Wikipedia talk:WikiProject Physics/Archive September 2012

This is an archive of past discussions on Wikipedia:WikiProject Physics. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Antimatter

More eyes are probably needed at Antimatter (edit | talk | history | protect | delete | links | watch | logs | views). Several edits were made by Eternalmonkey (talk · contribs) (from 28 August onward) that IMO could stand vetting. One of the regulars (SpinningSpark) has been monitoring the situation, but we're at a point where a third or fourth look would be helpful, and I'm not in a position to devote the required time myself.

Discrete spectrum

Today I looked, at last, to the article which I linked several times, and found an abomination. The meaning from spectroscopy is nothing but a trivial dictionary definition (a discrete emission spectrum or so) with a picture. The meaning from quantum mechanics is the same as in decomposition of spectrum (functional analysis) (mentioned in a hatnote). Of course, discrete emission/absorbtion spectra have a theoretical substantiation in the Hamiltonian's discrete spectrum from atomic physics, but these things are not the same. Should this be converted to a disambiguation page, or ? Incnis Mrsi (talk) 06:48, 27 August 2012 (UTC)

They are the same. Of course there are some issues why in spectroscopy books they are described differently from how they do it in mathematical physics books, and an elementary quantum mechanics textbook does it in a third way, but in my opinion they should stay on one page (it is best to be rewritten though but not split).--Ymblanter (talk) 07:31, 27 August 2012 (UTC)
They are not only described differently, they are different. The spectroscopists' "discrete spectrum" is an (observable) phenomenon. The quantum discrete spectrum is an abstraction. There is no 1:1 correspondence between them. The emission spectrum of a light-emitting diode is continuous (as an observable phenomenon), although the electron Hamiltonian's spectrum, theoretically, is discrete – the LED has a finite size, isn't it? On the other hand, the (observable) spectrum of an unmodulated radio wave transmitter is discrete, but where is an operator with a discrete spectrum? Incnis Mrsi (talk) 08:46, 27 August 2012 (UTC)
We always describe physical spectrum with an abstraction. We know that the Hamiltonian of a bound system has discrete spectrum. What spectroscopists observe is just the consequence of this, given that an electron in an atom is a bound system. There could be of course some details related to spectroscopy, which are best relegated to a different article - for instance, in your example with LED the spectrum is continuous, but there is a linewidth which is greater that the distance between the levels, and this is why the spectrum appears discrete (another way to say the same thing is that LED is coupled to the outside world strongly enough to describe it as infinite). The details on the linewidth may be best described in a separate article. But the principle is the same and should be described in the sense that (a) the spectrum of a bound system is discrete; (b) the way to observe this discrete spectrum is to perform spectroscopy measurements (c) there are some issues which may prevent spectroscopic measurements from yielding discrete spectrum.--Ymblanter (talk) 08:53, 27 August 2012 (UTC)
The proposal "to perform spectroscopy measurements… to observe a discrete spectrum [of a bound system]" is, generally, a heresy. The spin of many subatomic particles (AFAIK of all less stable than the muon) is known due to parity observations, or by various theoretical assumptions, not due to a direct "spectroscopic measurement" even in a general sense, including NMR or other techniques involving spin precession. Discreteness of the spin in general is only a "theoretical fact". "Spectral observations" of any kind, including such ones as Stern–Gerlach experiment, are not sufficient to support this theory. Incnis Mrsi (talk) 11:24, 27 August 2012 (UTC)
There is no such thing as a "spectrum of the spin". If we are talking about discrete values which the spin projection assumes, well, this is beyond the scope of the current article, but they can be perfectly measured, for instance, by Zeeman effect. Spintronics is a pretty much experimental field, with a Nobel prize.--Ymblanter (talk) 13:35, 27 August 2012 (UTC)
Sure, I mean any projection of the (3-dimentional) spin operator. It has $1 + 2 s$ eigenvalues, as you certainly know. It is not outside the scope, because the spectrum of such operator is discrete, and the nuclear magnetic resonance (i.e. a so named "spectroscopic measurement" on the particle those Hamiltonian is perturbed by a uniform magnetic field) is its direct consequence. Incnis Mrsi (talk) 13:47, 27 August 2012 (UTC)
Yes, I know. So what? The fact that this spectrum is discrete, can be (and in fact was 80 or so years ago) verified experimentally.--Ymblanter (talk) 14:06, 27 August 2012 (UTC)
So that this example is inside the scope, and its discreteness was experimentally verified for some particles. BTW I do not insist that the article has to be split. I insist only that spectroscopists does not observe operators' spectra. There is a relation with observables in some cases of an emission spectrum. Incnis Mrsi (talk) 15:30, 27 August 2012 (UTC)

