Talk:Duane's hypothesis

'Fringe theory' tag

An anonymous IP user has added a 'fringe theory' tag.

The article is about the mechanism of diffraction of particles by periodic structures. Presumably the tag writer thinks there is some mainstream physical explanation of such phenomena, against which the present article should argue. So far as I know, there is no mainstream attempt to explain the phenomena. It is usually treated with hand-waving references to a doctrine of wave-particle duality that does not claim to have a physical mechanism. The physical mechanism of the phenomena is not usually considered. There is thus no substantial mainstream explanation to argue against.

Considering the timing and context of the tag, it seems natural to suppose that it is anonymous because its author wishes to be anonymous. If he author of the tag thinks there is a mainstream view that is opposed by the present article, it would help if he would state it here. Then perhaps there would be something to argue against.

The article is well referenced to reliable sources, including Werner Heisenberg (1930).<The Physical Principles of the Quantum Theory, translated by C. Eckart and F.C. Hoyt, University of Chicago Press, Chicago, pp. 77–78.> and Linus Pauling.<Pauling, L., Wilson, E.B. (1935). Introduction to Quantum Mechanics: with Applications to Chemistry, McGraw-Hill, New York, pp. 34–36.> A credible attack on the article should have read and should deal properly with those sources. The article is about physics. I think that a physicist examining it will consider on their merits the physical reasons offered in the sources and indicated in the article.Chjoaygame (talk) 11:28, 30 January 2015 (UTC)Chjoaygame (talk) 11:43, 30 January 2015 (UTC)

Mainstream accounts of particle diffraction

There is little fringe about the material in the article, except for the section named the same as the title of this thread. While diffraction phenomena don't provide conclusive mathematical proof of "particles being waves" (overwhelming support only), there is little concrete support for the "particles only" idea, especially since in order to reproduce the experimentally verified diffraction patters, one has to use the De Broglie relation for the diffracted particle together with the momentum transfer.

Using the De Broglie relation and pretending that it is not related to waves is just total mumbo-jumbo.

The one reference that I could access and at the same time was related to the contested point is the second paper by Van Vliet. It states

Upon substitution of the de Broglie relationship, the usual angular distribution for interference is recovered. This has now been obtained by a quantization procedure for the possible states of the interferometer, rather than by partial wave superposition of the incoming particle.

Little is wrong in that paper (equation 2.2 is one example of something wrong, probably not beyond repair though), except for its blatant POV. YohanN7 (talk) 10:55, 24 March 2015 (UTC)

A helpful anonymous IP editor put up a 'fringe' tag. I wrote the section trying to comply with this. I have no interest in the section, beyond trying to comply with the demands of the helpful tag.

It is not clear to me why for the particle-only interpretation 'one has to use the de Broglie relation for the diffracted particle' if it is a material particle. The deflection of the particle at the screen, when it is loaded with a quantum of momentum from the screen, is governed by the two momenta, that of the particle before loading and the added load. I don't think the de Broglie relation comes in there. The de Broglie relation is needed when one wants to look at the diffraction pattern as if it were produced by waves. Yes, it can be produced by a wave picture; that is one part of Landé's point: either picture is adequate for the average results. He is a real believer in wave particle equivalence, as distinct from wave particle exclusive alternation which seems to be the official doctrine. In his view, the pictures are equivalent through the mathematical relations E = hν and p = h/λ, both of which use Planck's constant. To get beyond the averages, to the fluctuations, more is needed, because the fluctuations come from the phase relations, which indicate the departure from randomness of the beam. No one is pretending use of the de Broglie relation, p = h/λ, is not related to waves; it is explicitly stated that it, combined with E = hν, is used to translate between the particle and wave pictures.Chjoaygame (talk) 12:50, 24 March 2015 (UTC)

Let us postpone any technical discussion. Would you seem it fit to simply replace the section with one sentence, perhaps something like "the necessity of the wave-particle duality has based on this been questioned". While you think, I'll remove the fringe-tag (didn't put it there, I tend, as you already know, to be more direct in criticism.) I'll later include a little from Duane's original paper (if you don't mind), which is quite nice in providing good intuition. YohanN7 (talk) 13:16, 24 March 2015 (UTC)

How about 'Duane's hypothesis was offered in the days of the old quantum theory. It did not take into account de Broglie's wave picture. It is debated whether or not Duane's hypothesis is relevant to modern physics.<Van Vliet, K. (1967). Linear momentum quantization in periodic structures, Physica, 35: 97–106, doi:10.1016/0031-8914(67)90138-3.><Van Vliet, K. (2010). Linear momentum quantization in periodic structures ii, Physica A, 389: 1585–1593, doi:10.1016/j.physa.2009.12.026.>'Chjoaygame (talk) 21:21, 24 March 2015 (UTC)

