Wikipedia talk:WikiProject Physics/Archive April 2011

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

π (pi)

The usage of Π is under discussion, see Talk:Pi. Since π is also pion, I thought I'd let you know. 65.93.12.101 (talk) 01:30, 4 April 2011 (UTC)

Banana equivalent dose up for deletion edit was speedy closed as keep

I stumbled upon this banana equivalent dose by accident and I noticed that it was being considered for deletion. I am not hundred percent sure whether this fits into physics or not and I really can't comment on the article. I figure there are quite a few people here who could comment, though at its deletion page. (Wikipedia:Articles_for_deletion/Banana_equivalent_dose). If nothing else it is amusing and not too long of an article. TStein (talk) 01:50, 20 March 2011 (UTC)

The original proposer of the deletion asked for a speedy keep and it was kept.TStein (talk) 22:52, 20 March 2011 (UTC)

I agree (belatedly) that it should be kept. ---- Steve Quinn (talk) 05:23, 21 March 2011 (UTC)

The article still needs attention from a real expert who knows where to look things up (and cite them). The literature that I have found so far as severely lacking in detail: It gives tables of equivalent doses without explaining on which model they rely. Most of the sources that mention the BED directly are blog posts in which someone calculates the BED in one way or another, usually in a way that raises a red flag. I !voted for keeping the article, but given how hard it is to calculate a concrete value (and it seems impossible to keep a concrete value out of such an article), I now think we may have to turn it into a redirect. Hans Adler 07:20, 11 April 2011 (UTC)

Oseen's Approximation

New article Oseen's Approximation by new editor. I did some tagging and evaluation, but it needs a look at from an expert. Thanks. Safiel (talk) 22:04, 8 April 2011 (UTC)

What articles should be included in WikiProject Physics

Would the participants of this WikiProject consider that the Pushchino Radio Astronomy Observatory article should part of WikiProject Physics? I don't think it is but another editor disagrees with me. -- Alan Liefting (talk) - 03:52, 9 April 2011 (UTC)

I'd think that radio telescope might be, but that specific observatories would likely just be WikiProject Astronomy material. Your mileage may vary. --Christopher Thomas (talk) 04:18, 9 April 2011 (UTC)

It should definitely be tagged with {{WP Astronomy}}. IMO that would be enough, but either way doesn't make much difference to me. Headbomb {talk / contribs / physics / books} 04:30, 9 April 2011 (UTC)

I agree with Christopher Thomas, unless some significant discovery in astrophysics occurred here, it should not have the physics banner, since this is not an article on a physics phenomenon. 65.93.12.101 (talk) 08:49, 10 April 2011 (UTC)

Are these considered significant:

"discovery of the solar supercorona (Vitkevich [2], 1953), which gave impetus to further exploration of the upper layers of the solar atmosphere and interplanetary plasma"
"discovery of polarization of the Crab Nebula radio emission (Kuz'min and Udal'tsov [3], 1957), which confirmed its synchrotron nature"
"the first observations of galactic nebulae in the 21 cm radio line performed in Russia. (Sorochenko [4], 1958)"
It appears that during this period "LPI physicists performed extensive applied studies that greatly contributed to the elaboration of the theory of radio communication and radio wave propagation".
"many pioneering studies, such as imaging the Sun at radio wavelengths and identifying radio spots with active regions on its surface."
"The high-frequency break in the spectrum of radio galaxy Cygnus-A found in the same observational series enabled the first experimental estimates of the age of this class of objects."

There is probably more. This facility appears to do some leading edge research, imho.

Source document: Dagkesamanskii, Rustam D (2009). "The Pushchino Radio Astronomy Observatory of the P N Lebedev Physical Institute Astro Space Center: yesterday, today, and tomorrow" (PDF). Physics-Uspekhi, Turpion. 52 (11): 1159. doi:10.3367/UFNe.0179.200911i.1225.

