Wikipedia talk:WikiProject Physics

WikiProject Physics
WikiProject Physics Main / Talk	Members	Quality Control (talk)	Welcome

Gen Rel Intro

Introduction to general relativity has been nominated for a featured article review. Articles are typically reviewed for two weeks. Please leave your comments and help us to return the article to featured quality. If concerns are not addressed during the review period, articles are moved onto the Featured Article Removal Candidates list for a further period, where editors may declare "Keep" or "Remove" the article from featured status. The instructions for the review process are here. Reviewers' concerns are here.

Delaszk and relativity

Delaszk (talk · contribs) is spamming literally a dozen articles with the claim that special relativity is simply a necessary consequence of Galilean relativity (more specifically that Galilean relativity implies a maximal speed). This is true only in the most generous sense that if one assumes there exists a maximum speed then that plus Galilean relativity implies Lorentz transformations, but Galileo obviously assumed there was no maximum speed (equivalent to c -> infinity). Delaszk also claims that the accelerating expansion of the universe (i.e. dark energy) follows from Galileo, which seems to simply be nonsense as far as I can tell.

The idea that Galilean postulates, by themselves, imply special/general relativity is WP:FRINGE as far as I can tell, but I'd appreciate it if others could be attentive to this editor's contributions. Dragons flight (talk) 16:25, 30 October 2008 (UTC)

This logical fallacy has been put forward by several people over the years and has been repeatedly refuted at Talk:Special relativity. Delete it on sight! JRSpriggs (talk) 17:47, 30 October 2008 (UTC)

And block user for a while (or give proper warnings if he didn't receive them etc...).Headbomb {^ταλκ_{κοντριβς} – WP Physics} 18:04, 30 October 2008 (UTC)

JRSpriggs is accussing me of spam and vandalism. This is absolutely outrageous. If you disagree with the edits then say why. If you can't be bothered to do this or even link to where this has been discussed before then that is just lazy and uncivil. It is you who should be warned. Delaszk (talk) 18:11, 30 October 2008 (UTC)

Your statements lack references, and are completely false and this is obvious to anyone who passed an intro to special relativity class. See WP:FRINGE, WP:WEIGHT, WP:NOTABILITY, and WP:VERIFIABILITY. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 18:59, 30 October 2008 (UTC)

Hm, as I had suspected, people seem to get quite jumpy over this. With a little bit of mutual effort to establish a collaborative setting, I'm sure something could have survived here, although the essence is already sufficiently covered in subsection "From group postulates" and its closing statement. Pointing Delaszk to that section, providing some explanations, and a bit of plain talking might have prevented chasing him away. Reading the above I'm afraid it's too late now. Remember WP:DONTBITE and WP:AGF. Ah well, I tried. - DVdm (talk) 19:41, 30 October 2008 (UTC)

Someone who's been here for over 6 months isn't a newcomer. Science is not an endeavour where we have to try an salvage fringe pseudoscience because doing other will hurt someone's feelings. So no, "something" could not have survived because nothing from it was true or meaningful. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 19:58, 30 October 2008 (UTC)

Jumpy indeed :-|

I meant newcomer to the physics articles. Up to now Delaszk has been working on mathematics only. And I don't think that the closing lines of "From group postulates" are pseudoscience. I mean that with a bit of effort Delaszk could have been given an instructive lesson and might have become a valuable contributor to the physics articles. But of course no one can be forced to assume good faith. DVdm (talk) 20:08, 30 October 2008 (UTC)

Ok, upon further review, I take back some of what I said. I had a knee-jerk reaction since I thought Delask was some lunatic relativity denier. Now he may be that, but his recent edits are certainly cannot be called proof of that, and is most likely due to a misunderstanding of what Galilean transformations are. Galilean transformations are those of the type x'=x-vt and t'=t. What Delask is talking about is not Galilean transformation, but rather generalized linear transformations, of the form x'=ax+bt and t'=cx+dt, which include both Galilean transformations (a=1, b=-v, c=1, d=0) and Lorentz transformation (a=γ, b=-γv/c², c=-γv, d=γ). That is not WP:FRINGE and everything else I said it was, and is in fact a common way to approach SR and the derivation of Lorentz transformations. But it is not a derivation from Galilean relativity. So I offer my apologies to Delask for jumping the gun. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:58, 31 October 2008 (UTC)

