Wikipedia talk:WikiProject Physics/Archive October 2012

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BKL singularity

A quick skim of black hole related articles turned up something odd: BKL singularity (edit | talk | history | protect | delete | links | watch | logs | views) is linked from Schwarzschild metric and rotating black hole, even though to the best of my knowledge it's a) not related (it was a proposed mechanism replacing cosmic inflation) and b) not presently widely accepted. The link from general relativity is also probably undue.

That said, I'm not familiar enough with the literature to comment with certainty on how noteworthy or not this concept is. Anyone else care to look at it (and through the "what links here" list)? --Christopher Thomas (talk) 19:21, 2 October 2012 (UTC)

The BKL conjecture was significant in that it was the state of the art on singularities in GR before the work of Hawking and Penrose. The link in GR seems perfectly due. However, some of the other see also links are rather dubious.TR 06:16, 3 October 2012 (UTC)
Ok; it's probably worth editing BKL singularity itself to make its historical context clearer, as right now the lede reads like a puff piece while giving no indication of its place in the development of known solutions in GR. --Christopher Thomas (talk) 06:48, 3 October 2012 (UTC)
I don't see too much puff there. It gives an accurate description of what the solution is. Note that the BKL type solutions are not just of historical significance, but still play a role in various areas of research including investigations of cosmological averaging and loop quantum cosmology. Also note, that with this I am scraping the barrel of knowledge of the subject. (Making any editing on my part a rather large project involving lots of research, and time which I don't have).TR 07:17, 3 October 2012 (UTC)
The lede is the main part that bothers me, as it has words that come across as "This solution is much spiffier than other other solutions that you've heard of!", without making it clear that that's because this solution was derived _later_, performing a more complicated analysis after removing one of the assumptions (isotropy) of the Friedmann solution. Indeed, its relation to other solutions is buried deep in the prose of sections 1 and 2. In an ideal world, the lede would make context clearer and there'd be a brief history section, but in an ideal world I'd be getting tenure offers from Equestria.
I respect the fact that you'd rather not rewrite things; I've been in a similar position for quite a while now. Thanks for your response, as it's reassured me that nothing cranky is going on. --Christopher Thomas (talk) 09:54, 3 October 2012 (UTC)

Watchlist broken

The watchlists on the toolserver are not available because the user account tim1357 has expired. Until that is fixed, here is an alternative based on an expanded index of physics articles:

Unfortunately, they needed splitting because of the length of the list. RockMagnetist (talk) 23:56, 9 October 2012 (UTC)

David J. Wineland and Serge Haroche

Hey, over at In the news (from the Main Page) we'd like to post about the 2012 Nobel Prize laureates in Physics, but the articles need to have more content about each's research (especially what they worked on to deserve the award). We'd like someone - ideally with experience in this area or physics in general - to add more about what each has done. Examples of what this looks like is Shinya_Yamanaka#Professional_career or Brian_Kobilka#Research. Thanks in advance for any help you could provide! SpencerT♦C 20:53, 11 October 2012 (UTC)

Lanczos tensor

I've recently cleaned up the Lanczos tensor article, which used to be a total disaster. I'm done for now, but another fresh set of eyes would be appreciated. Teply (talk) 18:51, 10 October 2012 (UTC)

I, for one, consider your cleanup to be a major improvement. It reads very easily now, saying what it needs to say to someone previously unaware of this tensor, and defining it clearly for anyone. — Quondum 08:41, 11 October 2012 (UTC)
When I said I was done, I lied. I reorganized a bit, based in part on the suggestion on the talk page. I also added an example. It's a great enough change that I've put it up for WP:DYK, so please make it nice in case it goes onto the main page. Teply (talk) 10:17, 12 October 2012 (UTC)

Unit of length

A cluster of IP's is engaging in an edit war at Unit of length, repeatedly adding a table of length scales with units like "yoctoparsec" after three different registered editors have removed it. See also talk:Unit of length#Table. RockMagnetist (talk) 03:46, 14 October 2012 (UTC)

