Talk:Bohr magneton

Landé ratio?

I can not think of an instance where the Bohr magneton is called a Landé ratio. In the books I learned from, eigenvalues of the effective z-component of magnetic moment are equal to the product of the Bohr magneton, the Landé factor and the magnetic quantum number:

μ_z = m_j μ_B g_lj

--Peterlin 16:48, 3 Oct 2003 (UTC)

Significance?

The page doesn't discuss the significance of the magneton. (I unfortunately don't consider myself knowledgeable enough to add more to the page.) Anarchic Fox 06:55, 23 July 2007 (UTC)

Beta or μB?

In older books you'll sometimes find this represented by β rather than μB. 128.253.229.12 (talk) 23:50, 22 April 2009 (UTC)

Procopiu??

Are there any scholarly references for this? /Pieter Kuiper (talk) 20:26, 15 April 2010 (UTC)

Ref 2...? Headbomb {talk / contribs / physics / books} 04:51, 16 April 2010 (UTC)

I think a reference should be required to a (non-Romanian) work about the history of quantum mechanics. I have been looking around a bit, and it seems that the term "Bohr magneton" was introduced by Pauli in 1920. Now, it is not unlikely that someone had noticed that Planck's constant times the elementary charge divided by an electron mass had dimensions of magnetic moment, and that it had the size of atomic moments. That could even have been done before Bohr published his theory of the hydrogen atom. /Pieter Kuiper (talk) 06:14, 16 April 2010 (UTC)

There's nothing wrong with using Romanian scientific sources. Headbomb {talk / contribs / physics / books} 06:21, 16 April 2010 (UTC)

If this is only mentioned by Romanian writers about the history of science, it is probably not true. Anyway, there are more problems with the lead. It is true that the Bohr atom would have an orbital dipole moment, but this does not agree with reality. /Pieter Kuiper (talk) 15:01, 16 April 2010 (UTC)

Ref 2 is not wrote by a "Romanian writer about history of science", but it is the official bulletin of Romanian Academy (where the Procopiu's article was originally published). Probably a scanned copy of the article should be added —Preceding unsigned comment added by 92.81.95.56 (talk) 22:21, 18 July 2010 (UTC)

Removal of a primary source

Removing the reference to the original article of Procopiu and inserting instead the biographical work of A Pais about Bohr (who was Bohr's assistent) is POV-atitude. A link to the original work of Bohr is useful.86.125.160.110 (talk) 12:18, 5 May 2010 (UTC)

The book by Pais is a highly regarded scientific biography. This kind of secondary sources is much more reliable than original research with primary refrences that are hard to check. /Pieter Kuiper (talk) 21:41, 19 July 2010 (UTC)

Did you check Procopiu's article? Cutting the possibility for others to check it is censorship. Maybe the following references are more available to you

Stefan Procopiu, "Sur les éléments d’énergie", Ann. Sc. Univ. Jassy, 7, 1911-1913, p. 280

Stefan Procopiu, "Détermination du moment magnétique moléculaire par la théorie de M. Planck", Bull. Scient. Acad. Roum., no. 1, 1913, p. 151

O. von Auwers, "Gmelins Handbuch der anorganischen Chemie", 8-te Aufl., Eisen, System Number 59, Berlin 1934, p. 1438,

Muller-Pouillet, "Lehrbuch der Physik", 11 Auflage, Bd. IV, Teil 4 de 1934, p. 665

A. Colin, "Le Magnétisme", Paris, 1926, p. 171

Robert C. O'Handley "Modern magnetic materials: principles and applications". John Wiley & Sons, 2000, ISBN 0-471-15566-7 p. 83 Cristi Stoica (talk) 17:28, 22 July 2010 (UTC)

Ok, so it seems that Procopiu in 1911 wrote that eh/m had the dimension of a magnetic moment. It is possible but not certain that he was the first to do so. /Pieter Kuiper (talk) 14:54, 22 July 2010 (UTC)

It is not just the dimension, it is the magnetic moment for atoms and molecules. Until the priority of Procopiu's result is contested (with references), the references to his articles should stay there, being the oldest known so far. Otherwise, we should remove all paternities of all discoveries, because we can never be certain of any priority.

