Wikipedia talk:WikiProject Physics/Archive April 2013

Review The International Society for Condensed Matter Nuclear Science?

Hi. :) I wanted to stop by and see if any physicists (by profession or inclination) would like to review this article. It is far outside of my subject field - I was drawn to it solely in respect to the question of copied content - but I am having trouble verifying that the sources support its claims and suspect there is a COI. While some of the material is simply related to the society (and problematic there), there is a section with a bit of history on cold fusion that some of you may be able to quickly assess. --Moonriddengirl ^(talk) 13:10, 4 April 2013 (UTC)

It's not reliably sourced to anything except fringe material. I'll AfD. a13ean (talk) 15:02, 4 April 2013 (UTC)

Now at AfD Wikipedia:Articles for deletion/The International Society for Condensed Matter Nuclear Science. It's certainly fringe but is it notable fringe? Xxanthippe (talk) 21:56, 5 April 2013 (UTC).

Crosslist to WP:FRINGE

Please see Wikipedia:Fringe_theories/Noticeboard#Constructal_law if you have some time. Thanks, a13ean (talk) 17:06, 5 April 2013 (UTC)

John Hagelin - reassessment

I have put the article John Hagelin up for reassessment Wikipedia:Good_article_reassessment/John_Hagelin/1. More input is welcome, IRWolfie- (talk) 21:55, 5 April 2013 (UTC)

Category for discussion

RockMagnetist (talk) 16:52, 6 April 2013 (UTC)

Feynman diagram

General features of the scattering process A + B → C + D:

• internal lines (red) for intermediate particles and processes, which has a propagator factor ("prop"), external lines (orange) for incoming/outgoing particles to/from vertices (black),

• at each vertex there is 4-momentum conservation using delta functions, 4-momenta entering the vertex are positive while those leaving are negative, the factors at each vertex and internal line are multiplied in the amplitude integral,

• space x and time t axes are not always shown, directions of external lines correspond to passage of time.

It has been requested that more diagrams be added, and the the article is tagged "too technical" and I naturally agree strongly. I could draw lots of them for specific particle interactions (very easy). But first, it would be better to show what the diagrams mean, and how/why the diagrams compactify complicated mathematics. Here is a first attempt, according to the "DeMystified" book QFT (2008, McMahon), the best one I can find which introduces the mathematics of Feynman diagrams in a simple way. ---->

Obviously the caption is too long, though it's not easy to trim it unless it's spilt into the main text... Anyway is this correct and clear to others? Thanks, M∧Ŝc²ħεИ_τlk 07:46, 7 April 2013 (UTC)

Suggestion: Make a coordinate space diagram without loops with all labels inserted. Then put in the corresponding momentum space version. (With regard to previous discussions elsewhere, a coordinate space diagram is much needed. The momentum versions are derived from these in all treatments I've seen.) Then repeat with a one-loop diagram. On second thought, the article itself, at a glance, seems to make no distinction. It should. (The Feynman rules, and the factors associated with vertices and lines are different in momentum and coordinate space.) YohanN7 (talk) 18:14, 7 April 2013 (UTC)

"Make a coordinate space diagram without loops with all labels inserted." ? So what's missing/superfluous from this diagram? This is already in coordinate (aka position) space. What are "labels" of - the lines/vertices/particles/factors/what? By "loops" you mean loops in the internal lines in higher order corrections right? (Adding one to a separate diagram isn't a problem).

Not sure how to draw Feynman diagrams in momentum space, and have never even seen them, they always seem to be in space and time, but will look into those. M∧Ŝc²ħεИ_τlk 22:15, 7 April 2013 (UTC)

Fifth force

Could someone verify the accuracy and relevance of this 2009 addition to Fifth force, which is still present in a slightly modified form in the article today. I've caught one of the authors (X.-S. Yang) spamming citations to his papers on Wikipedia for the past few years. —Ruud 23:23, 7 April 2013 (UTC)

The reference is real and has a Xin-She Yang as the second author. They used a 320 meter tower to test non-Newtonian corrections to gravity. The paper references Fischbach and generated bounds on the strength of such a force. The paper looks legit and Physics Letters A is a mainstream journal. It was just one of several such experiments and was not the defining experiment. So the reference is appropriate, but perhaps is not necessary if the sentence it references is removed. --Mark viking (talk) 03:20, 8 April 2013 (UTC)

WP articles Quantum field theory (QFT) and Relativistic quantum mechanics (RQM)

are the same link (as you will already know) not the same. For RQM would it make sense to replace the redirect for an article? We would have a series like so:

1. Introduction to quantum mechanics and QM make the first step (wave-particle duality, first quantization, wavefunctions, Schrödinger picture...)
2. then RQM is a relativistic formulation of QM,
3. finally Introduction to quantum field theory and QFT (field operators, creation and annihilation operators, propagators, probability amplitudes, S-matrix, second quantization ...).