Are you really trying to argue that a spectrum observed by spectroscopist is not an observable? T R 15:36, 27 August 2012 (UTC)
I am not a QFT expert (maybe, I am a quite ignorant person in that domain) and could say nothing about a hypothetical observable those spectrum is observed in a spectroscope. First, I argue that spectral lines observed by spectroscopists correspond to differences between energy levels of a quantum system, not directly to that levels. Second, there exist spectra of various observables, not necessarily the Hamiltonian (quantum mechanics). Incnis Mrsi (talk) 16:00, 27 August 2012 (UTC)

That article is confused, mathematically speaking. Mct mht (talk) 08:29, 27 August 2012 (UTC)

This should definitely be covered in a single article, since it is one topic. (One being the theoretical explanation of the other). That article needs a lot of work though.T R 09:33, 27 August 2012 (UTC)
I have done some basic clean up to the article.T R 09:55, 27 August 2012 (UTC)

One topic, really? Consider, please, an attempt to refute at least some of my arguments. Incnis Mrsi (talk) 11:24, 27 August 2012 (UTC)

Afaik, in theoretical works; the use of discrete spectrum refers to discretisation of the continuum states and not the physically discrete states. A quick check through google scholar seems to confirm that. IRWolfie- (talk) 14:58, 27 August 2012 (UTC)

So what? The discrete spectrum of, say, a finite-dimensional operator is not a discrete spectrum? Which spectrum is it, indeed? Incnis Mrsi (talk) 15:30, 27 August 2012 (UTC)

(in case people don't remember, this continues a conversation from 6 months ago: Wikipedia talk:WikiProject Physics/Archive February 2012#Special:WhatLinksHere/Quantization (physics).) --Steve (talk)

From a mathematician's perspective: The discrete spectrum of an operator in a Banach space is the set of eigenvalues of the operator (i.e., all $\lambda$ such that $A-\lambda$ is not one-to-one). The continuous spectrum of an operator is the set of $\lambda$ for which the image of $A-\lambda$ is not dense in the space. Note that this is very different from the usage in spectroscopic lore (and Wikipedia), namely that "discrete spectrum" = "spectrum that is discrete" and "continuous spectrum" = "spectrum that is continuous". This is a fallacy from the point of view of a mathematician. Every operator has a discrete spectrum (which might be empty, or not topologically discrete) and a continuous spectrum (which might even be discrete). For instance, acting in the Hilbert space of positive frequency functions on the circle, the operator that multiplies $f(\theta )$ by $e^{i\theta }$ has empty discrete spectrum (mathematician's) and its continuous spectrum (mathematician's) is the set {0}.

I believe that the various parties in the above discussion are talking past one another, seemingly on the grammatical issue of whether the spectroscopist's phrase "discrete spectrum" makes sense interpreted as an adjectival phrase. I contend that it does not: "The Hamiltonian has a discrete spectrum" does not mean the same thing as "The Hamiltonian has a discrete-spectrum"; it means that "The spectrum of the Hamiltonian is discrete". So the only way (that I see) for "discrete" and "spectrum" to form an adjectival phrase (as would seem to be logical for an article by this title) is to adopt the mathematician's point of view. Of course, where we actually go from here should depend on the usual things like sources, NPOV, etc. Sławomir Biały (talk) 23:02, 27 August 2012 (UTC)

I guess this is indeed the point (or very close to the point) which Incnis Mrsi, who is a mathematician, is trying to make. But for me, as a condensed matter physicist, there is no problem to say that let us say the Hamiltonian has continuous spectrum which is observed as such in spectroscopy, or has discrete spectrum which is observed as continuous for a number of reason, or is observed as discrete as it should. In our field, any person doubting that the discreteness of the spectrum has been verified experimentally, would be immediately referred to a textbook. On the other hand, I appreciate of course that mathematicians would like to see it not just verified for many systems, but a proof that it has been verified for all possible systems except possibly a set of measure zero. This is smth experimentalists have difficulties to provide. (I am a theorist for the record)--Ymblanter (talk) 01:31, 28 August 2012 (UTC)