Yes, why not? I personally do not think the relevance of Duane's hypothesis is debatable (it is simply true under QM as far as I can see now). I have yet to convince myself that it is not debatable, but what I believe or not in my ignorance is of course of little importance. (A rigorous proof should involve Wigner's theorem. The Van Vliet article (can only read the second one) comes at least close.) YohanN7 (talk) 15:06, 25 March 2015 (UTC)

Fringe

Chjoaygame, you removed the fringe section and replaced it with a new one. Again the article is a Trojan horse for your whimsical theories about wave-particle duality. Momentum transfer between incoming particles (or waves if you want to) and a diffractor with periodic structures is quantized. This is totally uncontroversial and is what the article should be about. The wave-particle duality enters here in the usual way – either via the de Broglie relation or via the Planck–Einstein relation if you want to reproduce the diffraction pattern mathematically. Nothing new under the sun. YohanN7 (talk) 06:57, 7 April 2015 (UTC)

I removed the fringe tag before after we "agreed" on one sentence that "there had been a controversy" and removal of the POV pushing section. But you wrote a new section pushing the point of the minority party in that "controversy".

To give you an idea of what the article could look like without the fringe stuff, I edited it and removed the non-encyclopedic stuff. Naturally, you may not approve of this, in which case you will revert. But it is a bad idea to push a private opinion about wave-particle duality the way you do in a Wikipedia article. I have raised the issue before on the talk page of the physics project. It was suggested that the relevant portions of your article be merged into the main article on diffraction. I think this article could remain in the present shape (my edit), and develop into something good. But if you insist on having your particle-only POV (based on Hamilton's optico-mechanical analogy?) in it, I'll not be very supportive. YohanN7 (talk) 08:06, 7 April 2015 (UTC)

And oh, please find a better name. None of "quantal" or "translative" are English. YohanN7 (talk) 08:23, 7 April 2015 (UTC)

Thank you for this. I spent some time writing a talk-page response, but then found it superseded by your latest edit, so I didn't post it.

It is very far from true that I "wrote a new section pushing the point of the minority party". I copied that text more or less intact from the removed section. The text that I copied reported a carefully concerted and very public attack on Landé by Born. I am reasonably confident that many regard Landé as fringe. I think with fair confidence that most regard Born as mainstream. So I don't think the text put a minority viewpoint; it was intended to report the mainstream viewpoint with recognition that it was mainstream. Perhaps I am mistaken and Landé is not fringe and Born is not mainstream?Chjoaygame (talk) 09:53, 7 April 2015 (UTC)

Sorry about intersecting your post. I'll be careful to indent and sign. Here's my point: We don't need to comment at all about what is fringe and what is mainstream. It suffices to say that the topic of the article (or rather its interpretation) has been the subject of controversies. Saying that it has been controversial (as a subject) is probably wrong, even if some references put it that way (Van Vliet). YohanN7 (talk) 16:48, 7 April 2015 (UTC)

I am happy enough with most of your new edit, that "rinsed out most of the gibberish", but I think that it has some flaws.Chjoaygame (talk) 09:53, 7 April 2015 (UTC)

Indeed it has. It wasn't intended to last even this long. YohanN7 (talk) 16:48, 7 April 2015 (UTC)

In particular you write "Using Duane's 1923 hypothesis, the old quantum theory and the de Broglie relation, linking wavelengths and frequencies to energy and momenta, gives an account of diffraction of material particles." You removed Heisenberg's word that I quoted, "interesting". Duane in 1923 gave an old quantum theory particle-only account of diffraction, not knowing of de Broglie's 1923 work on wave particle relations.Chjoaygame (talk) 09:53, 7 April 2015 (UTC)

"Interesting" should of course go right back in if it belongs to a quote. Besides, it is interesting. YohanN7 (talk) 16:50, 7 April 2015 (UTC)

You removed the sentences "In this view, it seems impossible to explain diffraction purely in terms of particle beams. Commonly found in mainstream texts of quantum mechanics, such a classical formalism makes diffraction of particle beams seem explicable only by a concept of wave–particle duality expressed by quantum mechanics." What I call "mainstream" there is pretty nearly word-for-word from Dirac. I imagined that Dirac was mainstream, but I may be mistaken?Chjoaygame (talk) 09:53, 7 April 2015 (UTC)