Obviously QFT ≠ QM but RQM cannot be a synonym for QFT - can it? So there should be no redirect. Opinions? M∧Ŝc²ħεИ_τlk 10:21, 7 April 2013 (UTC)

Dirac's introduction of the Dirac equation was a significant independent theoretical advance (QM→RQM) that was associated with important predictions and discoveries (e.g. the positron). I would argue that the link relativistic quantum mechanics being a redirect to quantum field theory is misleading and confusing to someone not adequately familiar with the distinction (like me). QFT is a further substantial change from RQM. — Quondum 12:37, 7 April 2013 (UTC)

I don't think the historical approach is the best way to present this topic. Also today, most in the field don't like the phrase "second quantization", as it is extremely misleading. You don't quantize anything twice, there is only one quantum theory; QFT is in principle just the same quantum theory but now applied to fields. That there are mathematical complications here which then has led to the development of a formalism which makes the topic look like not the same quantum mechanics doesn't make it so. Don't forget that people in the early 1930s where able to derive many of the results you learn in introductory QFT textbooks using nothing more than the elementary formalism of QM you learn about in your first QM course. Their computations were, of course, extremely cumbersome compared to how we would do it today. Count Iblis (talk) 13:14, 7 April 2013 (UTC)

Except we would know historically how and why the theories came about. I really want to write the RQM article this second, just short of time and lacking knowledge... M∧Ŝc²ħεИ_τlk 14:24, 7 April 2013 (UTC)

Relativistic quantum mechanics is a separate topic from quantum field theory. Relativistic quantum menchanics by Bjorken ad Drell is a whole book devoted to the topic and is distinct from their book on Relativistic quantum fields. And this approach is still being used today, e.g., the 2011 paper An Introduction to Relativistic Quantum Mechanics. I. From Relativity to Dirac Equation. It should also be noted that there are plenty of quantum field theories that are non-relativistic, such as that for phonons and other quasiparticles. There really should be two separate articles, because the sources show that this distinction is made by practicioners in the field. --Mark viking (talk) 17:38, 7 April 2013 (UTC)

I agree with everything said here, including that the historical approach is not the best way to present this topic (QFT). Yet it is presented in the historical way in many textbooks, and perhaps still in introductory courses. In any case, RQM, as viewed today, is not entirely useless. It is a useful prerequisite for QFT, just like classical mechanics is. A separate RQM article would fill gaps and remove many sources for confusion, like the different free field Dirac equations of QFT and RQM. An excellent historical theoretical and experimental dividing line between RQM and QFT would be the Lamb shift. I think it would be easy to find sources for what distinguishes QFT from RQM. B t w, the main QFT article suffers a bit from having the second quantization as a main ingredient.

Not important: I think QFT should be relativistic by default. Non-relativistic QFT should be called, well, non-relativistic QFT. YohanN7 (talk) 17:54, 7 April 2013 (UTC)

I made a start by overwriting the redirect, all I have time for now. You will find an infinite number of ways to improve it, most obviously scope, depth, prose... Just make the changes and/or use the talk page. I'll add more references in time if no-one beats me to that.. M∧Ŝc²ħεИ_τlk 12:21, 9 April 2013 (UTC)

The article looks like more than just a start, it's already quite informative. Thanks for doing this! --Mark viking (talk) 03:50, 12 April 2013 (UTC)

Thanks, but there's plenty of room for more scope and coherency. I'll add more later (unless someone beats me to it). Best, M∧Ŝc²ħεИ_τlk 10:08, 12 April 2013 (UTC)

Charge density wave

Charge density wave (edit | talk | history | protect | delete | links | watch | logs | views)
Charge-density wave (edit | talk | history | protect | delete | links | watch | logs | views)
While scanning for typos I've stumbled across two near-identical new articles. I'll leave it to you experts to work out which title is best! -- John of Reading (talk) 20:28, 7 April 2013 (UTC)

They were created by the same editor, so I have asked the editor to choose one and redirect the other. RockMagnetist (talk) 01:10, 12 April 2013 (UTC)

Done. RockMagnetist (talk) 01:11, 12 April 2013 (UTC)

John Call Cook

Not sure if this is totally the right place to ask, but there's been a newish article John_Call_Cook which I'm not sure would meet the notability requirements, would be worth a second opinion from a subject expert i think. --_nonsense ferret 00:02, 9 April 2013 (UTC)

Would you like to tell us what you found for his citation record on Google Scholar? Xxanthippe (talk) 03:22, 12 April 2013 (UTC).