They did it again. It seems like sock/meatpuppetry, but I can't see any obvious pattern in their edits. I have requested semi-protection for the page, but I don't know if it will be accepted. Has anyone seen this sort of pattern before? RockMagnetist (talk) 04:39, 14 October 2012 (UTC)
They're all from SingNet, a Singaporean ISP, so I suspect that this is just 1 user, and the ISP rapidly changes the IP address assignment. Otherwise it just doesn't make sense how these edits are stacked up. -- (talk) 06:02, 16 October 2012 (UTC)
The article now has a soft block on it to force discussion, and the editing has died down. I'm wondering whether this article should be renamed to List of units of length. RockMagnetist (talk) 14:40, 16 October 2012 (UTC)
The renaming idea seems reasonable. But I can't help thinking there's something incomplete here – where're all the sister articles for time, mass, force, ...? Do they all belong in a single article, List of units of measurement? Also, this list is hardly comprehensive, even for length. — Quondum 15:38, 16 October 2012 (UTC)
You should check out the table of contents of this reference before considering an expansion of the subject. This list is indeed far from comprehensive and probably always will be. I think sister articles would be the best approach.
Woo-hoo! I feel thoroughly cowed by that encyclopaedia. I would have hoped for some systemetization of the topic, but... I see that there are actually a number of articles in WP that tackle aspects of this listing approach, but they are rather patchy so far. — Quondum 16:55, 16 October 2012 (UTC)

OER physics textbook hacking

A group of editors and physicists are getting together in Boston to hack on open physics texts, drawing from the amazing OER materials that are already out there. [yes, including the brilliant Light and Matter series :)] Your help would be welcome, in person or afar. See the event page if you can be there in person; maybe we can coordinate remote work on wikibooks. – SJ + 00:59, 19 October 2012 (UTC)

Michelson Gale Pearson Experiment

Proposed addition to Michelson–Gale–Pearson experiment to interpret the result from the perspective of Michelson and Gale (Pearson was the assistant). User DVdm suggested I might open a section at this talk page and propose the following additions my edit.

Note: No changes were made to the existing material. The Wiki entry describes the results from the perspective of Einstein's ether-less SR, therefore it seems only right to include the perspective from the original intent to detect the ether. I'm reading-up about the definition of reliable sources (listed as the main reason for the omission) and can't seem to find anything wrong with referencing peer-reviewed conference publications. If necessary, I can also reference the Chairman and Vice Chairman of the conference who actually attended the session in Moscow last month where this discussion took place, they commented that the new work is "of great value to the community". I would highly recommend (appreciate) anyone who responds to this entry to read the referenced conference paper before making any conclusions. it's a good read and only 5 pages in total.

Please also note that the addition was my first edit so please forgive me in advance for any misinterpretations to standard policies.

Thanks for everyone's great work on Wikipedia. Kelvin Wright (talk) —Preceding undated comment added 04:39, 19 October 2012 (UTC)

Nomination for deletion: Benz (unit)

I nominated the article Benz (unit) for deletion on the grounds of non-notability; the nomination was removed as one editor has objected. Opinions by others would be appreciated at Talk:Benz (unit)#Potentially Useful. — Quondum 12:14, 20 October 2012 (UTC)

Help requested for new article

Hello - I just wrote a new article, Peniche (fluid dynamics). It has a couple of sources, but I would greatly appreciate someone with an understanding a aerodynamics to take a look and check the accuracy. Feel free to add, subtract, or change whatever seems needed. Thanks! Dohn joe (talk) 20:17, 20 October 2012 (UTC)

Some questionable edits

I have come across some questionable edits by Real doing (talk · contribs). Almost without exception his edits seem to be promoting very recent work of Shiva Pudasaini. This raise some red flags with respect to POV pushing and possibly a COI. However, I am not very knowledgeable on the subject (geophysical flow simulations, I think). So, I cannot tell whether the edits deviate from what would be considered mainstream in the field. Some extra eyes would be welcome. So far, I haven't yet contacted the user, I would like some other input first.TR 12:19, 25 October 2012 (UTC)