---- Steve Quinn (talk) 13:04, 10 April 2011 (UTC)

These are all standard astronomical discoveries. Compare this with the Arecibo Observatory which is much much more important than this one, which also isn't tagged by {{WP Physics}}. Headbomb {talk / contribs / physics / books} 14:01, 10 April 2011 (UTC)

I think the test for whether things related to astronomy should be covered by our project is whether they would be of interest to physicists who are not astronomers, that is, do they have implications for other parts of physics such as: general relativity, quantum theory, materials science (e.g. plasma physics), electromagnetism, the standard model of particles, grand unified theories, or the theory of everything. JRSpriggs (talk) 23:51, 10 April 2011 (UTC)

OK. Based on this discussion I will remove the physics banner. I think Headbomb, JRSpriggs, Christopher Thomas and IP 65.93.12.101 have presented some really good arguments ---- Steve Quinn (talk) 01:14, 11 April 2011 (UTC)

Quality of Physics articles and Talk pages

I have become very concerned about the way many Quantum Physics articles have very little in the way of secondary sources. Many sections have no citations at all. I have said on some talk pages that the articles look like undergraduate essays without references. It would seem that editors have produced articles straight from their lecture notes.

Perhaps worse that this is the way some editors treat the subject of QM as Faith versus Heresy. I feel I was bullied out of editing or commenting on the Quantum entanglement article because what I was saying did not agree with someone's idea of the Faith. In this particular case I was actually trying to reduce the non-NPOV in the History section. I was told I shouldn't be editing this article if I didn't undestand QM. My assumed beliefs against QM were questioned at length in a bullying way, so as to get me to withdraw, which I did for a while. With a short hiatus on my part, my edits were reverted. There is something very wrong going on here. Myrvin (talk) 07:17, 8 April 2011 (UTC)

No offence, but having looked at the talk page, it appears that you were the one that polarized the discussion from the start by speaking in terms of "pro" and "against" entanglement. With your first comment, of the bat, you include assumptions of bad faith, by suggesting that editors were "trying to enlist the name of Einstein". Considering that the first responses were very patient. Yet at the first sign, of annoyance of one of the other editors, you jump to accusations of bad faith.

Having had a look at your "revisions" most of them were at least inaccurate and rightly reverted.T R 08:04, 8 April 2011 (UTC)

What is wrong with the term 'pro-entanglers'? Maybe you accept the phenomena of Q entanglement - it's not an insult. Of course there are people who think entanglement is dodgy - especially in the history of the subject. Why do you think that is provocative? Physicists are for things and against things as are other scientists about other matters. I could say pro and anti Darwinism or pro and anti heliocentrism without anyone raising an eyebrow - especially when discussing the history. Why is QM different? The first 'sign of annoyance' by an editor was: "They were wrong. If you don't like saying that Einstein and co. was wrong, well, unlucky you". Followed by:

By your use of this terminology, I presume you are "against entanglement". Exactly what this means? You think that the use of entanglement should be forbidden? Or you think the mathematical concept of entanglement is inconsistent? Or that it does not model the real world correctly? And what about the experiments? They are just lying, or do you believe in the loopholes?

It is completely over the top. Saying that the article looked as if Einstein was in favour of entanglement was my view of what it looked like. I wasn't trying to insult anyone. You will see from the other editors' comments that this was generally agreed with and altered. Saying my revisions were inaccurate is an opinion. The question is whether writers on the subject (secondary sources) think so. I said that Einstein disagreed with the Copenhagen interpretation of QM, why was this wrong? - sources I read say so. The point against me was apparently that you shouldn't say that the C interpretation makes predictions that Einstein thought were unlikely. I objected to the strength of saying that the 'reasoning' of EPR was 'flawed' (and, the edit comment that said: "They were just plain wrong"). This has now been changed to its 'argument' - that's better, but I'm still not that happy with it. Myrvin (talk) 08:54, 8 April 2011 (UTC)

Scientist typically are not "pro" or "against" anything, the position of scientists is typically much more subtle than that. By introducing such terminology your are needlessly polarizing a discussion.T R 11:40, 8 April 2011 (UTC)

I'd like to think that was true; but I'm nearly 60 now, and I've met with and read of many many scientists who are definitely pro or anti things in science. At the time of EPR there was a lot of polarisation on the issue. Anyway, the above gives my views on the QM articles, the Wiki community can make what it wants with them. Myrvin (talk) 12:03, 8 April 2011 (UTC)

