Misplaced Pages

Revision as of 08:40, 2 April 2015

Physics Redirect‑class Mid‑importance

This redirect is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Misplaced Pages. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.PhysicsWikipedia:WikiProject PhysicsTemplate:WikiProject Physicsphysics Redirect This redirect does not require a rating on Misplaced Pages's content assessment scale. Mid This redirect has been rated as Mid-importance on the project's importance scale.

Comparative test of explanatory power of structure models

Given the (apparent) lack of data concerning the magnetic moment of quarks, the quark structure model of the neutron has not much (higher) explanatory power to the magnetic moment of the neutron compared to Rutherford model.--193.231.19.53 (talk) 11:24, 10 December 2013 (UTC)

Will you stop ranting about the 'Rutherford model' already? The Rutherford model was a guess made in the 1920s when no one knew of quarks. Neutrons are made of quarks. This is a fact. They are not made of protons and electrons. This is also a fact. Protons and electrons cannot explain the magnetic moment of neutrons. This is also a fact.

The only people advocating this nonsense are Ruggero Santilli, Florentin Smarandache, and a handful of people (most of whom will publish results in Hadronic Journal and Progress in Physics, edited by... none other than Santilli and Smarandace!). If you have additional insights, I suggest getting them published in reliable journals (i.e. something like Physical Review D or Journal of Physics G). See also WP:FORUM and WP:NOTADVOCATE. Headbomb {talk / contribs / physics / books} 13:19, 10 December 2013 (UTC)

Please do not claim that this is an established fact until rigorous models testing according to the scientific method are pointed out.

Interesting mentioning of those people that I haven't heard before.

It couldn't be claimed that Rutherford model is a guess. The same thing can be said about quarks, their explanatory power is rather weak. Please point to a source which proves beyond doubt that Rutherford model cannot account for magnetic moment of the neutron.--193.231.19.53 (talk) 15:46, 10 December 2013 (UTC)

This is not any advocacy, just an application of the scientific method.--193.231.19.53 (talk) 10:12, 17 December 2013 (UTC)

Clarification of statement about relative proton–deuteron magnetic moments

In Neutron magnetic moment#Measurement, there is the statement "While the measured values for these particles were only in rough agreement, in both cases the magnetic moment for the proton was unexpectedly large." This does not seem to fit into the logical flow of the paragraph, but I do not have the references for checking. From the context, I would expect it to read "The magnetic moment of the deuteron was unexpectedly found to be significantly less than that of the proton." Comments? —Quondum 00:16, 22 January 2015 (UTC)

I'm not sure I see the logical difficulty, but don't deny that the paragraph might be confusing. The essence is that both groups measured mu for both proton and deuteron. The values varied widely and caused a bit of confusion. I assume (assume mind you) that the aim was to combine these two measurements to get at the mu for the neutron. In 1934 no one knew anything about these magnetic moments, so it was all new. Since d=p+n, the assumption was that one could subtract the measured magnetic moments for d and p to obtain a measure of mu for the n. There was agreement that, irrespective of the measured values for mu-p by the two groups, the values for mu-p were much larger than expected - expected value would have been the nuclear magneton, I believe, while mu-p was 3 times larger than that. And from the mu for d and p, the mu for n had to therefore be nonzero with a substantial value and negative, which was shocking everyone. The article by Breit and Rabi was useful - it commented on the general situation. Also the link to the Rabi biography is to the relevant pages via google books. (The Tamm values were a different animal; Breit and Rabi noted errors in some of the numbers they were using.) Hopefully that helps - feel free to rewrite to clarify what you find confusing. Bdushaw (talk) 03:02, 22 January 2015 (UTC)

I attempted a slight rewrite of the paragraph; perhaps it helps, perhaps not... Bdushaw (talk) 03:16, 22 January 2015 (UTC)

I follow te meaning now. I've tweaked it slightly as well. —Quondum 04:40, 22 January 2015 (UTC)

Sign of gyromagnetic ratio

I am pretty sure gamma is negative for the neutron. I write this here to note that I am overruling NIST on the matter. Bdushaw (talk) 22:47, 26 January 2015 (UTC)