Perhaps I'm doing something wrong, but searching for J C Cook on google scholar simply gives me a list of papers by every J C Cook that existed. The problem is that there are quite a few academics with these initials. Looking on Scopus you can find him listed twice (author ids:7404183769 and 7404184056) and it seems to list only three papers (I'm not sure why Scopus does not list the other papers noted in his article, or perhaps my searching is faulty):

• Radar transparencies of mine and tunnel rocks (1975) Geophysics
• Radar exploration through rock in advance of mining (1973) Trans Soc Mining Eng AIME
• Semi-remote, acoustic, electric and thermal sensing of small buried nonmetallic objects (1973) IEEE Trans Geosci Electron

Although there are 47 papers which cite this work, I don't really have anything to calibrate this against in terms of the average professor of WP:PROF. I should probably expect more citations for a notable professor to demonstrate impact on a field of research but if I'm not in the right ballpark with this however and Cook reasonably meets the average professor test then we would not need to consider this further.

However, notwithstanding the number of citations, I wondered whether there was a reasonable claim that he was critical to the development of a particular field? Grateful for your thoughts. --_nonsense ferret 11:12, 12 April 2013 (UTC)

I've now found [1] which Google Scholar seems to show 120 citations of one paper and that looks to me much more notable. Very odd to see such a different result from Google Scholar vs Scopus - I guess that has something to do with the age of publication and the field of study? Not sure. --_nonsense ferret 14:21, 12 April 2013 (UTC)

Fractional quantum mechanics and Fractional Schrödinger equation

It's high time someone do something about these articles, which mention prominently Nick Laskin (who is, apparently, User:Nlaskin the principal author of this articles). I should think that, at a minimum, a merger of the two article is warranted. But it is more worrying to me that it seems unlikely to have any article conforming to WP:NPOV when the principal author of the article is so keen to have his own work cited. I suggest that someone at this project should take up the mantle of cleaning up this issue, or I will nominate the articles in question for deletion. This project has already been notified twice about this, with (apparently) no action. Sławomir Biały (talk) 22:58, 11 April 2013 (UTC)

Indeed I said that here... Anyway... the article should have other some secondary sources [I added one - Fractional Calculus, An Introduction for Physicists (R.Herrmann), which references N.Laskin and others, can't remember who else, don't have the book right now]. Preferably the articles will not be deleted (but of course sources come first...) M∧Ŝc²ħεИ_τlk 07:20, 12 April 2013 (UTC)

There shouldn't be a problem with AfD. There aren't any independent sources. Xxanthippe (talk) 23:05, 11 April 2013 (UTC).

An AfD would probably fail because each article has several links to independent sources - but since they are in External links, they are probably not being used. The real problem here is WP:NPOV, and that will probably require a lot of work to solve. Don't forget Fractional Poisson process. RockMagnetist (talk) 23:22, 11 April 2013 (UTC)

What independent sources are you referring to? I can't see any. Xxanthippe (talk) 23:27, 11 April 2013 (UTC).

Sorry, I meant Further reading. Based on authorship at least, they are all independent, but probably they're all primary. RockMagnetist (talk) 23:46, 11 April 2013 (UTC)

It looks like there are 202 hits on GScholar for "Fractional quantum mechanics" and not all are due to Laskin. I have not found any secondary references. The theory is mathematically interesting and there is a small cottage industry working out solutions to the equations, but I could find no physical applications. So it is not exactly fringe, but is not mainstream physics either. Sort of like Tsallis entropy, but with none of the convincing applications. --Mark viking (talk)

Good. Which sources would you consider to be secondary sources, on which to base a putative article? Sławomir Biały (talk) 00:34, 12 April 2013 (UTC)

I have not found any secondary references in the form of review articles, news articles, or books on the topic. Most of the ~10 papers on the topic that I have skimmed have introductory sections that could be considered secondary for the basics of the topic, but I don't know of any that could be considered in depth. i.e., more than a couple of paragraphs. Laskin himself wrote a review paper, but it could not be considered secondary for the topic. The case for 'keep' based on secondary or tertiary sources looks weak, so far. --Mark viking (talk) 03:03, 12 April 2013 (UTC)

We don't have an article (or more) about every paper with 200 hits on GS. Incidentally, these two articles aren't the only ones with these problems. See the creator's other contributions. Xxanthippe (talk) 09:54, 12 April 2013 (UTC).

