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The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
A bit off-topic -- but -- virtually all of the edits I do at WP are on math articles, with some spill-over to physics and comp-sci. I've not been active for the last few years, because I got tired of the editorial nonsense that goes on. Despite being inactive, I recently was attacked, more or less unprovoked, by a new-age editor who had vandalized an obscure math article I wrote, and someone else reverted. When I told him off, I was promptly piled-on by five admins who blocked me for several weeks. I'm kind of shocked that the power structure here has changed so much that we've got these kinds of nasty, abusive people in admin roles. I complained to the Arb, but they ignored the case. I don't know what to do, other than to complain here, and ask everyone to try to band together, and to figure out how to get the ugly admins and the (incompetent?) leadership out of power, redo Wikipedia leadership, and restore some sanity. linas ( talk) 16:42, 13 October 2009 (UTC)
This has been forum-shopped to Mediation, to the Arbitration Committee, and now to the talk pages of several WikiProjects. Editors coming to this situation with no prior knowledge should read Wikipedia:Administrators' noticeboard/IncidentArchive564#Nuclear meltdown at User talk:Linas, Wikipedia:Administrators' noticeboard/IncidentArchive567#User:Linas again, Wikipedia:Requests for mediation/User:Linas, and this declined ArbCom request to get up to speed. Please place all further discussion at Wikipedia:Administrators' noticeboard/Incidents#Linas, soapboxing on wikiprojects (and userpage), rather than having lots of little disjoint discussions everywhere that this has been shopped around to. Uncle G ( talk) 02:05, 14 October 2009 (UTC)
Count Iblis: Wikipedia is never going to adopt different fundamental content or behavioral policies and guidelines for articles about math, science, or knitting. It is contrary to Wikipedia's culture. Further, the policies and guidelines work pretty well even in math and science. Editors in those areas do tend to get away with unsourced calculations, proofs, and "common knowledge", which is OK too. Also, why did you immediately jump to the conclusion that Linas was right and the admins were wrong, without checking? It's obvious that Linas's behavior is unacceptable, as a quick peek at his talk page shows. Finell (Talk) 20:41, 14 October 2009 (UTC)
People! Please! This has nothing to do with physics articles. Please take it to the WP:AN/I section linked-to above. Uncle G ( talk) 23:56, 14 October 2009 (UTC)
The article is incomprehensible for a non-expert. Can you please rewrite it such that an ordinary user can understand it? -- rtc ( talk) 22:38, 3 October 2009 (UTC)
Hi, can someone please have a look at the merits of this article? Looks like a deletion candidate to me, and at least needs a better title. -- Pgallert ( talk) 15:01, 5 October 2009 (UTC)
The image, in the article at "Explanation#Derivations", is incorrect in the lower part, below the interface. It shows the wavefronts as becoming hyperbolic, so that the portions at large distances from the central axis asymptotically become straight lines. However, the refracted rays below the interface would then not appear to diverge from a point, and that is not the case in reality. The point source position is shifted (upwards, in the figure), but the light source seen from below the interface still appears as a point. This means the wavefronts must continue to diverge from a point, and thus remain segments of a sphere, with only the center of the sphere being shifted. The figure needs to be corrected by someone with a facility in graphics animation. A few other editors should verify and confirm my conclusion, but it is really quite obvious, and easily apparent visually so that it needs to be fixed quickly.
Can some of our project members please verify my reasoning (? on the article talk page I guess, where I have made the same point) ASAP, so the figure can be fixed quickly, as it is embarrassing to the Wikipedia in general, and to the physics project in particular, in my opinion. Thanks! Wwheaton ( talk) 16:07, 23 September 2009 (UTC)
Could someone with some knowledge of geometrical optics please look at the Orthotomic article? Right now it's written as a purely mathematical subject and as such it's basically an alternate name for something else and is flagged for a merge. My research has turned up a possibly broader meaning in optics though so I'm raising the issue here to see if anyone wants to expand the article from that perspective.-- RDBury ( talk) 17:31, 11 October 2009 (UTC)
Hi all! I just completed a major rewrite and expansion of the list of elementary physics formulae. I'm just a student myself so I feel it would be smart to have someone check my work. The list attempts to be a complete 'cheat-sheet' or list of theorems for a first year two-semester college course or for non-specialists who need to keep the basics handy. I've tried to keep the theorems as unit-system agnostic as possible while avoiding changes which would render the material into an unrecognisable form to students (IE I've kept the SI magnetic and electric constants). I would be overjoyed if anyone would like to take a look and offer advice or corrections. Also I've lost the fluid dynamics section of my notes, so that still needs to be filled in. Stuff needs DABed too but I'm working on it. Regards, - Craig Pemberton ( talk) 22:46, 12 October 2009 (UTC)
Here's a challenge: by the end of the year, let's try to get all of our top-importance articles up to at least C class and our high-importance articles up to at least start class. We currently have 35 start-class/top-importance articles and 54 stub-class/high-importance articles. With 3 months to go in the year (decade...) then if a few people join in, we should be able to get both of these numbers down to 0 with a bit of effort! Djr32 ( talk) 22:05, 2 October 2009 (UTC)
We had a discussion in August ( link) about 195.47.212.108 ( talk · contribs · WHOIS), who has created 11+ dubious physics-y articles. Nothing seems to have happened since then. So I figure I'll get the ball rolling...I proposed deletion for one of those articles, selfconsistent electromagnetic constants. Please contribute to the AfD discussion. -- Steve ( talk) 20:50, 8 October 2009 (UTC)
See Here...there's some idea that modern quantum mechanics doesn't discuss capacitances and inductances enough, and is overly-focused on electric and magnetic fields. (That's what he or she may have meant by "feeld theory" at the AfD discussion.) That whole article is very strange, by the way. In reality, the quantum treatment of an electromagnetic cavity is very well known: The classical electromagnetic standing waves get quantized into photons, etc. This article does it differently, creates a nonsense Hamiltonian in "charge space", and calls the result "nonrelativistic quantum electrodynamics, which considers elementary particles from the intrinsic point of view. Note that, the standard quantum electrodynamics conciders elementary particles from the external point of view." It infers that the electron isn't a point charge but has a uniform mass distribution over a sphere of a certain radius, and that the electron mass comes from these quantum electromagnetic resonator oscillations or something.
OK, I found how to AfD multiple articles at once. I'll wait for this AfD discussion end first though. -- Steve ( talk) 17:10, 12 October 2009 (UTC)
Well...
The IP is active on the AfD again. I've reached my "dealing with this crud" limit, and I think they'll only accept responses from someone who can critique the math. I'm bowing out. -- Christopher Thomas ( talk) 06:55, 13 October 2009 (UTC)
The first AfD passed. Now eight more articles are listed for another AfD. Please contribute at Wikipedia:Articles for deletion/Selfconsistent gravidynamic constants. -- Steve ( talk) 22:30, 15 October 2009 (UTC)
I am learning about emission lines in physics right now, and I noticed that we don't have very many diagrams of them, and that it would be nice if they were standardized. So I am proposing that we make standard images for them according to the following plan:
Also, although not as aesthetically pleasing, it might be useful to include a "ruler" next to the spectrum like in this one File:Helium_spectrum.jpg. Additionally, to make these images easily created and edited by others, I was thinking that I (or someone) could create a continuous spectrum, and then black out the unseen parts in each specific picture. This method could work for the absorption lines as well. I'm not sure that we really need an image like this for every element, but it would be nice on ones named after their emission lines like Indium and Thallium. Any suggestions welcome. J kasd 09:14, 9 October 2009 (UTC)
Perhaps a better question to ask is: "What purpose would such pictures have and what information would we like them to convey?" Then we could have some sort of guiding principle for deciding on the details. J kasd 05:18, 10 October 2009 (UTC)
The top picture is a new one that I created using this method, while the bottom one is an actual photograph of it. I made the bottom half of the red line a little brighter by increasing the saturation, but I think to accurately depict the brightness, we would have to have a gradient from red to white to red, depending on the brightness. I think that since when we have an actual photograph we should use that, but since these photographs seem to be rare, I think it would be good if we had a way to create an accurate diagram. An additional way to convey brightness, also seen in the photo, is to increase the width. A combination of these methods may yield a tolerable result. The color spectrum I used was the one from here. (Note: I did not take much effort ensuring the accuracy of my top picture, it is merely a proof of concept.) J kasd 09:42, 17 October 2009 (UTC)
startwavelength=400
width=.1
def wav2RGB(wavelength):
w = int(wavelength)
if w >= 380 and w < 440:
R = -(w - 440.) / (440. - 350.)