A reference to Bohr's article should exist too, even if it is not prior to Procopiu's.Cristi Stoica (talk) 17:28, 22 July 2010 (UTC)

These things were pretty much "in the air". At the First Solvay conference in 1911, Langevin calculated a magneton from Planck's constant (an online source). And in 1913, S.B. McLaren published a theorem linking electrical charge, magnetic moment, and angular momentum. /Pieter Kuiper (talk) 18:27, 22 July 2010 (UTC)

In order to keep Bohr, it is fair to add all prior references one can find. Being "in the air" is not a reason to remove a reference. If it was "in the air" for Procopiu, it was for Bohr too. Is it fair to keep Bohr and "get rid of" Procopiu because "the idea was in the air"? And weren't almost all discoveries "in the air" at some time: calculus, non-euclidean geometry, special relativity, wave mechanics?Cristi Stoica (talk) 19:06, 22 July 2010 (UTC)

What Bohr did that had not done before (and what could not have been done before), was to calculate the Bohr magneton, the hypothetical magnetic moment of a hydrogen atom in its ground state according to the Bohr model. The prehistory of magnetons is interesting, but see the Weiss magneton, the Parson magneton, etcetera. /Pieter Kuiper (talk) 19:23, 22 July 2010 (UTC)

Yes, Bohr obtained the same value as Procopiu did (Weiss and Parson got other values), from his atom model. Bohr's model also explained Rydberg formula, but we do not get rid of Rydberg. Einstein obtained the Lorentz transformation from special relativity, but we do not get rid of Lorentz. Schrödinger's equation described better the hydrogen atom, but we do not get rid of Bohr's model, or name Bohr's contribution "prehistory of atom models". We should acknowledge properly the contribution of all these scientists. If by lack of information one censors someone's contribution, one should repair the injustice he made.Cristi Stoica (talk) 20:24, 22 July 2010 (UTC)

The prominence given to Procopiu in this article is still a matter of undue weight. The claims of priority are not supported by any evidence. In their study "The Genesis of the Bohr Atom" (1969), Heilbron and Kuhn wrote about this kind of expression for a magneton: "Bohr could either have produced this association himself or discovered it in the literature; it was in fact made by several people in the fall of 1911." (231-232). /Pieter Kuiper (talk) 15:55, 9 August 2010 (UTC)

Wholesale replacement of "Bohr magneton" by "Bohr-Procopiu magneton" is not supported by any common - or even rare - usage in English. Wikipedia does not publish original thought, so this is not the appropriate venue for renaming a fundamental constant.David C Bailey (talk) 23:19, 3 November 2010 (UTC)

Undue weight? Unsupported by any evidence? Renaming a fundamental constant?

Undue weight specifies that for mentioning it should be at least supported by a significant minority - I believe that the Romanian Academia does fit the description of a significant minority.

Unsupported by any evidence - for this we would need an original article from the period - I have requested this from the Ștefan Procopiu Museum, in the hopes that they will find such evidence.

Renaming a fundamental constant is not something new, nor is it something which should be viewed as taboo. You can't just name a fundamental constant after someone, even though someone else computed the same constant 2 years prior.

Cristi Stoica explains this pretty well above. Wikipedia is supposed to be unbiased, that means it has to include all the information that is necessary. You can't have an article about the NSA and avoid mentioning any of its controversies. That would be bias. You can't have an article about the Bose-Einstein condensate and call it the Einstein condensate or the Bose condensate - that would be bias. — Preceding unsigned comment added by 92.81.84.251 (talk) 21:51, 18 April 2014 (UTC)

Significant?

