broglie-Bohm" nets 251 (or, suspiciously, 42 if "... theory" is appended). Regarding Zicovich's point about a recent book, I'd have thought that use (or disuse) in the scientific literature should trump this. Anyway, good luck solving this one! --PLUMBAGO 11:31, 27 October 2009 (UTC)

Of course the literature should trump it. However, my point is that an analysis of the literature does not produce a definitive result. Therefore we must use other criteria.

Zicovich (talk) 12:21, 27 October 2009 (UTC)

Let me just start off by saying that I have no problem with calling the article "the de Broglie-Bohm theory" or something like that (though maybe not "de Broglie-Bohm pilot wave theory" since that's a little heavy and you can be a Bohmian without admitting that the pilot wave is something you're supposed to take ontologically seriously). My main goal was to (1) reflect the current literature and (2) help clear up historical ambiguities about the article's topic.

I have no objection to making this article about Bohm's 1952 theory which was rephrased by Bell in a simpler way, while making some other article to talk about Bohm's wackier positions. Once this happens, any reasonable title which enjoys at least some use in the literature will do. "Bohmian mechanics" is one such title, but "de Broglie-Bohm" is, arguably, another. Since both titles, to similar degrees, achieve the two goals I had set up, I'm okay with whichever one decreases strife, as long as the other title and the theory's modern formulation get their respective dues.

That being said, I think you're being slightly unfair in suggesting that Goldstein et al represent some sort of isolated position in terms of name and/or formulation. Now, I'm not a physicist or a mathematician. I'm a philosopher. My preference for "Bohmian mechanics" as a title came, in part, from the fact that this seemed to be the most common name used by philosophers talking about these issue. I'm not sure about what sort of foundational questions or theories physicists are talking about (or even if they're talking about foundational topics at all), but I know that the Bell or Goldstein presentation of the Bohm theory has received the lions share of serious philosophical attention.

It's really only in terms of this presentation that I hear the more nuanced issues talked about (things like Bohmian many-worlds, or the marvelous point argument, etc.), but I could just be mis-/under-informed.

As for the physics, though, it's not like Goldstein and his associates are some sort of fringe group. They're publishing peer reviewed articles and running research groups at major universities. If you think this isn't a representative sample of the people actively working on these topics in physics, show me why not (The book you mentioned seems to be about one important conference in 1927, so it hardly sounds unbiased with regard to whether the focus should be on de Broglie or Bohm, since Bohm was 10 at the time, while Bell, Goldstein, and so on weren't yet born). You also mentioned Cushing: Cushing edited a collection called "Bohmian Mechanics and Quantum Theory: An Appraisal" (of course, it was co-edited with Fine and Goldstein, so I suppose you'd just say that Goldstein tortured Cushing until he agreed to that particular title). I mean, insofar as we think about people devoting a majority or, at least, a significant portion of their time and effort to thinking and talking about this theory, the people you've cited as firmly opposed to "Bohmian mechanics" sound much more like they're expressing the super-vocal yet insignificant minority opinion, not Goldstein. (but I digress...)

As for my identity, I will say the following: I am not Goldstein, Durr or Zanghi, nor do I (or have I ever) work(/ed) in one of their research groups. I will admit (and have never denied, see my user page) that I did receive a degree from Rutgers. I also have met Goldstein (who is a very nice man, fyi), though I was already a Bohmian at the time and I consider myself neither a convert to nor an acolyte of his method or position with regard to these problems. As someone located in the New York/New Jersey area with an interest in the philosophy of physics, the influence of Goldstein's work is certainly present, but I assure you that my interest in fixing up this article is not (and has never been) "just part of the propaganda struggle currently taking place within the field"

All I wanted was a name that didn't bring along any biographical or historical baggage with regard to Bohm's later work. I suggested the title I feel is the most common in the literature (on both sides of the physics/philosophy coin). I was unaware there was such animosity and grief being thrown around with regards to this name. I am happy to go with "de Broglie-Bohm theory" as a title, both as a compromise and as demonstration of my complete lack of hidden agenda with regard to this article. Best, ZRPerry (talk) 22:33, 27 October 2009 (UTC)

Ah, so Goldstein did torture Cushing.. Seriously, I just wanted to remind folks that there is already a pilot wave article that talks about de Broglie. It says Bohm developed the Pilot Wave Theory into what is now called the De Broglie-Bohm Theory. --Michael C. Price ^talk 23:00, 27 October 2009 (UTC)