Again, it is the words "mainstream" and "fringe" I'm reacting against. Also, there is no concrete conflict between "particles" and "waves" other than in the physical interpretation of what really is going on in a scattering process. Quantized momentum transfer (based on the geometry of the scatterer/diffractor) and waves hitting a classical object with a given geometry provide two dual (and compatible) qualitative explanations of the same phenomena. In QFT it is always exchange of virtual particles. But associated with these particles, and especially the incoming and outgoing particles (the virtual ones have propagators attached), are wave functions. Weinberg does not get philosophical. He simply states that we simply don't know what is more fundamental, particles or waves. YohanN7 (talk) 16:48, 7 April 2015 (UTC)

I don't see how the particle-only view is closely related to Hamilton's optico-mechanical analogy. When I was a student, our classical mechanics lecturer presented Hamilton's optico-mechanical analogy as a helpful lead-in to quantum mechanical thinking. That view is attested by a fair number of very respectable writers, some of whom are cited. The particle-only view is Duane's, reported favorably by Landé, and belongs to the old quantum theory, not Hamilton. I don't in my mind derive an account of diffraction from Hamilton's optico-mechanical analogy. It would misrepresent Duane's old quantum theory thinking to omit mention of his particle-only view.Chjoaygame (talk) 09:53, 7 April 2015 (UTC)

Okay, I was just wondering (about Hamilton).

Then I don't interpret Duane's old quantum theory thinking as "particle-only". He might have thought so himself, but I think he means "quantum ideas without reference to interference laws" (quote from his paper). This is different from "particle-only". He is using the Einstein relations. These link what is at least called frequency and wavelength of the incoming and outgoing whatever to the energy and momentum of the quantum constituents of whatever. In the case of X-rays, it is pretty unquestionable that the wave interpretation of the underlying theory has been pretty successful (Maxwell's equations). It comes naturally to identify whatever with waves. Again, nothing new under the sun regarding the wave-particle duality. The ideas in Duane's paper were new and refreshing in other ways, linking momentum transfer to geometry. YohanN7 (talk) 16:48, 7 April 2015 (UTC)

Something seems historically lost to me and I'm not sure how to approach it given the tangential debates litigating the issues of the interpretation of wave-particle duality that ignore the content of Duane's work. Duane's paper starts out referring to earlier measurements of the deflection angles of secondary (inelastically scattered) 'Characteristic' radiation (i.e. the spectral lines of radiation produced by X-Ray fluorescence within the crystal), and explains that the angles at which the characteristic radiation emerge are not able to be explained in terms of Bragg interference resulting from the reflection of the incident beam off the crystal planes, and it is not claiming that Bragg/Laue wave diffraction model was unable to explain the elastic case.

At the time, a quantized model of X-Rays was already required to explain the absorption and emission processes of Characteristic radiation. X-Ray quanta explained the threshold beam energies that induced the Characteristic radiation, and quantization of angular momentum underpinned the Bohr-Sommerfeld atomic model that explained the discrete frequencies of the Characteristic emission lines of X-Ray flourescence.

Duane's paper sought to explain the angles at which the elastic (Bragg/Laue) and inelastic (Characteristic) beams emerged with common quantum principles. The first section of the paper describes how applying the Bohr-Sommerfeld momentum quantization rule to the elastic exchange of discrete impulses of linear momentum between an incident quantum/particle and a lattice. A little ironically, this analysis gives the correct result for the Laue/Bragg angles, but then failed with the inelastic case because the angles of emission of the fluorescent radiation do not involve momentum transfer via a reflection process. (see Kossel Lines [1]). Quiet42 (talk) 04:46, 6 June 2023 (UTC)

English words include ablative, allative, collative, dilative, elative, illative, lative, legislative, perlative, prolative, relative, sublative, superlative, and yes, according to the Oxford English Dictionary, translative. But I do accept that the clumsier translational is often used by physicists such as Dirac, to distinguish from angular momentum. And plenty of examples of quantal in the Oxford English Dictionary, and it is not too rare in physics writings. I find quantum feels like a substantive while quantal feels like an attributive. I accept that neither translative nor quantal is the commonest form used for these purposes. What about changing the title to 'quantum translational momentum transfer', to distinguish from quantum angular momentum transfer?Chjoaygame (talk) 09:53, 7 April 2015 (UTC)

The word 'quantal' is an adjective, natural in English, meaning, according to the Oxford English Dictionary, "of, pertaining to, or being a quantum or the quantum theory", used for example by Edward A. Guggenheim on page v of his 1949/1967 text on thermodynamics, and by Max Jammer on page 73 in his 1966 monograph The Conceptual Development of Quantum Mechanics, and four times by Mott and Massey in their The Theory of Atomic Collisions (third edition, 1965). According to the Oxford English Dictionary, its naturalness in the English language is advocated by Charles Galton Darwin at Nature (1936) 138: 908-911. Admittedly, this natural English usage is not very common amongst physicists.Chjoaygame (talk) 02:19, 25 July 2015 (UTC)

Other uses of the adjective 'quantal' by respectable physicists:

"Complementarity: Bedrock of the Quantal Description", the title of Part II, pp. 239–432 of volume 7 of Collected Works of Niels Bohr, edited by Jørgen Kalckar, Elsevier, Amsterdam, 1996.