I don't know that Mark is necessarily arguing that the topic is notable based on Google cites, just pointing to sources that could possibly be used. However, without looking at specifics it's very difficult to assess whether the topic is notable. My inclination is to say that it is not notable, but I could easily be dissuaded of this by a single good secondary source. (In fact, I think this is a potentially interesting and worthwhile topic of research—unlike most unsuitable topics for an encyclopedia—it just doesn't quite seem to be ready yet.) I'm not really happy with the idea of an article based on introductory sections qua secondary sources. Sławomir Biały (talk) 00:23, 13 April 2013 (UTC)

Yes, I am not arguing for keeping the articles, just presenting what evidence I've found so far for and against deletion The Google hits show that there is some activity around this topic, but I would not say that these confer notability by themselves. I agree with Sławomir that lack of in-depth secondary sources makes it hard to write a balanced article and likely makes the topic not yet notable. --Mark viking (talk) 00:46, 13 April 2013 (UTC)

By any chance has anyone seen the book I added in those articles and mentioned above? Is that not a secondary source or is it just factually wrong and to be rejected? It's just an introductory book on fractional calculus with physical applications and is not a thick, heavy, thoroughly in-depth one, but there is a chapter or two on fractional quantum mechanics, fractional spin groups, fractional quantum field theory (assuming correct recall...). M∧Ŝc²ħεИ_τlk 07:59, 13 April 2013 (UTC)

I unfortunately don't have access to this book. The frontmatter excerpt for the book shows that fraction quantum mechanics as described in these articles might be covered in pages 102-110. The excerpt from chapter 1 shows that Laskin's work is apparently a modest part of the book's larger story. If the book does cover Laskin's approach in those pages, it could be considered a secondary source. --Mark viking (talk) 08:56, 13 April 2013 (UTC)

It's not exactly Laskin's approach because the chapters are all fairly compact, but is still on fractional QM and cites Laskin's papers so it is a source independent of Laskin. But why should that stop it from being a secondary source?M∧Ŝc²ħεИ_τlk 11:03, 13 April 2013 (UTC)

Actually it's more like a tertiary source:

"Policy: Reliably published tertiary sources can be helpful in providing broad summaries of topics that involve many primary and secondary sources, and may be helpful in evaluating due weight, especially when primary or secondary sources contradict each other. Some tertiary sources are more reliable than others, and within any given tertiary source, some articles may be more reliable than others..."

which Herrmann's book more or less satisfies. M∧Ŝc²ħεИ_τlk 11:10, 13 April 2013 (UTC)

I would say that the Hermann book is probably an adequate secondary source. It might be worth stubbing fractional quantum mechanics and redirecting the fractional Schrodinger equation, pending expansion from secondary sources. This source may also show what relative weight to assign to the primary literature (at least, it is to be hoped). Sławomir Biały (talk) 18:51, 14 April 2013 (UTC)

OK. I'll try and get the book again soon, and we can see what weight is to due. In the mean time will continue to look for more (secondary/tertiary) sources... M∧Ŝc²ħεИ_τlk 20:50, 14 April 2013 (UTC)

Fringe alert: Eliyahu Comay

Please see my post at the fringe theory noticeboard regarding this article.

הסרפד (call me Hasirpad) (formerly R——bo) 02:44, 15 April 2013 (UTC)

This actually relates to an older post here: Wikipedia talk:WikiProject Physics/Archive January 2013#Nucleon spin structure and Proton spin crisis. הסרפד (call me Hasirpad) (formerly R——bo) 03:05, 15 April 2013 (UTC)

All primary sources. I've put it up for AfD. IRWolfie- (talk) 11:10, 20 April 2013 (UTC)

Jürgen Ehlers FAC

I've just put up Jürgen Ehlers as an FA candidate. Ehlers was a theoretical physicist specializing in Einstein's theories of relativity. Any contributions to the candidacy discussion welcome here. Markus Pössel (talk) 11:09, 16 April 2013 (UTC)