G = 0.0
B = 1.0
elif w >= 440 and w < 490:
R = 0.0
G = (w - 440.) / (490. - 440.)
B = 1.0
elif w >= 490 and w < 510:
R = 0.0
G = 1.0
B = -(w - 510.) / (510. - 490.)
elif w >= 510 and w < 580:
R = (w - 510.) / (580. - 510.)
G = 1.0
B = 0.0
elif w >= 580 and w < 645:
R = 1.0
G = -(w - 645.) / (645. - 580.)
B = 0.0
elif w >= 645 and w <= 780:
R = 1.0
G = 0.0
B = 0.0
else:
R = 0.0
G = 0.0
B = 0.0
if w >= 380 and w < 420:
SSS = 0.3 + 0.7*(w - 350) / (420 - 350)
elif w >= 420 and w <= 700:
SSS = 1.0
elif w > 700 and w <= 780:
SSS = 0.3 + 0.7*(780 - w) / (780 - 700)
else:
SSS = 0.0
SSS *= 255
hex = "0123456789ABCDEF"
return "#"+hexint(SSS*R)/16+hexint(SSS*R)%16+hexint(SSS*G)/16+hexint(SSS*G)%16+hexint(SSS*B)/16+hexint(SSS*B)%16
filename = "Hydrogen Emission.svg"
f=open(filename,"w")
r=open("H.esl")
f.write('<?xml version="1.0" encoding="UTF-8" standalone="no"?>')
f.write('<svg')
f.write(' xmlns:dc="http://purl.org/dc/elements/1.1/"')
f.write(' xmlns:cc="http://creativecommons.org/ns#"')
f.write(' xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"')
f.write(' xmlns:svg="http://www.w3.org/2000/svg"')
f.write(' xmlns="http://www.w3.org/2000/svg"')
f.write(' xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"')
f.write(' xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"')
f.write(' width="300"')
f.write(' height="60"')
f.write(' id="svg3813"')
f.write(' sodipodi:version="0.32"')
f.write(' inkscape:version="0.46"')
f.write(' version="1.0"')
f.write(' sodipodi:docname="Emission Spectrum.svg"')
f.write(' inkscape:output_extension="org.inkscape.output.svg.inkscape">')
f.write(' <sodipodi:namedview')
f.write(' id="base"')
f.write(' pagecolor="#000000"')
f.write(' bordercolor="#666666"')
f.write(' borderopacity="1.0"')
f.write(' />')
f.write(' <g')
f.write(' id="layer1"')
f.write(' inkscape:label="Layer 1"')
f.write(' inkscape:groupmode="layer">')
f.write(' <rect')
f.write(' style="fill:#000000;"')
f.write(' id="background"')
f.write(' width="300"')
f.write(' height="60"')
f.write(' x="0"')
f.write(' y="0" />')
for line in r:
x=float(line)
lineX=str((x-startwavelength-(width/2)))
lineColor=wav2RGB(x)
string='<rect style="fill:'+lineColor+';" id="h-line1" width="'+str(width)+'" height="60" x="'+lineX+'" y="0" />'
f.write(string)
f.write(' </g>')
f.write(' </svg>')
f.close()
r.close()
(Outdented; this was a reply to the previous section's thread.)
Also (again), could someone please explain the difference between the "Observed Wavelength" and the ""Ritz Wavelength" to me? — J kasd 22:23, 18 October 2009 (UTC)
(Outdented; this was a reply to the previous section's thread.)
I would expect using the information from NIST to be fine. (I actually was concerned about my use of the code from the blog). About the Ritz values, should I use those instead? Also, I have found that repeating a line increases the perceived brightness, to about 10 repetitions. I think that a combination of increasing the width (very slightly) and repeating a line could be used to achieve the desired effect. — J kasd 00:05, 19 October 2009 (UTC)
Here are images made using the first-pass version of my script. Top spectrum has linear intensity, bottom spectrum has logarithmic. So far, I have to download NIST data manually (though the script will parse it without me having to do data entry). I'm using lines instead of rectangles, and parameters like the visible range are hardcoded (though set up in a way that makes it easy to make them command-line parameters). If the displayed range extends into IR or UV, "IR" and "UV" labels are added at appropriate ends of the display (including the same one at both ends, if you're doing a close-up of a non-visible part of the spectrum). Everything including text scales to the correct size when a sub-range is being plotted. The aspect ratio of the image stays the same.
The main problem I've found so far is that the browsers I've tested don't like me trying to specify a rendering size for an SVG image. So, even though a picture of, say, the 500-600 nm range of the Magnesium spectrum can be scaled to arbitrary size, it renders as a nearly-unreadable thumbnail. I can kludge a solution by introducing a "preferred size" into the script, and wrapping everything in an object-group box and scaling it to the preferred size. Not tonight, though.
Comments about what works well and what could be changed are appreciated. Not sure when I'll next have time to modify the script (this weekend was semi-vacation, but next weekend is very busy).
(I know the Xenon spectrum looks dim; near as I can tell, there's a very strong line in near-IR that's messing with my autoscaling.) -- Christopher Thomas ( talk) 06:50, 19 October 2009 (UTC)
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Christopher those images look nice, but I'm having some trouble. Some comments:
( TimothyRias ( talk) 12:23, 19 October 2009 (UTC))
Cool! Non-black background. As this suggests, it allows to show realistically both colour and intensity. Essentially, you map the interval [min, max] to [0, 1] before applying the gamma correction. This is my take, for a constant-intensity spectrum:
If you drop the requirement that the same mapping should be used for each channel, you get this:
Actually, I didn't expect such good results for the latter. Apparently, the eye adapts to the environment's colours so well that not only colours don't move significantly (i.e. yellow appears to be around 580 nm, where it's supposed to be, etc.), but it's not even that evident that the legend (representing white light after rescaling) is coloured. (Anyway, using brown only in the horizontal zone of the spectrum itself and black above and below it, as NIST do, defeat the purpose.) The only problems with such an approach are 1) that it looks unusual, and 2) that very weak lines would be hardly visible. ___A. di M. 14:58, 19 October 2009 (UTC)
Would someone with a background in physics please run through this article once and correct the most glaring factual inaccuracies and edit what you can? I don't know what is going on with the article, other than severe ownership issues, but it has sentences like, "A recurrent issue with either naturally occurring, or conventional materials, is the lack of magnetic response." -- 69.225.5.183 ( talk) 19:36, 14 October 2009 (UTC)
The article is being copied into cyberspace as is. If it's inaccurate, it needs to be worked on outside of article space. I've learned from Ti-30X that magnetic response has nothing to do with magnetism, that "lack of" is quantitatively the same as "lack of large," and that even if a research group's name isn't on their page or anywhere else in cyberspace besides that article, it's still a verified name and acronym for the research group.
If the group is so unheard of, Ti-30X, that it isn't on a single google page, not even on the group's page, you've either made up the name (yes, you have!), or it's not noteworthy enough to be in the article (it's not because it only exists in your head, not in verifiable secondary sources, 'cause it doesn't exist).
I think that wikipedia has a responsibility to readers to not create articles in article space that are full of nonsense.
Wiki project physics members disagree with me.
Support for your local Essjay wins. I can't do anything but alert people who should be concerned. I don't have a week or two for every physics error, when there was no way to even show this user that
the reason the group name you made up isn't anywhere but your article, not even on the page you made it up for, is that you read the page wrong, and the name doesn't exist anywhere but where you made it up: in your head and in wikipedia article space.
And, you've read incorrectly almost everything you've added to the article. It's a randomized assortment of half pieces of information copied in strange orders from a number of good sources whose authors would be surprised to see what they say according to you.