Vetting needed at heat death of the universe

A recent edit by Chjoaygame (talk · contribs) has drastically altered the content of at least one portion of Heat death of the universe (edit | talk | history | protect | delete | links | watch | logs | views). I have doubts about the new content, but I don't have the expertise to vet it. Would anyone with a better thermodynamics background than mine care to do so? --Christopher Thomas (talk) 23:03, 9 September 2012 (UTC)

There might be a valid point in there somewhere, but the added text was argumentative in tone and extrapolated quite a lot from the source. I have reverted for now. --Amble (talk) 07:23, 10 September 2012 (UTC)
They've been editing quite a bit at Thermodynamics, First law of thermodynamics, and related articles, too. I haven't looked at the content of those edits, but if anyone has time on their hands, it might be worth doing so in case they've been similarly aggressive there. --Christopher Thomas (talk) 13:41, 10 September 2012 (UTC)

A quick glance suggests that they're still editing heavily at First law of thermodynamics (edit | talk | history | protect | delete | links | watch | logs | views) and are engaged in a spirited debate at the talk page of Heat (edit | talk | history | protect | delete | links | watch | logs | views). I can't comment on the merit of their edits, as I haven't vetted them, but an extra few pairs of eyes are probably a good idea either way. --Christopher Thomas (talk) 22:24, 29 September 2012 (UTC)

The debate at Talk:Heat death of the universe#entropy and the future of the universe as stated in this article could use more eyes. Right now there are two participants, lots of text, and no sign of a resolution. I don't have the expertise to contribute usefully myself. --Christopher Thomas (talk) 06:42, 6 October 2012 (UTC)

People without real knowledge of thermodynamics have been rewriting articles related with the concept of energy, thermodynamics itself, the laws of thermodynamics and such. They go to preposterous asumptions like that the laws of thermodynamics apply only to "thermal energy" and such. They are confusing heat with thermal energy, and seem to believe that entropy is not a function of state; they do not seem to know the difference between functions of state and functions of path: the difference between, on one hand, internal energy, enthalpy, entropy, free energy, and heat and work in the other. They also seem to confuse thermodynamics with heat transfer phenomena. — Preceding unsigned comment added by (talk) 21:33, 30 October 2012 (UTC)

If there are any physical chemists and or physicist with a deep understanding of thermodynamics out there it would be great for them to revise these articles. — Preceding unsigned comment added by (talk) 21:36, 30 October 2012 (UTC)

FYI, I think this comment is directed at me, in reference to Talk:Energy#Wrong_thermodynamics_perspective. I protest that I don't really believe those things :-P --Steve (talk) 00:17, 31 October 2012 (UTC)

I do not know who has written or rewritten what article: all I do know is that threre is a lack of understanding on basic thermodynamic principles in _many_ of wikipedias pages on the subject. i.e. in the thermodynamics page it says currently "Thermodynamics is the branch of natural science concerned with heat and its relation to other forms of energy and work.". Actually thermodynamics deals with the transformation of energy into heat and work. Energy is a function of state. Heat and work are functions of the path taken in a process. The transfer of heat is not thermodynamics: it is called "heat transfer". I had to suffer enough physics, chemistry, thermodynamics, physical chemistry, transport phenomena and heat transfer courses in my time to know the difference between heat transfer and thermodynamics. — Preceding unsigned comment added by (talk) 02:37, 31 October 2012 (UTC)

i.e. in the "energy" article it says, I quote: "Thermal energy, thermal energy in transit is called heat". As per the contributions that seem to misundestand basic concepts in thermodynamics: I checked and they do not seem to come from Sbyrnes321. Some seem to come from Sbharris, but not all. In general thermodynamics is quite an abstract topic with concequences in physics that are sometimes hard to grasp. The generalization of the laws of thermodynamics seems still to, even in general relativity and quantum dynamics or information theory, to hold, albeit with ever more abstract concepts. i.e. — Preceding unsigned comment added by (talk) 03:09, 31 October 2012 (UTC)

