Wikipedia talk:WikiProject Physics/Archive September 2007

Planck mass with 84.158.*.* insertions

As part of the ongoing issue with W. Kehler posting from 84.158.*.* I have just found another page where he has made modifications, unnoticed since July 2. I would appreciate another physics person having a look at Planck mass.

I cannot follow the changes. The English is atrocious, there is the recurring linkage being made to Tired Light, and the whole article seems to be used as yet another case where Kehler can slide in his rather unique perspective without being noticed. Relevance of the additions to Planck mass look dubious to me; but a real physicist better look at it please.

Is there any tool at Wikipedia where one can look at contributions from a range of IP addresses? —Duae Quartunciae (talk · cont) 04:34, 29 July 2007 (UTC)

There's an off-wikipedia tool here that can search a range (maybe limited to the last octet). It might time out a lot as it is getting some publicity [1] at the present time. Tim Shuba 23:27, 14 August 2007 (UTC)

Thanks. I couldn't make that one work; but I have since found a useful tool at tools.wikimedia.de that scans a recent database dump. See [2]. It's a bit limited; you can't search for 84.158.200-255. But you can enter "84.158" in the IP range, and "enwiki_p" in the pull down box of databases. This works like a charm. Here is a query all set up: 84.158 on en.wiki. He has since registered as User:DeepBlueDiamond, which is a good idea. I recently set up a user page to engage him directly. He's been busy on that over the last week or so. I've wasted a horrifying amount of time on it, which has to put my judgment in serious question. But at least it has been harmless. —Duae Quartunciae (talk · cont) 00:53, 15 August 2007 (UTC)

ANSWER, see [[[Related issue]]]

Back from vacancy I see that and how we were IP-chased and will begin to provoke: In 20 years Chinese will dominate the world. Chinese will become then more and more the dominant language and country, if you like it or not. You have to learn Chinese now instead to mock about English defects. Enhance bad English instead to attack serious work!

Our club decided today to resign. As cited Dr.Kießlinger wrote correctly: Wikipedian Admins are unable to “hear”. Who ignores a photon's mass (you confessed to know it) is not qualified for physics and maths, sorry! We have given enough other evidences to WP:PHYS: Not any GR-solution was found in the related article but some good "recipes for cooking" for experts only. When some few well-known solutions were given they were erased; and if the EXACT SOLUTIONS article begin with a (false) contravariant Einstein formula, both shows for every expert what the responsible ones know.

I got tired as well to search and search and link and link again and again serious evidences if noboby reads and cares. This manner of communication by bare (arbitrary or BB-infected?) ignorance makes no sense. If even you not try to understand basic maths, we cannot help.

ALSO TO RELATED SPECIAL MATTER HERE: An indicated “ambiguous PLANCK MASS” not comes from me! It was formerly seen mainly as THE photon's PLANCK MASS, I was told. For each mass you can calculate a mass to its frequency as given by PLANCK's E=hf and EINSTEIN's E=mc². If you have understood the principle of the COMPTON WAVELENGTH (or "Compton frequency") you must see:

It is only one special, modified form of "our" – by you even confirmed but in WIKI furthermore ignored – main formula for a phonon's mass:

m=hf/c².

If you know that c=fλ, replace c by fλ (and also all vice versa) in our formula above, you have simply to multiply both sides by λ and divide it by m (or all vice versa). So you CAN transform a SPECIAL "COMPTON WAVELENGTH" (or C.-frequency) for each(!) related MASS by any multiplying factor right- and leftside only; also getting it for a photon's mass of course its frequency and vice versa!

Sorry, but former physicists can not be guilty if Planck’s name was taken then for a certain group of natural constants, also taking a special mass only (multiply the formula with a - to photons or electrons, e.g. - related constant and we have all we want). May be in order to support BB and to forget old-fashioned physics? If old men know from 70 years ago, that a PHOTON'S "PLANCK MASS" had dominated anyhow, you can not change it, as I cannot! I was told that this is found so in old papers. I think that a 90 y.o. Professor certainly knows such ancient facts better than you and I and if he wrote it, I have to accept it; or not?