This article is a serious problem. There are some excellent physics articles on wikipedia, written by people who not only have a grasp of physics at a high level, but are able to transfer that knowledge clearly, concisely, and accurately to a general audience. Given this, I thought WP:physics members would be concerned to be represented by garbage. I'm wrong.
Enjoy. -- 69.225.5.183 ( talk) 16:08, 17 October 2009 (UTC)
Do we have a policy against using the project board in lieu of or along side of the arbitration, Administrative notice of incident, or the other arbitration processes available. I am thinking about both the post by Linas and the previous posts about Brews which caused all kinds of problems on this board, but did not lead to a solution.
In situations where discussion on the project talk page degenerates to the point that some sort of arbitration beyond the board is needed and/or when there is already such an arbitration already in place, I would like to either move, scratch, or put in a collapsed box, all material pertaining to that case. The material would be replaced by a carefully worded neutral statement pointing out the contention with a link to where the arbitration is at. (Possibly similar to UncleG's last post but in a neutral fashion; not discussing forum shopping for instance. It should also include the fact that Linas requests that..)
The board has a large and important role in deciding whether or not something should be sent to mediation, and on settling small grievances. We simply don't have the resources to arbitrate or mediate conflicts that are larger.
Having a consistent and neutral policy that everyone could agree on like this would discourage people from 'forum shopping'. More importantly it might keep the board from degenerating into a futile chaos and help to keep the inevitable frustrations contained.
As a side note, I would like to see the same policy for the discussion of material on the project page that is more appropriate to an article talk page.
I don't mean any of this as an attack on anybody involved in any of these cases. This policy will not work unless it is enforced with consistency and neutrality.
TStein ( talk) 20:56, 14 October 2009 (UTC)
While looking at the lists in " § Article status challenge" above, I've encountered the articles vacuum permeability and vacuum permittivity, which, IMO, focus way too much on the fact that these constants depend on the system of measurement (something which, to a larger or smaller extent, is true of any dimensionful quantity), and too little about what they serve for. They even state that the view that ε0 and μ0 are physical constant is "incorrect", but I can't see why they are any less of a physical constant than, say, the speed of light is, or than the Boltzmann constant would be if the kelvin was redefined in terms of it. (Imagine, for the sake of argument, that the kelvin were redefined so that the numerical value of kB became a defined constant. We wouldn't edit the Boltzmann constant article so that 75% of it is about the fact that it's only a measurement system-dependent constant with no physical significance, would we?) Also, some paragraphs in vacuum permeability seem to suggest that free space refers to an ideal medium with permittivity equal to 8.854...×10−12 farads per metre by definition. That's as backwards as claiming that water refers to an ideal medium with a triple point temperature of 273.16 K by definition.
What do you others think? -- ___A. di M. 09:42, 15 October 2009 (UTC)
My view is that the parameters called the electric constant and the magnetic constant do not refer to any realizable, real medium, but only to a reference state commonly called classical vacuum that is not found in the Universe. Of course, one can compare the behavior of real media with the predicted behavior of classical vacuum and determine how well or how poorly the real medium is modeled by classical vacuum; that is what a "reference state" means. There is no sense in which classical vacuum "dictates" to nature; one simply compares nature to the predictions for classical vacuum to see how they compare. There may be a notion above that "vacuum permeability" (aka magnetic constant) refers to the permeability of some real medium called "vacuum", but that is erroneous. It is a defined, not a measured number, as is the vacuum permittivity (aka electric constant). Brews ohare ( talk) 13:00, 15 October 2009 (UTC)
I do more or less agree with Brews here. But I would suggest discussing concrete examples and discussing them in detail from first principles. Otherwise it is not clear how relevant this all is. In QED you can integrate out the electrons and then you can obtain the effective Euler-Heisenberg lagrangian. You can then derive expressions for the permittivity and permeability tensors, see e.g. here. There are also nontrivial effects due to boundary conditions, e.g. the Scharnhorst effect etc. Count Iblis ( talk) 16:13, 15 October 2009 (UTC)
OK, OK, let's stick to what everyone agrees with. Are ε0 and μ0 physical constants? Yes, at least to the extent that c, NA and kB are. Are their numerical values in SI units fixed by definition? Yes, they are 1/(4π × 299,792,4582×10−7) and 4π×10−7, due to the definition of the units. Can you measure them in SI units? No, or more precisely, you can but it'd be pointless: assuming that classical electromagnetism and special relativity work and that your measuring instruments are correctly calibrated, you already know what you're going to get. Are they properties of a material medium? No, unless you consider empty space to be a material medium. I think everybody agrees about that, no? (Headbomb, maybe you're right. I shouldn't have started a thread with two things in the title whose product is the inverse square of the nominal subject of a pending arbitration. But I feel reckless. <g,d&rVF!>) ___A. di M. 20:26, 15 October 2009 (UTC)
The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
One of the reasons why the speed of light, the electric permittivity, and the magnetic permeability, and the inter-relationship between the three, so easily stirs up a hornet's nest, is because there are many opinions going around as to the physical significance of these quantities and their inter-relationship to each other. As we speak, an article on this very topic is being nominated for deletion because it contains points of view. Whatever one's opinions are, the facts are that the established opinion has changed drastically since the time of James Clerk-Maxwell in the early 1860's. In 120 years, we changed from a state of affairs in which the speed of light was the speed of a wave in an elastic medium, with the density and the elasticity of that medium being related to the speed of light through Newton's famous equation. Maxwell used his own vortex sea model to link density to the magnetic permeability, and elasticity to the dielectric constant, and he obtained the relevant numerical ratio from the 1856 leyden jar experiment of Weber and Kohlrausch. In the 20th century however, the luminiferous medium disappeared, and magnetic permeability became a defined constant. Then in 1983, the speed of light became a defined constant and so the electric permittivity was compelled to follow suit. Hence, what was once Newton's equation relating the density and elasticity to the speed of wave propagation, as adapted by Maxwell to the luminiferous medium, ended up becoming a mathematical equation relating three defined numbers without any physical significance.
It's not surprising that A. di M. is somewhat perplexed by the emphasis that is being put on the significance of permittivity and permeability in the wikipedia articles. The points of view being expressed in those articles will almost certainly be influenced by the thinking that came about in the wake of the 1983 SI definition of the metre. Such thinking is unlikely to entertain any physical significance to these quantities. And in particular, it is highly unlikely that any modern article will entertain the Maxwellian viewpoint that permeability is a density, and that permittivity is an elastic constant. David Tombe ( talk) 14:18, 15 October 2009 (UTC)
Brews, There was a discussion about that issue here at WT:PHYS in August. It'll be in the archives. That discussion led to the thorny issue of how can we measure the distance between the plates of a capacitor in the new SI system. And yes, Maxwell was indeed thinking about a real medium made of part aether and part ordinary matter. David Tombe ( talk) 14:34, 15 October 2009 (UTC)
Brews, I didn't follow their argument at all. Steven G. Johnson simply told me that we can't measure ε0 experimentally in SI units. I couldn't see why not. All we need to do is measure the distance between the capacitor plates and apply the C = ε/d formula. David Tombe ( talk) 14:58, 15 October 2009 (UTC)
I think that we need to get the facts straight here. This thread was begun by A. di M. with a perfectly legitimate query. He was asking why there has been so much emphasis on 'systems of units' on the electric permeability and the electric permittivity articles. I had noticed the same thing myself about two months ago. I had noticed that 'electric permittivity' had totally sold out to the modern SI system of units.
In response to A. di M. I was very careful not to state my own opinions on the matter. I merely charted the historical evolution of these two parameters from being 'elastic constant' and 'density' in the time of Maxwell, to being defined numbers with no physical significance post-1983.
We then see the same old hysteria erupting. My comments get archived, and the allegations of disruptive behaviour start to fly from the same two sources, which are Headbomb and Physchim62. David Tombe ( talk) 01:36, 16 October 2009 (UTC)
No Finell, It wasn't closed. I doubt if it will be closed for hundreds of years. It is only closed in the minds of certain people. David Tombe ( talk) 02:52, 16 October 2009 (UTC)
Finell, I don't quite see what the problem is here. You seem to hold up everything that I say as a being a crime as a matter of course, rather than actually examining the contents and making a rational assessment, based on that examination. If you would do that, you might learn something. You will have to snap out of this habbit of holding up every edit of mine as constituting evidence of wrongdoing.