I have no problem with an article on Bohmian Mechanics—I just don’t think changing the name of current article is the way to get there. As much as I believe the approach to be wrong-headed, ZR Perry is right that the term “Bohmian Mechanics” gets a certain amount of schrift these days, so it may be useful to have a separate article referencing the major works of that school and presenting the formalism the way they do. Alternatively, that could be done as an “extension” of current article. I also have no problem with renaming the article the De Broglie-Bohm Interpretation or something like that, though if we’re going to go that route the article would need to state in much clearer terms what the De Broglie contribution was all about, including a minimal presentation of the pilot wave theory. Sfwild (talk) —Preceding undated comment added 23:25, 27 October 2009 (UTC).

Look, the title obviously did come from Goldstein - whether torture was involved I don't know - but Shelly is so fervent on this issue it would have been hard to refuse him. The book that Cushing himself wrote on the subject - called "Quantum mechanics: historical contingency and the Copenhagen hegemony" - does not use the phrase 'Bohmian mechanics' at all. Look at the long list of textbooks in the Further Reading section of the Cambridge course. You will see precisely one (Durr) that calls it Bohmian mechanics.

And Michael - seriously - I don't mean to question your authority here - I know you've done a patient job over many years watching over the Bohm interpretation article. But if you can't see that the so-called 'pilot-wave theory' article is a complete troll written by a guy who is not only semi-literate but obviously has only the vaguest acquaintance with the issues at hand then it would seriously upset me. There is a 'History' section at the end in which - quite honestly - pretty much every statement is factually incorrect. The article is also plainly not about what de Broglie did in 1923-27 (he didn't copy it from Born in 1926 for Christ's sake!) but is also about what Bohm did years later. It really just needs to be deleted so someone can start over. And I repeat again - no-one seems to be listening - that what de Broglie did in 1927 and published in the Solvay proceedings is Bohmian mechanics.

Mr. Perry - no-one is suggesting that Goldstein et al are a fringe group. They have clearly done a lot of important work on the subject. However, what is clear is that when they decided what they were going to call their field of study in the 1980s (Bohmian mechanics) they made a mistake - the mechanics is - essentially verbatim - that of de Broglie. His priority is now completely established. It is understandable that Goldstein et al don't want the name changed; clearly then their work will crop up less often in Google searches. However it is not their fault that they made a mistake - the history was not properly understood even as late as the 1980s - and Bohm himself claimed the mechanics as his own and actively downplayed de Broglie's contribution.

Also, you say:

"(The book you mentioned seems to be about one important conference in 1927, so it hardly sounds unbiased with regard to whether the focus should be on de Broglie or Bohm, since Bohm was 10 at the time, while Bell, Goldstein, and so on weren't yet born)."

Good God man - you couldn't be misunderstanding me more if you were being paid to do so. The Proceedings of this 1927 conference contains, essentially word for word, the theory of 'Bohmian mechanics' albeit without some of its consequences worked out (compare, for example, Einstein's 1905 special relativity paper, he didn't work out all the consequences either). The fact that Bohm was 10 at the time is absolutely and completely the entire point. Do you not think this has some bearing on whether the theory should be named after Bohm?

You also say:

"though maybe not 'de Broglie-Bohm pilot wave theory' since that's a little heavy and you can be a Bohmian without admitting that the pilot wave is something you're supposed to take ontologically seriously".

Bell himself said that it was impossible to be a 'Bohmian' without believing in the ontological existence of the wave field. To my knowledge, the only people who have tried to claim otherwise are Goldstein and a few collaborators who have recently tried to make the point that it could be 'nomological'. At recent conferences that I have attended and in the literature this claim has simply not been taken seriously - I've even seen it ridiculed - it's hardly a mainstream view.

Zicovich (talk) 23:43, 27 October 2009 (UTC)

I'm not saying that the pilot wave article is perfect, but it is there for us to update -- and I don't think it should be deleted first. I haven't updated it because I am not familiar with de Broglie's papers, only Bohm's (although I can't see where we differ on our understanding of de Broglie's pilot wave, which suggest that Bohm's reporting of de Broglie was accurate, despite your claims to the contrary). Which leads me on too....

.... yes, I am listening to you about de Broglie's priority, but I don't believe you; you seem to be continually downplaying Bohm's extension in the area of measurement. This was a major advance, since all the philosophical issues with quantum theory lie in this area. It was the pilot wave's apparent deficiency in this area that caused de Broglie to abandon it, until Bohm cleared the matter up. Bohm was quite explicit in his 1952 papers that he was only extending de Broglie's theory -- to say that Bohm lied about de Broglie's contribution, or deliberately spread "misinformation" is ridiculous.