I think you might be missing the point here. The issue is not whether the spectrum is phenomenologically discrete or not. "Discrete spectrum", as a adjectival phrase, refers to a particular thing that may or may not be phenomenologically discrete: it could be continuous, empty, etc. "Continuous spectrum", as an adjectival phrase, refers to a particular thing that may or may not be phenomenologically continuous: it can even be a single point as I have illustrated. Each of these are things that are associated to any operator at all. When you say you have "observed as discrete" or "observed as continuous" or concluded that something has "discrete spectrum", you aren't using the phrase in the same way a mathematician would. It's like you're saying that you have observed a "wet lake", but to Poles "Wet Lake" is actually the name of a particular lake in Poland. So, yes, the lake is wet, but is it Wet Lake? Sławomir Biały (talk) 02:16, 28 August 2012 (UTC)

No, I am not using the phrase in the same way as a matematician would, this is exactly my point. And no physicists would ever do. So what? Is this a reason to have two articles, as suggested?--Ymblanter (talk) 05:11, 28 August 2012 (UTC)

Yes, because there is no relationship between the two different meanings of the phrase. Sławomir Biały (talk) 12:14, 28 August 2012 (UTC)

@Sławomir Biały

The thing you define as the "discrete spectrum" is more commonly called the "point spectrum".
It should, of course, read: "all $\lambda$ such that $A-\lambda$ is not one-to-one)"

T R 13:08, 28 August 2012 (UTC)

I have seen it called both in the literature quite often. For instance, most of the top google books hits use it in this sense. Sławomir Biały (talk) 13:32, 28 August 2012 (UTC)

I have gone ahead and made discrete spectrum a disambiguation page, since the two meanings of the term are unrelated. A similar problem was with continuous spectrum that I redirected to decomposition of spectrum (functional analysis). Sławomir Biały (talk) 22:06, 1 September 2012 (UTC)

Astonishing that Sławomir, who appeared to side with me in this dispute, made things even worse with his dab page. Look at his dab page as of September 1:

“

Discrete spectrum (physics): Refers to an observable whose spectrum is discrete.
Point spectrum: The set of eigenvalues of an operator.

”

This contrasts observables’ spectra (which, as demonstrated in this discussion and in discussion the half-year ago, is the same as discrete spectral decomposition) to Decomposition of spectrum (functional analysis). BTW Slawekb’s piped link violates WP:MOSDAB #Individual entries. The only thing is missing are spectroscopical discrete spectra, the thing less relevant to spectral decomposition in functional analysis, but not less important in science and much more important historically. I asked here: which observables correspond spectroscopical spectra to? Nobody answered. Certainly, I strongly prefer the discrete spectrum by Ymblanter to the discrete spectrum by Slawekb. Incnis Mrsi (talk) 08:07, 2 September 2012 (UTC)

The discrete spectrum (physics) article begins "In physics, an observable is said to have a discrete spectrum if it takes only distinct values." The first dab entry just reiterates that. Nothing is set in stone about the wording here. Sławomir Biały (talk) 12:10, 2 September 2012 (UTC)

I probably have delusions, but Sławomir apparently dodged the question about the spectroscopy. Namely the confusion between spectroscopy and quantum observables raised my concern in August, as well as Sbyrnes321’s concern in February. Sławomir tried to solve an insignificant problem separating observables from functional analysis, contrary to objections, but bypassed, if not aggravated, a significant one (read the thread from beginning). Is this a Wikipedian way? Does the responsibility exist or not? Incnis Mrsi (talk) 12:32, 2 September 2012 (UTC)

It's true that I solved a different problem than the one you originally objected to, namely the different use of the term in mathematics versus physics. What of it? Is it my responsibility to fix the issue that you raised initially? That's nobody's responsibility but yours. Sławomir Biały (talk) 12:47, 2 September 2012 (UTC)

quantum state tomography

there was an error in the quantum state tomography entry.

the following statement: "a single measurement can be performed repeatedly to build up a histogram which can then be used to express the pure state in the basis of the measurement"

is not true. using repeated measurements you may only get the square of the absolute value of the amplitude in the basis of the measurement. you dont get the phase.

for instance, given the state |+>, if you conduct this tomography in the standard basis, you will get 50/50 chance to get 0 and 1 . if you measure the state |-> you will get the same result. — Preceding unsigned comment added by 46.120.179.153 (talk) 17:08, 1 September 2012 (UTC)

