Wikipedia talk:WikiProject Physics/Archive August 2009

Help with Softvision (talk · contribs)

Over the last few weeks, I've noticed rather strange edits to physics-related articles by Softvision (talk · contribs). As near as I can tell, he comes up with long, rambing proclaimations on the nature of things like time, time dilation, and a few other topics (based on his edit history), and has been making large numbers of edits to talk pages to expound on this. I'm at a loss as to what to do, and I've also reached the limits of my available time/patience with the thread at Talk:Time. Suggestions and assistance would be appreciated.

Active or recently-active articles seem to be:

• Time (edit | talk | history | protect | delete | links | watch | logs | views)
• Speed of light (edit | talk | history | protect | delete | links | watch | logs | views)
• Time dilation (edit | talk | history | protect | delete | links | watch | logs | views)
• Photon (edit | talk | history | protect | delete | links | watch | logs | views)

My understanding was that he used to create new articles with material along these lines, but if so, that's before my encounters with him. Now, he just dumps material on to talk pages spun as questions or suggestions for article improvement. The thread at time seems to have started with him listening to a television documentary, taking one sentence out of context, and using it as the basis for the entire thread.

If anyone's feeling up to mentoring him, be my guest. With or without that, however, it's been disruptive enough that I'm considering going on wikibreak again. More eyes would be welcome. --Christopher Thomas (talk) 00:12, 1 August 2009 (UTC)

Sure. No mentoring, too much time committment, but I'll watch the pages and comment against philosophical extrapolations. Awickert (talk) 00:56, 1 August 2009 (UTC)

By the way, I am a little more ruthless about enforcing WP:TPG. This will hopefully bring sanity. Awickert (talk) 01:00, 1 August 2009 (UTC)

Thanks. --Christopher Thomas (talk) 07:25, 1 August 2009 (UTC)

Someone with more patience than I have can take a look at Talk:Imaginary time, too. I'm approaching the limit of my ability to useful contribute there. Talk:Speed of light seems to be an active area again, too. --Christopher Thomas (talk) 06:25, 5 August 2009 (UTC)

It doesn't appear that you've tried advising him on his talk page, nor notified him of this incident report. And he hasn't been that active the last few days, just tweaking details of his rant at Talk:Speed of light, where there are worse problems going on and he's just being ignored, pretty much. If all he does is talk, ignoring him might be the best strategy – looks to me like he has no article-space edits at all. Dicklyon (talk) 06:48, 5 August 2009 (UTC)

What exactly do you feel I should say on his talk page that isn't more appropriately placed in the threads in question? I have neither the time nor the desire to mentor him at length. I am just one of several people trying to nudge him towards understanding of what is and is not suitable content to add to Wikipedia.

He has edited article-space in the past; check back several hundred edits in his history (he makes large numbers of small edits in any given thread, so even a modest time means it'll be quite a ways back). The fact that he's attempting to work with others by going through the talk pages first is a promising sign, but there is considerably more mentoring that needs to be done to have him contribute usefully to Wikipedia rather than debatably-disrupting talk pages (certainly makes the history tab nearly useless, but beyond that disruption is marginal).

I'd certainly notify him if I launched an RFC regarding him, but I am not launching an RFC (he hasn't done anything seriously wrong). Consider this thread a call for volunteers for mentoring (probably a distributed effort, as nobody seems to want to do it one-on-one). --Christopher Thomas (talk) 07:23, 5 August 2009 (UTC)

The necessary condition to obtain interference fringes

In many articles that involve interferometry it is suggested that lasers facilitate interferometry 'because they produce coherent light'. That is in fact an incorrect attribution.

Before laser sources were available an often used light source for interference experiments was light from a Sodium lamp, as that light is so nearly monochromatic. Of course, monochromatic light helps accuracy, but it is not a condition for obtaining interference fringes. For instance, Newton's rings are obtained with daylight. Newton's rings are a stark illustration of the fact that to obtain interference fringes the light does not have to be coherent.

In a Young double slit experiment the crucial requirement is that the source of light is a point source.
If the interferometry uses sunlight two screens must be employed: one with a single slit, to obtain the equivalent of a point source, the second screen has the double slit. Without the first screen there will be no visible interference effects; the Sun is not a point source.

The hyperphysics site from Georgia State University shows a picture of Interference fringes in a Michelson interferometer obtained with a small incandescent bulb

Experimentally and theoretically we know that if we reduce the luminosity in an interference experiment down to such a low level that at any point in time only a single photon is present then an interference pattern will still build up. It is as if each photon interferes with itself.

If we assume that each photon that passes the first screen will subsequently only interfere with itself then there is no need for coherency. (Quite a leap of interpretation that, but it's a remarkably effective heuristic.)
Laser light leaves the laser cavity through such a small aperture that effectively it's a point source. That why laser light gives good interference fringes. (Interestingly, whether or not laserlight is coherent is moot.)

I don't think this is high priority, but when articles that involve interferometry are edited I think it's worthwile to address this matter as well. --Cleonis | Talk 11:19, 29 July 2009 (UTC)

Coherence (physics)#Spatial coherence explains it pretty well. The require for two-slit diffraction is that the incoming light is spatially coherent over the two slits. Lasers tend to produce light with good spatial coherence. So does a point source (like in the diagram above). Other kinds of interference have virtually no requirement whatsoever for spatial coherence in order to see the interference--e.g., Newton's rings, or the rainbows you see when there's a tiny bit of oil on a puddle of water.

Intensity of the light has nothing to do with anything. A source without enough spatial coherence will produce no diffraction at any intensity, even one photon at a time. The photons coming from the left side of the filament will build up a diffraction pattern, and the photons coming from the right side of the filament will build up a diffraction pattern, but when everything's put together there's no pattern, the different parts of the filament wash each other out.

So I guess I agree with some of what you wrote. :-) --Steve (talk) 15:31, 29 July 2009 (UTC)

But lasers do facilitate interferometry because of their high coherence. This is different than saying you can't do interferometry with incandescent sources. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 09:18, 5 August 2009 (UTC)

Need help determining if polymer physics publication is important

I have slowly been going through list of important publications in physics. In list of important publications in physics#Polymer physics there are three publications by Eugene Guth that I can't find any reference to other then in wikipedia or the hundreds of mirrors of this article. Can someone with knowledge of polymer physics help me out? TStein (talk) 21:20, 29 July 2009 (UTC)

Can anyone point me to a relevant wikiProject that might help. WP:WikiProject Polymers seems to be inactive.TStein (talk) 21:07, 3 August 2009 (UTC)

Try WP:CHEM/WP:CHEMS? Headbomb {^ταλκ_{κοντριβς} – WP Physics} 13:46, 5 August 2009 (UTC)

Quantum field theory, want second opinion

Could someone who knows quantum field theory double-check the accuracy of my edit here? Thanks! :-) --Steve (talk) 15:38, 3 August 2009 (UTC)

Looks ok, except when you write "mediated by virtual photons", because then you suggest that the pertubative expansion is the same as the real effect. But we know that there are non-perturbative effects that vanish to all orders in perturbation theory. Of course, the problem here is that in many popular books this statement about virtual photons can be found. Perhaps you can write that one can heuristically picture electromagnetic interactions in this way.

Perhaps you can also write about some quantum effects. E.g., even if we consider a classical magnetic field, the coupling of the magnetic field with the Dirac field causes the vacuum to become birefringent, so you have two effective indices of refraction when there is a region in the vacuum with a magnetic field (dependent on the polarization of the light w.r.t. the direction of the magnetic field). Count Iblis (talk) 17:50, 3 August 2009 (UTC)

Thanks! Hmm, I'm not sure I understand the connection between the phrase "mediated by virtual photons" and perturbative field theory. I can see how the phrase "mediated by virtual photons" would be evocative of a Feynman-diagram QED expansion, but is it a necessary implication? I mean, everyone says that quarks are held together by gluons, despite the fact that you can't do a perturbative Feynman-diagram expansion to quantify it. Do you think saying just "mediated by the photon field" would be better? Your suggestion (using the word "heuristic") would also work fine of course. Thanks again. :-) --Steve (talk) 19:32, 4 August 2009 (UTC)

Yes, I think mediated by "photon field" would be ok. Now, this is just a statement in the lead, and there you can't explain everything in detail anyway. Count Iblis (talk) 20:37, 5 August 2009 (UTC)

More trouble brewing

In the last week or so, Brews ohare (talk · contribs · deleted contribs · logs · filter log · block user · block log) has focused his attention on Speed of light. In his usual mode, he rewrites before discussing, and then spends full time dominating the discussion page, too, making it impossible for even dedicated editors to fend him off. In the last five days, the article has had over 100 edits, and the talk page over 400, with the majority of both being from Brews ohare in spite of the relatively large number of others trying to participate. This rapid-fire full-time article-focused editing style is how he gets his way. Does anything think that this project would be better off if we asked him to back off and let others collaborate in articles that he is interested in? Dicklyon (talk) 21:36, 1 August 2009 (UTC)

I don't think Brews is doing aything wrong. At least, I don't think he is wrong on the physics, and the discussions on the talk page are more about semantics, which is irrelevant in physics. I really think that the other editors are at fault here for not being able to discuss things in an effective way.

Thought experiment: Suppose I were to edit the article too, let's say, I change the flawed statement in the article about faster than light signals being forbidden because in some frames effect would precede cause and edit in the correct argument (which is that faster than light signals can allow you to create causal paradoxes, but there are exceptions, e.g the Sharnhorst effect, proving that my edit is correct, and the old is false), and removing the citation to the Book by Wheeler and editing in another source. How would the discussion on the talk page proceed? Count Iblis (talk) 22:07, 1 August 2009 (UTC)

You're totally missing the point. Dicklyon (talk) 22:14, 1 August 2009 (UTC)

It is unclear what the point is. As far as I can see Brews' edits were correct. He has even compromised on points where technically he is correct and the others were wrong after some discussions. E.g. on c being just a conversion factor. This is the standard view in theoretical physics, but in many textbooks it is (wrongly) stated that c is a fundamental constant of nature (the fact that c is not dimensionless is besides the point, dimensions are just human constructs).

So, when Brews is challenged, he does take the time to discuss things, but I think he is challenged on too large a number of issues, which leads to many unecessary discussions on the talk page. Clearly that is the fault of the other editors. Count Iblis (talk) 22:39, 1 August 2009 (UTC)

The point is not whether you agree with the content of the edits, but that the aggressive editing style makes it very difficult for other editors to collaborate. I've editing with Brews enough to know that among his edits are a fair number of errors, and idiosyncratic viewpoints, and that it's very hard to get him to let go of either. Dicklyon (talk) 03:03, 2 August 2009 (UTC)

I think you two are arguing all the time about things that are not so relevant to the actual physics. I've just made some edits to the article and I had no difficulties whatsoever. So, the dispute with Brews is not going to prevent someone from contributing to the article at all. What you and Brews are arguing about on this and other articles usually has to do with textbook definitions, like how to define wavelength. Such definitions from textbooks are often not perfect and you can discuss about that for ages.

Why not just step away from these sorts of disputes and focus more on the actual physics? Who says that you need to define everything in one sentence? Why can't you have a general description that is perhaps a bit vague in one paragraph? Count Iblis (talk) 03:16, 2 August 2009 (UTC)

You're right that my complaint is about the behavior, not about the physics. The trouble is that the behavior makes it very hard to "just step away from these sorts of disputes and focus more on the actual physics" since he doesn't leave time for other editors to have a say in what he's pushing through. Most of us don't have full time to devote to defending an article against his onslaughts. When I've tried that, like on Wavelength, it was exhausting. On Speed of light, I have not yet been able to figure out exactly what the argument is, physics wise, as I don't have time to read the 400 talk page edits of the last four days. It's clear that there's trouble brewing, and quite a few editors trying to push back on him, but there doesn't seem to be room to actually understand the issues due to his overwhelming style and devotion. Dicklyon (talk) 09:12, 2 August 2009 (UTC)

Dicklyon's comment that "I have not yet been able to figure out exactly what the argument is, physics wise" is typical, and indicative of his style of "hit-and-run" editing based upon an instant analysis and decision to revert with no understanding of the issues, just gut instinct. My "aggressive style of editing" certainly has not impeded Dicklyon's participation on any article one iota, nor caused him to try to understand the issues before his reversions. Brews ohare (talk) 14:19, 2 August 2009 (UTC)

What a strange baseless assertion; how can you know how much you have impeded me? And my edit history is open for others to inspect, and I'm sure will plainly contradict what you're claiming about instant analysis and no understanding of the issues. Dicklyon (talk) 15:44, 2 August 2009 (UTC)

Dicklyon says: The point is not whether you agree with the content of the edits, but that the aggressive editing style makes it very difficult for other editors to collaborate. Dick, it should matter whether the content of the edits is correct. And the claim that other editors have difficulty contributing is not factual, as the Talk page history shows clearly. Also, the majority of my edits on the actual article are minor, like adding a See Also or correcting the citation template for a source. Pretending an edit count indicates a host of major revisions is distortion, what ever else it might be (e.g. sloppy observation, laziness, building a case, venting). Brews ohare (talk) 03:37, 2 August 2009 (UTC)

Nobody is suggesting that correctness doesn't matter. But claiming to be correct should not be a license to dominate an article by aggressive full-time editing. Leave some room for collaborators to check and comment on your changes, instead of trying to leave them in the dust by opening several fronts in one article and dominating the talk page, too. Apparently we interpret the recent talk page evidence rather differently. Dicklyon (talk) 07:09, 2 August 2009 (UTC)

It would be nice if you had the desire to "check and comment", but I see little of that compared to reversion with a cryptic Edit summary line, and very limited tolerance of sourced additions that do not fit your own personal selection criteria. Brews ohare (talk) 15:56, 2 August 2009 (UTC)

Personally, if what is added is correct and improves the old version, Brews Ohare could have an edit rate of 1000 edits per hour. If you can't keep up, I suggest that you take a break from trying to monitor every tiny change to the article (or the talk page), and instead compare differences over an entire day. This will allow you to get a good feel of what has been changed, and you will be able to create a well-focused discussion more easily. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:37, 3 August 2009 (UTC)

Agreed. If I thought his edits were usually improvements, I wouldn't be talking about them. Dicklyon (talk) 15:01, 3 August 2009 (UTC)

If it is all about your thoughts, your actions would make sense. Brews ohare (talk) 17:47, 3 August 2009 (UTC)

I think that one can either complain about flawed physics being edited in artciles or one should shut up. If Brews is editing a lot and if that somehow causes "Brews to get his way", then it shouldn't be difficult to come here and show specific examples of erroneous edits that one has difficulty correcting because Brews (allegedly) doesn't give anyone the chance to do so.