A nitpick about convention and the the label "antiparallel"

The statement "The negative value for the magnetic moment means that the neutron's spin and magnetic moment are antiparallel" has been bothering me. Spin and magnetic moment are geometrically similar quantities (bivectors or pseudovectors), but whether they are regarded as being parallel or antiparallel is determined by the convention for the sign of electric charge, which as we know, is arbitrary. The correct form of this statement would be something like: "The negative value for the magnetic moment means that it is oriented as for a negatively charged elementary charge of the same spin". I am concerned that the existing statement might create the impression that there is something intrinsically antiparallel for the case of the neutron, beyond an arbitrary convention. —Quondum 19:36, 30 January 2015 (UTC)

The statement has bugged me to for a simpler reason - I am not sure antiparallel is very well defined; does "parallel" have a direction? On reflection the sentence does not seem necessary, so I've just removed it and ce'd a little bit. Bdushaw (talk) 12:21, 31 January 2015 (UTC)

A term such as "parallel" have multiple interpretations; no harm in avoiding it. My objection, while not being addressed, is circumvented by explicitly referring to the vectors representing the quantities rather than to the physical quantities themselves (as per my subsequent ce). —Quondum 13:57, 31 January 2015 (UTC)

1934-1964: 30 years of puzzlement?

Over on the Talk:Neutron talk page, someone noted the question of what people thought about why the neutron/proton magnetic moments deviated from their expected values during the 30 years until the quark models were developed. I know only a little about this question; enough to know that it is a tricky application of quantum field theory. The main theoretical approach seems to have been to employ such things as virtual pion fields, say, around the nucleons, much like the theory showing how the "bare" electron mass is different from the "effective" electron mass. So the idea was the "bare" nucleon magnetic moments were as expected for a Dirac particle, but the cloud of virtual particles surrounding the nucleons then caused the anomalous magnetic moments. The famous book Bjorken and Drell Relativistic Q.M. has a discussion, which presumably is a summary of the extensive work those guys did on the question. The book on the History of the Nuclear Force by Laurie Brown also touches on this subject. I'm not so sure this article should delve into such a discussion... (even if I knew enough about how it works to write it). It is obvious the question nagged at people for years. Perhaps just something like unconvincing attempts were made to derive expressions for magnetic moments using quantum field theory (?) approaches but the moments remained unexplained and a puzzle until the mid 1960s Suggestions? Ignore the question? Bdushaw (talk) 09:45, 19 February 2015 (UTC)

(The issue of "bare" vs. "effective" particle properties seems to come up on occasion - explaining this seems a complicated side track for Misplaced Pages. Must be explained somewhere.) Bdushaw (talk) 09:45, 19 February 2015 (UTC)

A discussion of the historical uncertainty about the measurement and origin of the neutron magnetic moment would not seem out of place for me, and makes for interesting reading for any WP reader, so I would not discourage distilling something from suitable sources. History is way outside my area of familiarity, though, so good luck. One observation, though: I'd suggest a phrase such as "unconvincing attempts were made": this sounds like editorializing; one should rather be observing that the attempts failed to convince the scientific community at the time. —Quondum 16:43, 19 February 2015 (UTC)

Just a note to record that Anomalous magnetic dipole moment may be a starting point for this discussion. QED had a great success in calculating the deviation of the g-factor for electrons from 2. The idea I was trying to get at above was that theoreticians then tried a similar formalism using the nuclear force and the particles that mediate that force, the pions. I don't think it worked so well, however. Bdushaw (talk) 01:28, 20 February 2015 (UTC)

As always, Pais Inward Bound has a discussion of this on p. 483. He calls this theory "a flop". Nice reference. Bdushaw (talk) 01:50, 20 February 2015 (UTC)

Well, I wrote the section as best as I could. As I feared, it got rather lengthy. I was as brief as I could be, but the issue is just rather complicated (and I grossly over simplified as it is!) Not committed to the section title, which is perhaps too much poetical flourish for an encyclopedia, but it is what came to mind. Bdushaw (talk) 05:42, 17 March 2015 (UTC)