Finally, yes I agree that de Broglie and Bohm both believed in the reality of the complex-valued wavefunction at one time, although Bohm may have gone soft in later years. --Michael C. Price ^talk 00:50, 28 October 2009 (UTC)

It's not ridiculous, Michael. Read what I quoted earlier:

The idea of a 'pilot wave' that guides the movement of the electron was first suggested by de Broglie in 1927, but only in connection with the one-body system. De Broglie presented this idea at the 1927 Solvay Congress where it was strongly criticised by Pauli. His most important criticism was that, in a two-body scattering process, the model could not be applied coherently. In consequence de Broglie abandoned his suggestion. The idea of a pilot wave was proposed again in 1952 by Bohm in which an interpretation for the many-body system was given. This latter made it possible to answer Pauli's criticism. [quote from Bohm and Hiley's 1993 'Undivided Universe']

This was written by Bohm in 1993 - forty-one years after he first published his two 1952 papers. Forty-one years, and you're trying to tell me that he still hasn't read what de Broglie wrote in 1927? The four glaring errors tell me that either he has not (which is highly unbelievable, given the existence of a clear priority distribute) or that he is being economical with the truth (unlikely certainly, but not impossible). Remember that (1) de Broglie published the N-particle theory in 1927. (2) Bohm was therefore not the first to do so in 1952, (3) Bohm's response to Pauli's criticism was simply incorrect (nothing to do with infinite plane waves), and (4) The use of the N-body theory is not the key to answering Pauli's criticism. One might also say that de Broglie did not abandon his theory immediately (it took several more years) and he did not abandon it specifically because of Pauli's criticism.

Also he was not 'quite explicit in his 1952 papers that he was only extending de Broglie's theory'. De Broglie was mentioned in a 'note added in proof'.

Tell me Michael. How do you explain Bohm's behaviour here?

88.104.247.161 (talk) 10:00, 28 October 2009 (UTC)

I'm getting tired of you repeating yourself, accusing everbody of making factual errors, not reading your stuff etc etc, when your own postings are riddled with errors.

The explanation given by Bohm in the introduction of his first 1952 paper seems entirely adequate (where de Broglie is repeatedly mentioned, and not just in a footnote added in proof, despite your claims to the contrary). De Broglie had not taken his theory far enough forward to fully include measurement by the observer. Had he done so, he wouldn't have abandoned it.

Bohm also says that Pauli's criticism was only part of the reason why de Broglie abandoned his pilot wave theory, so please stop accusing Bohm of lying or ignorance on this topic.

As for the Bohm/Hiley statement, I imagine that they are using the shorthand "N-body system" to mean a model that includes measurment and the observer (it is a popular book, after all), which seems enitrely reasonable, since that is how measurement is handled.

--Michael C. Price ^talk 10:33, 28 October 2009 (UTC)

I quote from Bohm's 1952 article: After this article was completed, the author's attention was called to similar proposals for an alternative interpretation of the quantum theory made by de Broglie in 1926.. This, by any definition, is a 'note added in proof'. I did not say 'footnote added in proof' as you misquote me.

You imagine wrongly about why Bohm-Hiley are using 'N-body system' - it is clear from their writing in many places that they literally mean that, and that they think de Broglie's theory was for single-particle wave functions. Now that is wrong, as a quick glance at the literature would have told them, so either they couldn't be bothered to read the literature or they're not telling the truth. Of course the former is more likely, but it is still reprehensible when there is a priority dispute.

It is a common misconception that 'The Undivided Universe' is a popular science book because of its funny title - it is actually a difficult texbook with lots of mathematics. If you think otherwise I can only assume that you haven't read that either.