The focus of discussions here should be on the physics. But the complaint now is 100% about Brews' editing style and 0% about any problems related to the physics of the topic. I think that's unacceptable and the next time we should simply delete such attack threads here. Count Iblis (talk) 18:00, 3 August 2009 (UTC)

I've heard alot of bogus complaints lately. One of those bogus complaints that is getting parroted alot has been that other editors can't edit on certain pages because of Brews ohare. If a person has a contribution to make to an article, there is absolutely nothing to stop them from making that contribution. The fact that Brews ohare is doing alot of edits on that same page shouldn't make any difference. If they have an important point to make, then it is arrant nonsense to claim that they can't make that point because Brews ohare is making too many edits on that page.

When some of these complaints were investigated in more detail at the recent circus, it transpired that those complaining didn't even know anything about the topic in question. They were nevertheless expecting us all to believe that they would have been making edits on the page, only for Brews ohare, and that it was their right to do so even though they knew nothing about the content matter. These bogus complaints will have to stop.

Brews is very good at typing the mathematical symbolism. He is good at providing diagrams. He is honest and open minded. Challenge him on a point of physics and he will go away and think about it. He may not concede on the spot, but give a day or two and you will notice the debate progressing. He is trying to learn. He already has a university level knowledge of the topics in question. He wants to make difficult topics easier for the lay readership to grasp. So let's end this witch hunt once and for all. It's time to make a closer scrutiny of those who have been opposing Brews and complaining about him. David Tombe (talk) 19:09, 3 August 2009 (UTC)

I agree with all of the above, except for the conclusion. We have to assume good faith not only on the part of Brews but also of those who oppose his editing. As far as I can tell everyone involved is doing the best they can to improve the articles. Both sides have legitimate complaints. Both sides, I believe, are willing to listen to reason and work together. It is time we find a solution rather then broadening the fight. The first step of which is finding out exactly what the problem is. TStein (talk) 20:59, 3 August 2009 (UTC)

Since writing the above section, I have realized beyond any doubt that it is actually Martin Hogbin and not Brews ohare who is the cause of the trouble at speed of light. Martin seems to insist that any short description in the history section of Maxwell's work in 1861 needs to be recorded in a distorted fashion. Martin is clearly very strongly opposed to the historical work of Maxwell in which Maxwell equated the transverse elasticity of his sea of molecular vortices to dielectric constant, and the density to magnetic permeability, and then substituted the numerical ratio of the two electromagnetic constants (based on the 1856 experimental results of Weber and Kohlrausch) into Newton's mechanical equation for the speed of sound to obtain a value equal to the speed of light, as measured by Fizeau. Martin will not allow this historical fact to be recorded. This strong prejudice against any physical rationale behind the speed of light is clearly behind his ongoing edit war with Brews, and it is Martin who is clearly in breach of wikipedia's rules in this intance.

I tried to mediate in the dispute between Brews and Martin in order to establish what exactly they were arguing about. Brews told me his point of view on the matter. Martin did not tell me his point of view. Brews indicated to me that he thought that Martin saw the speed of light as something in the realms of a platonic constant like π. Martin denied this. Meanwhile I decided to rectify the historical account of Maxwell's work in the history section. Martin's instant reversion of this correction was a clear sign of his strong prejudices against anything that might give a hint of physical meaning to the speed of light. My guess is that Brews has been encountering the exact same unacceptable behaviour. I have no doubt that Brews has been trying his best to explain a tricky topic and that Martin has been opposing him because Martin thinks that all these things are cut and dried. David Tombe (talk) 20:14, 3 August 2009 (UTC)

In responce to Count Iblis:The focus of discussions here shoud be about improving physics articles, IMO. Most of the time that means dealing with the physics, but it can include other things as well. There is obviously a problem here that needs to be fixed. I agree that the problem is not Brews ohare's physics. Perhaps deleting attack threads here is a solution, but I don't think it will go away if we ignore it. This has to be a common enough problem, that wikipedia has to have a resolving mechanism. Does anyone know what it is? Does it work?

In the meantime it might help to better define the 'conflict', for lack of a better term. I have been to a number of these articles in the hopes of being able to help, but I have had to leave since the 'conflict' ends up being too undefined. I agree strongly with Count Iblis that if Dicklyon and others need help from us they need to be more specific with their examples. I can understand his frustration. I don't want to loose him or Brews due to this. My sense of the problem is that Brews has a more detailed oriented editing style that is conflicting with other editors who want the article to be more concise and focused. (My personal bias may be shining through here, though.) If this is the case then a general discussion here about what is appropriate where along with links to appropriate wikipedia policies may help.TStein (talk) 20:42, 3 August 2009 (UTC)

In the case of Dicklyon, he does have a strong emphasis upon keeping articles short and at a simple level. My own view is different, and I believe that over the life of an article, it might begin with sections of different levels of difficulty and end with the more technical discussions spun off to separate articles as they developed further. Ultimately, one ends up with an overview accessible to anyone with a lot of "main article" templates to the spin-offs. However, I find Dicklyon does not wish to subscribe to this scenario. He wants WP to consist entirely of short & simple articles on the topics he is interested in. If I want to make a separate more technical article that he has no interest in, I think he'd go along with that. However, it would lead to a lot of stubs, and I have doubts that Dicklyon would agree to having "main article" templates directing to these one paragraph stubs in "his" articles. He would object that these stubs were either irrelevant, too technical, or deficient according to some other criteria. For example, I have tried to introduce Fourier series in the wavelength and dispersion articles, and just have this topic reverted on a variety of pretexts despite many efforts at reformulation. Of course, there are articles on Fourier series as a mathematical topic, but do we want a stub called "Wavelength (Fourier series)" or "Dispersion (Fourier series)" just to show how this tool works in particular contexts? Brews ohare (talk) 15:44, 5 August 2009 (UTC)

That's an odd interpretation of what I want; I want articles that are clear, reasonably comprehensive, but not "bloated" with every unsourced remote connection and rambling derivation that comes to someone's mind, which is what was happening in Wavelength. I'm reasonably happy with the content we ended up with there, though it's bigger than ideal and a bit tangential in places; it's just that I shouldn't have had to fight off a bunch of crap to get there. Brews did admit errors and back off here and there along the way, but each such event took a week of my time. It doesn't need to be this had to collaborate. Dicklyon (talk) 15:53, 5 August 2009 (UTC)

In response to Brews: I agree very strongly with the model of spinning technical discussions off and using the main article template. On the other hand, I think that they need to be spun off and not just left in the article. Even if they are just 'stubs'. Dicklyon may have an interest in 'short and simple' articles, but it seems to me that one of the causes of friction is that your idea of 'short and simple' differs from most. (I don't mean that as an insult; the same can probably be said about J.D.Jackson and Herbert Goldstein.) To be honest, I can sympathize; the hardest thing I had to learn as a teacher was that when a student asked a question you answer that specific question and not spend too much time linking that question to other important questions that they should have asked. No matter how brilliant and how useful those broader connections are students tune them out until they are ready. The same is true about wikipedia. People come to an article looking for a specific usually simple answers to a simple question. We have to give them that answer as quick as possible while dropping subtle hints about the other questions they should have asked including links to the answers. If we don't they won't come back and we will be talking to ourselves. Sometimes that means sacrificing points that 'if only' the reader will take 10 seconds to read and believe they would understand the world. TStein (talk) 19:35, 5 August 2009 (UTC)

This comment of Dicklyon is illustrative of another issue. He frequently resorts to polite remarks like "fight off a bunch of crap". Here's another example. In the wavelength instance, Dicklyon began with an incorrect view of the Fourier series aspects, got his dander up when I tried to explain about it, and eventually succeeded in dumping the whole thing. Now he says this was a lot of crap. My interpretation is that Dicklyon does not enjoy an evolution of viewpoint, and much prefers the role of oracle. When that role is at risk, he becomes abusive. That is not going to change.

In the case of wavelength I introduced a host of topics (with sources) that now are present in the article, and a number of figures. Every one of these additions was met initially with sneers, contempt and denigration, simply because Dicklyon initially did not find topics like "local wavelength", "aliasing", "interference", as very interesting. That abusive attitude creates an unpleasant atmosphere. Brews ohare (talk) 16:00, 5 August 2009 (UTC)

You have a right to be angry. I have read enough of the comments both here and on other pages to know that you have had to deal with more then your fair share of rudeness and bad behavior, and you have kept your cool better then I would have. I make no excuses for any of them including myself with magnetic field. It may help you to understand, though that many of them have devoted a lot of time to particular pages before you arrived. Rightly or wrongly they are emotionally invested in that page. Too, it might help EVERYBODY involved to realize that the article does not have to be perfect right away. It is an iterative process with steps back as well as forward. TStein (talk) 19:35, 5 August 2009 (UTC)

Brews, part of this is a very simple matter. I'll ask you very nicely: From now on, instead of making 15 tiny edits in rapid succession, could you please attempt to make fewer edits, each involving bigger changes? All I'm saying is, before pressing "Save page", please take another look and a third look, spend 30 seconds, and make sure there's probably nothing else you want to change in that section. This matter has nothing to do with the quality of your edits or with your physics or with wikipedia rules, just practical matters like how easy is it to scroll through an article history, and how quickly one can see the comparison page of what changes you made. Please, you can spend the same amount of time, you can make the exact same changes, but just please press "Save page" fewer times in the process, and I would really appreciate it as a nice favor, and I think I speak for other people too.

Now moving on to less superficial matters...

I think we should talk about (what I see as) Brews's track-record of "article bloat". For example, here's one, anyone who knows solid-state physics can judge for themselves whether Anderson's rule and Kohn-Sham equations are related to k·p perturbation theory. Or this one and this section "In general media" written only by Brews, again y'all can judge for yourselves whether these are appropriate additions to the article on "Maxwell's equations". Here's another, Brews wrote the entire section "speed of light and cosmology" for the article "Speed of light".

These links and topics that Brews adds in these cases are slightly important and slightly relevant to the subject of the article...but then there are hundreds of links and hundreds of pages worth of discussion that would be more important and more relevant but aren't in the article. And articles shouldn't be hundreds of pages long. For the Maxwell's equations example, I have a textbook that lists the four equations on the first page of the textbook and the entire rest of the textbook discusses their consequences. Brews takes this huge field, and he mentions/links a randomly-selected 50 of the thousands of articles/topics that are part of this field, and discusses in more depth a random 1 or 2 of the hundreds of important fundamental examples. I think he shouldn't have tried to undertake the topic of how Maxwell's equations lead to everything in electromagnetism, not unless he had an extremely deep, broad, and longstanding understanding of the full field of electromagnetism, and even then maybe not. My perspective is that Brews doesn't have the big picture sometimes, instead he knows a few things (or many things), and he puts them into articles, not fully aware that these things are tiny snippets of a huge huge field that he's mostly unfamiliar with. Yes, these few snippets are important, but they're not as important as a zillion other things that would never fit into the article.