It would help to begin with, if you would reply to issues that have been raised in the actual thread itself, rather than digging up old edits from the past to respond to. David Tombe ( talk) 14:14, 17 October 2009 (UTC)
A quick skim of Potential energy ( | talk | history | protect | delete | links | watch | logs | views) shows that it now has the same issue that gravitational potential did a while back: An unusual choice for sign convention (opposite the one used at scalar potential and in my textbooks). There's also an overly-complicated distinction made in potential energy between "potential" (a scalar field) and "potential energy" (energy required to bring a test particle in the field to a fixed reference location); for the types of potential being discussed, potential energy is just potential times the test particle's charge associated with that field (electric charge, mass, etc). For reference, see the discussion at Talk:Gravitational potential#sign (+ or -) of the gravitational potential P, from when this came up at the previous article.
It's possible that I'm off-base and that the majority of sources use the positive rather than the negative sign for things like gravitational potential, but I'd appreciate it if a few people with wider literature exposure than I have could take a look at Potential energy ( | talk | history | protect | delete | links | watch | logs | views) and comment as appropriate. -- Christopher Thomas ( talk) 18:28, 17 October 2009 (UTC)
At Talk:Electromotive_force#Introduction_Should_Include_More_Casual_Language, a user has complained about the uninterpretable lead here; I agree it's a problem, but not just a language problem. The lead says things that don't appear to make sense, citing sources that don't come close to supporting it. I learned a lot about emf and the confusion around it in my previous attempt to work on this article, but I'm no expert, so I'd like to get some help or suggestions before I dive in to try to fix it. Please come to the talk page there or here. Dicklyon ( talk) 01:46, 18 October 2009 (UTC)
Please see Talk:Alternatives_to_general_relativity#Why_is_this_article_such_a_mess.3F. Michael Hardy ( talk) 20:14, 18 October 2009 (UTC)
Can someone have a look at the new article Gravitational induction, a page created and maintained by Fedosin only, and entirely based on his own work. Is this appropriate? DVdm ( talk) 15:35, 21 October 2009 (UTC)
Caveat: In the interests of keeping a constructive atmosphere, I'd suggest proposing a merge to somewhere appropriate rather than an AfD. Surely this could be incorporated as a one-line reference to higher-order effects at gravitomagnetism or similar, once it's been vetted. -- Christopher Thomas ( talk) 17:20, 21 October 2009 (UTC)
I've taken a glance at these articles, and they both seem to contain some rather odd text describing the mechanism of light generation. The relevant text describes electrons moving in a circular path as generating EM radiation in the same manner as a dipole antenna, except with a frequency boost of . I'm almost positive that this description is incorrect with regards to the emission mechanism, though the frequency boost sounds reasonable. Could one of the resident EM-types take a look at this and adjust or clarify as-necessary? I've seen the proper derivation off-wiki, but I don't feel that I have enough expertise to adapt it to these articles -- Christopher Thomas ( talk) 06:31, 22 October 2009 (UTC)
It appears that the second RfD will pass, as soon as someone gets around to closing it (we'll know when the links turn red). All of these articles passed WikiProject Articles for Creation. Should this project be playing more of a role in that project? Also, 3 of the 8 articles now up for deletion have templates on their talk pages:
I say this version is superior. An IP claim this one is. Please leave comments and opinion at Talk:Journal of Optics. Headbomb { ταλκ κοντριβς – WP Physics} 05:17, 23 October 2009 (UTC)
The Gibbs paradox article probably needs the attention of someone from this Wikiproject. There have been two RfCs, but not a great deal of response, though what there has been seems to suggest that the article's current content is somewhat dubious. Could someone take a look? Thanks, Miremare 17:48, 23 October 2009 (UTC)
I have proposed SlipString Drive for deletion. I requested acceptable sources months ago, and none have been forthcoming. No serious (in my opinion) defense has been mounted on the article talk page. If anyone believes it should be saved, please open a discussion and make your case. (This is the first time I have done this, and I am not sure I know how the process should be carried out; apologies if I have goofed it up.) Thanks, Wwheaton ( talk) 05:35, 25 October 2009 (UTC)
There is disagreement on whether Focus fusion should redirect to Eric Lerner or Dense plasma focus, or be its own separate article. See Talk:Focus fusion. YellowFives ( talk) 23:37, 25 October 2009 (UTC)
Here it is. I'd particularly appreciate feedback from people who hadn't significantly contributed to the article (or to the surrounding disputes) before. I feel it's quite close to FA status, but I guess it's too soon to nominate it right now, just two days after an ArbCom case about it was closed. ___A. di M. 15:36, 22 October 2009 (UTC)
Perhaps we should directly contact some suitable people for this peer review, as many of them are not very active on Wikipedia. E.g., I think that User:Joke137 would be a good reviewer. Count Iblis ( talk) 16:36, 22 October 2009 (UTC)
This is a pretty interesting article, but the name could use some work IMO.
I was thinking 1964 PRL symmetry breaking papers, or 1964 Physical Review Letters symmetry breaking papers, or even 1964 PRL papers on symmetry breaking or 1964 Physics Review Letters papers on symmetry breaking or something along those line.
Comments/ideas/suggestions? Headbomb { ταλκ κοντριβς – WP Physics} 14:14, 26 October 2009 (UTC)
According to The Phenomenological Theory of Linear Viscoelastic Behavior by Tschoeogl NW, the Weichert/Wiechert model is named after Johann Emil Wiechert and not Dieter Weichert (named referred to originally, now changed). Which is right? Unfortunately, all other web sources were identical to (copied from) this wiki page. Zachareth ( talk) 10:52, 25 October 2009 (UTC)
The original name on the page with the title Generalized Maxwell Model was Dieter Weichert but it has now been changed to Emil Wiechert as quoted by several textbooks including The Phenomenological Theory of Linear Viscoelastic Behavior. Emil Wiechert (listed on Wiki) seems to be correct as he lived between about 1850 to 1930 which is when all the viscoelastic theory research was done. On the other hand, Dieter Weichert who is also listed on Wiki, was born in the 1950s and is still alive. 121.7.101.86 ( talk) 11:54, 25 October 2009 (UTC)
Found several scientific journal papers which state that Emil Wiechert worked closely with Voigt, Maxwell, Thomson, Kelvin, Poynting, etc. who pioneered viscoelastic theorem (Kelvin-Voigt, Maxwell-Wiechert, Poynting-Thomson, Zener models, etc.). So the Maxwell-Wiechert model is indeed named in part after Emil Wiechert. It's funny how the wrong facts can end up being copied from Wiki to everywhere else. Zachareth ( talk) 23:05, 25 October 2009 (UTC)
The Wikimedia Foundation received a note ( Ticket:2009102810027125 viewable to OTRS volunteers) suggesting that a piece of information in Neutron moderator is wrong. According to our correspondent, the sentence reading "The free neutrons are emitted with a kinetic energy of ~2 MeV each." should read "The free neutrons are emitted with a kinetic energy of 200 MeV each." (Actually, I can't tell if he believes we should be omitting the ~)
I have no idea if he's right, but it seems like either we or he are way off base.