Zicovich (talk) 12:42, 28 October 2009 (UTC)

You're right, I've never read 'The Undivided Universe'. This, I note, in no way counters my claim (that you're contesting so ardently) that Bohm says that he is only extending de Broglie's theory into the arena of measurement. And that de Broglie (and Rosen and Madelung) would have reached the same conclusions as Bohm but that they "did not carry this interpretation to a logical conclusion". This same point is made about three times (once in the footnote, once in Appendix B of paper II and once in the introduction of paper I). --Michael C. Price ^talk 13:06, 28 October 2009 (UTC)

Indeed. Look, Michael, I don't mean to offend, but the fact that you haven't read the primary literature on de Broglie-Bohm theory is painfully obvious. This is one of the reasons you think my posts here are 'riddled with errors', and is probably one of the reasons why this article remains in such a sorry state after being essentially under your jurisdiction for so many years. Please, we're grateful for your many contributions, but is it not time for you to take a back seat and concentrate your efforts on some of the other (no doubt many) subjects on which you are an expert? There can be honour in graceful retirement.. :-)

Zicovich (talk) 21:42, 28 October 2009 (UTC)

I get the impression that everything is "painfully obvious" you, regardless of whether you are right or wrong. Why don't you just substantively answer the point I made, instead of flinging further accusations of incompetence around? --Michael C. Price ^talk 01:55, 29 October 2009 (UTC)

Yep. It is obvious. Because I'm an expert who has read everything that there is to read on the subject (unlike you) and I have worked in the field for many years. The main page you must surely know is tagged with "This article is in dire need of an expert on the subject". Well now, lucky you, you've got one. Unfortunately with Wikipedia in its current state one has to check before contributing that the entry isn't ruled by a hostile egomaniacal editor who will likely delete anything one writes. I sadly see that it is. Well, I'm done here. Find someone else to help.

Zicovich (talk) 09:24, 29 October 2009 (UTC)

I never made any pretence of having "read everything that there is to read on the subject", unlike you. I note you still haven't responded to my substantive point, that Bohm says that he is only extending de Broglie's theory into the arena of measurement. And that de Broglie (and Rosen and Madelung) would have reached the same conclusions as Bohm but that they "did not carry this interpretation to a logical conclusion". Presumably you agree with this, but can't bring yourself to admit it. --Michael C. Price ^talk 10:48, 29 October 2009 (UTC)

Okay. So, as for my response to Zicovich's point about the book, I apologize. I misunderstood what you were getting at. I thought you were presenting the book as the most recent work in the field that mentions the de Broglie-Bohm view and then saying that the way it referred to the theory should be the way the article refers to the theory. I see now that you were presenting the book as evidence that the use of the name "Bohmian mechanics" is historically inaccurate and, thus, shouldn't be the title. As a source to back up this second point, the book is perfectly adequate. I apologize for my confusion.
As for my line about the pilot wave title, that was again my fault for not being clear (Everything I include in a parenthetical should be taken as false). In all seriousness, though, I was thinking of the 'pilot' wave as being a wave that pushes particles around. Insofar as we take the wavefunction seriously as defined on configuration space, it's not really something that pushes particles around unless you think that all we have in the world is one extremely many-dimensional wavefunction and one marvelous point. As far as I know, one needn't think that there is an additional wave (not identical to the wave on configuration space) that's waving around in 3-space pushing all the particles around. This is, most likely, just me misunderstanding the appearance of "pilot wave" in that title. Regardless, I'm not very knowledgeable about what has been said about this issue, so I'll just retract the statement and leave it at that.
However, I still think that "de Broglie-Bohm theory" rolls off the tongue (and is more common in the literature) than "de Broglie-Bohm pilot wave theory". I will repeat again that I have absolutely no problem calling the theory "de Broglie-Bohm theory" and I also don't have any problem with this new historical development (apparently) showing that a great deal of Bohm's contributions had been preempted by de Broglie. The reason I wanted to rename the article in the first place was to distance the article's topic from Bohm's peculiar personal worldview.
What are people's thoughts about the following arrangement:

Article title: "the de Broglie-Bohm theory"

It is mentioned that the theory was discovered by de Broglie, who later abandoned it, and was rediscovered and reformulated by Bohm in 1952, who later abandoned it. It was then reformulated again by Bell who defended it and extended the EPR argument to show that the common charge against the view (nonlocality) had to be true of (almost) any theory which got the quantum facts right. It is now defended by some under the header of "the de Broglie-Bohm theory" and by other as "Bohmian mechanics" though the theory and message are the same.

Article presents:

de Broglie's pilot-wave picture (both the single particle and the recently discussed later view) (kind of quickly, but there will be a link to its main page under the "pilot wave" article)

Bohm's '52 presentation (with Quantum potentials and all that hooey) (kind of quickly)

Bell's simplified formulation (where all you need is the SE and the guidance equation) (still kind of quickly but with just enough detail that you get everything you need)

and so on.