But that's just my opinion and perspective. Have other people found the same to be true? Maybe it's just me. :-) --Steve (talk) 16:52, 5 August 2009 (UTC)

First, my familiarity with electromagnetism and solid-state theory is extensive, and I have published papers in Phys Rev, IEEE Trans., J Appl Phys and Solid-State Electronics on these subjects. My reaction to looking at my Maxwell's equations contributions is that they are not just added topics of minor importance, a few among many of possibly greater importance. For example, the entire connection of Maxwell's equations to the rest of physics depends upon expressions for the currents and charges, and some introduction to these topics with appropriate links seems central to the understanding of how Maxwell's equations connect to the world. Likewise, the equations in infinite space are actually of limited practical value, so an introduction to the use of boundary conditions seems entirely appropriate, and not some minor item picked out of thousands. Is there a "big picture" that doesn't employ these topics? Are there other huge gaps in this article of greater interest? Well then, cough them up and put them in. Brews ohare (talk) 17:28, 5 August 2009 (UTC)

Well I posted links above. What do other people think? --Steve (talk) 18:00, 5 August 2009 (UTC)

I think we are in a catch-22 (as is Brews). Pointing out a general pattern is too broad and can be leveled at anyone, fairly or unfairly. Pointing out one or two cases is also unfair because Brews has done so many edits that it would be very unlikely that he did not make some mistake. Pointing out a number of cases only wastes everybody's time debating these few cases. Very few of Brews edits by themselves would cause much problems. Massed together, they significantly change the tone and focus of the article which is the problem. In my opinion that adds up to 'bloat' in many cases. I don't see too much of a problem with that though since other editors will pare that down with time keeping what is important. As one of the Brews' critics said above, the end result was that wavelength turned out good. Isn't that what we want?

The problem is about reducing the friction in that process so that we can keep all of the editors involved. I don't want to loose any of them. I think we have enough information in this thread to figure out where everybody stands. That information tells me that everyone is acting in good faith and that everyone understands the physics. It is about time that we focused not on expounding just how bad this or that person is, but to try and find some solutions. I have some proposals that I want to think about first. There are some things that Brews might be able to do and some things that his critics might be able to do and maybe something that the project can do. TStein (talk) 19:35, 5 August 2009 (UTC)

TStein: Yes, reducing friction is the problem. I hope you have some good ideas about this. Possibly the best antidote is some guidelines about how an article evolves over time, and how to keep its evolving nature in focus during the editing process. I know my understanding has evolved during the development of an article, and I wish that other editors would entertain that possibility as well. Even when we are "right", we can benefit from a different idea of what the article is about. That may not correspond to how we learned the subject, nor to the same topic in a print encyclopaedia that does not have features like links and unlimited (by comparison) space. Also, the article may contain explanations that are a result of editing history: some questions pop up again and again and require (perhaps too extensive) answers to defray the continued oscillation of the article over the same territory.Brews ohare (talk) 19:53, 5 August 2009 (UTC)

Content forking can be one way to reduce friction. I have only made large edits to articles that needed to be rewritten (because of major problems). When there already was a good article and I wanted to edit in large derivations I did that in separate articles or in appendices.

E.g., I have completely rewritten the articles Fundamental thermodynamic relation, Helmholtz free energy, part of the article Internal energy because the previous version (dating back from early 2008) was completely flawed. If these article had been ok. to begin with then very likely it would not have contained the detailed dderivation that I edited in. Then, I could not have just dumped the derivation in a good article as that would have upset the structure of the article. But these articles had serious problems, so that gave me the freedom to delete large parts of these articles and edit in my own style.

The article on heat capacity is an example where I could not edit in my own style, as that was a well written article without any problems. Here I wanted to write about the derivation of the relations between heat capacities and I did that in the separate article Relations between heat capacities. Count Iblis (talk) 20:32, 5 August 2009 (UTC)

I think a reasonable guideline is that each edit should make an article better. If the edit makes the article worse, then it should not be made. Also, don't take the Count's above advice. From WP:CFORK, "content forks and POV forks are undesirable on Wikipedia." I agree that commonly held misconceptions can be clarified in the article (if you can reliably source the discussion). The only relevant resources about article depth I have found are in WP:SS and WP:SCOPE. Note that the scope link doesn't have consensus support, but its existence suggests there is no absolutely clear guideline about what the scope of an article is. Pecos Joe (talk) 21:22, 5 August 2009 (UTC)

Sorry, but content forks are an excellent way to deal with the type of problem we're dealing with here. You have to understand that most wiki policies have evolved to deal with the vicious problems you see on wiki politics articles, articles on Israel/Palestine etc. etc. The wiki rules were never intended to be taken as gospel, as WP:IAR points out. So, if content forking works, then it is a good thing to do.

I really don't see why you would get undesirable effects if Brews were to create new articles and explain the details in there that don't fit in well in the main articles, provided what he is writing is good physics. Count Iblis (talk) 21:39, 5 August 2009 (UTC)

Your use of the term content fork led me astray. Please note that "Wikipedia does not view article forking as an acceptable solution to disagreements between contributors," (from CFORK) but if there is agreement to create a sub-article to expand on a topic, then that is absolutely the right thing to do. The guidelines I cited above explicitly mention they were crafted to deal with, in part, heated political debates. What you say in your second paragraph above indicates you were talking about creating sub-articles, which WP:SS deals with explicitly. I agree with that, and I think it would be a bonus if it were also good writing. Pecos Joe (talk) 01:16, 6 August 2009 (UTC)

Here are a couple of items that might lead to less friction:

1. Instead of simple deletion, try rephrasing the entry that you disagree with to suit you better. That process may soften your initial reaction to delete.
2. Instead of deletion, see whether the material would fit into the article better in a different place, maybe with some segue or new subsection title.
3. In general, try to work with the material you object to, and to salvage as much as possible, for example, sources and links, if not the text itself.

At a minimum, following these steps will lead to a more thoughtful presentation of reasons for reversion that will strike the reverted editor as constituting their day in court, instead of being brushed aside. Brews ohare (talk) 22:56, 5 August 2009 (UTC)

All those points sound like good ones to try to follow, although there may be times deletion is warranted. To avoid those times, it would be good if we all tried to place facts in their most appropriate places in the first place. If the fact directly relates to the subject, it is much less likely to be deleted. These remarks were not meant to be directed towards any specific editor(s), because most of the time when I see out-of-place facts, I have no idea who put them there. Pecos Joe (talk) 01:16, 6 August 2009 (UTC)

Good example

On Aug.5, Brews made 17 edits to this talk section; everyone else together made 15. This is a good illustration of his editing style, which makes it impossible to collaborate. Dicklyon (talk) 18:23, 6 August 2009 (UTC)

It makes it a pain in the tail to read the history, and I'd prefer he make fewer revisions to this page (using preview instead), but if that's your biggest complaint, I'm not sure why this being made a huge issue. It's far from "impossible" to read and participate in this page (just requires taking diffs across a larger section of the history list). --Christopher Thomas (talk) 19:33, 6 August 2009 (UTC)

(conflict) Brews is in the spotlight, what do you want him to do, sit back and not say a word? No one else seems to have a problem with it. If this is too fast-paced for you, I would suggest comparing different versions, such as one before Brews made a series of edits, and the last edit of that series (example:[1]).Headbomb {^ταλκ_{κοντριβς} – WP Physics} 19:41, 6 August 2009 (UTC)

Also, what about this thread? If you don't have trouble following and contributing to this very chaotic thread, how on Earth can you have problems with the articles Brews is editing? Count Iblis (talk) 20:01, 6 August 2009 (UTC)

Resolving Brews criticism

I am beginning to agree with Count Iblis that we should just delete all of the Brews threads and move on. I haven't seen anything useful there in a while and it has been eating up time and energy. I am creating this thread for the sole purpose of resolving the issue. Please keep any non-resolving issues to the above posts, thank you.

The complaints

1. Brews makes a lot of edits (often without good summaries) too fast
2. Brews contributes to bloat
3. Brews critics delete and revert without giving a fair chance such as:
   1. deleting when moving to more appropriate section is better
   2. deleting when rewording and or paring down material is more appropriate
   3. demanding that everything Brews does is sourced
4. Rude disparagement of other sides work (statements similar 'this is a load of crap')

(This list is only a summary of what each side feels about the other. Each side feels maybe rightly so that they have good reasons for their behavior. That is not the point of this section so please don't debate that here. Debate that above.)

Possible Resolutions

By the community

TStein: The complaints 1-3 seem to be within limits that the general community should not do anything about it. Particularly problematic is that most of the debates such as RFCs are not specific enough that people can settle them. We can take sides and say A needs to fix i,ii, and iii or B needs to fix iv,v,vi. While probably true, it is unfair to single either of them out and unlikely to solve the problem. It may be necessary to deal with the fourth problem by deleting articles discussing Brews' editing behavior on this page. It is a superficial solution but it may be necessary.

By both contending parties

TStein: (In this and the following sections I apologize about lecturing about what you probably already know. I am not trying to assess blame. The general behavior of all parties, IMO, are generally acceptable, it is only the friction they generate that is not.) Respect the work and viewpoint of the other party. Don't use terms like 'load of crap'. Be patient. Even high importance articles don't have to be perfect all of the time. Sometimes an article has to go through a low point before it can settle at a higher point. (We are looking for a global maximum not just a local one.) Discussing changes first in the talk page can also help.

By Brews Ohare

TStein: Some friction can be reduced if Brews would better use Edit summary (in particular the minor edit when fixing or extending an edit he made earlier). I believe that more technical pages are better suited for Brews style and energy. That is Brews decision, though.

By Brew's critics

TStein: Friction can be reduced by not just deleting material. Move it to more appropriate sections and articles. Rewrite it to simplify. (Brews is generally assertive about his position but also tries to compromise. Be ready to iterate this process.) If this is too much then only do what you can now. It may take weeks but the article will be better for it. Find ways to deal with the frustration of having Brews editing the articles to include more technical details. Don't check page as often for instance. Or take a break from the page. The page won't stay that way forever. TStein (talk) 22:14, 6 August 2009 (UTC)

Merge categories scattering and scattering theory

There are two separate categories for Scattering [2]] and Scattering Theory[3]. Shouldn't these be merged? Is there an easy way to do this without changing each category on each page by hand? Njerseyguy (talk) 16:25, 4 August 2009 (UTC)

If there's consensus for the merge, bots can handle it.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 18:44, 4 August 2009 (UTC)

Also, see WP:CfD for guidance about how to propose a merge and related stuff.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 18:53, 4 August 2009 (UTC)

I am not a scattering person, but I like the idea of scattering theory being in a separate category within scattering. I can see someone being interested in one without being interested in the other. Whether or not it is reasonable separable into these categories, I leave up to someone more knowledgeable then me. TStein (talk) 19:41, 5 August 2009 (UTC)

My position concerning the merge is pretty much that of TStein here. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 02:45, 10 August 2009 (UTC)

Spin–charge separation

This article is poorly written, and could probably use expert attention since the subject has been in the news lately due to the experimental observation of the phenomenon. Also, I am a layperson but according to your own basic criteria I would think it would be rated High or at least Mid. I had heard of this as an undergrad and I wasn’t even a physics major. --WikidSmaht (talk) 19:23, 7 August 2009 (UTC)

Problems at entropy

A new editor ( User Quantumechanic), who does not understand the very basics of thermodynamics, insists on making substantial edits to the entropy page. This is very problematic. The article had been rewritten by someone else giving it an information theoretical introduction, but needed more work. I can do some work starting from that version.

In principle, I would have no problems putting my own POV on how entropy should be defined (information theoretical or phenomenological using heat/work/temperature) aside and let someone else have his/her prefered version.

So, I gave this new user the benefit of the doubt, letting him do the writing and I would just comment, suggest improvements. But that process failed today as it is clear that he is either a kook or he is an expert who deliberately tries to edit in nonsense (e.g. you can imagine that a Professor at some unversity has made a bet with a colleague that he can turn a wiki article on physics topic into complete nonsense such that the nonsensical verion will stick).

I first edited in corrections still consistent with his preferred version (phenomenological definition), but then I spotted a completely nonsensical edit to another section, that I missed previously. A question about that on the talk page which he wasn't able to answer proved, beyond a reasonable doubt, that he shouldn't be editing this article (apart from correcting typos or grammar). Count Iblis (talk) 20:36, 9 August 2009 (UTC)

User:Quantumechanic and User:Subversive.sound are very likely the same individual. They also are redolent of Scibaby, though that's a little more speculative. Short Brigade Harvester Boris (talk) 20:03, 10 August 2009 (UTC)

I am willing to help but will be mostly out of contact for the next week, and will probably need to do some review of the material. Awickert (talk) 03:36, 11 August 2009 (UTC)

Headbomb's administrator candidacy

Physics project member Headbomb is currently a candidate to receive access to administrative tools. Project members, and others, who have an opinion of Headbomb's fitness to receive these tools are invited to comment on Wikipedia:Requests for adminship/Headbomb 3. -- Crowsnest (talk) 15:22, 11 August 2009 (UTC)

Is this valid or BS?