Although the comment seems not to be deeply considered (a quantum system exhibits an unitary evolution, and if the time interval is not very small, compared to steps of the energy spectrum – cf. quantum Zeno effect – then even "the same" measurement will effectively be not the same), but the article quantum tomography apparently needs an expert attention. Incnis Mrsi (talk) 17:32, 1 September 2012 (UTC)

The first sentence in the article indicates that it is talking about the density matrix, which contains only relative (not absolute) phase information. JRSpriggs (talk) 00:41, 3 September 2012 (UTC)

J0651

J0651 has been requested to be renamed to its catalogue entry in the SDSS, see Talk:J0651 -- 76.65.128.252 (talk) 23:19, 5 September 2012 (UTC)

Infinitesimal quibble: L or ℒ for Lagrangian?

Some articles use L and it's script ${\mathcal {L}}$ for the Lagrangian. It doesn't really matter since the literature does also. However for the Lagrangian density, script is almost always used. As long as there is no confusion within an article it's not a problem, although some readers may get confused reading from one article to another article in keeping track which is which...

For notational consistency and zero conflict between these different quantities, throughout WP we should use always use L for Lagrangian and script ${\mathcal {L}}$ for Lagrangian density, agreed?

Similarly for the Hamiltonian H and it's density ${\mathcal {H}}$ ?... Maschen (talk) 13:04, 7 September 2012 (UTC)

I doubt that it is feasible to enforce consistency across multiple articles. It's enough of a challenge avoiding confusion within a single article - for example, the symbol L is also used for angular momentum, and no doubt for some other quantities. In Lagrangian, we have the statement: "Notice L is used in the case of one independent variable (t) and

\scriptstyle {\mathcal {L}}\,

is used in the case of multiple independent variables (usually four: x, y, z, t)." In Momentum, I used script for the Lagrangian and Hamiltonian to distinguish them from directly measurable quantities. Also, they look pretty. RockMagnetist (talk) 16:29, 7 September 2012 (UTC)

When something happens like this in a math article, the advice usually given is: "Don't bother changing that unless you have other substantial changes to make to the article." Rschwieb (talk) 19:39, 7 September 2012 (UTC)

Unfortunately, the script

{\mathcal {L}}

is also used for the Lie derivative which creates a conflict of notation at Noether's theorem#Field-theoretic derivation. JRSpriggs (talk) 19:41, 7 September 2012 (UTC)

Unless they appear in the same article somewhere (do they?!) it's probably not a soluable problem. Pan-Wikipedia consistency, especially between math and physics, is as impossible as it ever was. And if it were then there would always be some mook switching the notation back. Rschwieb (talk) 20:44, 7 September 2012 (UTC)

Oy, they do conflict there! Better break out alternative L's then! Rschwieb (talk) 20:45, 7 September 2012 (UTC)

I don't see any conflict in Noether's theorem#Field-theoretic derivation. The script is used for the Lie derivative and plain type for the Lagrangian. It would only be a problem if someone insisted on changing the symbol for the Lagrangian - but to paraphrase Rschweib's comment: If it ain't broke, don't fix it. RockMagnetist (talk) 20:53, 7 September 2012 (UTC)

Responses in plenty - clearly the answer is to leave things alone and that I raised a false alarm for nothing (not to mention forgetting the Lie derivative notation). Thanks to all. Maschen (talk) 22:10, 7 September 2012 (UTC)

You're pretty hard on yourself today, Maschen. It's a perfectly reasonable question for this talk page. RockMagnetist (talk) 00:14, 8 September 2012 (UTC)

(It sounds silly, but I'm still just becoming acquainted to using these talk pages properly which I never have done till recently, and I'm not being harsh on myself.) Maschen (talk) 00:39, 8 September 2012 (UTC)

Biographical query at BPH taskforce

I've initiated a discussion over among the tumble-weeds at Wikipedia_talk:WikiProject_Physics/Taskforces/BPH#Awards_for_later_discredited_research. John Vandenberg ^(chat) 14:47, 7 September 2012 (UTC)

Forms of energy is frequently IP attacked

This article is frequently attacked by IP's, as you can see from the edit history (some "edits" are pathetic, look back to last year 2011 as well as recently). Shall we lock it from IP's? Maschen (talk) 00:47, 8 September 2012 (UTC)