When I said Galilean relativity, what I meant was the principle of relativity, not the galilean transformations. Anyway the derivation of the Lorentz transformation does seem to imply a finite c without having to assume a finite c as a postulate. For details see here: Talk:Lorentz transformation#Group Postulate Derivation. —Preceding unsigned comment added by Delaszk (talk • contribs) 13:31, 2 November 2008 (UTC)

Calling generalized linear transformations to be the "principle of relativity" is rather ambiguous and certainly very misleading as far as readers are concerned. And the Lorentz transformations do assume that c is finite; if c was assumed infinite, then you'd have Galilean transformations rather than Lorentz transformations.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 03:00, 3 November 2008 (UTC)

My initial edits on this topic were misleading because I did not fully understand the issue. As a result of the ensuing debate I have changed my argument somewhat. The point is that neither the Galilean transformations nor the Lorentz transformations can be ruled out using Galileo's principle of relativity. But the Galilean transformations can be ruled out by experiments involving high-velocities, and this is before anything has been said about light. The bit about the expanding universe, is that it may be the case that high-energy experiments could show that the Lorentz group should be replaced with a de Sitter group and hence the universe would be expanding. See de Sitter relativity. Delaszk (talk) 14:17, 26 November 2008 (UTC)

What Delaszk means is the following: The only possible symmetry groups which generalizes SO(3) to 4 dimensions and reduce to Galilean group at low velocities are SO(4) (rotations in 4d) and SO(3,1) (Lorentz group). SO(4) is ruled out as a symmetry of space-time, because then objects moving really fast would start going backwards in time, so it's SO(3,1). From the structure of the Lorentz group, you can deduce that there is a maximum speed. So to figure out relativity you only need the principle of relativity plus "it's not like you think". There's only one other choice.Likebox (talk) 06:20, 6 December 2008 (UTC)

To Likebox: Is there not a third alternative? The group of matrices of the form

${\begin{bmatrix}Rot&Trans\\0&1\end{bmatrix}}$

where Rot is in the group of rotations SO(3) and Trans is a 3-vector in R³. This is the group of Galilean-Newtonian space+time, i.e. the Galilean group itself. JRSpriggs (talk) 06:46, 6 December 2008 (UTC)

The Galilean group is not the third alternative, the Galilean group is the first alternative, it comes before either of the above two groups. So you need principle of relativity plus "what went before ain't right". Nothing about light, nothing about maximum speed. Delaszk (talk) 14:43, 6 December 2008 (UTC)

Taskforces

I noticed that WP Relativity, WP Fluid dynamics and WP Acoustics all have low level of participation, if any. I would propose making them taskforces rather than WikiProjects due to the relatively low number of articles under their wings. I think participation in them would increase if they were made taskforces, as well as make it easier to coordinate efforts. Any thoughts?

I'm also posting this on the relavant WP talk pages.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:20, 10 November 2008 (UTC)

Well no one commented on anything, so I'll just go ahead and move them to Wikipedia:WikiProject Physics/Taskforces/Foobar. I've updated the banner to handle them as taskforces. Parameters are relativity=yes, fluid-dynamics=yes, and acoustics=yes. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 13:13, 24 November 2008 (UTC)

I've made the bot request [1] to tag articles as being part of the taskforces.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 13:29, 24 November 2008 (UTC)

Hmm. I'm not sure of some of the side effects this is having. Some of the articles that were clearly inside the scope of these projects are not really within the scope of WP physics. As example take the article 3D ultrasound, it clearly was in the scope of WP acoustics, but I don't really see it as falling within the scope of this WP. (TimothyRias (talk) 14:51, 25 November 2008 (UTC))

Well 3D ultrasound article sounds (no pun intended) like something that's completely compatible with WP Physics. It's an imaging technique, which is IMO, just as much under the scope of WP:PHYS than the MRI article is. Anyway, it's quite possible that some ill effects followed the "merger", but these wikiprojects are inactive (last edits on these pages are months away), so there's very little harm done. Plus, someone else could always restart the old projects if interest is there.