I have no idea whether stealth technology as a pliable electromagnetic envelope is a valid article or not, so I'd like someone here to take a look. It's probably perfectly fine, just needs some cleanup, but better safe than sorry. --NE2 00:57, 7 August 2009 (UTC)

This is a way of looking at metamaterial-based "cloaking devices" that's commonly used in literature. I don't usually hear stealth technology described this way, though. That's generally more about absorbing or deflecting radar. I also usually see the metamaterial stuff described in terms of "constructing a coordinate system where paths do not intersect the hidden object" rather than as a "pliable envelope", but that's a fixable issue (and it's possible that this term has come into vogue and I just missed it). --Christopher Thomas (talk) 01:57, 7 August 2009 (UTC)

The core of the article is derived from peer reviewed journals. Content related to current stealth technology was gleaned from books, magazines, and a good Washington Post newspaper article. Ti-30X (talk) 16:00, 7 August 2009 (UTC)

My point is that while the stealth technologies described in the article are properly sourced, describing them as a "pliable electromagnetic envelope" might not be. I've never heard that term used for them before, and I've followed metamaterial research off and on for a while (labmate is doing his thesis on it, so I get a fair bit of exposure). I'll vet the article if I have time, but I should be working on my own thesis :). First impression was that it looked like a peculiar duplication of stealth technology. --Christopher Thomas (talk) 16:53, 7 August 2009 (UTC)

Christopher - OK, I see what you are geting at. The "pliable envelope" part would be controlling responsive electromagnetic fields. It's kind of a metaphor. The envelope would also be in enveloping the object in the electromagnetic fields. It's a two word description of a mature future technology, perhaps sometime in the 2040's, 2050's, or 2060's. I have no problem in letting that go from the title, at this time. It sounds too glitzy, anyway. To provide further clarity - I am not refering to current stealth technology as a pliable electromagnetic envelope. Current stealth is about the physcial materials used. It is actually used as a contrast, in the article. So the sourced material on current stealth technology, is about current stealth (today). Thank you for your input. Ti-30X (talk) 01:06, 8 August 2009 (UTC)

My concern is that it looks like you're making a content fork of material from Stealth technology and of Metamaterial#Cloaking_devices. I agree that this could use a better treatment, and that focusing on the idea of using a deformed coordinate system as the basis for constructing metamaterial cloaking systems is worthwhile. I'd just feel more comfortable if there was less duplication between your article and existing articles, and if your article's terms were tied more closely to terms verifiably used in literature about metamaterial-based stealth and cloaking. I'm not trying to attack your efforts - I'm just trying to avoid forking or the appearance of OR. --Christopher Thomas (talk) 05:48, 8 August 2009 (UTC)

Christopher, I understand your concern. I was concerned about the same thing, when I started to write it. The science of the theory of negative refractive index is much more in depth than any other article. Also, perhaps, I have a more in depth description of the properties of Metamaterials. Furthermore, the view of stealth technology is unique, in that I point out metamaterials (along with electromagnetic concealment) is a solution, to the current problems expeienced to today. There is no other Wikipedia article that has listed the limitations of cureent stealth with sourced references. I have managed to do this. Another article or two summarizes limitations, but most of those summarizations lack sources. They are just there without citations. Also, the limitations that I have discussed are not the same as their's because of sourcing and citations.

If you don't mind, one more thing. I would like you to come and work on the article with us. Right now, I have a team of four or five editors starting to dig in on the article. With your knowledge of this science you would be an incredible asset. I know that you are working on your thesis. But, if you could put in some time, any amount of time, that would be great. BTW, the article has been renamed to a more appropriate title. But even a new title is being discussed, as a possibility. Anyway - come on in, the water is fine. (It might look like mayhem on the talk page though). Ti-30X (talk) 18:40, 8 August 2009 (UTC)

I might have time to take a look at this on Monday (undetermined). Based on a cursory skim of the talk page, I'd vote that the stealth material be moved back into stealth technology, some of the metamaterial material be moved back to metamaterial, and the article renamed to something like "metamaterial invisibility cloak" (a term which, while corny, was used in at least a couple of places; I'll check more thoroughly before formally suggesting it). The existing short section on cloaking in metamaterial and in cloaking device would have "main article: metamaterial invisibility cloak" in this scenario. I realize that the techniques you've described in the article have applications more general than just cloaking, but so far the lion's share of papers (that I'm aware of; an incomplete set) apply coordinate transformations to construct metamaterials that implement cloaks. Again, I'll do a more thorough literature search before formally suggesting anything. --Christopher Thomas (talk) 05:22, 9 August 2009 (UTC)

Thanks. Ti-30X (talk) 15:57, 9 August 2009 (UTC)

Still no time to pursue this, so I'm shelving any intention to look at it (I really should still be on wiki-sabbatical, but it's almost as bad as tvtropes.org for addictiveness). I'll post a link to this thread on the article talk page. --Christopher Thomas (talk) 22:24, 12 August 2009 (UTC)

any experts willing to work on Gauge theory and Nontechnical introduction to gauge theory?

It would be wonderful if someone with expertise could help out with these two articles. We actually have some people already working on the articles who consider themselves to have the relevant expertise (including me and user Bakken), but have not been able to reach a good consensus on a variety of issues. The Gauge theory article has a long history of intractable disputes relating to accessibility to the general reader, and is currently extremely disorganized. It would be great to have someone with relevant expertise who could come in and help to break the logjam, having no ego preinvested in these two articles.--76.167.77.165 (talk) 20:44, 13 August 2009 (UTC)

Wave-icle

Feedback on this? Seems like a WP:Neologism to me. A user on the talk page also pointed that that Wavicle redirects to Wave-particle duality, and I don't think it's all that inappropriate. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 02:41, 13 August 2009 (UTC)

Based on the extreme sparsity in books, it looks like a neologism that didn't catch on. Make it a redirect. Dicklyon (talk) 03:03, 13 August 2009 (UTC)

Done.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 03:16, 13 August 2009 (UTC)

Someone who typed "wave-icle" or "wavicle" might be looking for Wavelet rather than wave-particle duality. JRSpriggs (talk) 10:40, 14 August 2009 (UTC)

"Wave-icle" is surely just a mis-spelling of "wavicle", which is a reasonably well known term (though, I agree, one that is better redirected to Wave-particle duality than given an article of its own). I can't see any reason that someone interested in wavelets would search for either "wavicle" or "wave-icle". Djr32 (talk) 11:50, 14 August 2009 (UTC)

Electrical material

Freshly created disambiguation page. Expand and prettify at will. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 23:28, 14 August 2009 (UTC)

Heim theory

Ixfd64 (talk · contribs) has recently added links to Heim theory to the Alcubierre drive (edit | talk | history | protect | delete | links | watch | logs | views) and Faster-than-light (edit | talk | history | protect | delete | links | watch | logs | views). My understanding was that Heim theory was fringe enough to not deserve mention in these articles, but it's not my field, so I'd like second opinions before rolling back those additions. --Christopher Thomas (talk) 17:28, 10 August 2009 (UTC)

I agree with removing Heim theory from these articles. The fact that Heim theory is allowed to be represented at all here on wikipedia is a result of a compromize. It survived VFD but there was a consensus that thre article should not promote a pro-Heim theory POV. So, promoting Heim theory on other pages is completely out of the question. Count Iblis (talk) 18:28, 10 August 2009 (UTC)

I've removed it from Alcubierre drive, but so far I've left it in the FTL article. I really hate to say this, but getting a long write-up in New Scientist may be enough to justify the (short) mention it gets, given all of the other handwaving in the Faster-than-light article. --Christopher Thomas (talk) 22:15, 17 August 2009 (UTC)

Wikibreak.

I'm moving out soon and I will have limited access to the internet for the new few weeks (should be back in early September). I will check-in and take messages on a semi-regular basis. Luckily the Article Alerts are working again, and the New Article feed from AlexNewArtBot is up and running as usual, so there shouldn't be too much problems for the Physics project. Please keep an eye on these two things while I'm gone (I'll go through all the new articles once I'm back from my wikibreak, but it would be nice if you could keep an eye out for crank/POV-pushing/spammy content).

Headbomb out, see you in 2-3 weeks. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 14:11, 17 August 2009 (UTC)

IP creating questionable articles

See Selfconsistent electromagnetic constants. Seems like definite OR in places, but I can't make much sense of it. Maybe there's good material in there somewhere?? Anyone else have an opinion? --Steve (talk) 19:18, 4 August 2009 (UTC)

I looked at it and I agree with both not being able to make much sense of it and that places seemed like OR. On the other hand, this would not be the first article that does not make sense to me. The main contributor is an anonymous IP with an interesting history. From a very cursory look, some of the other articles seem to be skirting OR as well. TStein (talk) 21:12, 4 August 2009 (UTC)

I agree with TStein on this. I never heard of "self-consistent constants", nor is "self-consistent" ever defined (at least clearly). I say let's send it to AfD on grounds of WP:OR/WP:Neologism and we can give it bigger scrutinity then. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:00, 4 August 2009 (UTC)

Seconded (you actually beat me to it, as I was about to make a post about this IP contributor). Long story short, 195.47.212.108 (talk · contribs · WHOIS) has been making a very large number of minor edits to selected physics articles (mostly good-faith equation formatting tweaks, as far as I can tell). They've also been creating a large number of rather dubious articles and linking to them. As near as I can tell, their behaviour pattern has been to submit requests at "articles for creation", wait until they're rubber-stamped, and fill in the resulting blank articles. --Christopher Thomas (talk) 04:46, 5 August 2009 (UTC)

Articles created in this manner, that could use a review by experts in the field:

• Gravitational characteristic impedance of free space (edit | talk | history | protect | delete | links | watch | logs | views)
• Maxwell-like gravitational equations (edit | talk | history | protect | delete | links | watch | logs | views)
• Selfconsistent gravidynamic constants (edit | talk | history | protect | delete | links | watch | logs | views)
• Selfconsistent electromagnetic constants (edit | talk | history | protect | delete | links | watch | logs | views)
• Quantum Hall composite resonator (edit | talk | history | protect | delete | links | watch | logs | views)
• Quantum electromagnetic resonator (edit | talk | history | protect | delete | links | watch | logs | views)
• Quantum inductance (edit | talk | history | protect | delete | links | watch | logs | views)
• Quantum capacitance (edit | talk | history | protect | delete | links | watch | logs | views)

The vast majority of this user's edits have been to these articles, not to existing articles in Wikipedia. Also of interest are the following articles:

• Quantum LC Circuit (edit | talk | history | protect | delete | links | watch | logs | views)
• Semicircular potential well (edit | talk | history | protect | delete | links | watch | logs | views)
• Anti-symmetric operator (edit | talk | history | protect | delete | links | watch | logs | views)

These were created by Dahnamics (talk · contribs), who stopped editing on the same day the IP user started, and by Liphe (talk · contribs), who stopped editing roughly when Dahnamics (talk · contribs) started. My guess is that they're the same person who just forgot their passwords or discarded their accounts.

I'm not accusing this editor of malicious intent. However, they seem to be very industriously building a "walled garden", may not be adequately sourcing (per comments by TStein and Headbomb), and in at least one case (noted at User talk:Liphe) were flagged as duplicating material already covered in another article.

If anyone wants to try to talk to this user to explain to them how to work with existing material, by all means do so. I'm in deadline season again, so the best I can do is bring it to your attention. --Christopher Thomas (talk) 23:38, 6 August 2009 (UTC)

This IP has become active again, and is now adding a lot of material to articles like Planck charge, linking to their "quantum electromagnetic resonator" article. A review of the changes to Planck units articles, and of the new articles listed above, is probably in order at some point. I'm still not in a position to do this. --Christopher Thomas (talk) 08:06, 21 August 2009 (UTC)

Kazuhiko Nishijima

I've significantly expanded the article based on his obituary from Yoichiro Nambu, and a hefty dose of google searches. If you have more to add, or feedback to give, go right ahead. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:27, 18 August 2009 (UTC)

Experimental determination of the electric permittivity

There is a well known experiment which appears in the literature in relation to determining the numerical value of the electric permittivity. It involves an electric capacitor circuit with a vibrating reed switch, and it operates in conjunction with the equation C = Q/V = εA/d. We can determine ε from this experiment since all the other parameters in the equation can be directly measured. This experiment is closely related to the famous experiment of 1856 by Wilhelm Eduard Weber and Rudolf Kohlrausch in which they used a Leyden jar and linked the electrostatic/electromagnetic ratio to the speed of light. The modern conclusion of this experiment is the equation,

c^2 = 1/(εμ)

The modern version of this experiment is (or was) prolific in the advanced physics textbooks, and it has generally been accepted (at least until recently) that the electric permittivity can never be accurately determined because it is subject to experimental accuracy.