It looks like there's only been about one questionable edit per month. Semi-protection (which is what you'd be asking for here) is generally only granted when vandalism edits are much more frequent than that (taxing editors' abilities to revert them manually). --Christopher Thomas (talk) 01:18, 8 September 2012 (UTC)

Ok - just thought to let everyone know anyway. Maschen (talk) 01:20, 8 September 2012 (UTC)

image:Birk.jpg

File:Birk.jpg has been nominated for deletion. It's a schematic of the Birkeland currents. -- 76.65.131.248 (talk) 06:25, 8 September 2012 (UTC)

Per similar threads at WT:AST, the person tagging these (Bulwersator (talk · contribs)) has been on an automated or tool-assisted tagging spree for a few days now. People have challenged them on their talk page about it already, without any response visible. Given that quite a few of these were flagged as NASA-derived, and threads on their page refer to other images that had rationales but were marked as "unsourced", it's looking like it's WP:AN/I time. --Christopher Thomas (talk) 06:50, 8 September 2012 (UTC)

Go ahead then. Xxanthippe (talk) 06:52, 8 September 2012 (UTC).

Someone seems to have beaten me to it. --Christopher Thomas (talk) 19:33, 8 September 2012 (UTC)

The person doing it, Bulwersator, has been indef Topic-Banned from XfD at ANI, but given certain leeway at WP:AN for Commons duplication, his own userpages. (though he is active on Commons deletions as well...) -- 76.65.131.248 (talk) 23:16, 12 September 2012 (UTC)

Talk:White dwarf#I don't think white dwarfs are true stars

The above linked comment is by a registered editor, and comments from people who specialize in astronomy/physics are needed for this discussion. 217.147.94.149 (talk) 02:24, 11 September 2012 (UTC)

Non-dimensionalization and Scaling of Navier-Stokes Equation

I nominated Non-dimensionalization and Scaling of Navier-Stokes Equation for deletion. But it may be of more general interest, since all kinds of equations can and are non-dimensionalized. See the AfD discussion page. -- Crowsnest (talk) 13:05, 11 September 2012 (UTC)

"Lists of quantities/units/symbols (etc)" articles

In short: see here.

In more detail: does anyone have any objections to absorbing "lists of quantities articles" like:

List of physical quantities,

SI electromagnetism units,

List of common physics notations,

(possibly but not essentially SI derived unit) etc.
~~into~~
defining equation (physics)

(else other chemical defs into defining equation (physical chemistry))?
~~By this I mean combining table styles between the definitions article and the other tables into one:~~
common names,

common symbols,

defining equations,

SI units (before each table, emphasis on other more useful units, say Gaussian units, can be made),

SI dimensions,

comments/notes/descriptions
Also plan to insert the equations from the radiometry table in the definition article to {{SI radiometry units}}, and create similar templates for collections of common physical quantities (as already collected in the definition article) which would be portable if needed (like {{SI radiometry units}}) and cut the byte size of the definition article.

I can understand most people dislike this article, so need to know if it's fine to merge them... If it is, or no responses in the next couple of months - I will not hold back on merging, it's too much redundancy (content forking) across a few articles... Maschen (talk) 14:23, 11 September 2012 (UTC)

Sorry, Maschen, but I have strong objections. It would not occur to me to look for something like SI electromagnetism units in Defining equation (physics); and the traffic stats demonstrate that it isn't occurring to most other people either (views since 201209):

Defining_equation_(physical_chemistry) 324
Defining_equation_(physics) 787
List of physical quantities 2024
SI electromagnetism units 952
List_of_common_physics_notations 6793
SI derived unit 13512

The defining equation pages already seem to be trying to encompass everything, and they are quite forbidding. I think it would be better to narrow their focus, and if they are really lists they should be renamed so that is obvious. RockMagnetist (talk) 16:39, 11 September 2012 (UTC)

So you mean to do it the other way: split out content from the definition pages? I don't mind if so. Maschen (talk) 16:57, 11 September 2012 (UTC)

Something like that. It would require some thought about the purpose of the page, though. RockMagnetist (talk) 17:05, 11 September 2012 (UTC)

Too easy - the definition pages can be deleted once emptied into already list of physical quantities, SI electromagnetism units Radiometry/photometry tables, etc (see below for more). Maschen (talk) 17:49, 11 September 2012 (UTC)

There is a lot to think about here! It would help if you gave your "related point" its own section. As for defining equation (physics), I would like to know how notable it is. The only direct reference for the definition is to the Physics Encyclopedia, which I don't have access to. If the sources exist, an article on the defining equation might discuss the kinds of defining equation, for example constitutive equations and definitions of SI derived units (in summary form). Otherwise, a merge proposal would be appropriate before splitting the article up. RockMagnetist (talk) 17:05, 13 September 2012 (UTC)

There are many sources in that article (most I added), and all the equations can be found in those books. I didn't inline cite them at the time since that would clutter the names in the tables, but there are some articles (like Laplace transform) which have columns of refs...