None of these articles are tagged with importance ratings anyway, so if they aren't part of WP Physics, they'll be untagged over the next months.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 21:40, 25 November 2008 (UTC)

FAR for photon article

The photon article has been nominated for a Featured Article Review, due to concerns about lack of references and other issues. The article may no longer meet the FA criteria. Please comment here. Thank you.—RJH (talk) 19:35, 11 November 2008 (UTC)

e-p scattering/annihilation

There's these two images on wiki. Now it seems to me that these just aren't right. I'm gonna ask the graphic labs to fix them, but I just want to make sure that I don't end up looking like idiot in doing so.

What I'd propose for the fix is this:

e+        e-

     γ

e-        e+

instead of

e+        e+

     γ

e-        e-

Is that all right?

Feynman Diagram of Electron-Positron Annihilation

For one thing, when people talk about "electron-positron annihilation", they're not talking about either of those diagrams, they're talking about this one on the right. Your diagrams (regardless of the labels) both describe scattering. --Steve (talk) 01:28, 12 November 2008 (UTC)

Thanks for pointing that out. I should've picked that up, but for some reason I didn't.

• Concerning the EP annihilation diagram, isn't the "middle part" sorta useless? Why not simply go for a single vertex diagram?
• I am correct in assuming the proposed correction for the scattering diagram is fine?

Headbomb {^ταλκ_{κοντριβς} – WP Physics} 01:44, 12 November 2008 (UTC)

I'm not sure about your proposed changes. Here's what I would do.

(1) Make it clear that time goes from left to right. This could be done by editing the diagram, inserting a little arrow and label, as in Image:Feynmann_Diagram_Gluon_Radiation.svg. It could also be done in the caption. Maybe you were assuming that time was going bottom to top? Both conventions are used (for example look at the figures in Feynman diagram), but I think whoever made this diagram wanted time to go from left to right.

(2) Sort out the directions of the arrows. A proper Feynman diagram should have arrows pointing opposite the physical motion of positrons, and the same as the physical motion of electrons. If you do it right, every vertex has one arrow in and one arrow out. Anyway, I think you would want to switch both of the top arrows in both of the diagrams.

To answer your other question, for the annihilation diagram, the middle part can't be thrown out. The rules of Feynman diagrams say that you're only allowed to use certain vertices in your diagrams (the list of allowed vertices is determined by the standard model Lagrangian). The vertex where two electrons and two photons come together at one vertex, isn't on the list of allowed vertices. --Steve (talk) 05:39, 12 November 2008 (UTC)

I mean the single vertex diagram
e⁻
+
e⁺
→
γ⁰
, not
e⁻
+
e⁺
→
γ⁰
+
γ⁰
. See [2] and [3] for what I mean.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 19:38, 12 November 2008 (UTC)

Oh. An electron and positron have to annihilate into at least two photons, not just one. Otherwise it's impossible to satisfy energy-momentum conservation. To see this, put yourself in the reference frame where the total initial (electron+positron) momentum is zero...then the outgoing photon would be stuck with zero momentum but lots of energy. :-) --Steve (talk) 19:46, 12 November 2008 (UTC)

Also such designations as
γ⁰
should be avoided, because it is a gamma matrix. Use
γ
. Ruslik (talk) 20:12, 12 November 2008 (UTC)

Well there's a lot of notations that looks likes a lot of other notation in physics, so that's rather moot to argue that we shouldn't write the charge on photons when its clear we're talking about particle processes. I mean, we wouldn't argue against writing He⁺ because it "might be" confused with the interaction of Hydrogen and an antielectron :P. As for the single photon vertice, I'm not quite sure what you're getting at. If you're arguing that the single photon diagram is wrong, then wouldn't the diagram posted by Sbyrnes up there be twice as wrong, since there would be two reference frames where a photon is stuck with zero momentum but non-zero energy. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 02:49, 13 November 2008 (UTC)

And yes I'm making no distinction between real and virtual process, 'cause I'm crazy like that. If you're talking about pair annihilation in real processes then we're on the same page. Headbomb {^ταλκ_{κοντριβς} – WP Physics} 03:01, 13 November 2008 (UTC)

I think we're talking past each other, and also getting off topic. I'm taking the liberty to move this entire thread to User talk:Headbomb#e-p scattering/annihilation. --Steve (talk) 03:49, 13 November 2008 (UTC)

Fractal cosmology

Fractal cosmology has been nominated for deletion at AfD. 76.66.192.6 (talk) 05:30, 13 November 2008 (UTC)