It seems however, that this experiment has recently been sacrificed in order to preserve the new 1983 definition of the metre. The 1983 definition of the metre in terms of the speed of light has resulted in the speed of light now being defined in terms of itself, along with an arbitrarily assigned number. This fact has been the cause of prolonged confusion and discussions at the speed of light article.

However, the matter gets alot worse. With the sacrificing of the above mentioned experiment, one might have thought that the resulting equation c^2 = 1/(εμ) should have also been sacrificed as a matter of course, since it is an integral part of the same package. But this does not appear to have happened. The equation c^2 = 1/(εμ) has been inexplicably retained without any rationale, and it is being used in reverse, in conjunction with the new post-1983 speed of light in order to define an exact value for the electric permittivity.

I now need to clarify whether or not I am correct in suspecting that the above mentioned experiment has been sacrificed. Do we have evidence of a large scale purging of this experiment from the literature in the years following 1983? Does anybody have an advanced level physics book printed after 1983 in order to see if the above experiment has been removed? The experiment certainly appears in the 1979 version of 'Nelkon & Parker' "Advanced Level Physics", but then that was before the 1983 SI unit conference.

This matter needs to be confirmed one way or the other as a matter of importance, because the present introduction to vacuum permittivity contains new physics that simply wasn't heard of until very recently. We need to confirm its authenticity. We need to know if it's really true that they are teaching that electric permittivity is a defined quantity that is all tied up with the SI units system, and that any physical significance that this quantity was believed to possess in the past is now being officially denied. David Tombe (talk) 22:33, 16 August 2009 (UTC)

The constant ε0 only relates charge and voltage to the mechanical units. That is why "electrical constant" is a better name than "permittivity of free space" etcetera; this is defining the unit system, it is not a materials property. /Pieter Kuiper (talk) 23:45, 16 August 2009 (UTC)

Pieter, we're not discussing that here. I'm asking whether or not the experiment mentioned above involving the capacitor and the vibrating reed switch has been purged from the textbooks since 1983. David Tombe (talk) 00:18, 17 August 2009 (UTC)

You can open any electronics or even electromagnetism textbook and learn how to experimentally measure the capacitance of a capacitor. (Hint: Use a current source, a voltmeter, and a stopwatch!) So, I don't know about the historical experiment, but I can confirm that in post-1983 textbooks it's still made clear that capacitances are measureable electronically. And yes, you can make a parallel-plate capacitor in vacuum and use it to "measure" ε0. Try it at home! If your current source and voltmeter and stopwatch were calibrated correctly at the factory, and your parallel-plate capacitor is good enough (negligible fringing fields, etc.), you'll get the true value of ε0. :-) --Steve (talk) 02:57, 17 August 2009 (UTC)

c_0, μ_0 and ε_0 are all defined units. If you "measure" one of them, you are not in fact measuring these quantities but rather are calibrating your rulers, charge meters, etc... In the example given by Steve, assuming you are able to realize the perfect version of this, you are not measuring the separation of the plates, but rather are making sure that your ruler is calibrated. In practice this may be called "measuring the value of ε_0", but only because rulers are common and "trust" them, and we are used to measure speeds by taking a ruler and comparing against time. Here, the speed of light, combined with the definition of the second, decides what a meter is. We chose an arbitrary value for it that coincided with the accuracy of the old definitions at the time. We could have chosen the speed of light to be 1 m/s, and have long meters and short seconds (relative to now) but we chose to have short meters and long seconds. c is the equivalent of hbar. We choose big joules and long seconds, so the energy contained by a photon oscillating at 1 Hz is ridiculously low. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:45, 17 August 2009 (UTC)

Steve and Headbomb, Thanks for your answers. That's the very experiment that I was talking about. Thanks for confirming that it still exists in post-1983 textbooks. Headbomb obviously missed the entire point that the equation c^2 = 1/(εμ) follows from that experiment.

So Steve takes my view that the experiment in question is still officially valid, whereas Headbomb is adopting the viewpoint that the equation c^2 = 1/(εμ) which follows from that experiment is merely a calibration, and that the experiment no longer measures ε. So under Headbomb's viewpoint, where did the equation c^2 = 1/(εμ) come from in the first place? David Tombe (talk) 10:59, 17 August 2009 (UTC)

c^2 = 1/(εμ) is the relation between the strength of magnetic and electric components of an EM wave. You know, $\nabla \times \mathbf {B} =\mu _{0}\varepsilon _{0}{\frac {\partial \mathbf {E} }{\partial t}}$ (or differently, $\nabla \times \mathbf {B} ={\frac {1}{c^{2}}}{\frac {\partial \mathbf {E} }{\partial t}}$) and all that. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 13:29, 17 August 2009 (UTC)

Headbomb, We know that. But you didn't tell us how Maxwell discovered the connection to the speed of light. It was through the experiments of Weber and Kohlrausch in 1856 using a Leyden jar. David Tombe (talk) 19:42, 17 August 2009 (UTC)

Give a reference that clearly states that it is possible (even in principle) to measure the permittivity of vacuum and look for discrepancies compared to ε₀ (in the current SI units), otherwise this discussion is pointless. (And no, general descriptions of measurements of permittivities don't count: you can measure velocities, too, but you can't measure the speed of light in vacuum in the current system of units because the yardstick is defined by c. This is not a statement about the "validity" of experiments, but rather it is about what the experiments are measuring.) We're not here to debate our own interpretations of physics. — Steven G. Johnson (talk) 17:13, 17 August 2009 (UTC)

Stevenj, you keep saying that this discussion is pointless. But it obviously isn't pointless because we have already had conflicting responses. You haven't explained what has changed since 1983 with respect to the above mentioned experiment, that means that we are no longer measuring the ε in C = εA/d. We can measure d directly even though Headbomb says that we can't. If Headbomb is correct, which I know he isn't, then there is something seriously wrong with the 1983 definition of the metre if it means that we can no longer put a ruler across the plates of a capacitor and measure the separation distance. And with the separation distance 'd' measured, then all we have to do is substitute the other values and hence determine ε experimentally. Without an experimental determination of ε, we could never have had the equation c^2 = 1/(εμ) in the first place. That equation is rooted in experimental measurements.

It strikes me that you are trying too hard to defend what cannot be defended. Once I hear people telling me that when you measure the distance across the plates of a capacitor with a ruler that, to quote from above you are not measuring the separation of the plates, but rather are making sure that your ruler is calibrated then I know that they have lost the argument. Nobody engaged in serious scientific debate ever says something like that.

Think about it Stevenj. It makes no sense to try and make sense out that from which sense cannot be made. David Tombe (talk) 18:53, 17 August 2009 (UTC)

David - you seem to have confused the BIPM with George Orwell's MiniTrue. The definition of the metre was changed, nothing has been "purged". The problem you identify was always there. Pre-1983 it wasn't possible to put a ruler across the international prototype metre and measure the distance between the marks --- the distance was (by definition) 1 metre, and so what you were doing was not measuring the separation between the marks, but making sure your ruler was calibrated. Djr32 (talk) 20:36, 17 August 2009 (UTC)

Djr32, The problem that I have identified wasn't there pre-1983. Prior to 1983, the capacitor (or the older Leyden jar) experiment in question appeared in the textbooks, and the formula C = εA/d contained quantities that could be measured. And from this equation we were able to determine ε experimentally, and hence conclude the existence of the equation c^2 = 1/(εμ). As far as I am concerned, nothing has changed today regarding that experiment. I am waiting to hear whether or not it has been purged from the textbooks. What has changed since 1983 is that they have forgotten the experimental origins of the equation c^2 = 1/(εμ), and they are using this equation in reverse, without questioning where it came from, in order to produce a defined value of ε from a defined value of c. Meanwhile, based on Headbomb's statement above, it seems that we have now moved into some kind of Alice in Wonderland world in which rather than measure a distance with a ruler, the distance in question actually calibrates our ruler. There also seems to be a prevailing ignorance which claims that the linkage of c^2 = 1/(εμ) to the speed of light follows directly from Maxwell's theoretical work, without any involvement of the experimental works of Weber and Kohlrausch in 1856. My guess is that the delegates at the 1983 conference got carried away with themselves because they were so drunk on relativity. David Tombe (talk) 00:05, 18 August 2009 (UTC)

To clarify my previous statement: the problem that was always there is that there is some physical "thing" that you can hold a ruler up to, and not be able to "measure" because its length is a defined quantity. In Maxwell's day, that "thing" was the distance between two marks on a particular metal bar; nowadays it's the distance between the parallel plates of this capacitor in a hypothetical perfect experimental setup. Djr32 (talk) 22:20, 18 August 2009 (UTC)

I think that people are confusing a pedagogical measurement with a cutting edge research measurement. I have my students measure c and εo all the time. Any difference between their measured value and the true value is rightly attributed to the precision of their equipment. Their calculated c says more about the measuring apparatus and the measuring technique then it does about the actual speed of light. If on the other hand someone needs c to further precision then normal they look it up and use the exact for extremely precise measurements.

Let say you were trying to measure the speed of light, with the most precise equipment possible, though. Eventually you would need to use the most precise 1983 definition for determining the distance. Once you start doing that (by say using a clock to determine the distance that light travels in 1/2998.....s then you are not measuring c anymore. The same is true for εo, the charge is set by mu_o and the distance is set by ct so that any direct measure of εo is impossible using precise measurements.

As far as whether textbooks dropped the experiment where εo is measured. I don't know. Most of my textbooks are theoretically bases and don't have any interest in these type of examples. Books like, Griffith's and Jackeon focus on using the experiment to calculate the capacitance, rather than the permittivity in free space. More experimentally oriented books may focus more on calculating εo (as a pedagogical exercise), I don't know. Even if textbooks don't include that experiment it probably doesn't mean anything though. It could be that textbooks dropped it for any other number of reasons such as not being trendy at this moment.TStein (talk) 22:00, 17 August 2009 (UTC)

Tstein, You're probably correct when you say that the experiment was dropped because it was no longer trendy. Physics certainly appears to have its trends. But the actual reasons why this experiment is no longer trendy is what I am interested in. Has it been sacrificed to preserve a foolish mistake which took place at a conference in 1983? People keep forgetting the fact that the equation c^2 = 1/(εμ) only exists because of the experimental determination of ε. We have seen cases above of editors believing that this equation just happens to exist as a matter of course, and that we are free to use it in reverse to determine ε theoretically. When pressed on the matter and forced to think a little, they then seem to think that it was initially wheeled in with Maxwell's equations, forgetting of course about the crucial role of the predecessor experiment in 1856 by Wilhelm Eduard Weber and Rudolf Kohlrausch.

As far as I am concerned, the experiment still holds, as does the equation C = εA/d. And if I measure d with a ruler, then I can obtain a value for ε. But they are actually trying to tell me above, that since 1983, I can no longer measure the distance between the plates of a capacitor. They are trying to tell me that if I try to do so, I will merely be calibrating the ruler, and the equation c^2 = 1/(εμ) is the calibration factor. And they seriously expect me to swallow all these absurdities. David Tombe (talk) 00:26, 18 August 2009 (UTC)

Your opinion of what is absurd is irrelevant to Wikipedia. You are simply wasting everyone's time by this unreferenced postulation; see WP:V and WP:NOR. — Steven G. Johnson (talk) 00:43, 18 August 2009 (UTC)

David, are you denying that the equation c^2 = 1/(εμ) for the propagation speed of EM waves can directly be derived from Maxwell's equations? (Because, if you are. We are done, any undergrad can show you how to get the wave equation from Maxwell's equations (hint: take the double curl), and read of the propagation speed as sqrt(1/(εμ)).

That Maxwell required the equation as input for deriving his theory is completely irrelevant. Since Maxwell's time there have appeared much more elegant derivations of his equations based on more fundemental physical concepts. (Like U(1) gauge symmetry and the action principle). It is a very simple physical fact that the equation c^2 = 1/(εμ) now follows from current theory. (If you think that it doesn't follow from Maxwell's theory you'll just have to accept that it does follow from QED.) So, fixing to of the quantities by definition of our units for length and current also fixes the third quantity. Plain and simple. (TimothyRias (talk) 10:36, 18 August 2009 (UTC))

Stevenj, We're trying to establish whether or not the experiment in question was purged from the literature subsequent to 1983. You are the one who said that I have got no sources. There are plenty of sources pre-1983. We need to know what happened to those sources after 1983. David Tombe (talk) 00:53, 18 August 2009 (UTC)

Then we are in Wonderland, since the definition of one meter [1 m] is the distance light travels in vacuum in a time of 1⁄299792458 of one second. And one second [1 s] is "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom." If you want to know how big is the seperation between two plates, you need to check against a caesium clock, and a pulse of lightbeam travelling in vacuum. Otherwise you are relying on something that was calibrated against a caesium clock and a pulse of lightbeam travelling in vacuum.