"Followers of fashion” or “modern physicists” make not only such banal faults as we over here: They need many, many, many “mysteries” and in each case GOD!!!

- Everything came from nothing! 
- And from one point in spacetime! 
- Normally any time would be unable to begin within its SCHWARZSCHILD-Radius of a BB!
- Only a GOD can do all such miracles and mysteries - ok? 

All mysteries and miracles (as finally now also a not existing “dark matter”) must save BB-people and its followers of fashion! Or are they followers of religions only? For them all (such old-fashioned) physics make of course no sense at all. Religion - with all here mentioned and not mentioned mysteries and miracles - must replace then physics and maths...

I would like to send you 2 pictures of another impeded man who died meanwhile. German texts, trans.: “1. It is better to be as stupid as everyone” because “2. stupor is able to do everything”. The first picture shows a (too intelligent) sheep in middle of its sheep-herd (fearing dogs around); the other pic shows a helmed soldier trying to split a rock by running steadily against the rock with the peak of his helmet ahead...

Here involved WP:PHYS, incl. you, are a too big rock for us. We will not copy that stupid soldier but follow the intelligent sheep not to be bitten. Therefore our club-section decided to resign (of course each for his own can do what one wants). I’m tired as well and have to care my family and baby and have to work since Monday...

DeepBlueDiamond 15:29, 1 September 2007 (UTC)

I have no idea what any of that means... --Falcorian ^(talk) 16:34, 1 September 2007 (UTC)

No doubt we'd understand if we hadn't been educated stupid. :)

@DeepBlueDiamond: Wikipedia reflects the current state of knowledge: it declines to be a front in any war against modern physics. Any POV which is widely held can be included, but only with plenty of verifiable, reputable sources, and even then only with the proper context. --Starwed 05:43, 2 September 2007 (UTC)

Ignorance and lack of crucial knowlede is no stupor. But it effects misunderstandings and mental "wars" partly comparable to religious wars. Please see what was written to that matter in

[Related issue]. 

Not only Duae acts without referring to the main object. Ignoring linked and cited content of (partly famous, original) papers, even of most famous physicists. Thus, nobody can understand - as here - the discussion: Nobody can build the 10th floor of a building before having build 9 floors. Confusion like here is the (wanted?) effect.

We reprimanded even multiply with masses of crucial evidences: WIKI is no more objective as it really was initially. Serious physics and maths and its basic - simply ignored! Thus hidden to people searching for information. Thus, ignorance - also by Wiki-Admins - perform real "wars" of physicians by bare lack of knowledge of alternatives as shown there.

Wiki-Admins seem to be "infected" by bare opinions instead. Especially according to Big Bang utilizing (not only above mentioned) "mysteries" (as Duae even confessed!) in masses needed by BB-theories! Instead by a "BB-religion" infected people abuse the fact that alternatives have relatively minor faults, but at least obviously not needing any miracles at all...

DeepBlueDiamond 08:39, 2 September 2007 (UTC)

One-way Glass

Would it be possible for someone fluent with Optical Coatings to have a look at One-way Glass? It would be helpful to have the input from an expert on what the actual reflective substances are in this case and how they are applied to the glass. Also, I admit that I tend to understand its use from a Security point of view and balance is required in the article. Exit2DOS2000^•T•C• 07:44, 3 September 2007 (UTC)

A quick glance didn't find anything out of place with it. The coating is usually a thin layer of metal (formerly silver, generally aluminum now, I think). If it's thin enough, it passes some fraction of the light that strikes it. Viewers on the bright side do receive light from the dim room; it's just swamped by the light reflected from the bright room. Viewers on the dim side see both transmitted bright-side light and reflected dim-side light, but as there's very little of the latter, the light from the bright room is what's mostly seen. --Christopher Thomas 03:36, 14 September 2007 (UTC)

Thanks for the input. Exit2DOS2000^•T•C• 03:45, 14 September 2007 (UTC)

Fluid physics contra Fluid mechanics

The physics of fluids IS NOT fluid mechanics.