The concept of collecting all definitions together, with their common symbols, units, dimensions etc. is notable since physics encyclopaedias (including those cited) do have tables like this, though as things stand this all severely needs rewriting to make it less forbidding.

All I'm basically saying is to leak the definition articles and other long equations-list articles into the focused equations-list articles which already exist, and if need be create new ones/merge content-forked ones along the way.

(As you request the other comments have been moved down below, new section). Maschen (talk) 19:43, 13 September 2012 (UTC)

My reason for mentioning sources is that they might help to determine what should be done with the article after much of the info is moved to other articles (I suggested one idea above). RockMagnetist (talk) 18:21, 14 September 2012 (UTC)

Sorry, which idea? Maschen (talk) 18:47, 14 September 2012 (UTC)

"If the sources exist, an article on the defining equation might discuss the kinds of defining equation, for example constitutive equations and definitions of SI derived units (in summary form)." RockMagnetist (talk) 19:00, 14 September 2012 (UTC)

Of course... sorry for thinking so slow, you mean that once the lists of equations have moved out the main article discusses the types of defining equations. I already tried this last year (see also edit history) but the article became too big so that content was moved to physical quantity (Physical quantities defined from equations) (the table in physical quantity (Base quantities) was also from defining equation (physics)), since the main intent of the article at the time was to provide the lists of equations. So: move the stuff back into defining equation and rewrite? Maschen (talk) 23:20, 14 September 2012 (UTC)

Yes, that looks like the right sort of content (preferably with more citations). Perhaps you could move the tables out first. RockMagnetist (talk) 23:56, 14 September 2012 (UTC)

I'll make a start, it may be better to take this to talk:defining equation (physics) and reduce further clutter here (I know most of this thread is my posting...). Citations will be added soon. Maschen (talk) 00:04, 15 September 2012 (UTC)

Edit war at Pendulum

I don't know if this is the right place to mention it, but there is a conflict developing at Pendulum over which large-angle period equation to use. Anyone who wants to stop by and express an opinion would be welcome - it would help build consensus. It's rated a vital article. --Chetvorno^TALK 21:39, 13 September 2012 (UTC)

Please do fix it — but ignore the "vital articles" silliness. It's just a forum to argue about why what's important to me is more important than what's important to you. Should have been scrapped years ago. --Trovatore (talk) 21:49, 13 September 2012 (UTC)

Category:Modern Physics

Category:Modern Physics, which is within the scope of this WikiProject, has been nominated for deletion. If you would like to participate in the discussion, you are invited to add your comments at the category's entry on the Categories for discussion page. Thank you. --BrownHairedGirl (talk) • (contribs) 20:27, 14 September 2012 (UTC)

Splitting off Pendulum sections

Please see here if interested. Although it's a well-written article, it's very long (112.36kB), so editors are considering which bits to split into new or existing articles. Maschen (talk) 10:41, 15 September 2012 (UTC)

MfD nomination of Portal:Xray Crystallography

Portal:Xray Crystallography, a portal in which you may be interested, has been nominated for deletion. Your opinions on the matter are welcome; please participate in the discussion by adding your comments at Wikipedia:Miscellany for deletion/Portal:Xray Crystallography and please be sure to sign your comments with four tildes (~~~~). You are free to edit the content of Portal:Xray Crystallography during the discussion but should not remove the miscellany for deletion template from the top of the page; such a removal will not end the deletion discussion. Thank you. ···日本穣^? · 投稿 · Talk to Nihonjoe · Join WP Japan! 17:13, 15 September 2012 (UTC)

Early black hole publications

There's an edit request at Talk:Black hole#Edit request on 16 September 2012 about paper chronology that I'm not in a position to answer. Would someone familiar with GR history be willing to take a look at it? --Christopher Thomas (talk) 03:19, 16 September 2012 (UTC)

Superfluid vacuum theory

Googling the phrase "superfluid vacuum theory" turns up nothing except copies of the Wikipedia article and a couple of random message board posts. "Superfluid vacuum" turns up some dubious-looking papers (the top non-Wikipedia hit is "Superfluid Vacuum as a Basis for Explanation of Some Phenomena of Parapsychology"), and some papers that may be legitimate but are clearly on the fringe. As far as I can tell no physicist notable enough to have a Wikipedia article is doing research on this.