In the time of Maxwell, the definition of what a meter (or any units of distance) was different. You would say "this stick is one unit of distance", and "one second is 1/84600th of the duration of the rotation of the Earth against the stars", and would express speed in terms of that. Then you could measure the speed of light, since the definitions of relevant units were how big a stick was and how fast Earth rotated. You could only measure the speed of light up to your knowledge of the stick's length. In 1983, people decided it was more convenient to decide how long the sticks should be, because we need to build lots of sticks, and the speed of light is vacuum is constant. And it is convenient, because a stick can be damaged, bent, stolen, and we'd look pretty foolish if we suddenly stopped knowing how big a meter is because someone thought it made a good prying bar.

So yes, if you could somehow build a perfect plane capacitor with negligible edge effects, you would not be measuring the distance between the plates, but rather making sure your ruler's ticks are at the right place. What happens in undergraduate experiments is that you have a clock, calibrated against a caesium clock, and a stick, calibrated against a pulse of light travelling for 1⁄299792458 seconds. Forgetting experimental factors, if you do not get 299792458 for answer, either your clock is off, or your ruler's ticks are off, or both. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 00:50, 18 August 2009 (UTC)

Headbomb, If you are happy enough with that Alice in Wonderland arrangement in which the act of measuring a length becomes an act of calibration of the measuring instrument, then so be it. But you also need to address that other important issue. Further up the page, you wheeled in Maxwell's equations (Ampère's circuital law to be precise), and you thought that you had solved the mystery of where the equation c^2 = 1/(εμ) comes from. But you overlooked the fact that even Maxwell had to resort to the experimental results of Wilhelm Eduard Weber and Rudolf Kohlrausch in order to obtain the linkage to the numerical value of the speed of light. Nothing has changed today. The capacitor experiment in question is simply a modern day variation of the Leyden jar experiment performed by Weber and Kohlrausch in 1856. Without these experiments, there is no equation c^2 = 1/(εμ). That equation is not the calibration device that you seem to think that it is. You have got this entire aspect of electromagnetism upside down. David Tombe (talk) 01:04, 18 August 2009 (UTC)

David is clearly willing to waste everyone's time by arguing ad infinitum, hoping to somehow sway by the force of his logic despite his lack of sources and despite Wikipedia policy on unsourced material. Don't feed the troll, don't bother to explain (unless you enjoy debating to no purpose). It suffices to point out he has no reputable sources. — Steven G. Johnson (talk) 02:19, 18 August 2009 (UTC)

Stevenj, What lack of sources are you talking about? The whole point of this section was to try and establish what exactly the sources are saying. You are the one who told me that I don't have any post-1983 sources for the point that I was trying to make at vacuum permittivity. Correct. But I do have pre-1983 sources, and the evidence is the the experiment in question is widely known in physics circles. So it is a matter of importance for everybody to know whether or not this very important experiment has been purged from the literature, beginning 1984. So far, we have had two replies. Steve Byrnes tells us that this experiment is still easily found in the literature. Tstein tells us that he hasn't seen it much in the post-1983 in relation to ε, although he has seen it in relation to capacitance (as also have I), and that it has probably been dropped because it is no longer trendy. To say that is of course somewhat of a euphemism. We need to know the facts here. You are not correct in stating that this thread is a waste of time. There is clearly a case to be answered. Your statement that I have got no reputable sources is a gross misrepresentation of the facts. David Tombe (talk) 12:06, 18 August 2009 (UTC)

What part of WP:V and WP:NOR don't you understand?

Debating without unambiguous post-1983 sources describing (or at least proposing) measurements of the vacuum permittivity, clearly stating the possibility of measuring discrepancies against ε₀ (as opposed to simply calibrating instrument error) is pointless.

Without clear sources, debating our interpretation has no relevance for Wikipedia. Since no clear sources have been provided, this discussion can go nowhere. — Steven G. Johnson (talk) 14:44, 18 August 2009 (UTC)

Stevenj, This is a situation in which the onus is clearly on you to show that the experiment in question was purged from the literature in the years following 1983. The lead in the vacuum permittivity article is far too presumptious. Physics doesn't change as drastically as that, just because of a decision in 1983 to re-define the metre. Three measured quantities can't suddenly become a single definition and a calibration factor. I opened this section as an inquiry regarding the issue of to what degree the physics literature has been altered as a consequence of the 1983 conference. You are now instructing everybody not to reply to this request. And the lack of replies so far indicates that the literature has not been substantially altered since 1983. David Tombe (talk) 18:20, 18 August 2009 (UTC)

Just in case Hanlon's razor applied there: that Maxwell didn't himself derive the speed of light before the experiments of Weber and Kohlrausch is irrelevant. The speed of electromagnetic waves can be derived theoretically from the Maxwell-Hertz equations as 1/√ε₀μ₀ without recourse to experiment (and this is what pushed Einstein to introduce special relativity). That no-one had done that before 1856 is totally irrelevant. --___A. di M. 15:51, 18 August 2009 (UTC)

A. di M. The equations which you have just mentioned link to the speed of light, exclusively because of the 1856 experiment by Weber and Kohlruasch. If that is not true, then can you please tell me exactly how that linkage was established. You can't seriously be trying to tell me that the numbers fell out of the theoretical derivation of the equations, without any experimental input. David Tombe (talk) 18:24, 18 August 2009 (UTC)

Nope, the onus is not on me. Numerous textbooks and standards documents are already referenced stating that the permittivity of vacuum is ε₀ and that ε₀ has a defined (i.e. not measured) value in SI units. No one is discussing a "purge" of anything, just a reinterpretation of what precisely is being measured. For example, the new system of units and why certain quantities are now defined rather than measured (and the pitfalls of the previous definitions) is discussed in detail in the appendix of Jackson's Classical Electrodynamics, an reputable source if there ever was one.

The onus is on you to provide unambiguous post-1983 sources describing (or at least proposing) measurements of the vacuum permittivity, clearly stating the possibility of measuring discrepancies against ε₀ (as opposed to simply calibrating instrument error). You have not done so. Ergo, this discussion is pointless. — Steven G. Johnson (talk) 18:56, 18 August 2009 (UTC)

Steven, This post asks a question. I don't need sources to ask a question. I am asking whether or not thre has been a large scale purging from the textbooks of the experiment that uses a capacitor and a vibrating reed switch to determine electric permittivity experimentally. I have a pre-1983 textbook with this experiment, and I taught it myself. We are now trying to get a definitive answer as to whether or not this experiment has been sacrificed in order to preserve this new physics in which three previously measured physical quantities have now all been consumed in a definition. If it can be established that it has been sacrificed, then that will settle the issue. And if we establish that it is still taught, but in the new Alice in wonderland context such that measuring the distance between the plates of a capacitor really means that we are calibrating the ruler, then that will also settle the issue, and we will all know where we stand as regards modern physics. David Tombe (talk) 19:56, 18 August 2009 (UTC)

(edit conflict) In free space (ρ = J = 0) the Maxwell equations say that $\nabla \cdot \mathbf {E} =0,\nabla \cdot \mathbf {B} =0,\nabla \times \mathbf {E} =-{\frac {\partial \mathbf {B} }{\partial t}},\nabla \times \mathbf {B} =\mu _{0}\epsilon _{0}{\frac {\partial \mathbf {E} }{\partial t}}.$ Take the curl of the last: $\nabla \times \nabla \times \mathbf {B} =\mu _{0}\epsilon _{0}\nabla \times {\frac {\partial \mathbf {E} }{\partial t}}.$ Symmetry of second derivatives says you can swap $\nabla \times$ with ${\frac {\partial }{\partial t}}$ and by substituting the third equation in it you get $\nabla \times \nabla \times \mathbf {B} =\mu _{0}\epsilon _{0}{\frac {\partial ^{2}\mathbf {B} }{\partial t^{2}}}.$ Now, apply Vector calculus identities#Curl of the curl, substitute in the second equation and you'll get $\nabla ^{2}\mathbf {B} =\mu _{0}\epsilon _{0}{\frac {\partial \mathbf {B} ^{2}}{\partial t^{2}}}.$. Ta-dah! That's D'Alembert's equation with 1/c² = μ₀ε₀. Finding the same equation for E is left as an exercise. --___A. di M. 19:05, 18 August 2009 (UTC)

A. di M., I've known about that derivation for nearly thirty years. It's a standard textbook derivation that is taught on second year undergraduate courses. But you haven't explained how it was established that the product εμ is numerically equal to 1/c^2. That is the crucial part that requires the experiment. David Tombe (talk) 19:42, 18 August 2009 (UTC)

Ah, I get it now. From a 19th-century perspective, if you had measured ε₀, μ₀, and c, and that you found that that relation didn't hold, then it could have meant that Maxwell's equations are wrong. Since then, Maxwell's equations have been verified in many, many, many more other ways; so if you measured ε₀ by the method you describe and found any other value than ${\frac {1}{\mu _{0}c^{2}}},$ that'd be far, far, far more likely to mean that your measurement was inaccurate than that you were the first to discover that Maxwell's equations are wrong in more than a century. --___A. di M. 20:14, 18 August 2009 (UTC)

(Well, Galilean relativity was shown to be wrong after over two centuries, but before Fizeau's experiment and the Michelson-Morley one no-one had tested it to any speed anywhere near that of light; OTOH Maxwell's equations have been verified in an enormous variety of temporal and spatial scales, so if there's a violation of them you're unlikely to discover them with an experiment you can perform in a classroom. --___A. di M. 20:21, 18 August 2009 (UTC))

A. di M., I'm not doubting Maxwell's equations. But the linkage of ε and μ to the speed of light is an experimental fact. There was never any way of linking εμ to the speed of light, other than by experiment. Maxwell himself used the 1856 experiment of Weber and Kohlrausch. You seem to think that the equation c^2 = 1/(εμ) was handed to Maxwell on a plate as a result of his theoretical manipulations. David Tombe (talk) 20:42, 18 August 2009 (UTC)

That's where you are wrong. c^2 = 1/(εμ) is not merely an empirical fact,or happenstance. The relation has a reason behind it, and that reason is that the E and B fields are coupled through $\nabla \times \mathbf {B} ={\frac {1}{c^{2}}}{\frac {\partial \mathbf {E} }{\partial t}}$. See A. di M.'s comments above, or pick up Jackson (grad-level) or Good (undergrad-level), or any other textbook on the subject if you need a refresher. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:33, 18 August 2009 (UTC)

Headbomb, You've just repeated what A. di M. has said, and you have made the exact same mistake. You have forgotten that the numerical linkage of ε and μ to the speed of light in Maxwell's equations is a purely experimental observation. The numerical relationship c^2 = 1/(εμ) does not follow from any theory. Maxwell's theoretical work linked ε and μ to Newton's equation for the speed of sound. But it took the experimental results of Weber and Kohlrausch in order to produce a value close to the speed of light from Newton's equation. David Tombe (talk) 00:01, 19 August 2009 (UTC)

But A. di M. just derived it right in front of you! So stop claiming that you can't derived c^2 = 1/(εμ) from Maxwell's equation and that we "fail to realize" that c^2 = 1/(εμ), because that's insulting beyond belief. Go write a blog about it if you want, redefine physics in any way you like, or complain at the BIPM, but realize that Wikipedia is not your soapbox. The speed of light is by definition 299,792,458 m/s, exactly. The second is defined as a fixed number of the transition between the hyperfine structure of a caesium-133 at 0K, in its ground state, at rest, exactly. The meter is defined as the distance light in vacuum in 1/299,792,458 of a second, exactly. You don't have to like it, but this is how science is done today. Now please stop being disruptive. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 02:24, 19 August 2009 (UTC)

Headbomb, The issue is whether or not we can still measure the distance between the plates of a capacitor subsequent to the 1983 definition of the metre. See my response further down the page. If you knew what you were talking about, you wouldn't be making allegations of disruptive behaviour. David Tombe (talk) 11:39, 19 August 2009 (UTC)

Perhaps David means that the fact that light is an electromagnetic wave could not be directly verified at the time. So, Maxwell using his equations predicts the existence of electromagnetic waves, the speed of which is close to the speed of light. That leads to the idea that light is the predicted electromagnetic wave. Count Iblis (talk) 23:46, 18 August 2009 (UTC)

Headbomb, I think I can understand David Tombe's point. It is akin to saying: "According to those who defined the metre in terms of the speed of light, you cannot experimentally verify special relativity, as the speed of light is constant in any inertial frame of reference because the metre is defined that way without reference to any frame, and couldn't possibly depend on a choice of frame. This is absurd." (Now replace "special relativity" with "Maxwell's equations", add "and ampere" after "metre", add "and magnetic permeability" after "speed of light", etc.) That would only be a valid point if special relativity hadn't been verified zillions of times in zillions of circumstances before the metre was redefined. (BTW, I've fixed the indent in his post.) --___A. di M. 11:54, 19 August 2009 (UTC)

Count Ibliss, If it was a prediction, the prediction came from the linkage to the speed of light through the 1856 experiment of Weber and Kohlrausch. Maxwell used those results in Newton's equation for the speed of sound in order to predict that light was a wave. But Headbomb and A. di M. have overlooked this. They know about how textbooks present Maxwell's equations and that the equation c^2 = 1/(εμ) comes with the package. But they have both failed to realize that c^2 = 1/(εμ), although used by Maxwell in his equations, is in fact an experimental result which he looked up in London in 1861. There seems to be a prevailing misunderstanding about this, and many people seem to think that c^2 = 1/(εμ) was a built in part of the theoretical package that Maxwell derived.