Blazed grating

I just did a major rewrite of the article on blazed gratings (it's basically a translation of the German article I rewrote some weeks ago). Since English isn't my native language it would be nice if a native speaker could look over it and fix obvious errors. -- Patrick87 (talk) 19:18, 28 October 2012 (UTC)

I find it very well written both linguistically and scientifically :) --Steve (talk) 13:13, 29 October 2012 (UTC)
Thanks for the compliment! I was afraid that there was a whole lot of linguistic errors in there. Nice to see it it's not that bad after all. -- Patrick87 (talk) 16:33, 29 October 2012 (UTC)
I worked a few commas in where appropriate and edited your lead a little. I also unpiped some of your inter-wiki links so that they read a little clearer and added another reference (which I pulled from the same one you used). Hope this helps, the article looks pretty good! Livewireo (talk) 21:47, 29 October 2012 (UTC)
Well, I would have but we hit an edit conflict! I'm trying to think of how to reword that last sentence in the lead, it seems fairly tacked on at the end just to mention blaze angle. Livewireo (talk) 21:51, 29 October 2012 (UTC)
Yes, seems so, just searched the reference and unpiped links. You're right it sounds a little strange but blaze angle should definitely be mentioned in the lead section. If you use a blazed grating you basically have to now its blaze wavelength and blaze angle. Those are the crucial characteristics. -- Patrick87 (talk) 21:58, 29 October 2012 (UTC)
Sorry to partially revert some of your changes again. I don't know if your're working with diffraction gratings but I'm afraid you mixed up a few things in your last edit.
  • Firstly I did yet another try on the introductory sentence regarding blaze angle (it's not actually measured — it's a number you'll find in the grating's datasheet).
  • Secondly a grating is specifically manufactured for Littrow configuration — Littrow configuration doesn't occur (at least if "occur" isn't some kind of linguistic nuance I didn't get. Is English your mother tongue? You could add some WP:Babel information on your user page so it is easier for people speaking a foreign language to evaluate your changes).
  • Thirdly I changed the sentence "The beams are perpendicular to the step which is in turn parallel to the step normal." because I think you can get it wrong in that the step itself is parallel to the step normal (which would be a little confusiung after all ;) ).
Let's see if we'll finally manage to find some consensus on the article. Let me know what you think of the current version! -- Patrick87 (talk) 23:31, 29 October 2012 (UTC)

Fractional quantum mechanics et al.

The articles Fractional quantum mechanics, Fractional Schrödinger equation and Fractional Poisson process could use some expert attention. Notability of the subjects seems to be given, the articles are based on papers for which Web of Knowledge finds 92, 72 and 24 citations. There might be a COI of the main author Nlaskin though, leading to what looks like undue weight regarding the description of the contributions of Nick Laskin to these concepts. — HHHIPPO 22:12, 28 October 2012 (UTC)

It (fractional powers of the Laplacian) might be interesting mathematically, but is there any evidence that it is relevant physically? JRSpriggs (talk) 07:02, 29 October 2012 (UTC)
I don't know. Just saw that it's discussed in major physics journals, so I guessed that it's notable enough to deserve cleanup rather than deletion. I'm not sure though, that's why I brought it up here before investing too much work in it. — HHHIPPO 07:51, 29 October 2012 (UTC)

Mathematical Trick

Hey everyone. As you can see here, [1], a fellow wikipedian is a little confused over the term "mathematical trick." It shows up on quite a few physics pages, and the best my artsy culture brain can comprehend is that it describes a solution tailored to fit a problem rather than a solution to a problem. Is there a specific meaning to "mathematical trick," and could someone chime in on that noticeboard or just let me know and I'll pass it on? Thanks in advance, and I appreciate the hard work everyone does here! Livewireo (talk) 16:07, 29 October 2012 (UTC)