I just read your last edit and yes the quote you gave "We are thus forced to conclude that the quantum-mechanical description of the physical realitygiven by wave functions is not complete" is correct - but the paper qualifies what it means by reality and gave a very important bit in the next paragraph "Indeed, one would not arrive at our conclusion if one insisted that two or more physical quantities can be regarded as simultaneous elements of reality only when they can be simultaneously measured or predicted." Physical reality in the paper is a hypothesis as they say "we left open the question of whether or not such a description exists". So overall even though I was expecting them to plant a flag in the ground as it were they did not and were much more careful about what they had actually established than I'd ever have been. Dmcq (talk) 12:17, 8 April 2011 (UTC)

Thanks D. I am wary of the QE talk pages now, but I think we should do this there. Myrvin (talk) 12:59, 8 April 2011 (UTC)

Another case in point: A whole section on Popper's criticisms of the Uncertainty principle - there for a while I think - has been deleted because: "Popper is great as a philosopher of science, but why should we care (WP:DUE) that someone who was neither physicist nor mathematician misunderstood QM? Lots of people do that.)". A heretic then. I reverted the delete, but no doubt it'll go again. I think it's the "why should we care" that's most worrying. Who is this "we"? Myrvin (talk) 06:51, 9 April 2011 (UTC)

After discussion, this section was actually enhanced by the original reverter using the citations I had found. I would like to thank that editor. Myrvin (talk) 18:30, 13 April 2011 (UTC)

ANI discussion on apparent Russian fringe physics in articles

See WP:ANI#Speculative physics theories being promoted in Wikipedia and Wikiversity. Hans Adler 07:22, 11 April 2011 (UTC)

See the contributions of Fedosin (talk · contribs) who is the subject of that inquiry. JRSpriggs (talk) 11:16, 11 April 2011 (UTC)

AfD for Strong gravitational constant

Although an earlier AfD was withdrawn by the nominator, discussion is now invited at Wikipedia:Articles for deletion/Strong gravitational constant (2nd nomination). Strong gravitational constant was created by and expounds the physics theories of w:User:fedosin, who has disputed efforts to re-direct the article title to Strong gravity, where a different editor has created a short historical discussion of strong gravity theories. betsythedevine (talk) 16:32, 13 April 2011 (UTC)

Heads up at Theory of Everything

Someone more eloquent than me can have a word with them if problems persist. I pointed to the relevant policies in my edit summary (they've already demonstrated they read edit summaries). --Christopher Thomas (talk) 00:30, 14 April 2011 (UTC)

Additions to entropy article

Hello,

Bernhlav has suggested some additions to the entropy article (Talk:Entropy#Inaccurate_Statements). They have, however, been contested by another editor, who has since left the discussion. I don't have sufficient background in this area, so I was wondering if any of you could check it.

Thank you! InverseHypercube 21:59, 14 April 2011 (UTC)

Can anyone access this source for a copyright check?

Hi. New article Oseen's Approximation was tagged by Coren searchbot for potential copyright issues here. While only the abstract of the source it tagged is visible (here), there are red flags of copying, including both the formatting of the piece and the reference here: "The streamline pattern of the flow is shown in the Figure 5:8:1." The article, of course, has never had a figure 5:8:1. I'm wondering if anybody can access the article (part of the IPAP Online Journals to which some institutions subscribe) to help compare? It would be most appreciated. :) --Moonriddengirl ^(talk) 17:13, 17 April 2011 (UTC)

I have been helped. :) Thanks! --Moonriddengirl ^(talk) 20:46, 17 April 2011 (UTC)

Comments on inclusion criteria for list of important publications in physics needed

The criterion given for inclusion in list of important publications in physics are quite vague in my opinion. Yet the five criteria are from an inclusion that hasn't been edited in five years and is used in a number of other articles. Is it time to divorce ourselves from these criteria (like list of important publications in chemistry did) and create our own? If so what should the criteria be? Please comment at here. Thanks. TStein (talk) 02:59, 18 April 2011 (UTC)

Proposal to rename the Torque article to Moment of force

There is an issue of inconsistent terminology between physics and engineering courses regarding torque. As the article states: "The terminology for this concept is not straightforward: In the US, in physics it is usually called "torque" and in mechanical engineering it is called "moment".[2] However outside the US this varies. In the UK for instance, most physicists will use the term "moment". In mechanical engineering, the term "torque" means something different,[3] described below. In this article the word "torque" is always used to mean the same as "moment"."