? I'm not so much interested in whether you think any of the things I've said as approximations of the content are true, but whether you think an article with approximately this form would satisfy your desires that appropriate credit be given to the theory's many historical discoverers, defenders, reformulators, and renamers. If you've got a problem with the fact that the historically important de Broglie version isn't gone into in detail, just rewrite the (currently really horrendous, you were very right Zicovich) pilot wave article as you please and enjoy the fact that de Broglie's version gets (in addition to its own page) top billing in the de Broglie-Bohm article.
Thoughts? Does this sound like a nice compromise both in terms of name and also in terms of historical credit and weight given to different formulations of the view? Cheers, ZRPerry (talk) 03:35, 28 October 2009 (UTC)

Hi Perry,

That's a great improvement, and I'm happy with the title 'de Broglie-Bohm theory'. I think in the final version, it should have that title and underneath something like also known as the Bohm interpretation, Bohmian mechanics, pilot-wave theory, the causal interpretation, the ontological interpretation, the quantum theory of motion and so on.. - perhaps there should be a.. what do you call it.. disambiguation where any of the latter titles link to de Broglie-Bohm theory.

I do disagree slightly with the structure of the article you propose, because you still seem to misunderstand what de Broglie did. You distinguish between:

   de Broglie's pilot-wave picture (both the single particle and the recently discussed later view)
   Bohm's '52 presentation (with Quantum potentials and all that hooey)
   Bell's simplified formulation (where all you need is the SE and the guidance equation)

I've never seen anyone refer before to 'Bell's simplified formulation'. The version of the theory where you have the Schrodinger equation and the first-order guidance equation with a N-particle wave function in configuration space is precisely de Broglie's 1927 pilot-wave theory. Bell didn't have a theory of his own, and I'm not sure how you propose to distinguish it from the original pilot-wave theory. As for Bohm's 'quantum potential hooey' this is how you get it: write down de Broglie's guidance equation v = grad S/m and er.. take its time derivative. This gives you F=ma with the force given by -grad (V+Q) where Q is the quantum potential. It's entirely equivalent. Note that although he chose not to emphasize it, de Broglie made it clear in his 1927 presentation that the theory could be written in this second-order form. So even taking the time derivative of the de Broglie guidance equation was not Bohm's idea either.

To summarize - the three different versions of the theory you propose are actually the same theory - that is the same mechanics/dynamics. What one chooses to apply the theory to (e.g. macroscopic systems, measurement) is irrelevant for the question of who invented the basic theory.

Note that the quantum potential can in no way be described as 'hooey'. It is simply the potential energy function for the wave field (which is a supposed to be a repository of energy or more strictly energy-momentum) - that is, Q represents the amount of energy available to a particle (configuration) at its particular position in the field.

I therefore propose that 'pilot-wave theory' should not have a separate article as it currently does, since the 1927 pilot-wave theory just is perfectly ordinary 'Bohmian mechanics'. It doesn't matter what positions de Broglie and Bohm later took up with respect to their own theories.

The first half of lecture 7 of Towler's Cambridge course has a good summary of the historical context.

Let me finally address your issue of the 'pilot wave can't possibly objectively exist because it lives in configuration space'. First, the whole point about the de Broglie-Bohm theory is that this wave is supposed to objectively exist. However, you must distinguish between the real objectively-existing field (let's call it the 'wave field') and the mathematical object that represents it (call it the 'wave function'). The former lives in 3 space, the latter in 3N configuration space; writing the mathematical object in configuration space simply implies the introduction of forces between particles. Again I quote the Cambridge course:

Use of wave function defined on a multi-dimensional configuration space does not imply this space exists in same sense that physical 3d space may be said to exist. (Remember even in classical mechanics we can use a configuration space description).

In CM, config space representation is just convenient summary of positions of all particles; in QM situation different since the physics is different - possibility of entanglement due to non-local interactions. So a simply-connected 3d space alone cannot describe the holistic quantum connectiveness and nonlocality features of multi-particle quantum systems. Instead this is done formally by employment of the N-dimensional config space. Problems with such a space actually existing are considerable:

(1) Need at least three separate dimensions for every particle in the universe.

(2) Continual variation in total number of dimensions in universe as particles are created and destroyed.

(3) Extra dimensions always completely unnoticeable at macroscopic scales.

(4) Complete lack of any experimental evidence for the existence of multi-dimensional physical spaces.

Currently don't know the `means' by which quantum non-local connections are actualized. Not because of non-relativistic context since non-locality is also present in relativistic versions of QM.