Category talk:Nuclear physicists

Should this category be a subcategory of Category:Nuclear engineers? Please see ongoing reverts there. --Guillaume2303 (talk) 23:14, 29 October 2012 (UTC)

  • The user insisting on categorizing this way has now been blocked, however, he did make several extensive changes to the categorizations or articles belonging to this project, so it might be worthwhile for an experienced editor here to comb through his edits to check things. --Guillaume2303 (talk) 04:37, 30 October 2012 (UTC)

eddy current brakes/induction motors

There's some editors at the induction motor/eddy currents article that are edit warring away the idea that eddy current brakes and induction motors do work by eddy currents.

If you recall from basic physics lessons eddy current braking slows plates down when they swing past a magnet. Clearly that's a lossy process, the energy ends up dissipated in heat, the eddy currents form magnetic fields and the fields tend to stop the plate.

Only slightly less obviously, from basic physics if you sweep the same magnetic field pattern past the plate, it causes thrust- and that's actually how induction motors work. If you think about it, from Galilean/Special relativity, it's actually the same process.

Sometimes induction motors work exactly that way (there's literally a sheet of conductor) but often they have a shaped conductor called 'a cage' and there's some iron to help shorten the flux circuit, but the eddy currents through the cage still pushes it all around/along.

I tried giving references, but Wtyshmanski and Guy Macon and Andy Dingley are systematically removing it anyway.

I couldn't really get any sense out of them. Their argument seems to be that the term 'eddy current' is rarely used, but the term 'induced current' is commonly used instead (which is true but the induced currents are the eddy currents), and the false arguments were made that 'that's not the way I was taught', 'eddy currents are always only lossy' and that eddy currents are always 'small currents' and then they really seemed to lose it and they started talking about angels; yeah, I didn't get that bit either.

I can't correct the page on my own with 3 apparently very clueless people edit warring into the dirt, and even adding the references I found seems pointless, they remove it all anyway, and they're consistently using the Chewbacca defence on the talk page.

ummm. Help?Embrittled (talk) 03:43, 31 October 2012 (UTC) ────────────────────────────────────────────────────────────────────────────────────────────────────

Please note that User:Embrittled is currently using the following pages as his battleground:

Induction motor

Eddy current

Wikipedia talk:WikiProject Physics

--Guy Macon (talk) 09:43, 31 October 2012 (UTC)

Thanks Embrittled for mis-representing pretty much all of the detail arguments. Please people, if you're going to wade in, first read the (relatively short) past discussions on the article talk: pages. Andy Dingley (talk) 10:27, 31 October 2012 (UTC)
I misrepresented nothing.
There are lots of references that say they are eddy currents, and not a single one, anywhere that say they aren't. Educational institutions, text books, common physics demonstrations and simple logic all point out that they are eddy currents. And you're going around edit warring this away.
Meanwhile the relevant articles are confused and have strange gaps. Apparently you can slow things down with eddy currents, but never make them go faster! (You say.) You can make things fly with a linear induction motor using eddy currents, but it's a total mystery to you how those same currents make them move forward!
What on earth going is in your heads???Embrittled (talk) 20:31, 31 October 2012 (UTC)

I can only repeat my request, there must be somebody else that understands the physics of eddy currents on Wikipedia?Embrittled (talk) 22:14, 31 October 2012 (UTC)

I'm not too much an expert in the field, and I don't have time to read more than a few pages of discussion, but my impression is that the problem here is not whether people understand the underlying physics, but that people use different definitions of eddy current. As usual, the question that should therefore be discussed is not which of the definitions is right, but which ones are notable. This can be difficult to establish since sources like textbooks often give a description, rather than a strict definition of a term like this. Once it is established which definitions are notable, they should all be mentioned at Eddy current, emphasizing their differences. Finally, any other article using the term should make clear which definition it is assuming.
And please, stay calm. No matter what eddy currents are doing, discussions definitely should transform energy into useful work, not into heat. — HHHIPPO 22:51, 31 October 2012 (UTC)