I am proposing to change the article title from the physics term torque, to the engineering term, moment of force. You can agree or disagree at Talk:Torque. :-) --Steve (talk) 04:25, 8 April 2011 (UTC)

Fair enough. Here's my vote: Strongly opposed. I think we should stick to the terms preferred by physicist whenever talking about basic physical quantities such as torque. I think it is OK to include the common alternate names somewhere in the articles themselves. Dauto (talk) 19:29, 18 April 2011 (UTC)

Spin-statistics theorem

Sorry, I've just encountered this edit and have to go off-line. Could someone check it please. Materialscientist (talk) 14:12, 18 April 2011 (UTC)

I think it should be reverted. We can check out the proof based on ordinary QM published in Foundations of Physcs and then perhaps include it in the article (I haven't seen it before. Even if correct, you can have extra assumptions compared to the traditional proof based on QFT). But as written now, it puts far too much weight on this new result. Count Iblis (talk) 15:11, 18 April 2011 (UTC)

Analogues in Physics

User AndreRD has recently created an article at User:AndreRD/Analogues in Physics about (to quote from the article) "different phenomena that might seem unrelated share some similar underlying structure". I think that this article has great potential, and although it is in its very basic stages at the moment, he and I request aid from this project who are more knowledgable in both the physics concept, and in Wikipedia code to help the article flourish. I have hastily gathered a couple of sources on a few topics that AndreRD has in the article (yet to be expanded upon), and written a short section to demonstrate how the information could be represented as more than just tables (which was previously what constituted the entire article).

Thankyou :)--Coin945 (talk) 16:00, 18 April 2011 (UTC)

As it is this concept article worries me. The subject of the article is kind of vague, and therefore has a high risk of turning into an arbitrary collection of things its authors found interesting. In particular, it runs the risk of turning into original synthesis.

To write any article on the role of analogues in physics (which could be interesting), you need to find a good reliable secondary sources that discuss that subject. Sources that just discuss some particular example are not enough. Without a general source any general statements you make about the subject will be synthesis.

An alternate route would be to write the article as a list class article. Please see WP:LIST and WP:STANDALONE. In particular, you would the formulate a set of unambiguous selection criteria (see WP:LSC). This might be hard in this case. An exhaustive list of all analogues in physics probably would be unmanageable.T R 08:33, 20 April 2011 (UTC)

Nuclear spin deserves an article

There is only a redirect from Nuclear spin. I read articles like isotopes of bismuth and see these tremendously intriguing data about nuclear isomers with spins like 1/2+ and 13/2+ and 9/2-. But I don't know what they mean. I don't really grasp how to relate this reliably with things like nuclear magnetic resonance, induced gamma emission, nuclear shells, and nuclear magnetic moment. Even if the topic is addressed in other articles, I think a fresh bite at the apple might clarify things. Could someone competent set this up? Thanks! Wnt (talk) 03:58, 17 April 2011 (UTC)

Since you don't know what they mean, it is evident that you don't grasp the concept of spin, not just the spin of nucleus.--Netheril96 (talk) 08:16, 17 April 2011 (UTC)

You shouldn't be so dismissive. Understanding spin does not help you understand what the "-" means in "spin 9/2-". The article isotopes of bismuth doesn't explain it anywhere, and neither does the spin article. I tried searching the references, and I'm still not sure. Is +/- the parity? Also isotopes of bismuth says that parentheses mean "weak assignment arguments". What does that mean??

In my opinion the problem is not a lack of article on nuclear spin, but the fact that isotopes of bismuth does not explain its chart. Unfortunately basically the same chart and explanation are in ~100 articles, one for each element, so it would be very time-consuming to fix. I guess these pages have a headquarters at Wikipedia talk:WikiProject Elements/Isotopes?