Help would be much appreciated. :) -- Moonriddengirl (talk) 11:29, 28 October 2009 (UTC)
Don't have ref for the temp and density figures typical of carbon burning inherited with the article. Similar problem with the (stub) articles on neon burning process etc. Would like feedback about my mention of stellar models, in particular can references be improved. From the stellar models article, I noticed only description of the 1D models with r as ind. var., yet the refs only appear to refer to 1D models with mass m as ind. var.. I understand the latter are helpful for isochrones of groups of stars of the same age evolving in the HR diagram. But for my article would like to illustrate more elementary concepts in models of individual stars, as well as comparing how the features change with mass. For example, would like to illustrate how the total mass of core nuclear fuel burnt increases during different stages of evolution. Is this related to shell-burning? Puzl bustr ( talk) 12:59, 29 October 2009 (UTC)
![]() | This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
A bit off-topic -- but -- virtually all of the edits I do at WP are on math articles, with some spill-over to physics and comp-sci. I've not been active for the last few years, because I got tired of the editorial nonsense that goes on. Despite being inactive, I recently was attacked, more or less unprovoked, by a new-age editor who had vandalized an obscure math article I wrote, and someone else reverted. When I told him off, I was promptly piled-on by five admins who blocked me for several weeks. I'm kind of shocked that the power structure here has changed so much that we've got these kinds of nasty, abusive people in admin roles. I complained to the Arb, but they ignored the case. I don't know what to do, other than to complain here, and ask everyone to try to band together, and to figure out how to get the ugly admins and the (incompetent?) leadership out of power, redo Wikipedia leadership, and restore some sanity. linas ( talk) 16:42, 13 October 2009 (UTC)
This has been forum-shopped to Mediation, to the Arbitration Committee, and now to the talk pages of several WikiProjects. Editors coming to this situation with no prior knowledge should read Wikipedia:Administrators' noticeboard/IncidentArchive564#Nuclear meltdown at User talk:Linas, Wikipedia:Administrators' noticeboard/IncidentArchive567#User:Linas again, Wikipedia:Requests for mediation/User:Linas, and this declined ArbCom request to get up to speed. Please place all further discussion at Wikipedia:Administrators' noticeboard/Incidents#Linas, soapboxing on wikiprojects (and userpage), rather than having lots of little disjoint discussions everywhere that this has been shopped around to. Uncle G ( talk) 02:05, 14 October 2009 (UTC)
Count Iblis: Wikipedia is never going to adopt different fundamental content or behavioral policies and guidelines for articles about math, science, or knitting. It is contrary to Wikipedia's culture. Further, the policies and guidelines work pretty well even in math and science. Editors in those areas do tend to get away with unsourced calculations, proofs, and "common knowledge", which is OK too. Also, why did you immediately jump to the conclusion that Linas was right and the admins were wrong, without checking? It's obvious that Linas's behavior is unacceptable, as a quick peek at his talk page shows. Finell (Talk) 20:41, 14 October 2009 (UTC)
People! Please! This has nothing to do with physics articles. Please take it to the WP:AN/I section linked-to above. Uncle G ( talk) 23:56, 14 October 2009 (UTC)
The article is incomprehensible for a non-expert. Can you please rewrite it such that an ordinary user can understand it? -- rtc ( talk) 22:38, 3 October 2009 (UTC)
Hi, can someone please have a look at the merits of this article? Looks like a deletion candidate to me, and at least needs a better title. -- Pgallert ( talk) 15:01, 5 October 2009 (UTC)
The image, in the article at "Explanation#Derivations", is incorrect in the lower part, below the interface. It shows the wavefronts as becoming hyperbolic, so that the portions at large distances from the central axis asymptotically become straight lines. However, the refracted rays below the interface would then not appear to diverge from a point, and that is not the case in reality. The point source position is shifted (upwards, in the figure), but the light source seen from below the interface still appears as a point. This means the wavefronts must continue to diverge from a point, and thus remain segments of a sphere, with only the center of the sphere being shifted. The figure needs to be corrected by someone with a facility in graphics animation. A few other editors should verify and confirm my conclusion, but it is really quite obvious, and easily apparent visually so that it needs to be fixed quickly.
Can some of our project members please verify my reasoning (? on the article talk page I guess, where I have made the same point) ASAP, so the figure can be fixed quickly, as it is embarrassing to the Wikipedia in general, and to the physics project in particular, in my opinion. Thanks! Wwheaton ( talk) 16:07, 23 September 2009 (UTC)
Could someone with some knowledge of geometrical optics please look at the Orthotomic article? Right now it's written as a purely mathematical subject and as such it's basically an alternate name for something else and is flagged for a merge. My research has turned up a possibly broader meaning in optics though so I'm raising the issue here to see if anyone wants to expand the article from that perspective.-- RDBury ( talk) 17:31, 11 October 2009 (UTC)
Hi all! I just completed a major rewrite and expansion of the list of elementary physics formulae. I'm just a student myself so I feel it would be smart to have someone check my work. The list attempts to be a complete 'cheat-sheet' or list of theorems for a first year two-semester college course or for non-specialists who need to keep the basics handy. I've tried to keep the theorems as unit-system agnostic as possible while avoiding changes which would render the material into an unrecognisable form to students (IE I've kept the SI magnetic and electric constants). I would be overjoyed if anyone would like to take a look and offer advice or corrections. Also I've lost the fluid dynamics section of my notes, so that still needs to be filled in. Stuff needs DABed too but I'm working on it. Regards, - Craig Pemberton ( talk) 22:46, 12 October 2009 (UTC)
Here's a challenge: by the end of the year, let's try to get all of our top-importance articles up to at least C class and our high-importance articles up to at least start class. We currently have 35 start-class/top-importance articles and 54 stub-class/high-importance articles. With 3 months to go in the year (decade...) then if a few people join in, we should be able to get both of these numbers down to 0 with a bit of effort! Djr32 ( talk) 22:05, 2 October 2009 (UTC)
We had a discussion in August ( link) about 195.47.212.108 ( talk · contribs · WHOIS), who has created 11+ dubious physics-y articles. Nothing seems to have happened since then. So I figure I'll get the ball rolling...I proposed deletion for one of those articles, selfconsistent electromagnetic constants. Please contribute to the AfD discussion. -- Steve ( talk) 20:50, 8 October 2009 (UTC)
See Here...there's some idea that modern quantum mechanics doesn't discuss capacitances and inductances enough, and is overly-focused on electric and magnetic fields. (That's what he or she may have meant by "feeld theory" at the AfD discussion.) That whole article is very strange, by the way. In reality, the quantum treatment of an electromagnetic cavity is very well known: The classical electromagnetic standing waves get quantized into photons, etc. This article does it differently, creates a nonsense Hamiltonian in "charge space", and calls the result "nonrelativistic quantum electrodynamics, which considers elementary particles from the intrinsic point of view. Note that, the standard quantum electrodynamics conciders elementary particles from the external point of view." It infers that the electron isn't a point charge but has a uniform mass distribution over a sphere of a certain radius, and that the electron mass comes from these quantum electromagnetic resonator oscillations or something.
OK, I found how to AfD multiple articles at once. I'll wait for this AfD discussion end first though. -- Steve ( talk) 17:10, 12 October 2009 (UTC)
Well...
The IP is active on the AfD again. I've reached my "dealing with this crud" limit, and I think they'll only accept responses from someone who can critique the math. I'm bowing out. -- Christopher Thomas ( talk) 06:55, 13 October 2009 (UTC)
The first AfD passed. Now eight more articles are listed for another AfD. Please contribute at Wikipedia:Articles for deletion/Selfconsistent gravidynamic constants. -- Steve ( talk) 22:30, 15 October 2009 (UTC)
I am learning about emission lines in physics right now, and I noticed that we don't have very many diagrams of them, and that it would be nice if they were standardized. So I am proposing that we make standard images for them according to the following plan:
Also, although not as aesthetically pleasing, it might be useful to include a "ruler" next to the spectrum like in this one File:Helium_spectrum.jpg. Additionally, to make these images easily created and edited by others, I was thinking that I (or someone) could create a continuous spectrum, and then black out the unseen parts in each specific picture. This method could work for the absorption lines as well. I'm not sure that we really need an image like this for every element, but it would be nice on ones named after their emission lines like Indium and Thallium. Any suggestions welcome. J kasd 09:14, 9 October 2009 (UTC)
Perhaps a better question to ask is: "What purpose would such pictures have and what information would we like them to convey?" Then we could have some sort of guiding principle for deciding on the details. J kasd 05:18, 10 October 2009 (UTC)
The top picture is a new one that I created using this method, while the bottom one is an actual photograph of it. I made the bottom half of the red line a little brighter by increasing the saturation, but I think to accurately depict the brightness, we would have to have a gradient from red to white to red, depending on the brightness. I think that since when we have an actual photograph we should use that, but since these photographs seem to be rare, I think it would be good if we had a way to create an accurate diagram. An additional way to convey brightness, also seen in the photo, is to increase the width. A combination of these methods may yield a tolerable result. The color spectrum I used was the one from here. (Note: I did not take much effort ensuring the accuracy of my top picture, it is merely a proof of concept.) J kasd 09:42, 17 October 2009 (UTC)
startwavelength=400
width=.1
def wav2RGB(wavelength):
w = int(wavelength)
if w >= 380 and w < 440:
R = -(w - 440.) / (440. - 350.)