The physics of fluids is much larger, a new and quickly developing branch of physics.

The deletion of the article is inappropriate and the redirect incorrect. See and compare:

[3] and [4] --LidiaFourdraine 07:17, 7 September 2007 (UTC)

In case it isn't clear, the above comment is regarding the recent redirect of Fluid physics. Sancho 07:42, 7 September 2007 (UTC)

Looked at the above. Are they not covered in fluid mechanics? Maybe Im missing something.

CaptinJohn 14:07, 7 September 2007 (UTC)

I can't for the life of me determine what the difference between fluid physics and fluid mechanics is. That's why I redirected the page. Nondistinguished 19:45, 7 September 2007 (UTC)

As a branch of continuum mechanics, fluid mechanics ignores the existence of molecules. This becomes problematic when you are talking about phenomena on a scale comparable to or smaller than the mean free path of molecules (i.e. high Knudsen numbers), and breaks down when you are actually talking about the molecules themselves. A couple of things that would be fluid physics, but not fluid mechanics, are the study of the structure and properties of water [5] and "large-scale numerical computations determine the trajectories of individual molecules" [6]. (Of course, all of fluid mechanics would be included in fluid physics.) So I support the existence of a separate fluid physics page. Cardamon 10:53, 8 September 2007 (UTC)

Kinetic and atomic theories are not properly found fluid physics. Fluid physics in its proper form assumes the fluid approximation and therefore is automatically only subject to continuum mechanics. When you start dealing with an atomized constituents you are no longer doing fluid physics. Nondistinguished 20:20, 8 September 2007 (UTC)

Are there any reliable sources to support a distinction? Sancho 05:16, 9 September 2007 (UTC)

[outdent] The usual definition of a fluid is that it is substance with a shear strength of zero. There is no requirement for the continuum approximation to be valid. So, there is the possibility of fluids, for which the continuum approximation is not valid, and physicists can study them. (Analogously, solid state physicists are allowed to discuss atoms.) It would be useful to have a name for the study of the physics of ‘’all’’ fluids. I suggest “fluid physics”. (Fluid mechanics is the part of fluid physics that can be done using the continuum approximation.

Even if you insist on treating fluids using the continuum approximation, there is no way to know why they have properties they do without talking about what they are really made of. For example, people sometimes add long polymers to fluids injected into declining oil wells in order to increase the viscosity of the fluid so as to reduce viscous fingering and enhance the recovery of the oil. In order to talk rationally about how this works, and how to improve it, we pretty much need to talk about the polymers as being long molecules. As another example, consider superfluids. To explain how and why they work, people use quantum mechanics. Both these phenomena are definitely physics and definitely deal with fluids, neither one falls within fluid mechanics, because you can’t really explain them while using the continuum approximation. So we need another name for topics in the physics of fluids that are not fluid mechanics. Again, I suggest “fluid physics”.

Is this suggestion compatible with how people actually use the words “fluid physics”? From a couple of NASA websites: “Fluid physics is the study of the properties and motions of liquids and gases” from NASA [7] and “Fluid physics is the study of the basic behavior of liquids and gases” [8] These definitions are similar to what I have been suggesting, although perhaps not quite as broad. They say nothing about the continuum approximation needing to be valid. How about the relation between fluid physics and fluid mechanics? Another site from NASA says “Fluid physics research consists of basic and applied research in fluid mechanics, heat and mass transport and other physical principles governing the behavior and dynamics of processes that involve fluids.” [9] treats fluid mechanics as a subfield of fluid physics. Here’s a quote from a book[10] which seems to consider fluid mechanics to be a “special branch” of fluid physics when it says : “The term "fluid physics" is appropriate in the context of this report. However, owing to the broad range of interests of its practitioners, it uses several names, each of which is proper in its own context. Therefore, terms such as "fluid mechanics," "gasdynamics," and "biofluid mechanics" are often used to describe special branches. “. So, yes, there seem to be at least some reliable sources that consider fluid mechanics to be a subfield of fluid physics. (To garner more, I might have to visit a good university library.) Cardamon 07:50, 9 September 2007 (UTC)