"A phenomenon is therefore a process (endowed with the characteristic quantal wholeness) involving a definite type of interaction between the system and the apparatus." Rosenfeld, L. (1957). Misunderstandings about the foundations of quantum theory, pp. 41–45 in Observation and Interpretation, edited by S. Körner, Butterworths, London.Chjoaygame (talk) 07:26, 11 August 2015 (UTC)

The natural title might be "quantum momentum transfer in scattering and diffraction", but that is too clumsy. Needs some thought. It should be possible for someone knowing what he is looking for to locate the article. (This is impossible with the current title.) YohanN7 (talk) 16:48, 7 April 2015 (UTC)

I am glad you take by blunt edit this way. I think we actually can cooperate. My edit was just a proposal to show you what I meant the article to be for a start (instead of endless debating on the talk page), and I wouldn't have been offended by a revert. I'll read your reply here carefully. It might take one day or more because real life keeps intruding. Cheers! YohanN7 (talk) 11:53, 7 April 2015 (UTC)

As far as my POV regarding wave-particle duality goes: I don't think I have one. I just take the presence of wave functions (regardless of their physical interpretation) as mathematically unavoidable. If you want to understand precisely what I mean by the above statement, see my last edit in wave-particle duality, last paragraph in the lead. YohanN7 (talk) 12:01, 7 April 2015 (UTC)

Ok.Chjoaygame (talk) 15:20, 7 April 2015 (UTC)

I have commented on some of your points above (by rudely intersecting your post, tell me if it is unacceptable, but I think it is easier to follow this way). YohanN7 (talk) 16:48, 7 April 2015 (UTC)

I put in about "fringe" and "mainstream" only because of the anonymous IP editor. It is easy for him to write "fringe" and near impossible to counter it except by some explicit statement using that word. I would be perfectly happy to remove all mention of 'fringe' and 'mainstream', if safe from another attempt to use the words.

As I read it, wave-particle puzzles never suggest omission of or objection to wave functions. They assume wave functions, and ask about how they can be pictured in terms of "waves" and/or "particles". Landé thought that every phenomenon could be pictured both ways, particle-only and wave-only; the two ways were distinguishable and intertranslatable. Neither picture captured all aspects of any phenomenon; only the formulas of quantum mechanics do that. The opinions of Bohr, Heisenberg, and Born are perhaps not quite so easy to comprehend or summarise; I am not keen to try to do so. Some writers think that energy and momentum refer to particles (no mention of Planck's constant), while wavelength and frequency refer to waves (no mention of Planck's constant). Wave and particle pictures are intertranslatable by the Einstein-de Broglie formulas which rely on Planck's constant.Chjoaygame (talk) 20:08, 7 April 2015 (UTC)

Introduction

The introduction could be improved and in plain English. Difficult I know with obscure and technical topics, but it's the wiki way.--Lucas559 (talk) 17:46, 22 June 2015 (UTC)

Purpose of this article

As far as I can tell, this is an article about Bragg diffraction. However it has a very strange title ("quantal"??) and seems redundant, since there are lots of other articles on wikipedia about diffraction (such as diffraction). What is the purpose of this article, and why does it have such an obscure name? Waleswatcher (talk) 23:23, 5 November 2015 (UTC)

The purpose of this article is to report how Duane's hypothesis has entered quantum theory. So far as I know, Duane's hypothesis is not otherwise covered. Quantal is an ordinary English adjective. Of the three words with identical meanings, translational, translatory, and translative, the latter has the fewest syllables.Chjoaygame (talk) 01:05, 6 November 2015 (UTC)

In that case, Duane's hypothesis should be the focus of the article, which it isn't right now, and it should be clear that this is an article about the history of science. Specifically the title of the article and the lede should refer to Duane's hypothesis, and most of the rest of the material should be removed. The question remains whether the topic is important enough to warrant a separate article (rather than a subsection in the article on diffraction or Bragg scattering, for instance).

As for "quantal", I agree it's a word in English, but it's not the correct word to refer to phenomena in quantum mechanics, because it's never used that way by experts. The language we use here should reflect standard usage in the field. Waleswatcher (talk) 01:11, 6 November 2015 (UTC)

fresh start on talk page comment that was posted without regard for customary protocol

'Fringe theory' tag

An anonymous IP user has added a 'fringe theory' tag.