G = 0.0
B = 1.0
elif w >= 440 and w < 490:
R = 0.0
G = (w - 440.) / (490. - 440.)
B = 1.0
elif w >= 490 and w < 510:
R = 0.0
G = 1.0
B = -(w - 510.) / (510. - 490.)
elif w >= 510 and w < 580:
R = (w - 510.) / (580. - 510.)
G = 1.0
B = 0.0
elif w >= 580 and w < 645:
R = 1.0
G = -(w - 645.) / (645. - 580.)
B = 0.0
elif w >= 645 and w <= 780:
R = 1.0
G = 0.0
B = 0.0
else:
R = 0.0
G = 0.0
B = 0.0
if w >= 380 and w < 420:
SSS = 0.3 + 0.7*(w - 350) / (420 - 350)
elif w >= 420 and w <= 700:
SSS = 1.0
elif w > 700 and w <= 780:
SSS = 0.3 + 0.7*(780 - w) / (780 - 700)
else:
SSS = 0.0
SSS *= 255
hex = "0123456789ABCDEF"
return "#"+hexint(SSS*R)/16+hexint(SSS*R)%16+hexint(SSS*G)/16+hexint(SSS*G)%16+hexint(SSS*B)/16+hexint(SSS*B)%16
filename = "Hydrogen Emission.svg"
f=open(filename,"w")
r=open("H.esl")
f.write('<?xml version="1.0" encoding="UTF-8" standalone="no"?>')
f.write('<svg')
f.write(' xmlns:dc="http://purl.org/dc/elements/1.1/"')
f.write(' xmlns:cc="http://creativecommons.org/ns#"')
f.write(' xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"')
f.write(' xmlns:svg="http://www.w3.org/2000/svg"')
f.write(' xmlns="http://www.w3.org/2000/svg"')
f.write(' xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"')
f.write(' xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"')
f.write(' width="300"')
f.write(' height="60"')
f.write(' id="svg3813"')
f.write(' sodipodi:version="0.32"')
f.write(' inkscape:version="0.46"')
f.write(' version="1.0"')
f.write(' sodipodi:docname="Emission Spectrum.svg"')
f.write(' inkscape:output_extension="org.inkscape.output.svg.inkscape">')
f.write(' <sodipodi:namedview')
f.write(' id="base"')
f.write(' pagecolor="#000000"')
f.write(' bordercolor="#666666"')
f.write(' borderopacity="1.0"')
f.write(' />')
f.write(' <g')
f.write(' id="layer1"')
f.write(' inkscape:label="Layer 1"')
f.write(' inkscape:groupmode="layer">')
f.write(' <rect')
f.write(' style="fill:#000000;"')
f.write(' id="background"')
f.write(' width="300"')
f.write(' height="60"')
f.write(' x="0"')
f.write(' y="0" />')
for line in r:
x=float(line)
lineX=str((x-startwavelength-(width/2)))
lineColor=wav2RGB(x)
string='<rect style="fill:'+lineColor+';" id="h-line1" width="'+str(width)+'" height="60" x="'+lineX+'" y="0" />'
f.write(string)
f.write(' </g>')
f.write(' </svg>')
f.close()
r.close()
(Outdented; this was a reply to the previous section's thread.)
Also (again), could someone please explain the difference between the "Observed Wavelength" and the ""Ritz Wavelength" to me? — J kasd 22:23, 18 October 2009 (UTC)
(Outdented; this was a reply to the previous section's thread.)
I would expect using the information from NIST to be fine. (I actually was concerned about my use of the code from the blog). About the Ritz values, should I use those instead? Also, I have found that repeating a line increases the perceived brightness, to about 10 repetitions. I think that a combination of increasing the width (very slightly) and repeating a line could be used to achieve the desired effect. — J kasd 00:05, 19 October 2009 (UTC)
Here are images made using the first-pass version of my script. Top spectrum has linear intensity, bottom spectrum has logarithmic. So far, I have to download NIST data manually (though the script will parse it without me having to do data entry). I'm using lines instead of rectangles, and parameters like the visible range are hardcoded (though set up in a way that makes it easy to make them command-line parameters). If the displayed range extends into IR or UV, "IR" and "UV" labels are added at appropriate ends of the display (including the same one at both ends, if you're doing a close-up of a non-visible part of the spectrum). Everything including text scales to the correct size when a sub-range is being plotted. The aspect ratio of the image stays the same.
The main problem I've found so far is that the browsers I've tested don't like me trying to specify a rendering size for an SVG image. So, even though a picture of, say, the 500-600 nm range of the Magnesium spectrum can be scaled to arbitrary size, it renders as a nearly-unreadable thumbnail. I can kludge a solution by introducing a "preferred size" into the script, and wrapping everything in an object-group box and scaling it to the preferred size. Not tonight, though.
Comments about what works well and what could be changed are appreciated. Not sure when I'll next have time to modify the script (this weekend was semi-vacation, but next weekend is very busy).
(I know the Xenon spectrum looks dim; near as I can tell, there's a very strong line in near-IR that's messing with my autoscaling.) -- Christopher Thomas ( talk) 06:50, 19 October 2009 (UTC)
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Christopher those images look nice, but I'm having some trouble. Some comments:
( TimothyRias ( talk) 12:23, 19 October 2009 (UTC))
Cool! Non-black background. As this suggests, it allows to show realistically both colour and intensity. Essentially, you map the interval [min, max] to [0, 1] before applying the gamma correction. This is my take, for a constant-intensity spectrum:
If you drop the requirement that the same mapping should be used for each channel, you get this:
Actually, I didn't expect such good results for the latter. Apparently, the eye adapts to the environment's colours so well that not only colours don't move significantly (i.e. yellow appears to be around 580 nm, where it's supposed to be, etc.), but it's not even that evident that the legend (representing white light after rescaling) is coloured. (Anyway, using brown only in the horizontal zone of the spectrum itself and black above and below it, as NIST do, defeat the purpose.) The only problems with such an approach are 1) that it looks unusual, and 2) that very weak lines would be hardly visible. ___A. di M. 14:58, 19 October 2009 (UTC)
Would someone with a background in physics please run through this article once and correct the most glaring factual inaccuracies and edit what you can? I don't know what is going on with the article, other than severe ownership issues, but it has sentences like, "A recurrent issue with either naturally occurring, or conventional materials, is the lack of magnetic response." -- 69.225.5.183 ( talk) 19:36, 14 October 2009 (UTC)
The article is being copied into cyberspace as is. If it's inaccurate, it needs to be worked on outside of article space. I've learned from Ti-30X that magnetic response has nothing to do with magnetism, that "lack of" is quantitatively the same as "lack of large," and that even if a research group's name isn't on their page or anywhere else in cyberspace besides that article, it's still a verified name and acronym for the research group.
If the group is so unheard of, Ti-30X, that it isn't on a single google page, not even on the group's page, you've either made up the name (yes, you have!), or it's not noteworthy enough to be in the article (it's not because it only exists in your head, not in verifiable secondary sources, 'cause it doesn't exist).
I think that wikipedia has a responsibility to readers to not create articles in article space that are full of nonsense.
Wiki project physics members disagree with me.
Support for your local Essjay wins. I can't do anything but alert people who should be concerned. I don't have a week or two for every physics error, when there was no way to even show this user that
the reason the group name you made up isn't anywhere but your article, not even on the page you made it up for, is that you read the page wrong, and the name doesn't exist anywhere but where you made it up: in your head and in wikipedia article space.
And, you've read incorrectly almost everything you've added to the article. It's a randomized assortment of half pieces of information copied in strange orders from a number of good sources whose authors would be surprised to see what they say according to you.