A nuclear spin article is possible. Actually a lot of the content could be copied from nuclear magnetic moment. --Steve (talk) 18:17, 17 April 2011 (UTC)

Since the source speaks of "spin and parity" and parity is not otherwise mentioned in the article on isotopes of bismuth, I think that it is almost certain that parity is that to which the "+" (even parity) or "-" (odd parity) refer. JRSpriggs (talk) 05:37, 18 April 2011 (UTC)

Parity is something I really don't understand. Why wouldn't a nucleus have the same energy whether it has even or odd parity? In small nuclei I think of NMR as "flipping spin", but does it really mean flipping parity then? Does it make a 9/2- nucleus go to 9/2+, for example? Can it transform nuclei to other states? (perhaps only in some cases where the isomers have similar energy?) And I vaguely remember parity having something to do with left-handed particles, neutrinos, mirror matter and so forth ... though I admit I never really had the distinction from spin clear in my mind. As I said, I really am clueless here, and an article would be so welcome. Wnt (talk) 07:49, 18 April 2011 (UTC)

In nuclear magnetic resonance, what is changing is not the spin quantum number s (e.g. the 9/2 listed in the table) but rather its component (spin direction s_z) in the direction of the constant (not RF) magnetic field which can be any of the values: -9/2, -7/2, -5/2, -3/2, -1/2, +1/2, +3/2, +5/2, +7/2, or +9/2 (these signs are numerical signs for s_z, not parity). As far as I am aware, parity does not change in NMR. Like yours, my grasp of parity is weak. But I believe that it is a function of the other quantum numbers (including s, but not s_z) rather than an independent variable. JRSpriggs (talk) 10:24, 18 April 2011 (UTC)

Some more specific questions I have... (an answer to any would be most welcome, or an idea for something to add to an article...)

Is it possible for Förster resonance energy transfer to work on induced gamma emission? Can this work at the range of atoms in an ionic or covalent compound, even though the fluorescing units are nuclei? Or between a (very low energy) nuclear isomer and an electron excitation?
Are all the unmentioned nuclear spin states possible but merely undiscovered, or are they impossible? For example the isotopes of tantalum include one (177m4) with a 49/2- spin. Does that mean that there are at least 98 different nuclear isomers with various energy levels?
An interesting reference^[1] shows 176Lu or 180Ta as being stimulable to start decaying using photons. Shoot a photon into 176Lu 7-, it goes into a K-mixing state, falls down to 1- (123 keV higher state) and then beta- decays in 3.7h (to stable 176Hf) rather than 4.1x10⁹ years. Shoot a photon into apparently metastable 180Ta 9-, it goes into a K-mixing state, falls down to 1+ (75 keV lower state) and then beta- decays in 8.1h (to nearly stable 180W) rather than >1.2x10¹⁵ years. How frequent are such wide disparities in stability between nuclear isomers, and can they be used for curious things (like starting fission reactions or triggering useful transmutations)?
How many "stable" common nuclear isomers are actually metastable (like 180Ta 9-), with lower energy states currently unknown? How are these distributed among the periodic table?
Are there currently unstable or dangerously radioactive elements that might be rendered stable and chemically useful by means of excitation to some as yet unknown nuclear isomer?

Wnt (talk) 09:28, 18 April 2011 (UTC)

The energies listed for excited states of Tantalum-177 are assuming no significant external magnetic field is imposed on the nucleus. In that case, s may vary from one excited state to another, but s_z does not affect the energy. If the magnetic field B (assumed to be in the z direction) is nonzero, then a small additional energy would be added proportional to Bs_z. In the case of Ta-177m4, this would split the energy level into 2(49/2)+1=50 sublevels. JRSpriggs (talk) 10:58, 18 April 2011 (UTC)

This was a helpful answer, but I still want that article! :) Besides, now I'm wondering if some of the very lowest energy nuclear isomers could overlap with the energy split imposed in a magnetic field, and if so, does that give you a way to excite them or stimulate fluorescence from them? Wnt (talk) 21:19, 18 April 2011 (UTC)