I did not tag this article, however, I find it understandable why someone who is familiar with solid state quantum theory would dismiss it as 'fringe'. The article purports to be about Duane's Hypothesis, but instead appears to be vague as to the actual hypothesis that Duane put forward. The added discussion/explanations about the mechanisms of diffraction of particles by periodic structures looks to be muddled as to the distinction between diffraction patterns, and scattering patterns and does not reflect the simple clear descriptions in Duane's actual paper.

"Presumably the tag writer thinks there is some mainstream physical explanation of such phenomena, against which the present article should argue.So far as I know, there is no mainstream attempt to explain the phenomena."

I agree (personally) that the significance of Duane's work is misunderstood and underrated, however IMO the article as it is does a disservice to Duane's Hypothesis. Surely it is the job of an encyclopaedia to present the hypothesis in a clear simple plain language, be consistent with the source, and be accessible. It need not provide a "mainstream explanation" - surely that needs to be worked out in the scientific arena, not litigated on Wikipedia. That being said, Duane's rule is completely consistent with modern mainstream solid state physics.

It is usually treated with hand-waving references to a doctrine of wave-particle duality that does not claim to have a physical mechanism. The physical mechanism of the phenomena is not usually considered. There is thus no substantial mainstream explanation to argue against. - No, some quantum interpretations do not explain Duane's rule well, and their proponents may well obfuscate, but that is a different matter to providing a clear account of the the hypothesis.

The article is well referenced to reliable sources, including Werner Heisenberg (1930).<The Physical Principles of the Quantum Theory, translated by C. Eckart and F.C. Hoyt, University of Chicago Press, Chicago, pp. 77–78.> and Linus Pauling.<Pauling, L., Wilson, E.B. (1935). Introduction to Quantum Mechanics: with Applications to Chemistry, McGraw-Hill, New York, pp. 34–36.> A credible attack on the article should have read and should deal properly with those sources. The article is about physics. I think that a physicist examining it will consider on their merits the physical reasons offered in the sources and indicated in the article.Chjoaygame (talk) 11:28, 30 January 2015 (UTC)Chjoaygame (talk) 11:43, 30 January 2015 (UTC)

However despite this, the article does not provide a clear, concise account as to Duane's hypothesis, and also does not appear to clearly represent the positions of the other authors cited.

The above is a copy-and-paste of this unsigned post of Editor Grok42. I did this copy-and-paste, and the associated undo. I couldn't see a better way to remedy the damage.Chjoaygame (talk) 08:10, 3 March 2016 (UTC)

It is very good to see Editor Grok42 take a positive interest in this article. I expect he will do it a power of good. I look forward to his efforts. As is evident, I have undone his initial talk page commentary and copy-and-pasted it here. As is evident, he did not sign his post. I don't know a better way by which I might have tried to remedy the damage. I trust my effort will be taken in good part.Chjoaygame (talk) 08:18, 3 March 2016 (UTC)

This is a fringe theory

This is definitely a fringe theory, which has been extensively disproved by modern x-ray crystallography and electron diffraction. It comes from the days when sources and detectors were poor, so only Bragg's law was detectable. We have been far beyond that for many, many decades. There has been masses of experimental and theoretical work showing that diffraction is due to waves, and corpuscular models fail.
As an additional point, this article takes many of its sources out of context. It should stay as history, but needs to be caveated.
I added four standard texts for people to look at for established science. Ldm1954 (talk) 13:22, 14 August 2023 (UTC)

Duane's original work used the (integer) Bohr-Sommerfeld condition and so only approximates diffraction patterns in the same way that integer momentum quantization in Bohr's atom approximated the angular momentum expectation functions found in contemporary QM.

The argument about the accuracy of instruments does not fit the historical context; As Duane stated in his paper, his model was motivated by the fact that the Bragg model was inadequate for describing the quantized momentum exchanges he observed in detailed fluorescence experiments that used a new high-energy X-ray tube. In 1926, Duane proposed the detailed diffraction pattern is achieved by moving to a continuous expectation function for a crystal's possible reactions by taking the Fourier transform of the electron distribution multiplied by Planck's constant; this latter model is equivalent to applying quantization to the Laue model, has stood the test of time, and was theoretically linked to contemporary QM in Carolyne Van Vliet's 2010 paper. While Duane's discrete quantization model is passe in crystallography, it is not a fringe theory scientifically. Quiet42 (talk) 04:04, 9 October 2023 (UTC)