This article is a serious problem. There are some excellent physics articles on wikipedia, written by people who not only have a grasp of physics at a high level, but are able to transfer that knowledge clearly, concisely, and accurately to a general audience. Given this, I thought WP:physics members would be concerned to be represented by garbage. I'm wrong.
Enjoy. -- 69.225.5.183 ( talk) 16:08, 17 October 2009 (UTC)
Do we have a policy against using the project board in lieu of or along side of the arbitration, Administrative notice of incident, or the other arbitration processes available. I am thinking about both the post by Linas and the previous posts about Brews which caused all kinds of problems on this board, but did not lead to a solution.
In situations where discussion on the project talk page degenerates to the point that some sort of arbitration beyond the board is needed and/or when there is already such an arbitration already in place, I would like to either move, scratch, or put in a collapsed box, all material pertaining to that case. The material would be replaced by a carefully worded neutral statement pointing out the contention with a link to where the arbitration is at. (Possibly similar to UncleG's last post but in a neutral fashion; not discussing forum shopping for instance. It should also include the fact that Linas requests that..)
The board has a large and important role in deciding whether or not something should be sent to mediation, and on settling small grievances. We simply don't have the resources to arbitrate or mediate conflicts that are larger.
Having a consistent and neutral policy that everyone could agree on like this would discourage people from 'forum shopping'. More importantly it might keep the board from degenerating into a futile chaos and help to keep the inevitable frustrations contained.
As a side note, I would like to see the same policy for the discussion of material on the project page that is more appropriate to an article talk page.
I don't mean any of this as an attack on anybody involved in any of these cases. This policy will not work unless it is enforced with consistency and neutrality.
TStein ( talk) 20:56, 14 October 2009 (UTC)
While looking at the lists in " § Article status challenge" above, I've encountered the articles vacuum permeability and vacuum permittivity, which, IMO, focus way too much on the fact that these constants depend on the system of measurement (something which, to a larger or smaller extent, is true of any dimensionful quantity), and too little about what they serve for. They even state that the view that ε0 and μ0 are physical constant is "incorrect", but I can't see why they are any less of a physical constant than, say, the speed of light is, or than the Boltzmann constant would be if the kelvin was redefined in terms of it. (Imagine, for the sake of argument, that the kelvin were redefined so that the numerical value of kB became a defined constant. We wouldn't edit the Boltzmann constant article so that 75% of it is about the fact that it's only a measurement system-dependent constant with no physical significance, would we?) Also, some paragraphs in vacuum permeability seem to suggest that free space refers to an ideal medium with permittivity equal to 8.854...×10−12 farads per metre by definition. That's as backwards as claiming that water refers to an ideal medium with a triple point temperature of 273.16 K by definition.
What do you others think? -- ___A. di M. 09:42, 15 October 2009 (UTC)
My view is that the parameters called the electric constant and the magnetic constant do not refer to any realizable, real medium, but only to a reference state commonly called classical vacuum that is not found in the Universe. Of course, one can compare the behavior of real media with the predicted behavior of classical vacuum and determine how well or how poorly the real medium is modeled by classical vacuum; that is what a "reference state" means. There is no sense in which classical vacuum "dictates" to nature; one simply compares nature to the predictions for classical vacuum to see how they compare. There may be a notion above that "vacuum permeability" (aka magnetic constant) refers to the permeability of some real medium called "vacuum", but that is erroneous. It is a defined, not a measured number, as is the vacuum permittivity (aka electric constant). Brews ohare ( talk) 13:00, 15 October 2009 (UTC)
I do more or less agree with Brews here. But I would suggest discussing concrete examples and discussing them in detail from first principles. Otherwise it is not clear how relevant this all is. In QED you can integrate out the electrons and then you can obtain the effective Euler-Heisenberg lagrangian. You can then derive expressions for the permittivity and permeability tensors, see e.g. here. There are also nontrivial effects due to boundary conditions, e.g. the Scharnhorst effect etc. Count Iblis ( talk) 16:13, 15 October 2009 (UTC)
OK, OK, let's stick to what everyone agrees with. Are ε0 and μ0 physical constants? Yes, at least to the extent that c, NA and kB are. Are their numerical values in SI units fixed by definition? Yes, they are 1/(4π × 299,792,4582×10−7) and 4π×10−7, due to the definition of the units. Can you measure them in SI units? No, or more precisely, you can but it'd be pointless: assuming that classical electromagnetism and special relativity work and that your measuring instruments are correctly calibrated, you already know what you're going to get. Are they properties of a material medium? No, unless you consider empty space to be a material medium. I think everybody agrees about that, no? (Headbomb, maybe you're right. I shouldn't have started a thread with two things in the title whose product is the inverse square of the nominal subject of a pending arbitration. But I feel reckless. <g,d&rVF!>) ___A. di M. 20:26, 15 October 2009 (UTC)
The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.
One of the reasons why the speed of light, the electric permittivity, and the magnetic permeability, and the inter-relationship between the three, so easily stirs up a hornet's nest, is because there are many opinions going around as to the physical significance of these quantities and their inter-relationship to each other. As we speak, an article on this very topic is being nominated for deletion because it contains points of view. Whatever one's opinions are, the facts are that the established opinion has changed drastically since the time of James Clerk-Maxwell in the early 1860's. In 120 years, we changed from a state of affairs in which the speed of light was the speed of a wave in an elastic medium, with the density and the elasticity of that medium being related to the speed of light through Newton's famous equation. Maxwell used his own vortex sea model to link density to the magnetic permeability, and elasticity to the dielectric constant, and he obtained the relevant numerical ratio from the 1856 leyden jar experiment of Weber and Kohlrausch. In the 20th century however, the luminiferous medium disappeared, and magnetic permeability became a defined constant. Then in 1983, the speed of light became a defined constant and so the electric permittivity was compelled to follow suit. Hence, what was once Newton's equation relating the density and elasticity to the speed of wave propagation, as adapted by Maxwell to the luminiferous medium, ended up becoming a mathematical equation relating three defined numbers without any physical significance.
It's not surprising that A. di M. is somewhat perplexed by the emphasis that is being put on the significance of permittivity and permeability in the wikipedia articles. The points of view being expressed in those articles will almost certainly be influenced by the thinking that came about in the wake of the 1983 SI definition of the metre. Such thinking is unlikely to entertain any physical significance to these quantities. And in particular, it is highly unlikely that any modern article will entertain the Maxwellian viewpoint that permeability is a density, and that permittivity is an elastic constant. David Tombe ( talk) 14:18, 15 October 2009 (UTC)
Brews, There was a discussion about that issue here at WT:PHYS in August. It'll be in the archives. That discussion led to the thorny issue of how can we measure the distance between the plates of a capacitor in the new SI system. And yes, Maxwell was indeed thinking about a real medium made of part aether and part ordinary matter. David Tombe ( talk) 14:34, 15 October 2009 (UTC)
Brews, I didn't follow their argument at all. Steven G. Johnson simply told me that we can't measure ε0 experimentally in SI units. I couldn't see why not. All we need to do is measure the distance between the capacitor plates and apply the C = ε/d formula. David Tombe ( talk) 14:58, 15 October 2009 (UTC)
I think that we need to get the facts straight here. This thread was begun by A. di M. with a perfectly legitimate query. He was asking why there has been so much emphasis on 'systems of units' on the electric permeability and the electric permittivity articles. I had noticed the same thing myself about two months ago. I had noticed that 'electric permittivity' had totally sold out to the modern SI system of units.
In response to A. di M. I was very careful not to state my own opinions on the matter. I merely charted the historical evolution of these two parameters from being 'elastic constant' and 'density' in the time of Maxwell, to being defined numbers with no physical significance post-1983.
We then see the same old hysteria erupting. My comments get archived, and the allegations of disruptive behaviour start to fly from the same two sources, which are Headbomb and Physchim62. David Tombe ( talk) 01:36, 16 October 2009 (UTC)
No Finell, It wasn't closed. I doubt if it will be closed for hundreds of years. It is only closed in the minds of certain people. David Tombe ( talk) 02:52, 16 October 2009 (UTC)
Finell, I don't quite see what the problem is here. You seem to hold up everything that I say as a being a crime as a matter of course, rather than actually examining the contents and making a rational assessment, based on that examination. If you would do that, you might learn something. You will have to snap out of this habbit of holding up every edit of mine as constituting evidence of wrongdoing.