The article was created by User:Brainssturm, almost all of whose edits are edits to that article or adding links to it from other articles. Some of those have been deleted, but it's still linked from Quantum gravity and Template:Beyond the Standard Model among others, and entire paragraphs are devoted to it in Vacuum and Gravitational wave.

I would prefer to delete the article, but I'd like to see some support here before I nominate it. Failing that, the article should be renamed to something like "superfluid models of the vacuum" and edited to make it clear that it's an idea with little support. I'd rather not be the one responsible for making the changes and policing the article in perpetuity. -- BenRG (talk) 18:48, 15 September 2012 (UTC)

Dear BenRG,

thanx for asking my opinion. This theory has been started in fact by works by Dirac as well as Sudarshan and coauthors, and it is properly referenced WP:SCHOLARSHIP, as far as I can see. True, it has not gained popularity yet (unlike Paris Hilton) but this circumstance can't be a reason for deletion because the scientific truth can't be decided on grounds of majority. As a matter of fact, all new theories in physics were always coming from minority, and often had a long way to go before the acceptance.

Please, notice also that all currently popular high-energy theories beyond the Standard Model haven't received ANY experimental confirmation either, yet they've already got an extensive coverage in Wiki and mass-media. Even gravitational waves you mentioned haven't been directly detected but their existence is being advertised everywhere as an established fact. Just think about it: they all can be wrong regardless of how much effort and money was invested into them!

What I also want to emphasize, the superfluid vacuum theory satisfies the standards of a scientific approach: it is self-consistent, mathematically non-contradictory, published in peer-reviewed journals, makes certain predictions and thus can be rejected or approved by experiment. Therefore, it is not worser than other theories, at least. Thus, what exactly you are trying to achieve by deletion, depriving people of alternative views on the subject?

P.S. You mentioned that somebody wrote "Superfluid Vacuum as a Basis for Explanation of Some Phenomena of Parapsychology"... well, if you google the phrase "Quantum mechanics and Parapsychology" (without quotes) then you might find even more crackpot articles yet it doesn't mean that Quantum mechanics must be deleted from Wiki...

P.P.S. I believe that if the Wiki physics community prefers to stay with old dusty theories then it must delete all articles about superfluid vacuum theory. After all, there is no point of teaching people who doesn't want to learn anything new...

Brainssturm (talk) 20:04, 15 September 2012 (UTC)

It is completely irrelevant here if the theory is scientifically true or experimentally verified, it only matters if there are reliable sources establishing notability of the subject. Wikipedia is an encyclopedia. — HHHIPPO 20:55, 15 September 2012 (UTC)

It is relevant if the theory is accepted as being part of the scientific mainstream. If it is not this must be clearly stated to prevent readers being misled by cranks who peddle their own theories. The is also a difference between theories which were once accepted as mainstream but have fallen from favor and theories which have always been fringe. These distinctions must be made clear. Xxanthippe (talk) 23:01, 15 September 2012 (UTC).

Sure. What I meant is that notability is the relevant criterion for keeping or deleting the article. People tend to argue that their theory deserves an article because it's true/proven/brilliant/helpful/... even if it's not notable. Regarding the contents of the article, I fully agree that fringe theories must be clearly marked as such. — HHHIPPO 08:32, 16 September 2012 (UTC)

The article makes several general vague descriptive claims, but does not allow one to get any sense of what the so-called superfluid vacuum is supposed to be. I even came across an apparent confusion in Mass generation#Models which involve gravity with quark superconductivity of the QCD vacuum (as described by Frank Wilczek) as an explanation of particle rest mass. It is not clear that Brainssturm's claims about it can be corroborated. I consider it fair to challenge the article as failing WP criteria. — Quondum 22:54, 15 September 2012 (UTC)

As far as I can tell from literature digging, this is mostly based on a few 1976 articles proposing a variation on aether theories ("The superfluid vacuum state, time-varying cosmological constant, and nonsingular cosmological models", K. P. Sinha, C. Sivaram, E. C. G. Sudarshan, Foundations of Physics, vol 6, no 6, 1976; "Aether as a superfluid state of particle-antiparticle pairs", K. P. Sinha, C. Sivaram, E. C. G. Sudarshan, Foundations of Physics, vol 6, no 1, 1976). Modern hits to "superfluid vacuum" are papers about using superfluid helium as a model for various physical systems, including the event horizons of black holes (along the lines of a sonic black hole).