Allowing for the definition of a fluid to be one where shear strength is zero automatically implies the continuum approximation since allowing for relaxation through an applied force would yield a film of infinitessimal thickness and that cannot happen if there are any atoms. Such an occurrence can only happen if fluid is a continuum. It is also not true that one doesn't use the continuum approximation to explain superfluids. Such a statement is akin to claiming that one cannot study thermodynamics without understanding statistical mechanics. One can study a fluid based on its atomic/molecular constituents, but then one is not studying the subject as a fluid. We can get insights into various terms of the Navier-Stokes equation by studying the atomic/molecular constituents, but ultimately fluid mechanics happens at the level of the fluid approximation not at the level of quantum mechanics or statistical mechanics. I recognize that many times people need to consider the atoms of a fluid to understand certain fluid behaviors (intermolecular forces determine a lot of fluid variables, for example), but ultimately that consideration is made to aid in the understanding of fluid equations when one is doing fluid physics: fluid mechanics is not separable from the endeavor.

As for the insistence that there are those who distinguish between fluid physics and fluid mechanics, I must insist that these sources are either nebulous in their attempt at making distinctions without differences or they are weirdly misleading. In particular, the NASA quotes all seem to give a rather basic grade-school definition of fluid physics without distinguishing it from fluid mechanics. The study of liquids and gases is, of course, fluid physics and fluid mechanics because those are the kinds of fluids we find in the physical world. However, in principle, fluid mechanics and fluid physics can be studied on any extended system for which the continuum approximation holds and the shear strength is zero. The NASA citations do not refer to the continuum approximation because they are not interested in rigorously defining the subject: they are not offering even a basic physics course in the subject. The book provided is one that was trying to define the current state of the fields of plasma and fluid physics as of 1986. The book is not distinguishing between fluid physics and fluid mechanics but is rather positing a direct equivalence! That there are apparently "subdisciplines" is not evident in my reading of the text. There is no indication that the gasdynamicists and those working on biofluids are somehow not doing fluid mechanics. Instead, it is a recounting of subfield jargon and is indicating that different people use different terms to mean the same thing. To put it another way, imagine if someone writing a book today were to write about astronomy were to write "The term "astronomy" is appropriate in the context of this report. However, owing to the broad range of interest of its practiioners, it uses several names, each of which is proper in its own context. Therefore terms such as "astrophysics" are often used to describe special branches." Does this mean that astronomy and astrophysics are different subjects? Of course not: it merely means that there is different jargon.

I think that the way to consider whether there is a separation between fluid physics and fluid mechanics is to consider the texts written on the subject. Are there texts written on fluid physics that are not about fluid mechanics? It would appear not. For example, the standard Landau and Lifshitz treatment of fluid physics is called Fluid Mechanics, Toktay's treatment of the history and philosophy of the subject is called: A History and Philosophy of Fluid Mechanics. The challenge is, can you find a book which is broader in scope than either of these classic texts that covers fluid physics rather than "just" fluid mechanics? I don't think you can.

Nondistinguished 14:28, 9 September 2007 (UTC)

There are no texts on geophysics which are not about geology, but that doesn't mean that geophysics should be made a redirect to geology. KP Botany 02:05, 12 September 2007 (UTC)

PS The editor is gone, so there's no point in discussing this. She wrote very well on a technical subject at an appropriate level for Wikipedia. KP Botany 02:07, 12 September 2007 (UTC)

A few comments. 1) Assuming zero shear strength does NOT imply the continuum approximation. A good counter-example is the molecular flow regime in a vacuum system, in which the mean free path of gas molecules is large compared to the smallest dimension of the apparatus you are talking about. (If you are talking about a pipe used in pumping down a vacuum system to ultra-high vacuum, the molecular flow regime would be when the mean free path is large compared to the diameter of the pipe.) In the molecular flow regime, the continuum approximation does not apply, yet the shear strength is obviously zero.