Scale relativity

Scale relativity has been nominated for deletion at AfD. 76.66.192.6 (talk) 05:30, 13 November 2008 (UTC)

Help for list of mesons

I'm currently expanding the List of mesons to be something similar to the List of baryons. Right now I'm identifying the vector mesons equivalent of the pseudoscalar mesons and I'm having some trouble. If you could head over to Talk:List of mesons#Completing the tables and give a hand, that would be much appreciated.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 05:30, 13 November 2008 (UTC)

Subsectioning of the Template:Infobox Particle

It was suggested during a PR that the physical properties portion of {{Infobox Particle}} could be formed into a subsection with its own header. What do you think of this suggestion? The template could also use a little color. Thank you.—RJH (talk) 17:43, 13 November 2008 (UTC)

The centrifugal force debate

Could somebody have a look at the centrifugal force page with a view to shortening it and unifying the topic into one single article. I have given up trying. The article has been split and forked as a result of different interpretations surrounding a certain dilemma regarding the radial planetary orbital equation. This hasn't been helped by the fact that as well as the disagreements over how to interpret the dilemma, there are also those editors who refuse to acknowledge the dilemma at all.

The radial planetary orbital equation in question is,

A = B + C

Everybody agrees that C is centripetal force, and that if A equals zero we will have circular motion.

But the argument gets bogged down in pointless semantics about whether or not A is called "radial acceleration". OK, so call A Alfred. If Alfred is zero then we will have circular motion.

But the argument then gets bogged down in pointless semantics over what to call B. Some say it is centrifugal force. Others say it is only centrifugal force in the co-rotating frame of reference. OK, so call it Billy.

The point is that when we have circular motion, then Alfred will be zero and Billy and Centripetal force will sum to zero. If we ever get rid of Billy, then Alfred will come back again and we won't have circular motion.

We cannot therefore have a circular motion that only involves centripetal force and nothing else. This fact has serious implications when it comes to extrapolating the rotating frame transformation equations to objects that are at rest in the inertial frame as viewed from the rotating frame of reference. That is were the dilemma lies, because making this extrapolation leads to an absurdity which is actually published in some textbooks.

Somebody needs to go there and take a look. There is only one universal centrifugal force, and anybody who thinks otherwise lacks an overall comprehension of the topic. David Tombe (talk) 18:24, 14 November 2008 (UTC)

Physics article replaced

Please discuss this edit from a couple months ago, which replaced Physics with a "Development Article." Is the current version an improvement? 200.72.246.90 (talk) 11:24, 16 November 2008 (UTC)

Vector space

I'm currently working on vector spaces, which has a passage reading

The solutions to various important differential equations can be interpreted in terms of Hilbert spaces. For example, a great many fields in physics and engineering lead to such equations and frequently solutions with particular physical properties are used as basis functions, often orthogonal, that serve as the axes in a corresponding Hilbert space. As an example from physics, the time-dependent Schrödinger equation in quantum mechanics describes the change of physical properties in time, by means of a partial differential equation determining a wavefunction.

I personally don't have access to physics books right away, so I'd like to kindly ask whether somebody around could provide references for the facts. Probably it's not a big deal for you guys ;) I think I could come up with some math book covering the claims, but I think a physics book for a physics statement might be better. Thanks, this is about the last bit preparing the article for WP:GAN. Jakob.scholbach (talk) 14:59, 17 November 2008 (UTC)

I'll have a look later today. I think Kreyzig (a popular engineering mathematics text probably could yield a good reference for the first statement. The second statement should be referencable from any QM textbook. I'll check my copy of Griffiths. (TimothyRias (talk) 16:03, 17 November 2008 (UTC))

Thank you, I appreciate it. Please be sure to make the ref precise (with a chapter or page number). Jakob.scholbach (talk) 16:31, 17 November 2008 (UTC)

Thanks again, Timothy, for your swift help. I have now nominated the vector space article for WP:Good article nomination#Mathematics. I'd be thankful if people around could have a look. Jakob.scholbach (talk) 09:30, 18 November 2008 (UTC)

Statistical physics / mechanics / thermodynamics

There are currently three articles on this topic - Statistical physics, Statistical mechanics and Statistical thermodynamics - which seems to be at least one too many. Would it be worth reorganising the information on this topic? If so, what would be the best approach?