It would help to begin with, if you would reply to issues that have been raised in the actual thread itself, rather than digging up old edits from the past to respond to. David Tombe ( talk) 14:14, 17 October 2009 (UTC)
A quick skim of Potential energy ( | talk | history | protect | delete | links | watch | logs | views) shows that it now has the same issue that gravitational potential did a while back: An unusual choice for sign convention (opposite the one used at scalar potential and in my textbooks). There's also an overly-complicated distinction made in potential energy between "potential" (a scalar field) and "potential energy" (energy required to bring a test particle in the field to a fixed reference location); for the types of potential being discussed, potential energy is just potential times the test particle's charge associated with that field (electric charge, mass, etc). For reference, see the discussion at Talk:Gravitational potential#sign (+ or -) of the gravitational potential P, from when this came up at the previous article.
It's possible that I'm off-base and that the majority of sources use the positive rather than the negative sign for things like gravitational potential, but I'd appreciate it if a few people with wider literature exposure than I have could take a look at Potential energy ( | talk | history | protect | delete | links | watch | logs | views) and comment as appropriate. -- Christopher Thomas ( talk) 18:28, 17 October 2009 (UTC)
At Talk:Electromotive_force#Introduction_Should_Include_More_Casual_Language, a user has complained about the uninterpretable lead here; I agree it's a problem, but not just a language problem. The lead says things that don't appear to make sense, citing sources that don't come close to supporting it. I learned a lot about emf and the confusion around it in my previous attempt to work on this article, but I'm no expert, so I'd like to get some help or suggestions before I dive in to try to fix it. Please come to the talk page there or here. Dicklyon ( talk) 01:46, 18 October 2009 (UTC)
Please see Talk:Alternatives_to_general_relativity#Why_is_this_article_such_a_mess.3F. Michael Hardy ( talk) 20:14, 18 October 2009 (UTC)
Can someone have a look at the new article Gravitational induction, a page created and maintained by Fedosin only, and entirely based on his own work. Is this appropriate? DVdm ( talk) 15:35, 21 October 2009 (UTC)
Caveat: In the interests of keeping a constructive atmosphere, I'd suggest proposing a merge to somewhere appropriate rather than an AfD. Surely this could be incorporated as a one-line reference to higher-order effects at gravitomagnetism or similar, once it's been vetted. -- Christopher Thomas ( talk) 17:20, 21 October 2009 (UTC)
I've taken a glance at these articles, and they both seem to contain some rather odd text describing the mechanism of light generation. The relevant text describes electrons moving in a circular path as generating EM radiation in the same manner as a dipole antenna, except with a frequency boost of . I'm almost positive that this description is incorrect with regards to the emission mechanism, though the frequency boost sounds reasonable. Could one of the resident EM-types take a look at this and adjust or clarify as-necessary? I've seen the proper derivation off-wiki, but I don't feel that I have enough expertise to adapt it to these articles -- Christopher Thomas ( talk) 06:31, 22 October 2009 (UTC)
It appears that the second RfD will pass, as soon as someone gets around to closing it (we'll know when the links turn red). All of these articles passed WikiProject Articles for Creation. Should this project be playing more of a role in that project? Also, 3 of the 8 articles now up for deletion have templates on their talk pages:
I say this version is superior. An IP claim this one is. Please leave comments and opinion at Talk:Journal of Optics. Headbomb { ταλκ κοντριβς – WP Physics} 05:17, 23 October 2009 (UTC)
The Gibbs paradox article probably needs the attention of someone from this Wikiproject. There have been two RfCs, but not a great deal of response, though what there has been seems to suggest that the article's current content is somewhat dubious. Could someone take a look? Thanks, Miremare 17:48, 23 October 2009 (UTC)
I have proposed SlipString Drive for deletion. I requested acceptable sources months ago, and none have been forthcoming. No serious (in my opinion) defense has been mounted on the article talk page. If anyone believes it should be saved, please open a discussion and make your case. (This is the first time I have done this, and I am not sure I know how the process should be carried out; apologies if I have goofed it up.) Thanks, Wwheaton ( talk) 05:35, 25 October 2009 (UTC)
There is disagreement on whether Focus fusion should redirect to Eric Lerner or Dense plasma focus, or be its own separate article. See Talk:Focus fusion. YellowFives ( talk) 23:37, 25 October 2009 (UTC)
Here it is. I'd particularly appreciate feedback from people who hadn't significantly contributed to the article (or to the surrounding disputes) before. I feel it's quite close to FA status, but I guess it's too soon to nominate it right now, just two days after an ArbCom case about it was closed. ___A. di M. 15:36, 22 October 2009 (UTC)
Perhaps we should directly contact some suitable people for this peer review, as many of them are not very active on Wikipedia. E.g., I think that User:Joke137 would be a good reviewer. Count Iblis ( talk) 16:36, 22 October 2009 (UTC)
This is a pretty interesting article, but the name could use some work IMO.
I was thinking 1964 PRL symmetry breaking papers, or 1964 Physical Review Letters symmetry breaking papers, or even 1964 PRL papers on symmetry breaking or 1964 Physics Review Letters papers on symmetry breaking or something along those line.
Comments/ideas/suggestions? Headbomb { ταλκ κοντριβς – WP Physics} 14:14, 26 October 2009 (UTC)
According to The Phenomenological Theory of Linear Viscoelastic Behavior by Tschoeogl NW, the Weichert/Wiechert model is named after Johann Emil Wiechert and not Dieter Weichert (named referred to originally, now changed). Which is right? Unfortunately, all other web sources were identical to (copied from) this wiki page. Zachareth ( talk) 10:52, 25 October 2009 (UTC)
The original name on the page with the title Generalized Maxwell Model was Dieter Weichert but it has now been changed to Emil Wiechert as quoted by several textbooks including The Phenomenological Theory of Linear Viscoelastic Behavior. Emil Wiechert (listed on Wiki) seems to be correct as he lived between about 1850 to 1930 which is when all the viscoelastic theory research was done. On the other hand, Dieter Weichert who is also listed on Wiki, was born in the 1950s and is still alive. 121.7.101.86 ( talk) 11:54, 25 October 2009 (UTC)
Found several scientific journal papers which state that Emil Wiechert worked closely with Voigt, Maxwell, Thomson, Kelvin, Poynting, etc. who pioneered viscoelastic theorem (Kelvin-Voigt, Maxwell-Wiechert, Poynting-Thomson, Zener models, etc.). So the Maxwell-Wiechert model is indeed named in part after Emil Wiechert. It's funny how the wrong facts can end up being copied from Wiki to everywhere else. Zachareth ( talk) 23:05, 25 October 2009 (UTC)
The Wikimedia Foundation received a note ( Ticket:2009102810027125 viewable to OTRS volunteers) suggesting that a piece of information in Neutron moderator is wrong. According to our correspondent, the sentence reading "The free neutrons are emitted with a kinetic energy of ~2 MeV each." should read "The free neutrons are emitted with a kinetic energy of 200 MeV each." (Actually, I can't tell if he believes we should be omitting the ~)
I have no idea if he's right, but it seems like either we or he are way off base.
Help would be much appreciated. :) -- Moonriddengirl (talk) 11:29, 28 October 2009 (UTC)
Don't have ref for the temp and density figures typical of carbon burning inherited with the article. Similar problem with the (stub) articles on neon burning process etc. Would like feedback about my mention of stellar models, in particular can references be improved. From the stellar models article, I noticed only description of the 1D models with r as ind. var., yet the refs only appear to refer to 1D models with mass m as ind. var.. I understand the latter are helpful for isochrones of groups of stars of the same age evolving in the HR diagram. But for my article would like to illustrate more elementary concepts in models of individual stars, as well as comparing how the features change with mass. For example, would like to illustrate how the total mass of core nuclear fuel burnt increases during different stages of evolution. Is this related to shell-burning? Puzl bustr ( talk) 12:59, 29 October 2009 (UTC)