Given strong reasons against taking multi-dimensional space as real, the strong evidence in favour of physically real wave fields, and absence of info about the `means' of non-local connections, it is a coherent position to take psi to be a mathematical representation of a real field in physical space.

Notion of an N-particle system described in pilot-wave theory by its trajectory which is traced out in 3N-dimensional config space. Even though this description is given using a multi-dimensional space, the motion of individual particles can be calculated since there is a natural mapping from the system's trajectory in 3N-dimensional space to trajectories in 3d space.

Zicovich (talk) 12:28, 28 October 2009 (UTC)

Hey Zicovich,

I don't have a lot of time, so this will be quick: I also like the idea of starting the article off with something to make clear what the different names that get thrown around are.

As for your issue with the suggested structure, part of that was just because I didn't know what de Broglie's many-particle theory consisted in. If you'd prefer, we could have a quick presentation of the de Broglie's one-particle formalism, then Bohm's '52 formalism, then Bell's simplification of Bohm, with an added section at the end (or beginning) of Bell's section pointing out that, in fact, de Broglie had presented a theory almost exactly like this

Part of the point of the proposed article structure was to emphasize that these weren't different theories, or even different versions of theories, but simply reformulations (which is just a nicer way to say "rephrasing") of the same view.

(Here's another way to look at it. There are two ways you can arrive at the theory de Broglie presented in 1927. One way is to just reproduce de Broglie's theory, another is to take Bohm's '52 paper and simplify it. Bell was doing the second. Even if it turns out that this was just a roundabout way of reproducing a formulation of the view that de Broglie offered years before, the article should at least give lip service to the rather remarkable (and convoluted) journey that this theory took.)

To reiterate, I don't have a problem with a well-sourced presentation of why de Broglie's theory was, in fact, complete enough that the contributions of Bohm were minimal-to-nonexistent. I request only that the article about the theory be structured so that appropriate credit be given to the various champions it had over the years, since it was their contributions in terms of public exposure and clearing up objections that is responsible for the fact that the theory is even being talked about today. Regards, (also, you can call me "Zach") ZRPerry (talk) 15:30, 28 October 2009 (UTC)

Hi Zach. No problem with any of that, other than your mentioning 'a quick presentation of de Broglie's one-particle formalism'. As I said, although his thinking did pass through a one-particle stage, his mature 1927 theory was an N-particle one. The continual stressing of 'de Broglie - one-particle' is merely to repeat misleading propaganda. I think we're converging, nonetheless! Zicovich (talk) 21:32, 28 October 2009 (UTC)

Zach and ERPerry: you are much closer than you think! The irony is that if you re-formulate Bohm’s thinking into what the adherents of “Bohmian Mechanics” call a “first-order” theory about particle velocities and positions, and reduce the theory to a kind of reductionist determinism (though in configuration space), then in fact what you get is a theory of dynamics or motion very close to de Broglie’s original pilot wave formulations with an ideological baggage of quasi-La Placean determinism. At that point, you might as well drop not only the unfortunate “Bohmian Mechanics” misnomer, but drop Bohm altogether. To me this appears as a kind of paedomorphism, the reappearance of earlier, less evolved traits for evolutionary advantage, but it’s a free world and such a presentation of the “mechanique De Brogliean” or whatever you want to call it probably has a place somewhere in Wikipedia (start with trying to fix current “pilot wave” article?). Proposed outline above seems to me a good overall approach, though you might want to add a section on Bell, as what’s important—in the lineage described—is not at all Bohm but Bell’s reading of Bohm, which is the source of many insights but also misunderstandings about what Bohm and the Causal Interpretation (as Bohm understood it) was all about. Good luck!

Sfwild (talk)

I agree, Sfwild. I also prefer the first-order form of the theory without the quantum potential.--Michael C. Price ^talk 01:17, 30 October 2009 (UTC)

Most physicists working on the current incarnation of the theory would probably agree--and I concede the point that the Bell/Bohmian Mechanics approach has a certain heuristic value. Note though that from a "foundations of physics" perspective it is a bit odd to present a De Broglie-Bohm Theory in a form which both De Brogle (after 1927) and Bohm (already in 1952)would have rejected. Not impossible, just awkward. Note also that when de Broglie returns to his theory after 1953 (with Bohm's encouragement and Vigier serving as a kind of mediator), it is under the rubric of what he calls the theory of the double soulution--now containing an explicitly stochastic dimension--and not in the form of the earlier pilot wave presentation.

Sfwild (talk)  —Preceding undated comment added 18:37, 30 October 2009 (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.