Can you please explain what you mean by "poetical flourish for an encyclopedia"? --Urdugo (talk) 05:44, 17 March 2015 (UTC)

Merely that the language "thirty years in the wilderness" might not be appropriate for an encyclopedia, where things are supposed to be staid and objective. If no one objects to the title, then that's ok by me! Thanks for checking in. Bdushaw (talk) 07:47, 17 March 2015 (UTC)

Well, until someone finds a title that succeeds in communicating succinctly what the section is about as effectively, perhaps it should remain. —Quondum 14:48, 17 March 2015 (UTC)

I see that user Bdushaw has removed a chunk of clarifying info about the magnetic moment of undetectable free quarks. It is about matching models to observational data, not the other way around. This link underlies (Carl Witthoft physicist statement) this procedure.--5.15.54.113 (talk) 07:36, 18 March 2015 (UTC)

What is an "undetectable free quark"? And what can we say about its magnetic moment? Also, I see no relevance of this link. —Quondum 16:13, 18 March 2015 (UTC)

Even I would like to know what @5.15.54.113: means by "undetectable free quark"? --Urdugo (talk) 04:55, 20 March 2015 (UTC)

I think it is obvious: free quarks can not be detected/observed as standalone particles, something called colour confinement.--5.15.23.241 (talk) 21:46, 30 March 2015 (UTC)

A question arises in this context: if free quarks cannot be observed, how is their magnetic moment measured or inferred to express the neutron magnetic moment as a function of the quark moments? Magnetic moment of quarks can only be expressed based on moments of observable particles like proton and neutron, not the other way around.--5.15.23.241 (talk) 21:53, 30 March 2015 (UTC)

This is (mostly) nonsense - the section on this in the article is well cited to undergraduate textbooks on this subject. The quark/magnetic moment table actually goes on and on, with the magnetic moments of all manner of baryons accounted for. It is true that the magnetic moment of a "free" quark will never be measured...but so what? Neither will its electric charge. I leave it to the article on the quark model to handle that. This anonymous editor, in the guise of wide ranging IP addresses, has introduced challenges to the quark model all over wikipedia - this is his POV. Bdushaw (talk) 22:23, 30 March 2015 (UTC)

So what if the quark model is challenged?(It is utterly irrelevant if it is challenged by an anonymous editor or different anonymous editors) I think it is normal for a scientific model to be challenged and not to taken as reality by confusion of the map with the territory. Models have a key role in scientific reasoning. Challenges of models are also part of the logic of science. (It seems that the quark model is the pet model of some editors who for some reasons do not take scientific inference very seriously). The real nonsense is to speak of the properties of unobservable entities and to claim that these entities account for the properties of observable particles. This is the normal flow of observational data from neutron to quarks.--5.15.23.241 (talk) 23:35, 30 March 2015 (UTC)

You seem to be suggesting that WP is a forum for advancing science. Challenges to generally understood concepts whether these are correct or not, do not belong in WP. —Quondum 04:03, 31 March 2015 (UTC)

Please do not introduce distracting factors in this discussion by mentioning supposedly forum aspects in order to have an excuse to avoid conceptual clarifications. I see no reason to proceed differently here on Misplaced Pages than in a usual science/maths seminary when different models are analyzed and their logical consequences are deployed.--5.15.185.197 (talk) 05:34, 31 March 2015 (UTC)

What is the exact meaning of this phrase challenges to generally understood concepts? It seems rather ambiguous. What is the point of using this expression other than an obfuscating one? What are these general understood concepts and what makes the impression that they are generally understood?--5.15.185.197 (talk) 05:41, 31 March 2015 (UTC)

An equality like this μ_n = 4/3 μ_d − 1/3 μ_u from article is meaningless for determining the magnetic moment of the neutron from the unknown moments of up and down quarks.--5.15.185.197 (talk) 06:17, 31 March 2015 (UTC)

The quark model is overrated. Is there other reason for not mentioning in the article that quark magnetic moments are unknown? Not mentioning creates misleading impressions which are to be avoided.--5.15.185.197 (talk) 06:46, 31 March 2015 (UTC)

