Wikipedia talk:WikiProject Physics/Archive May 2016

Administrators' noticeboard/Incidents
You may want to comment on there. This concerns, at least in part, the famous and ongoing frame-dragging dispute between Lorenzo Iorio and Ignazio Ciufolini. It'll be a mess, but one that will need the eyes of the community at large, especially WP:PHYS and WP:AST. Headbomb {talk / contribs / physics / books} 13:11, 8 May 2016 (UTC)

Josephson effect
I recently performed a merge on Josephson effect that had been approved a long time ago. Apparently there are some issues with inconsistent notation and other things that need to be straightened up. I'm not an expert on this topic myself, could someone perhaps take a look? Antony–22 (talk⁄contribs) 02:52, 10 May 2016 (UTC)

vg*vp = c*c
Your expertise would be appreciated at Talk:Phase_velocity. Thanks. fgnievinski (talk) 15:47, 16 May 2016 (UTC)

Template:Quantum mechanics and Template:Quantum mechanics topics
Sorry if this has been raised before, but why should two templates on QM exist? For context the first has been around since December 2006‎ while the second "topics" one since March 2013‎. (Despite fairly active editing in 2013 I don't actually remember seeing the topics template created or used at all). IMO they should be merged. Any thoughts? 'M'&and;Ŝc2ħεИτlk 17:29, 17 May 2016 (UTC)


 * This seems like a sidebar vs navbox thing. People prefer different template styles. I tend not to use them myself. MOSPHYS has some good guidance here. I could see a navbox being useful if one wanted to place a lead picture where the sidebar would normally be. I'm in favor of a merge in the sense that both templates should have the same set of links. --Mark viking (talk) 20:30, 17 May 2016 (UTC)

Disagreement at Superluminal communication
Two apparently qualified editors have a disagreement about a figure at Superluminal communication. The issue concerns a basic space-time diagram used to "disprove" superluminal communicatoin. I have 21 refereed publications in journals such as AJP, EJP, and Physics Teacher and am convinced the figure is correct. But is it original? I can't believe I discovered something this basic. It's a purely pedagogical issue, not research in the sense of changing great ideas. I couldn't find this argument on the internet, but am convinced that one of the introductory relativity or modern physics books must have it.--Guy vandegrift (talk) 08:13, 18 May 2016 (UTC)
 * I'm pretty sure this is resolve.--Guy vandegrift (talk) 04:48, 19 May 2016 (UTC)

In need of an expert on Special Relativity regarding the Minkowski diagram
In an effort to explain the impossibility of superluminal information flow I made a diagram with many features of the Minkowski diagram. Is the connection real? The question can be found at:
 * Could somebody tell me if these images are related to the Minkowski diagram?
 * I also have something on Minkowski diagram

--Guy vandegrift (talk) 21:36, 17 May 2016 (UTC)


 * I have removed the image and the analysis per wp:unsourced and wp:NOR from the article: and commented at Talk:Minkowski diagram (not at Minkowski diagram, as I don't know the rules there) - DVdm (talk) 06:51, 18 May 2016 (UTC)


 * It seems you're trying to communicate the message: "Superluminal information flow is impossible because, in some frame of reference, the message is received before it's sent." Is that right? If so, you can find that message in pretty much any SR textbook. And I personally think this sentence I just wrote is much easier to understand than your diagram.
 * There's just too much going on in your diagram, it's too hard to parse, I think most readers' eyes will glaze over.
 * If you made a minkowski diagram showing "event A can be before event B in one frame of reference, but after in another"—without trains and photons and faces—I think it would be a simpler diagram and thus more likely to succeed. (And more closely based on textbooks.) And once that's established, you're just a small step away from making the connection to the point you want to make about superluminal communication. --Steve (talk) 12:47, 18 May 2016 (UTC)


 * Your phrase, "more closely based on textbooks" suggests similar figures have already been made in the same way by the textbooks. Is that true? The figure was moved for lacking a citation.  Once we establish that the figure has been cited, we can talk about where to place the diagram and how it should look.  Your hint that the reader will glaze over it suggests the figure should be placed later in some sort of "proof" or even linked to on Wikiversity where such proofs are the norm.--Guy vandegrift (talk) 13:06, 18 May 2016 (UTC)


 * I deleted and made small the aforemenioned comment because I just realized that the figure I tried to insert into Superluminal communication is all over the internet, but without the icons Bob, Alice, and the Train. In fact, almost the exact figures appear in Relativity of simultaneity with the train drawn as a dotted line, and Bob and Alice as unmarked points.  So, this brings us back to one of the two original questions: Yes, the figure can be cited; I just embelished the labeling when I placed it in Superluminal communication.  I did this because to create an understanding of paradox in the reader's mind, they need an actual scenario.--Guy vandegrift (talk) 13:30, 18 May 2016 (UTC)
 * Note that the scenario in the caption must be sourced as well. The caption that you made with this edit didn't make much sense to me. - DVdm (talk) 14:09, 18 May 2016 (UTC)

The entire figure needs the be redone in light of the fact that these simultaneity diagrams are all over the internet, including Wikipedia where not everything is cited. I need to make the icons less garish so that Wikipedians will recognize this as a common set of images. This will take a while, and the whole thing might wind up being on Wikiversity.