I'm on the fence about deletion. Content could probably be written neutrally about the original papers, but that would probably be better off folded into Luminiferous aether or Aether theories. It's also not clear that even the original papers pass the notability threshold: it would have to be shown that some other scientists took the ideas seriously or otherwise considered them worthy of note, not just the original authors. --Christopher Thomas (talk) 03:13, 16 September 2012 (UTC)

Graphite/water room temperature superconductivity

arxiv:1209.1938 from reputable researchers at a world-renowned institution has been accepted for publication in Advanced Materials and covered in the secondary technology news press (please see). I am not expert enough to try to add this but it does appear to me as a layperson to be substantially significant. —Cupco 02:12, 17 September 2012 (UTC)

Let's wait for duplication by other groups before anyone gets too excited about this. Anything on arxiv is a preprint - other scientists haven't vetted it to the degree necessary for publication, much less confirmation. If the effect does occur as described, it'll make a very large splash soon enough, don't worry. --Christopher Thomas (talk) 03:00, 17 September 2012 (UTC)

It appears to have passed peer review this month. —Cupco 03:57, 17 September 2012 (UTC)

It's a primary source. If something seems to be very big, it's better to wait for appropriate secondary sources which can provide the analysis of the primary source (that is something we are not allowed to do ourselves on wikipedia). IRWolfie- (talk) 23:30, 17 September 2012 (UTC)

New article: Bargmann-Wigner equations

Someone had to start the article at some point... And yes I apologize for my rude post to this wikiproject. Maschen (talk) 17:38, 17 September 2012 (UTC)

Expert in numerical simulations of dark matter and baryonic matter large scale structure and galaxy formation needed

There is a dispute at galaxy rotation curve and someone knowledgeable in this subject is needed. Junjunone (talk) 19:19, 17 September 2012 (UTC)

This is cross posted, see Wikipedia talk:WikiProject Astronomy#Need a dark matter.2Fbaryonic matter simulations expert. I suggest that page be used for all discussions on this topic? Aarghdvaark (talk) 04:24, 18 September 2012 (UTC)

Or, editors could just go to the talk page of galaxy rotation curve. IRWolfie- (talk) 23:59, 18 September 2012 (UTC)

OK, agree with that. Aarghdvaark (talk) 04:01, 20 September 2012 (UTC)

file:Peratt-galaxy-formation-simulation.gif

image:Peratt-galaxy-formation-simulation.gif has been nominated for deletion. There is a dispute as to the owner of the copyright. -- 76.65.131.248 (talk) 03:45, 26 September 2012 (UTC)

Saturable absorption in graphene

While you can make a case for the added text belonging at Graphene, I'm concerned because a) they're being rather indiscriminate about where they add material (IMO this one rather tentative result isn't noteworthy enough to belong in most articles), and b) they're exclusively citing work attributed to "Zhang et. al.", suggesting a possible conflict of interest.

If someone more tactful than I am wants to have a polite word with them to explain how notability and primary sourcing and self-promotion guidelines work, that would be handy. Please bear in mind that they're probably acting in good faith; just unfamiliar with the wiki's rules. I'd do it myself, but I'm on cold medication at the moment, which is not conducive to coherent explanations.

More importantly, their additions to these articles should be vetted for notability/appropriateness. Someone else already removed it from Terahertz radiation on the grounds of WP:CRYSTAL (it was speculating about applications of the paper's result), and I'm inclined to endorse that removal.

137.132.3.9 (talk · contribs · WHOIS) may or may not be the same person. They've added similar-looking subsections (at Saturable absorption, for instance), but seem to write cleaner prose than Vectorsoliton does (VS stated at an AFD that English is not their primary language). --Christopher Thomas (talk) 20:48, 29 September 2012 (UTC)