2) I'm not aware of any policy that the names of articles must be exhaustively cited.

3) The current issue (August 2007) of [Physics of Fluids] has a couple articles that do not seem to use the continuum approximation.

There is more that I could say but it may be moot if the editor has left. Cardamon 09:49, 12 September 2007 (UTC)

1) The shear strength isn't exactly zero in the molecular flow regime. It's close, but not arbitrarily so.

2) I wasn't really concerned with citing the name as much as I was concerned with how others treat the subject.

3) I actually don't see the articles to which you are referring. Every article I checked used the continuum approximation or at least obliquely referred to it.

Nondistinguished 12:04, 13 September 2007 (UTC)

Your unsourced statements on the topic are original research and not a part of Wikipedia--if this is why she was hounded out of here, then more shame. Interesting the article she wrote is exactly what Wikipedia should strive for, and it was replaced by an article that is being used on a web blog to show the unreadable crap on Wikipedia. No need to respond, I won't be watching this page any more. KP Botany 05:09, 13 September 2007 (UTC)

Article attention

Hi, can someone look at Bose-Einstein condensation: a network theory approach? Someone emailed in saying that this was a joke/hoax. I don't have the background to tell really, but it is orphaned so... Thanks for your help! - cohesion 23:38, 18 September 2007 (UTC)

No comments on the article itself, but there's a suspicious amount of "image made by data collected by me" in the contribution log of the original author (Paul ayan (talk · contribs)). This suggests checking all articles the user was involved with for self-promotion.

At least it's not likely to be a recurring problem (they seem to have stopped editing in December 2006). --Christopher Thomas 03:35, 19 September 2007 (UTC)

True mass

True mass

Someone's asking for comments on this article at the astronomy wikiprojects. I thought you guys might also want a look. 132.205.44.5 23:45, 26 September 2007 (UTC)

Physics lead

I'd appreciate some comments on the lead of Physics. It looks like a big mess to me, and I'm not sure where to start on improvements. For example, the first paragraph reads:

Physics is the science of matter and its motion—the science that deals with concepts such as force, energy, mass, and charge. It is the general analysis of nature, conducted in order to understand how the world around us behaves.

Here the 2nd sentence is more a definition of science than physics (as the footnote clearly indicates).

There are other problems, but I haven't been able to make much headway with the authors, who recently replaced the previous lead with other major, perhaps questionable, edits to the article. The previous lead was inadequate, but I'm not sure the new one is an improvement. The guys who put in the new lead are well-intentioned and friendly, but seem prone to philosophical diversions. Any help would be appreciated. Please let me know if I'm being overly critical. Gnixon 01:20, 22 September 2007 (UTC)

Is not physics the catch-all science — physics is all the science which is not part of some specific science such as: chemistry, biology, geology, economics, etc.. JRSpriggs 02:11, 22 September 2007 (UTC)

That implies biology and economics are somehow subfields or outgrowths of physics. I think scientists in those fields would disagree.  :) Gnixon 04:59, 22 September 2007 (UTC)

There is a tension here between the concept of the field of physics as a human endeavor and a more philosophical view of the science. You can't really argue that biology isn't encapsulated in physics in the sense that all biological systems must also obey the laws of physics, while there are plenty of things that don't operate under the principles of biology(electrons for example). On the other hand, it's pretty clear that there are separate scientific fields of physics and biology and being an expert on physics doesn't get you far in knowledge of biology. So the definition of physics should capture these dual features. Joshua Davis 17:30, 28 September 2007 (UTC)