This most important chapter of scientific history has now degenerated into the abominable post-1983 new physics that is summed up in the lead to the vacuum permittivity article. What was once three independent measurable physical quantities, (1) the speed of light, (2) density (μ), and (3) transverse elasticity (1/ε), that all related to each other through Newton's equation for the speed of sound, has now been reduced to a calibration factor with no physical significance whatsoever.

The question now is, what happened to the physics books from 1984 onwards? Where they all revised in order to remove references to the experiment for determining the value of ε ? This shouldn't be a hard question to answer. Has anybody got a copy of Nelkon & Parker "Advanced Level Physics" that has been printed since 1984 so that we can compare its contents in this respect with the contents of my 1979 edition. David Tombe (talk) 00:20, 19 August 2009 (UTC)

I don't understand what you mean by "many people seem to think that c^2 = 1/(εμ) was a built in part of the theoretical package that Maxwell derived". As I shown above and you said you have known for thirty years, that relationship can be shown theoretically from Maxwell's equations, so if the speed of light were anything else than 1/√εμ, that'd mean 1) that Maxwell's equations are wrong, or 2) that light isn't an electromagnetic radiation. (Indeed, my high school textbook claims that Maxwell predicted the speed of electromagnetic waves to be 1/√εμ, observed that that value was within experimental errors of the measured speed of light, and thence hypothesised light to be an electromagnetic radiation. I was not 100% sure that's an accurate account, but Count Iblis seems to have heard this story too.) And I don't understand why choosing a set of measurement units such that fundamental constants have exact values is "abominable physics". If the coulomb was defined as "the electric charge equal to exactly 6,241,509,647,120,417,390 elementary charges", then the value of the elementary charge in coulombs would no longer be measurable and would be reduced to a calibration factor with no physical significance whatsoever. What would be abominable in that? BTW, that is exactly what is done in natural units, except that values such as "1" rather than "299,792,458" are used. And in CGS units, ε equals 1/(4π) by definition, and that was long before 1984. --___A. di M. 01:01, 19 August 2009 (UTC)

A. di M., All Maxwell's predictions in this regard were based on the experimental results of Weber and Kohlrausch. Why not look at the paper itself. Go to page 49 of the pdf file in this link [4]. Equation (132) is the equation c^2 = 1/(εμ) with ε being the inverse of the transverse elasticity and μ being the density. Maxwell linked these quanitities in the equations (80) through to (105). Note however that in order to get the numerical linkage to the speed of light how he mentions the experimental results of Weber and Kohlrausch just before equation (130) and just after equation (137).

Hence, this equation comes from an experimental determination of ε and μ. It is not theoretically derived. Hence we cannot use it in reverse to obtain a defined value of ε. To do so would be a tautology. The modern experiment involving the capacitor and the vibrating reed switch was still taught in recent times and it is in my 1979 Nelkon & Parker. Has this experiment been purged from the literature since 1984? David Tombe (talk) 01:30, 19 August 2009 (UTC)

Wikipedia is not here to cater to David's whims, answer his questions, or to debate his interpretations of physics. There is no obligation to argue with him.

The onus is on him to provide unambiguous post-1983 sources describing (or at least proposing) measurements of the vacuum permittivity, clearly stating the possibility of measuring discrepancies against ε₀ (as opposed to simply calibrating instrument error). He has not done so. Ergo, this discussion is pointless. — Steven G. Johnson (talk) 02:15, 19 August 2009 (UTC)

Stevenj, The onus is on you to show sources which explicitly state that the 1983 definition of the metre means that I can no longer put a ruler to something and measure a distance. David Tombe (talk) 11:41, 19 August 2009 (UTC)

Headbomb, We need to get one thing quite straight. A. di M. did not derive what you have claimed he derived. A.di M. copied a well known derivation of the EM wave equation out of the textbooks. That EM wave equation relates to the speed of light because we know that the product εμ is equal to 1/c^2. The reason we know that c^2 = 1/(εμ) is because Maxwell substituted the experimental results of Weber and Kohlrausch into Newton's equation for the speed of sound. You can check it out for yourself at page 49 of the pdf file at this link [5]. The situation has not changed to this day. An experiment can still be performed to measure ε. The experiment is in the physics textbooks. It involves an electric circuit with a capacitor being discharged using a vibrating reed switch. The equation C = εA/d is then invoked. In my world of physics, we can measure d using a ruler. The delegates at the 1983 conference assured us all that the new definition of the metre would leave everything equivalent. So I am not prepared to accept your argument that we can no longer measure the distance across the plates of a capacitor. David Tombe (talk) 11:35, 19 August 2009 (UTC)

David, the EM wave equation as derived from Maxwell's equation (as shown by A. di M. above) tells us that EM waves travel with a speed sqrt(1/(εμ)). This is a simple mathematical fact. The fact that this speed closely agreed with the speed of light, was reason for Maxwell to suggest that light is, in fact, an EM wave (as can be read on the page you keep telling everybody to read). Hence his conclusion that this close agreement must in fact be exact. Since Maxwell's time a ton of different ways have come up that confirm Maxwell's hypothesis that light is an EM wave. This clearly hasn't changed since 1983, so even after the redefinition of the meter in terms of lightseconds, the conclusion that the equation c^2 = 1/(εμ) is exact still holds.

As for your experiment with a capacitor. Ever since the SI definition of the Ampere fixed the value of μ, this experminent has just been an alternative way to determine c. After 1983, you can still preform this measurement to determine ε, but any deviation from the exact defined value is due purely due to calibration errors in your measuring devices. Similarly, you can still measure the speed of light with a ruler calibrated in lightseconds and a stopwatch measuring seconds, but any deviation from 1 lightsecond per second will be pure measurement error. (I know it is not very practical to measure the speed of light with a ruler and a stopwatch, but any experiment that does at somepoint will use a ruler and a stopwatch of some sort. So you get the gist.) (TimothyRias (talk) 12:16, 19 August 2009 (UTC))

No Tim, David won't get the gist. Nice try, though. --Michael C. Price ^talk 12:21, 19 August 2009 (UTC)

No, unfortunately he doesn't. (TimothyRias (talk) 13:30, 19 August 2009 (UTC))

Timothy, I'm glad that you have confirmed that we can still do the experiment subsequent to the re-definition of the metre. On your other point, Maxwell only ever became aware of the fact that electromagnetism was numerically related to the speed of like because of the 1856 experiment of Weber and Kohlrausch. That is a well known fact. What is not so well known are the details of how Maxwell first became aware, because the sources about this matter are conflicting. There are a number of stories circulating around. One is that Weber and Kohlrausch were not explicitly aware of their result because it was masked by a factor of root2, and that Weber simply talked about a factor C that became referred to as the Weber constant. Another source says that they were most excited about their discovery of the link to the speed of light. Another source says that when Maxwell heard about it he knew that he then had to work towards a wave equation. As you know, in 1855, prior to Weber and Kohlrausch's experiment, Maxwell had already done a substantial part of his theoretical work in a paper entitled 'On Faraday's Lines of Force'. Another source says that while writing his 1861 paper, Maxwell travelled from Galloway, Scotland, to London to look up the experimental results of Weber and Kohlrausch. He then put them in a suitable form for substitution into Newton's equation for the speed of sound and hence obtained the linkage to the speed of light. You can read the final conclusion at page 49 of the pdf link at [6].

And nothing has changed to this day. The speed of light can be measured directly, or it can be obtained by experimental measurements of ε. These are two independent experimental approaches which converge, and that is the full significance of Maxwell's work. But this convergence does not fall out of Maxwell's equations alone. It falls out of the experimental results of Weber and Kohlrausch as applied to Newton's equation for the speed of sound as then applied to Maxwell's EM wave equation.

We are seeing a string of people above who are reciting Maxwell's equations from the textbooks and who have no idea how the linkage between the product εμ and the speed of light comes about. David Tombe (talk) 12:50, 19 August 2009 (UTC)

David, you seem to be only person here that doesn't understand how that comes about. (TimothyRias (talk) 13:30, 19 August 2009 (UTC))

We all understand that experiments drive theory, and theory drives experiments, and it's all a nice little ecosystem. What we don't understand is why one test of Maxwell's equations (or if you like, one piece of evidence that led Maxwell to formulate them) is so sacrosanct, nor why it being so means you can't define the quantities it measured. But as Steven G. Johnson has pointed out, it doesn't matter much in the grand scheme of things if we're just arguing about our understand without source. --Falcorian ^(talk) 14:30, 19 August 2009 (UTC)

The equation c^2 = 1/(εμ) is a purely experimental result that was incorporated into Maxwell's equations, originally by Maxwell himself. We cannot then cite Maxwell's equations as being the justification of this numerical relationship. And nothing has changed since the time of Maxwell in this respect. There is no other way, apart from by experiment, to determine the relationship c^2 = 1/(εμ). It is pointless to keep copying Maxwell's equations from the textbooks as if this constitutes a theoretical proof of c^2 = 1/(εμ). And the modern experiment, which is in the textbooks, uses the equation C = εA/d. It is nonsense to deny that experiment on the grounds that we can no longer measure the distance between the plates of a capacitor because of the new 1983 definition of the metre. Of course we can measure that distance. If the separation distance is 1 centimetre, then I will know that by putting a ruler across the plates, irrespective of the 1983 definition of the metre, and I will obtain a measured value of ε. And that measured value of ε will confirm the equation c^2 = 1/(εμ). David Tombe (talk) 15:25, 19 August 2009 (UTC)

Alright David, at this point you're just wasting out time. We went over this several times now. If you have a problem with the definition of the speed of light, write the BIPM and contact us when they have changed it. Or alternatively, pick up any modern EM book on the topic. If you want one at the graduate level, see Jackson, and if you want something more accessible, see Good. Until then, please stop beating the horse. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 15:54, 19 August 2009 (UTC)

Headbomb, You are mixing up two disputes. This is about the fact that the equation c^2 = 1/(εμ) arises from an experiment which can still be performed, and that it can arise on no other basis. The modern definition of the speed of light is a side issue. The speed of light, whether pre-1983, or post 1983, cannot however be reversed into the above equation in order to determine ε theoretically. David Tombe (talk) 16:23, 19 August 2009 (UTC)

Which is simply not true. You are basically saying that all literature on the matter that concludes that ε has become a defined quantity since the 1983 fixing of the speed of light is wrong. Well, you better have a hell of source to back-up that rather strong claim. Since you don't, why don't you just get a life? (TimothyRias (talk) 16:59, 19 August 2009 (UTC))

Timothy, What I'm saying is that the equation c^2 = 1/(εμ) has only ever been justified on the basis of experimental measurement of the right hand side. You and a number of others have been showing me Maxwell's equations, as if I hadn't ever seen them before, and then claiming that this equation falls out of Maxwell's equations. You have all been overlooking the fact that Maxwell himself used an experimental result in order to incorporate this equation into his equations. This is clearly a part of the 'history of physics' regarding which most modern physicists appear to be somewhat rusty.

The consequence of defining c at the 1983 conference has been that they are now reversing c into this equation in order to define ε theoretically. This is known as cooking the books. The next step is of course to ban the experiment that measures ε. And this is what the current controversy is about. That experiment is in my Nelkon & Parker (1979). The question being asked here is whether or not this experiment has been removed from the more recent textbooks. It's a very simple question, but so far the responses have been mixed. David Tombe (talk) 18:07, 19 August 2009 (UTC)

How Maxwell came by his equations is irrelevant. We now have much better (more fundamental) ways of deriving those equations. Maybe Maxwell needed experimental input to derive his equations, we no longer do. U(1) Yang-Mills theory (aka Maxwell Theory) is essentially unique and completely determined by the U(1) gauge symmetry. You clearly don't understand this, but that is just your lack of knowledge. (TimothyRias (talk) 19:43, 19 August 2009 (UTC))

Timothy, It doesn't matter what theory we use. The actual numerical relationship c^2 = 1/(εμ) can only be deduced from experiment. Yang-Mills did not work out that numerical relationship theoretically. Neither Maxwell, nor anybody since Maxwell, has ever worked out that equation, other than by experimental determination of the numerical value of the right hand side. David Tombe (talk) 19:50, 19 August 2009 (UTC)

David, that's just another of your strawman arguments. Which units are derived/defined and which are "free" makes no difference to the empirical basis of c. --Michael C. Price ^talk 20:04, 19 August 2009 (UTC)

Michael, You are confusing two things,

(1) The direct experimental determination of the speed of light. And,

(2) The direct experimental determination of electric permittivity which results in the equation c^2 = 1/(με)

The point of interest to physicists is that these electric and magnetic constants are closely related to the speed of light as is indicated by the above two converging experimental results.