NONENG sources

Does the WP:NONENG policy applies here? It seems that some wikieditors are not aware of its existence by removing a source that has valuable info on magnetic moment measurement, but it is seemingly available only in Romanian and Russian editions, I'm not aware of the availability of an English translation.--5.15.30.188 (talk) 23:54, 30 March 2015 (UTC)

I see that there isn't an answer here to this aspect.--5.15.185.197 (talk) 05:46, 31 March 2015 (UTC)

The page you give has Citations to non-English sources are allowed. However, because this is the English-language Misplaced Pages, English-language sources are preferred over non-English ones whenever English sources of equal quality and relevance are available. You did not give a citation, but a "Further reading" entry. Citations support particular facts in an Encyclopedia, hence one might need a non-English citation from time to time. But a non-English "Further reading" entry...nope. Bdushaw (talk) 06:13, 31 March 2015 (UTC)

This seems to be a formalist answer. Instead of correcting a misplaced addition of non-eng sources by adding a section like Bibliography (as one all of further reading sources is already cited in the article) you preferred to revert.--5.15.185.197 (talk) 06:24, 31 March 2015 (UTC)

The title of the subsection has been adjusted to comply with the use of non-eng sources, which indeed are not advisable in a Further reading section.--5.15.185.197 (talk) 07:59, 31 March 2015 (UTC)

It seems that some user Jonathan A Jones is making tendentious edits to this article by opposing non-English sources to be cited. — Preceding unsigned comment added by 5.15.181.104 (talk) 11:01, 31 March 2015 (UTC)

Actually I'm just following WP:NONENG which has already been explained to you above. Jonathan A Jones (talk) 11:04, 31 March 2015 (UTC)

Seriously? Please give more details because it seems that you are opposing to the citation of source not written in English by labeling it extraneous.--5.15.181.104 (talk) 11:13, 31 March 2015 (UTC)

"Citations to non-English sources are allowed. However, because this is the English-language Misplaced Pages, English-language sources are preferred over non-English ones whenever English sources of equal quality and relevance are available." So you have to explain what this non-English source brings to the article which English sources (whether currently included or not) don't bring. Jonathan A Jones (talk) 11:31, 31 March 2015 (UTC)

That's a more appropriate reaction and response than previously that should have been followed in the first place. Indeed the key word is availability. But it matters to whom. If an an English source (or a related English language edition similar to the non-en book intended to be used) is not available to an editor (temporarily or not) , then the editor can use what he has to source additions to articles. Anyhow there may relevant info in the non-en older source than in a more recent English similar book by same author.

Going from general aspects about availability to specifics about the non-en Vonsovski book, it has to be said that it is a good/comprehensive review/gathering of info on the topic of magnetic moments of particles.--5.15.185.115 (talk) 16:15, 31 March 2015 (UTC)

Two Vonsovski

I think that two Vonsovski books must be compared by someone who has access to both and understands at least one of the two non-en languages, namely Romanian or Russian.--5.15.183.125 (talk) 18:10, 31 March 2015 (UTC)

Why? You have still given no reason why this source should be used at all. Recall that per WP:NONENG the presumption is against its use unless you can explain why it is better suited to being used here than any English source. Jonathan A Jones (talk) 19:44, 31 March 2015 (UTC)

Huh? No reason at all? You must be kidding! Haven't you read above the availability reason? There is no explicit presumption at all given the probability of finding infos that might be contained only in the non-eng V and not in the English Vonsovski and even in any other English source.--5.15.29.207 (talk) 20:19, 31 March 2015 (UTC)

As I said, you have given no reason at all why this book has any relevance to this article. Unless and until you do then, per WP:NONENG, it has no place here. Jonathan A Jones (talk) 21:02, 31 March 2015 (UTC)

You are becoming (both of you including Bdushaw) unreasonable and tendentious. (It may seem that it has no place here is your whim/whish). A user who wants to add some info to an article but he has only a good non-en source available to him source is better than no user adding valuable info to an info even though he has the best English sources. The probabilistic reason is a very strong one. Until know there haven't been too much users having access to the best imaginable English sources to add details here about the measurement of this quantity. You can't stop a user who wants to add info but it has only a non-en source available by saying his source is not good enough.--5.15.29.207 (talk) 21:20, 31 March 2015 (UTC)