You might like to read Induced gamma emission. I am afraid that I have now told you everything I know about your topic of interest. JRSpriggs (talk) 08:35, 19 April 2011 (UTC)

I calculate that the energy splitting from nuclear spin in a magnetic field is much less than 1 meV, even if the magnetic field is absurdly high. There is no nuclear transition with such a low energy...the lowest is 229Th, which has an 8eV nuclear transition. Most nuclear transitions are thousands or millions of times higher-energy. Förster resonance energy transfer between nuclei sounds unlikely -- it's an electrical dipole-dipole interaction, but nuclei must have very small electrical dipole moments, because they're so small physically. I'm not an expert, just my thoughts. :-) --Steve (talk) 15:44, 19 April 2011 (UTC)

Doesn't the IGE suffer from WP:OWN issues? Seems like the whole lot of articles concerned with hafnium isomer induced gamma release has ownership issues. 65.94.45.160 (talk) 06:05, 20 April 2011 (UTC)

To 65.94.45.160: I see a lot of different editors in the edit history of induced gamma emission. Who do you think is trying to "own" the article? Please give some diffs where he arbitrarily reverted reasonable changes by other editors. What are the other affected articles? JRSpriggs (talk) 06:05, 21 April 2011 (UTC)

A while ago, I remember something at one of the WPMILHISTs about someone repeatedly obliterating DARPA research from the whole set of articles, deleting the bomb article as being "not physics" (ofcourse not, it's a military article, which does not necessarily involve realistic physics, witness the pie-in-the-sky research programs that come out of military proposals (flying up-armored Humvees, recently)) etc. 65.94.45.160 (talk) 07:29, 22 April 2011 (UTC)

I haven't checked it recently, but as of my last skim, it had been mostly taken over by fringe types. Type "hafnium bomb" into the archive search box at the top of this page, and that'll probably turn up the threads (here) that I was involved in about the topic. Way back when I'd made a stub for one professor's "hafnium bomb" based on IGE that had gotten a bit of press, then it got folded into something from left field that was being called "ballotechnics", then various cleanup efforts were attempted. It's possible that cleanup has been successful in the intervening years, but at the time I'd abandoned it, there were quite a few fringe types with a lot of time on their hands watching the articles in question. --Christopher Thomas (talk) 20:53, 21 April 2011 (UTC)

Sagnac effect

The article deals for some time with Wang's experiment (Sagnac effect#Sagnac Effect in translational motion). I've tried to formulate it in a balanced way, but I'm not quite sure whether the whole section is appropriate (WP:Notability?). Also user "Stcloudstatewang" (possibly the author himself?) was involved in those edits. --D.H (talk) 17:27, 21 April 2011 (UTC)

Signpost Interview

Hello WikiProject Physics,
My name is Thomas888b and I am here today representing The Wikipedia Signpost. I am interested in interviewing several of your members for an upcoming edition of The Signpost. If you would be interested in being interviewed, please leave a note at my talk page.
Thanks,
Thomas888b (Say Hi) 17:29, 21 April 2011 (UTC)

RfD for Ashketar gravity

The redirect Ashketar gravity (current target: Seven-dimensional space) has been nominated at Redirects for Discussion. The discussion would benefit from input from one or more people who understand theoretical physics. The discussion can be found at Wikipedia:Redirects for discussion/Log/2011 April 23#Ashketar gravity. Thryduulf (talk) 12:55, 23 April 2011 (UTC)

Planetarium hypothesis

Planetarium hypothesis has been nominated for deletion. As this is a cosmology hypothesis, I thought I'd let you know. 65.94.45.160 (talk) 06:30, 25 April 2011 (UTC)

Antigalaxy

Antigalaxy has been nominated for deletion. 65.94.45.160 (talk) 06:25, 27 April 2011 (UTC)

Moderated nuclear explosion

Moderated nuclear explosion has been nominated for deletion. Yakushima (talk) 04:34, 29 April 2011 (UTC)

Background for third-parties: this article has serious problems with references that don't appear to support the statements they're used with, as noted by multiple people on the AfD page. --Christopher Thomas (talk) 07:08, 29 April 2011 (UTC)