(I'm asking this here rather than on each article's own discussion page as I think the issue needs people with a general overview of the topic as a whole. I'm also cautious about just doing it myself, as it isn't really my area. As an added advantage, dealing with the question should allow us to get rid of the final Top-importance Stub-class article!) Djr32 (talk) 13:14, 22 November 2008 (UTC)

I've merged the first two but more work is needed. Abtract (talk) 19:21, 22 November 2008 (UTC)

Is that a vote for merging Statistical physics with Statistical mechanics, and keeping Statistical thermodynamics separate? I'm not sure I agree - I've always seen Statistical thermodynamics as being another name for Statistical mechanics. The two articles seem to cover the same area, though the Statistical thermodynamics article is a nice introduction while the Statistical mechanics article is quite heavy on equations. I'm not sure about Statistical physics. Sometimes it seems to be used as another name for the same thing, but sometimes (as Jheald said on Talk:Statistical_physics) it seems to be used to cover a wider range of topics - including, but not limited to, stat mech. What does anyone else think? (For anyone who wants it, the old Statistical physics article is here) Djr32 (talk) 22:08, 24 November 2008 (UTC)

I am pretty sure Statistical mechanics and Statistical thermodynamics are more or less synonyms. But Statistical physics is wider, including topics that are not related to thermodynamics at all, such as complex networks. Have a look at the list of invited speakers in StatPhys 23: topics 10 and 11 are clearly far from the usual Statistical mechanics domain, but are considered bona fide Statistical physics areas. --Daniel (talk) 10:17, 25 November 2008 (UTC)

Following this discussion, I've resurrected the Statistical physics article, and tried to expand it a bit to show why it's not a synonym for Statistical mechanics. I still think there's work to do, both on expanding the Statistical physics article and perhaps by merging Statistical mechanics and Statistical thermodynamics. Djr32 (talk) 11:26, 30 November 2008 (UTC)

De Sitter relativity at AfD

De Sitter relativity has been nominated for deletion 76.66.195.63 (talk) 06:54, 24 November 2008 (UTC)

It seems that Delaszk (talk · contribs), who wrote this article, has been adding a lot of questionable information about (special) relativity to wikipedia lately. See also the section Wikipedia talk:WikiProject Physics#Delaszk and relativity. JRSpriggs (talk) 20:58, 24 November 2008 (UTC), redacted by User:LessHeard vanU 13:30, 28 November 2008

I understand your frustration with people editing articles on topics that they don't understand and persisting with it. However, calling other editors a crank does not help. It does not matter whether you couch that statement in weasel words. Why don't you remove the first sentence? Surely it's enough to say that Delaszk has been adding questionable information. -- Jitse Niesen (talk) 11:43, 28 November 2008 (UTC)

My first edits on special relativity a few weeks ago were misleading and they have been deleted. I have taken notice of what other editors have said and my more recent edits on the topic have reflected that.

But this issue is about the article de Sitter invariant theories (previously titled de Sitter relativity) under deletion discussion. The quality of some of the edits I have previously made is not pertinent to the question of notability of the topic google hits for de Sitter invariant. If JRSpriggs has anything to say about that topic he should say it on the AfD page. JRSpriggs has indulged in a pattern of inflammatory language about this from the beginning. Prior to this AfD our last encounter was a discussion in which he argued against time measured in metres and then gave up when he realized that time in metres is possible. But that's no reason to abandon that time-in-metres discussion and then wait for an opportunity to sabotage an article I created. Delaszk (talk) 12:35, 28 November 2008 (UTC)

To Delaszk: I am sorry that my comment offended you. However, please let me correct a point in what you have said. I did not realize "that time in metres is possible" when one is in a Galilean-Newtonian space+time (i.e in the absence of the second postulate). It is not possible. I simply chose not to respond, as is often the case, because my time available for working on Wikipedia is limited and I am watching about 200 articles. Also I was not trying to specifically influence the AfD, but merely making a more general comment. JRSpriggs (talk) 06:00, 29 November 2008 (UTC)

My original posts weren't accurate, but the main point about deriving the theory without making prior assumptions on light was accurate and Markus Poessel agreed on this. Certainly in Newtonian world there is no unique way of defining time in metres but that doesn't stop you using the concept of arclength of a clockhand to describe an interval during which things happen. Delaszk (talk) 19:07, 4 December 2008 (UTC)