For all the lines of (convoluted) text above, I also see no rationale for keeping the non-English reference. Bdushaw (talk) 21:13, 31 March 2015 (UTC)

Please stop the biased and tendentious reasoning against non-en sources. On the other I'll consider the possibility of getting the English V to compare with non-en V to see what is the symmetric difference between them, although I'm not obliged to get the en V to add info to the article. This would be an absurd situation.--5.15.29.207 (talk) 21:26, 31 March 2015 (UTC)

All we are doing is giving a clear an accurate statement on policy on the use of non-English sources on the English Misplaced Pages as described at WP:NONENG. Jonathan A Jones (talk) 21:36, 31 March 2015 (UTC)

This is your biased impression.You can't force an editor to get the English Vonsovski in order to add info to the article(s).--5.15.29.207 (talk) 21:56, 31 March 2015 (UTC)

Bdushaw, you said something about unacceptable behaviour. Don't use WP:IDONTLIKEIT to the proposed content addition to obstruct the improvement of article by conceptual clarifications. And please do not you use terms like gibberish logic in relation to wikieditors who happen to not agree to your preferences. This is very close to personal attack.--5.15.29.207 (talk) 21:59, 31 March 2015 (UTC)

An example about clear an accurate statement about use of NONENG needs to be mentioned. How do you see the History of Lithuania, if I recall correctly, where (almost) exclusively NONENG sources are used?--5.15.29.207 (talk) 22:06, 31 March 2015 (UTC)

About the waste of time mentioned by Bdushaw, your unreasonable persistence in dismissing NONENG sources is a pretty adequate example.--5.15.29.207 (talk) 22:14, 31 March 2015 (UTC)

Johnathan, you're basically asking to prove there is completely no <something>, in this case, an English reference. But the thing is, you can't prove a negative. That is why I am quite confident the phrase "English sources of equal quality and relevance <...> available" refers to sources available to a particular person, or, to be exact, at least one of people willing to improve the article. An English-language source would be better, yes. If you happen to have access to one, please add it. If not, remember that while a source in English is better than a source in another language for our purposes, a source in a foreign language is better than no source at all (this statement, again, requires applying some common sense).--R8R (talk) 08:56, 1 April 2015 (UTC)

This is all beside the point - the policy quoted above twice already is that foreign sources can be used to support particular facts from the article. That is not what happened here - the reference in question supports no fact in the article. The editor attempted to mindlessly paste in a foreign reference in the "Further Reading" section, a reference that was associated with no fact, a reference unintelligible to most readers of this English encyclopedia. If there were a fact the reference supported, there would have to be a reasonable case that no English source could be used instead (there is a very low bar there). The article on the Neutron has several such references. You guys are playing mind and word games; this behavior is insidious. Bdushaw (talk) 09:48, 1 April 2015 (UTC)

Quite. There's no problem with a non-English source being used to support a particular statement in the text, though it should be replaced by an English source where possible. But here there is no statement being supported: just an insistence that a random text book be mentioned. Jonathan A Jones (talk) 10:06, 1 April 2015 (UTC)

I comment here as an uninvolved editor: Has it occured to some here that the disputed source will probably or certainly be used in the near future to support a fact after a more detailed reading of the source? I think we should see things in perspective, not just for a day or two.--193.231.20.25 (talk) 08:36, 2 April 2015 (UTC)

I'm not playing games here :) I actually missed that, I was tricked by how the conversation was flowing. In that case, I agree with you. While it is not an obvious choice, I am leaning toward not using foreign-language Further reading (or whatever) books in articles. So few English speakers speak Romanian or even Russian (sadly), it couldn't be a good thing to trick them into reading a book they could not read, since books, like the one in question as you describe it, are not essential for this article, unlike references.--R8R (talk) 12:39, 1 April 2015 (UTC)

• Redirect-Class physics pages
• Mid-importance physics articles
• Redirect-Class physics articles of Mid-importance