Category:German inventions

is being added to lots of articles by NeapleBerlina (talk · contribs). Clearly some of them are not inventions, but I'm not sure where to draw the line, e.g. regarding theories. I don't quite see the point of this kind of categories anyway, but there might be some consensus in favor of them. — HHHIPPO 19:30, 15 April 2013 (UTC)

Indeed. This is for the maths project, there is also this edit by another IP in integral symbol, that particular case I favored since the integral sign is a German invention (Leibniz). Anyway it's something for discussion. M∧Ŝc²ħεИ_τlk 19:56, 15 April 2013 (UTC)

i think here are some too proud american writers in english wikipedia at work. So i found three (?!?) list of american inventions in timeline. Best wishes from Germany. German Wikipedia is there more neutral than english wikipedia. NeapleBerlina (talk) 20:02, 15 April 2013 (UTC)

We assume your edits are in good faith by all means, but the title is probably too restrictive, maybe you want category:German physics contributions or terms to that effect? Not sure if that's much help or harm... M∧Ŝc²ħεИ_τlk 20:15, 15 April 2013 (UTC)

(edit conflict) I dislike those categories in general, not just the German one. Especially within physics topics, it's often not so easy to define what should count as an invention, and who should count as the inventor(s). On top of that we'll have the usual endless debates about the nationality of people, now not only in biographies but for many more articles. I think we should at least make sure that all articles in this category are clearly inventions, not abstract concepts or discoveries (otherwise the first article to go to the category should be Germany).

Regarding "by another IP": this doesn't look like too many different people. Was that all you, NeapleBerlina? — HHHIPPO 20:41, 15 April 2013 (UTC)

I anticipate there will be objections to my above category suggestion, just trying to be fair. Really a well-written article should clearly say who historically invented/innovated/contributed to the theory/notation/formalism/equation/whatever. Categories are not really for such intricate things. M∧Ŝc²ħεИ_τlk 21:13, 15 April 2013 (UTC)

I think that it is inappropriate to claim glory for Germany (or any other nation or race) for the inventions, theorems, theories, notations, etc. created by individuals who someone has classified as belonging to that nation or race. It seems especially inappropriate in the case where credit is being claimed on behalf of Germany for the work of certain Jewish individuals who in many cases would have been disowned or persecuted by earlier German governments. Individuals deserve the glory, not States. JRSpriggs (talk) 05:08, 16 April 2013 (UTC)

Last point: Agree! Since individuals themselves are part of categories like Category:German physicists the assignment to which country an invention "belongs" should be possible in most cases already.
The rest: Keep politics out of Wikipedia categories. It really doesn't aid clarity and therefore is detrimental for their main purpose. -- Patrick87 (talk) 09:00, 16 April 2013 (UTC)

By now there are 11 articles in that category which are also tagged for WikiProject Physics: for three of them the categorization might be justified (Electron microscope, Geissler tube, Krueger flaps), two are hardly inventions (Stern–Gerlach experiment, Mössbauer effect) and the rest is at least questionable regarding whom to call the inventor and their nationality (Anti-reflective coating, Fahrenheit hydrometer, Geiger counter, Geiger–Müller tube, Scanning tunneling microscope, X-ray tube).

Instead of having lengthy discussions for each of the questionable cases I propose to remove the category tag from all pages within our scope. The task attempted by the category is better fulfilled by List of German inventions and discoveries, where it's possible to add references. Anything called a German invention in reliable sources can go there. — HHHIPPO 19:45, 24 April 2013 (UTC)

Agreed, for reasons above. M∧Ŝc²ħεИ_τlk 20:08, 24 April 2013 (UTC)

And now we have the same story in Dutch. To address the problem more neutrally, I've generated a list of pages that are both in the scope of WikiProject Physics and in a subcategory of Category:Inventions by country. I also added a summary of relevant guidelines and policies. If no better ideas come up here, I suggest we proceed along the lines of those policies by challenging and removing category tags where appropriate. — HHHIPPO 13:49, 26 April 2013 (UTC)

Coherence and realisability in metrology

I have recently created two new metrology articles:

• Realisation (metrology)
• Coherence (units of measurement)

I have rated both articles as being of high importance in measurement and in physics. I believe this assessment to be fair in respect of measurement, but I am looking for a second opinion in respect of physics. Both articles are still stubs, but are referenced from the artcile Metric system. Martinvl (talk) 07:06, 23 April 2013 (UTC)