Talking about "maximum speed" rather than "speed of light" does not obviate the necessity of having a second postulate. You still need to say that there is a finite maximum speed in addition to saying that the laws of physics are invariant when one changes the speed of the observer. Of course, the arc-length can be used to describe the interval, but that is changing the meaning of your claim that "The transformations are then derived using just the principle of relativity and have a maximal speed of 1, ..." which implicitly assumes that the way of measuring time in meters is by using the maximal speed to do the conversion. JRSpriggs (talk) 04:14, 5 December 2008 (UTC)

But you don't need to postulate the maximum speed. The maximum speed is built-in to the transformations. If you exceed the maximum speed then the transformations don't make physical sense.

The derivations from relativity gives you a choice of Galilean or Lorentz and all you have to do is rule out the Galilean transformations by accurate or high velocity experiments. As for the taiji transformations - the maximal speed of 1 comes from the form of the derived equations not from an assumption. But anyway I used the taiji stuff as an example of single postulateness but that was not the authors main reason for using this formulation. They did things that way as a starting point for introducing practical ways of doing relativistic many-body calculations, amongst other things. Delaszk (talk) 10:51, 5 December 2008 (UTC)

But in order to know that using "the taiji stuff" is legitimate, you have to already know that the transforms are Lorentz and not Galilean, so finite maximum speed is a requirement of it, not a consequence. As for whether you use two postulates or one postulate and something else, that's arbitrary; Einstein did the former in the first 1905 paper, but the latter – with the "something else" being the form of Maxwell's equations – in some later paper. But knowing that the maximum speed is finite (either by "accurate or high velocity experiments", or by the form of some particular physical law) doesn't follow by postulating the principle of relativity alone. So the second option is actually "one postulate and experimental data", or "one postulate and the form of Maxwell's equations" (or whatever physical law), not "one postulate and nothing else". -- Army1987 (t — c) 12:01, 6 December 2008 (UTC)

Regarding the taiji stuff - The derivation of the taiji transformations should not be confused with the derivation of the Lorentz transformations. In the taiji setup with all 4 coordinates of spacetime measured in the same units, the taiji transformations are the only transformations that come out. You can't get anything like the Galilean transformations out of the taiji formulation. Using Maxwell's equations allows you to convert between taiji time in metres with dimensionless speed and conventional time in seconds with speed in m/s. You don't have to know that the transforms are already Lorentz. If special relativity had been discovered by this route then people would have said: hmm ... time in metres sounds weird, but the theory fits with experiments better than Newtonian dynamics. So it would have been accepted just as Einstein's formulation was.

Regarding the single postulate stuff - Knowing that either the Galilean or the Lorentz are consistent with the principle of relativity, to get the Galilean transformations you must do inaccurate experiments. So to go from Galilean to Lorentz you just need more accurate experiments. That's not extra information, that's the just same information measured more accurately. Delaszk (talk) 14:05, 6 December 2008 (UTC)

As for the taiji stuff, you can only measure time and space with the same units hoping that the result is invariant under those transformations if there is a God-given universal speed to use as a conversion factor. So it is a prerequisite, not a consequence. In a Galilean world there would be no meaningful way to measure time in metres. As for the single postulate stuff, what you say is true, but experimental data do not pop out of postulates; so "you need more accurate experiments" means "you need something more than a postulate", as experiments are something more than a postulate. -- Army1987 (t — c) 14:18, 6 December 2008 (UTC)

Found these two images, which I find wonderful, but I don't know where to place them.

(Complete Omega- decay chain) (discovery of the Omega-)

I've placed the links on the Omega baryon page, but it seems to me that the one with the complete decay chain should be on more pages than that one.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 23:45, 25 November 2008 (UTC)

I realize now that it's the same image.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 23:59, 25 November 2008 (UTC)

Assessment update

Assessment progression graph

Keep up the good work people.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:55, 27 November 2008 (UTC)

Category:physicists

I went through Category:physicists and tried to shove everyone in a nationality, but I've hit a wall. If anyone of you knows from which countries the remaining people are, please shove them where they belong.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 06:07, 29 November 2008 (UTC)