I still need to know whether Figure 4 on Minkowski diagram really is a Minkowski diagram.--Guy vandegrift (talk) 15:56, 18 May 2016 (UTC)

After studying the literature, it seems that by some definitions, any such diagram is a Minkowski diagram. Moreover, I am pretty sure this one is, but haven't actually done the algebra yet. --Guy vandegrift (talk) 04:50, 19 May 2016 (UTC)

One of your project's articles has been selected for improvement!
As to your description of an alternator. An alternator can either be used as an electric motor connected to voltag and thus deliver mecanical rotation, or opposite as a generator delivering voltage when it's shaft is rotated from a mecanical source. From alternative, two opposite options. Best regards, Aage Chr. Bucher. Mail, aabucher@frisurf.no.

List of candidate planets by an index that is calculated by one person
Articles for deletion/List of Kepler exoplanet candidates by ESI (2nd nomination).

Please comment.

jps (talk) 23:12, 24 May 2016 (UTC)

New physics article for review
The recently created article Interaction without interaction could use review by an expert. One issue is an apparent conflict of interest and/or self-promotion: all references used in the article are by an author whose name matches the username of the article's creator. Regards, -- Ed (Edgar181) 14:15, 25 May 2016 (UTC)
 * The page has been nominated for deletion. Input at that discussion is also welcome. Primefac (talk) 16:31, 25 May 2016 (UTC)

Thermodynamics
I'm considering reverting this article to an older version, for instance https://en.wikipedia.org/w/index.php?title=Thermodynamics&oldid=417201632. It's more concise, and I think the language is much clearer in most places. It may be missing some important elements that were added later, so after reverting I will try to add back anything that is sufficiently notable. I think this procedure will work better than trying to trim or rewrite the current article in a more evolutionary manner. This would be a major change to an essential physics article, so I'm asking for opinions first. Please post comments on the talk page.  Waleswatcher  ( talk ) 16:21, 27 May 2016 (UTC)

New category "Functions of space and time"
A new category, Category:Functions of space and time, was created yesterday by. It needs to be in a parent category. Any ideas as to which one? JRSpriggs (talk) 17:31, 27 May 2016 (UTC)

.. parent category: physics? maths? (engineering?) differential equations? maybe Equations of physics/ Physics_equations ? I don't know which is best. I was a bit unsure if it made sense at all, but I added it because I like something explanatory to click on for such common 'noun-phrases' (and it probably doesn't deserve a page) — Preceding unsigned comment added by Fmadd (talk • contribs) 17:39, 27 May 2016‎


 * What is the scope of the template? It seems too broad, almost anything in the subjects mentioned will involve space and time at some level, it is not clear where to draw the line for adding the category to articles. 'M'&and;Ŝc2ħεИτlk 09:36, 28 May 2016 (UTC)

maybe it is too broad, feel free to delete; however some equations describe forces, some describe energy. Also graphics (not physics) involves 'functions of space and time'. What I was after was a specific link, e.g many pieces of text say "blah blah is a function of space and time", .. instead of linking to function,space,time, I wanted a link for that noun-phrase, from which you could diverge later. To me wikipedia is an emergent AI resource, being trained with the links (labelled text), semantic rich links make the world smarter. Fmadd (talk) 10:16, 28 May 2016 (UTC)


 * Yes, anything of the form F(x, t) with x = (x, y, z) could be a number of things in different contexts. In classical mechanics, a holonomic constraint takes that form, in addition x = x(t) is the position of the particle at time t. Or in classical field theory it could be a scalar field (where x is a point in space, not the position of a particle). So far F is a real-valued function of space and time, it could be a complex-valued function, or a vector-valued function, etc. In quantum mechanics it could be the wave function for a particle in the position representation (with other degrees of freedom suppressed). Articles with any instances of such functions would be included in the category. But these functions arise from some equation of motion (a wave equation, a field equation, ...), or as constraints, would any article with any instance of these equations be in the category? There would likely be too many. 'M'&and;Ŝc2ħεИτlk 16:41, 28 May 2016 (UTC)


 * I think it should be deleted. Members of the category have essentially nothing to do with each other. There's no body of knowledge about "function of space and time" that goes beyond the meanings of the five individual words. It's like Category: Words whose third letter is "p", a category that is logically coherent but shouldn't exist. --Steve (talk) 18:09, 28 May 2016 (UTC)

Sources at Four-gradient
Can somebody have a look at user 's (and the IP's they used before they signed up for this username) edits to article Four-gradient? I have tagged a number of subsections for sources. After that SciRealm has added some sources, one of which I can't verify because I don't have Rindler's 2nd edition. This request follows my undoing their edits (with lots of original research) at Mass–energy equivalence (do, undo, redo with sources, reundo, warn). Thx. - DVdm (talk) 16:14, 30 May 2016 (UTC)