There is no way, other than by experimental measure, to determine the numerical relationship c^2 = 1/(εμ). This equation cannot be worked out theoretically.

This fundamental fact has been overlooked by alot of people, and it is the realization of this oversight that has resulted in the cries for a topic ban and the malicious allegations of crankery at ANI, admittedly not from yourself. David Tombe (talk) 20:22, 19 August 2009 (UTC)

There is no way, other than by experimental measure, to determine the numerical relationship c^2 = 1/(εμ). That's odd because that's precisely what we derived in my school physics class (High School for you Yanks, Sixth Form for us Brits). --Michael C. Price ^talk 20:36, 19 August 2009 (UTC)

Well Michael, can you then show us this theoretical determination that doesn't use experimenatl values of ε and μ. I'd be really interested to see it. David Tombe (talk) 21:41, 19 August 2009 (UTC)

That's called moving the goalposts. I addressed what you said, not what you now claim you said. --Michael C. Price ^talk 22:47, 19 August 2009 (UTC)

David, I think you're overlooking something. Pretend, for a moment, that there's a constant "c" that has nothing to do with the phenomenon we call "light". This constant shows up in the equations governing electricity and magnetism, and is related to other parameters as a direct consequence of the way the equations are derived, via any of several methods. This produces the "c^2 = 1/(εμ)" relation. If one assumes that the equations governing EM are a correct description of electromagnetism, then one must assume the above relation (because otherwise the equations are inconsistent).

Your argument appears to boil down to a statement that we need experimental evidence linking the measured speed of light with this magical constant "c" that shows up in Maxwell's equations, or QED, or whatever model we're choosing to use for EM. That's fine and dandy, but it doesn't change the fact that we can relate c, ε, and μ without recourse to experiment. --Christopher Thomas (talk) 20:37, 19 August 2009 (UTC)

Christopher, In your above example, how would you ever know that 1/(εμ) was numerically equal to the square of the speed of light unless you had numerical values of ε and μ to substitute into the expression? The equation itself, without the involvement of numbers, appears at equation (132) in Maxwell's 1861 paper. I have provided the link on a few occasions, further up the page (see page 49 in the pdf file in the link). The equation is essentially Newton's equation for the speed of sound. Maxwell theoretically linked permittivity to transverse elasticity, and he theoretically linked permeability to density. He then used the numerical results of the 1856 experiment of Weber and Kohlrausch in order to reveal the numerical value of the speed of light. Weber and Kohlrausch's experiment gave a numerical value for 1/(εμ). You cannot escape the fact that c^2 = 1/(εμ) is an experimental result. David Tombe (talk) 21:31, 19 August 2009 (UTC)

You miss my point. You can easily prove, as multiple people have shown you above, that 1/(εμ) is equal to the square of the magic constant called "c" in Maxwell's equations. What takes experimental evidence, is showing that the constant called "c" is equal to the speed of light. This was a big result, back in the day (showing that light could be treated as being a Hertzian wave). --Christopher Thomas (talk) 21:41, 19 August 2009 (UTC)

Christopher, You said, "What takes experimental evidence, is showing that the constant called "c" is equal to the speed of light". That's what I've been saying too. So why are you arguing with me? The numerical relationship c^2 = 1/(εμ) is an experimental result. If the variables are undetermined, we merely have equation (132) in Maxwell's 1861 paper without the numbers. But it is the numbers, and hence the linkage to the speed of light that are the important thing. Without the numbers in equation (132), it is simply Newton's equation for the speed of a wave in an elastic solid. But without the numbers in the modern day c^2 = 1/(εμ), it is just a meaningless equation because the linkage to Newton's wave speed equation is no longer recognized today. David Tombe (talk) 23:35, 19 August 2009 (UTC)

No it is not a meaningless equation because we now have many other lines of evidence that say light is a Hertzian wave. Hence we can now derive c²εμ = 1. --Michael C. Price ^talk 23:53, 19 August 2009 (UTC)

Michael, Read what I said. The equation is meaningless unless there are numbers involved. Those numbers come from experiment only. I'm still waiting to see how you derive those numbers theoretically. David Tombe (talk) 00:15, 20 August 2009 (UTC)

The reason that few people have answered you is twofold. First it is difficult to do a full literature search. Second, most people don't think it is important. In the end, it is an argument by authority and one vulnerable to many problems such as a dependency on the motivation of the authors to do so. I wish I can help you more with that but I only have theoretically oriented textbooks such as Griffiths and Jackson.

Just as important is that it seems to bother you and others (I am not just singling you out here) that defining something such as c precludes measuring it. I can see why you think this is 'cooking the books' or 'tautology' but it is far less worse then you think. For example, for a time, the hour was defined as 1/24 of the mean solar day. With that definition, of course, it is impossible to measure the mean solar day. (It is defined as being 24 hours.) That did not stop scientists from figuring out that the mean solar day was not a constant. (It may even be possible that it helped scientist figure out that fact since testing standards for consistency is a vital part of metrology.) Defining c to be a certain value is exactly the same. It precludes one from 'measuring' a value of c, but does not preclude determining how valid the definition (d=ct) is. TStein (talk) 21:01, 19 August 2009 (UTC)

Tstein, The issue about the defined speed of light itself is a side issue. My concern here is about the defined value of electric permittivity. My point is that the equation c^2 = 1/(εμ) is an experimental result based on numerical values of ε and μ. Most people here have totally failed to realize that fact. They think that it automatically comes with Maxwell's equations as a theoretical result. And because they have forgotten this important fact, they are using the equation in reverse, in conjunction with the new defined value of the speed of light, in order to produce a defined value for electric permittivity. And they are then further saying that we can no longer do the experiment to ascertain the numerical value for the electric permittivity. They have turned physics totally upside down. David Tombe (talk) 21:38, 19 August 2009 (UTC)

David, you are the one who keeps on missing the point. Take TStein's example of the day. You can measure the length of a day against some standard "hour", or you can define the day to be 24 hours and then when you measure the day length you are actually measuring ("calibrating") how long an hour is. It makes absolutely no difference whatsoever which you opt for. Same with the speed light and the meter and all the other constants. Get it? --Michael C. Price ^talk 23:01, 19 August 2009 (UTC)

Right Michael, That's enough. I don't know what you're talking about. I'll make my point one more time. I can't keep repeating it for everybody who decides to come into the ring without reading what I have already repeated quite a few times above.

The well known numerical relationship c^2 = 1/(εμ) is a purely experimental result. It links measured values of electric permittivity to the speed of light. This equation has got nothing to do with any direct measurements of the speed of light, never mind the post-1983 defined speed of light. The equation in question has its origins in Newton's equation for the speed of a wave in an elastic solid in conjunction with an experiment with a Leyden jar that was performed by Wilhelm Eduard Weber and Rudolf Kohlrausch in the year 1856. Maxwell used those experimental results in the derivation of his famous equations (Maxwell's equations) in 1861. The modern experiment is done with a discharging capacitor and a vibrating reed switch in conjunction with the well known equation C = εA/d. This experiment appears in recent textbooks, and despite what some people say, the separation distance d across the plates of the capacitor can still be measured despite the new definition of the metre. I don't expect anybody to come here and agree with what I have said, because that is not in the nature of things. But you all know fine well that what I have said is true. You must all realize by now that this equation cannot be used in reverse to define the very measured quantities that are the cause of its existence in the first place. I'm not going to answer anymore questions on the this issue. You can all go away and have a long and hard think about the matter. This page is here for the purposes of increasing the knowledge of those who edit on physics articles. I hope that this thread has increased that knowledge considerably. David Tombe (talk) 00:00, 20 August 2009 (UTC)

I have learnt something important here: cranks can't analogise. Thank you. --Michael C. Price ^talk 00:59, 20 August 2009 (UTC)

The only issue I can see that hasn't been raised yet is that in practice we never have a perfect vacuum. So, you have an epsilon that differs from the vacuum value and this also depends on frequency. If you measure epsilon using capacitors you perform a measurement at zero frequency, while if you measure the speed of light you're doing a measurement at very high frequency.

You can also assume a perfect vacuum and consider exotic theories, e.g. a massive photon described by the Proca Lagrangian or theories in which Lorentz invariance is broken. But I think it would be a good thing if David himself would point out how and why c would not be given in terms of epsilon derived from experiments with capacitors. So, basically, David has to stick to what I wrote in WP:ESCA about arguing from first principles. :). Count Iblis (talk) 23:48, 19 August 2009 (UTC)

Count Ibliss, c IS given in terms of epsilon derived from experiments with capacitors. That's what I've just said above. We don't need to involve the frequency of a light wave because we are not directly measuring the speed of any light wave. David Tombe (talk) 00:19, 20 August 2009 (UTC)

Comments at AN/I

I realize everyone's likely sick of this discussion, but over the last week there's been a substantial amount of traffic at the AN/I thread regarding Mr. Tombe's editing. Further comments (edit: at the AN/I thread) from all involved parties would likely help clarify matters for the administrators assessing the thread. --Christopher Thomas (talk) 04:56, 24 August 2009 (UTC)

I've checked at the science library. I found only one book, post-1983, which dealt with the experiment described above. It was the 1995 (seventh edition) of Nelkon & Parker 'Advanced Level Physics'. The experiment was described on page 247 just as it appeared in the fourth edition of 1979. The rest of the modern books that I checked did not deal with this experiment. They treated electric permittivity as a defined quantity that is obtained by substituting the defined speed of light into the equation c^2 = 1/(εμ). The balance of sources would therefore confirm the position adopted by Steven G. Johnson regarding the introduction at vacuum permittivity, as far as the issue of what the sources are saying is concerned. The 1995 Nelkon & Parker however contradicts Steven G. Johnson's bold assertion that this discussion is pointless. This discussion has revealed that since the 1983 re-definition of the metre, a significant historical experiment has been side-lined and the associated equation has been reversed from a right hand reading to a left hand reading equation. Hardly a basis for allegations of disruptive behaviour at AN/I and talk about sanctions. David Tombe (talk) 17:33, 24 August 2009 (UTC)

Endless repetition on the speed of light talk page - Search for the words, 'equation', 'tautology', '1983'. Allusions to 'wrongness' of special relativity.

Compare with

• profile at NPA and what NPA stands for: "The central theme that concerns nearly all members, both because of its highly honored position in current dogma and because its rather simple mathematics makes it comparatively easy to deal with, is special relativity (SR). A very large majority in the NPA believe it is seriously flawed, and a clear majority believe it is totally invalid. I earnestly subscribe to the latter view: SR has no validity whatsoever. I agree with most of my NPA colleagues that SR never was valid, never will be valid, and in fact cannot possibly be valid."
• publications at babin and babin purpose: "The original and continued purpose of these pages is to present an assessment of special relativity".

DVdm (talk) 21:14, 24 August 2009 (UTC)

I probably should have clarified: Further comments at the AN/I thread would probably be useful. Apologies for the confusion. --Christopher Thomas (talk) 21:39, 24 August 2009 (UTC)

I disagree with adding to the thread at the drama board known as AN/I. The issue has been noted by several admins and non-admins, and there is no benefit in belaboring it there. While admins make plenty of mistakes, the vast majority of them are not in general dumber than a box of rocks. Tombe's behavior there, here, on King Jimbo's page, and elsewhere has not gone unnoticed. If anything, it would be better to directly addresss one of the admins on their talk pages, especially the one who initiated the page ban. Tim Shuba (talk) 22:30, 24 August 2009 (UTC)

Request third opinion

To prevent a potential edit war on the article Solid, I am asking the project members to vote here. Thank you. Materialscientist (talk) 01:20, 28 August 2009 (UTC)

Category:Markov chains and Category:Markov models

There is a naming dispute considering the correct name for the category for the main article Markov chain and related articles, see WP:CFD. 76.66.192.144 (talk) 03:22, 28 August 2009 (UTC)

Confinement articles are tangled

• Quark–gluon plasma is a medium-sized article
  • Its redirects include Deconfining phase
• Color confinement is a short article
  • Its redirects include Quark deconfinement
• Deconfinement is a stub with no redirects
• Onset of deconfinement is a stub with no redirects

It seems to me that there are at most two articles here, and the redirects don't make a great deal of sense. I'm not sure what exactly is the best solution. Melchoir (talk) 03:36, 28 August 2009 (UTC)

Deletion discussion for Introduction to Dirac's constant

Wikipedia:Articles for deletion/Introduction to Dirac's constant. Please read the history of the debate and voice your opinions there. - 2/0 (cont.) 17:20, 29 August 2009 (UTC)