Two are under P but I didn't know how to correct it. Also Chilean shows (0) but there is one (I didn't check SA.) [+] Chilean physicists (0) [+] South African physicists (0) Abtract (talk) 11:30, 30 November 2008 (UTC)

Gilbert Jerome Perlow

I just created the page about Perlow, so if you have anything to add to it, go right ahead.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 22:33, 29 November 2008 (UTC)

New category: Energy in physics

Category:Energy was crammed with articles related to all aspects of energy, such as energy policies and power supply. To provide a home for the "pure" physics related articles, I created Category:Energy in physics, added the project template on its talk page, and I'm filling it right now. Please direct any discussion to Category talk:Energy in physics. — Sebastian 03:33, 30 November 2008 (UTC)

Some further discussion at Category talk:Energy makes me rethink my decision. I now feel it may make more sense to keep Category:Energy for the physics term, and create a different Category:Power and energy use for all the rest. — Sebastian 05:55, 4 December 2008 (UTC)

De Sitter invariant theories

De Sitter invariant theories is at WP:DRV undergoing deletion review 76.66.195.63 (talk) 02:16, 1 December 2008 (UTC)

Grammar, etc.

The Great Formula says:

a = b + c.

Where a is the number of rabbits...

Are physicists actually taught to write like this, putting a period at the end of the formula and capitalizing the "W" as if it's the beginning of a sentence rather than part of the same sentence? I keep seeing that in physics-type articles.

Is this correlated with the hostility physicists often express for precise definitions and the like? Michael Hardy (talk) 20:24, 3 December 2008 (UTC)

Physicists as group are not really taught to write in any particular way, at least not in my experience. That is, I never took a physics class on writing, nor have I heard of one. But it's pretty common to put proper punctuation after an equation. I agree that the above is poor writing. I would have used a comma instead of a period and not capitalized the "W". As to your final comment, physicists are happy with precise language, as long as it doesn't get in the way. Context is the key. Joshua Davis (talk) 20:59, 3 December 2008 (UTC)

I took a math class in high school where the teacher told us that every equation should be part of a complete sentence with correct grammar, punctuation, capitalization, and so forth, keeping in mind that "=" is a verb, "+" is a preposition, etc. That was a really great teacher, and I agree with Joshua that most scientists (sadly) are never formally taught or tested on equation-related grammar. Luckily, even without formal instruction, most (but not all!!) scientists seem to be able to figure it out themselves. :-) --Steve (talk) 01:36, 4 December 2008 (UTC)

So this is a style issue somewhat, but it really really grates on me when people put periods at the end of displayed math, even when it is the end of a sentence. It strikes me as the same as putting periods inside quotation marks, when the quoted text does not end in a period. It's sort of a use–mention confusion.

Logically the period should go at the start of the next line (undisplayed). Unfortunately that is not a style in wide diffusion. So next best (or next least bad) is simply to omit the final period entirely, when the sentence ends with displayed math. This will hardly ever cause confusion, whereas a period just might, because someone could try to interpret it mathematically. --Trovatore (talk) 01:42, 4 December 2008 (UTC)

Interesting point. However, since it's a near-universal convention, Wikipedia is somewhat compelled to follow it. How about putting periods at the end of displayed equations...except in the rare cases when it would cause confusion, (like "a=b+.3.") and there's no simple way to rewrite the equation so that it wouldn't cause confusion (like "a=.3+b." or "a=(b+.3).")? --Steve (talk) 02:20, 4 December 2008 (UTC)

With leading zeroes, italics and spaces that's not very confusing: a = b + 0.3. Looks clear enough to me. -- Army1987 (t — c) 11:51, 6 December 2008 (UTC)

Nothing's ever really been said in classes about how to write with equations, but in science journal, I've always seen in done in this way:

This leads to the relation
   A=B+C,
where A represents something, B another thing, and C something else.

or similar ways. On wiki, I follow WP:MOSMATH, with I find to make a ton of sense.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 02:55, 4 December 2008 (UTC)

The journal manuals of style I've seen generally say equations should make sense as parts of complete sentences, and so should be punctuated accordingly. Very commonly that means you need a comma or a period after an equation, but the important thing is that it make sense grammatically. There is also an ancient weird confusion about the order of quotation marks and other terminal punctuation, that I think goes back to typesetters' mechanical problems with isolated slivers of type metal, but which has become the stylistic norm and has endured even though it no longer makes any sense (and never did, grammatically or logically, as far as I can see). If I recall it would have us, eg, put a quote after a period, even when logically it makes no sense -- as in, say:

The teacher preferred "had had" to "had."

Personally, I try to follow logic and grammar except when some copy-editor with M.O.S. in hand demands otherwise, but it only really matters when the meaning is actually liable to be misunderstood—which is rare, luckily Wwheaton (talk) 04:18, 4 December 2008 (UTC)

"...the important thing is that it make sense grammatically..." :-)

The weird reversal of punctuation with double-quotes has survived on this side of the Atlantic; this is one of the very few cases where I prefer the choice made by our English friends. That, and judg(e)ment — the American spelling looks unpronounceable. --Trovatore (talk) 05:52, 4 December 2008 (UTC)

Quantum pseudo-telepathy

The new article Quantum pseudo-telepathy made it to "Did You Know". Whilst listed on the Main page, Quantum pseudo-telepathy was viewed on average once every 6 seconds. As a result, the article got quite some attention from a general audience, and consensus seems to be that it needs some "dumbing down". Just want to bring this to your attention, so that (hopefully) some subject matter experts get involved as well. Thanks, JocK (talk) 00:45, 5 December 2008 (UTC)

Giuseppe Cocconi

I significantly expanded the article on the late Cocconi (died 9 November 2008). If you have anything to added, don't be shy. I also didn't give an importance rating to his article since I wrote it, so feel free to assess it.Headbomb {^ταλκ_{κοντριβς} – WP Physics} 07:13, 5 December 2008 (UTC)

Energy functional

I added an example of the energy functional to the functional (mathematics) quite sometime ago. However I was and still is surprised that WP does not have an article on the energy functional, even though I have seen use of this term in many places. I am not a physicist to write a comprehensive article on this topic, but I thought to let you know that it was linked to a description of optimization (mathematics). I created a stub, I may come back later to check on progress and add references if I can find any. (Igny (talk) 02:06, 6 December 2008 (UTC))

Perhaps you should redirect it to Hamiltonian mechanics or Hamiltonian (quantum mechanics) since "Hamiltonian" is what the energy functional is usually called. JRSpriggs (talk) 05:41, 6 December 2008 (UTC)

You probably mean something like this, I was thinking about something like that. (Igny (talk) 16:04, 6 December 2008 (UTC))

Although the notation is significantly different, I believe that the basic idea is the same. You could add some examples like those in the wikiversity article to Hamiltonian mechanics and then redirect to that. JRSpriggs (talk) 16:45, 7 December 2008 (UTC)

I was thinking about a standalone article with hamiltonian as one example. I have seen other examples as well, different problems, like image recognition for example, with Mumford-Shah energy functional. (Igny (talk) 01:47, 8 December 2008 (UTC))

I have expanded the stub a bit, but like I said I lack physics background to write more coherent prose. (Igny (talk) 01:14, 14 December 2008 (UTC))

Gravitation

Could someone please have a look at Talk:Gravitation, User:Logicus seems insistent on removing the 1919 Eddington eclipse from the article, saying that it did not confirm the prediction of general relativistic gravitational deflection, or, at least, that it did not disconfirm the Newtonian corpuscular theory. To the best of my own understanding (and that of several eminent astronomers), the Eddington expedition did indeed confirm Einstein's theory and disconfirm Newton's. Would someone with more experience, either in astronomy or in the history and philosophy of science, please investigate User:Logicus's point of view. I'm not interested in getting into an argument, but that seems to be Logicus's chief aim. siℓℓy rabbit (talk) 00:23, 9 December 2008 (UTC)

I hate to say it, but User:Logicus seems to have a contentious editing history. The 1919 Eddington eclipse observation was certainly accepted as confirmation at the time (1919), and made "Einstein" a household name overnight. I am not expert enough to have a valid opinion either way, but would not remove the common wisdom since then without a new consensus clearly against the old story. Wwheaton (talk) 05:52, 14 December 2008 (UTC)

Spin-½

Is there any reason that this is not a simple redirect to fermion?Headbomb {^ταλκ_{κοντριβς} – WP Physics} 04:29, 14 December 2008 (UTC)