The Bohr magneton constant x c x Planck length = 5e-67. — Preceding unsigned comment added by Seb-Gibbs (talk • contribs) 12:23, 8 August 2016 (UTC)

Bohr's magneton definition has an extra 2\pi

Hi,

I am new to editing the Wikipedia, so I will just post my comment here in case someone with more experience knows how to edit the text properly. My point is that I believe the definition for Bohr's magneton is wrong. It should read: \mu_{\rm B} = \frac{e \hbar}{2 m_{\rm e}}.

In other words, the current version contains an extra 2\pi in the denominator. I suppose the author intended \mu_{\rm B} = \frac{e h}{4\pi m_{\rm e}} but the h was mistyped as an h bar.

Josep — Preceding unsigned comment added by 188.77.74.138 (talk) 17:46, 19 April 2019 (UTC)

It has been fix'd. Eric Kvaalen (talk) 16:05, 18 April 2021 (UTC)

Numerical Value

The numerical value given in ref. 1 (https://physics.nist.gov/cgi-bin/cuu/Value?mub) has changed from 2012 to 2018. — Preceding unsigned comment added by Nayano2 (talk • contribs) 08:59, 9 March 2021 (UTC)

Gaussian cgs

Copied from User talk:Eric Kvaalen:

Concerning [1], Gaussian units are weird, and there is a difference between these two unit systems, which makes it important to stipulate which system is used for which equations, because the dimensions aren't preserved from one system to another. Headbomb {t · c · p · b} 12:22, 17 April 2021 (UTC)

@Headbomb: Yes, I know that. But the formulas that were referred to do not contain anything about the actual units. That's why I changed the wording. And you shouldn't have reverted my edit of Bohr magneton anyway, because I did more than just chnage that sentence! Please restore what I did. Eric Kvaalen (talk) 14:59, 17 April 2021 (UTC)

Look at the article history, the other changes were restored two minutes later. Headbomb {t · c · p · b} 17:52, 17 April 2021 (UTC)

@Headbomb: Ah, so you put it back. I got a notice sayin' you had reverted, and I didn't check what you did after that. But I don't see why you think "SI units" or "Gaussian CGS units" is better than "International System of Units" or "Gaussian system of units". After all, the formula

$\mu _{\mathrm {B} }={\frac {e\hbar }{2m_{\mathrm {e} }}}$

could be applied using mass in grams and so on. Maybe it shouldn't be, but someone could do that, and then it wouldn't have "SI units". Same comment for the nuclear magneton. Eric Kvaalen (talk) 10:23, 18 April 2021 (UTC)

The distinction here is between SI/normal and Gaussian/rescaled. And grams are still SI. Headbomb {t · c · p · b} 12:25, 18 April 2021 (UTC)

@Headbomb: Well, feet and pounds then! 16:05, 18 April 2021 (UTC)

Orbital angular momentum of hydrogen

I've been reverted by Evgeny with the comment that the orbital angular momentum of hydrogen in its ground state is zero. It isn't. As one can contemplate Heisenberg's uncertainty relation with zero angular momentum! I believe it is worthwhile including the comment that the Bohr magneton refers to the angular momentum of the electron in its ground state of the hydrogen atom. Bdushaw (talk) 15:42, 19 February 2023 (UTC)

The orbital angular momentum of hydrogen (its bound electron) in the ground state is zero. Have a look at any QM textbook. The state is called "1s". "s" stands for l=0. Evgeny (talk) 17:32, 19 February 2023 (UTC)

PS. There is no Heisenberg's uncertainty relation for angular momentum. There is for coordinate and momentum, or for energy and time, etc. Evgeny (talk) 17:39, 19 February 2023 (UTC)

Further investigation turns out to be interesting. So, yes, in modern QM the ground state of hydrogen has zero angular momentum. By the uncertainty relation for angular momentum-angle, which does indeed exist, e.g., link, this can be interpreted to mean the angle for the electron is completely unknown. However, for the Bohr model for the hydrogen atom, the ground state has angular momentum h-bar, see, e.g., Hydrogen_atom#Bohr–Sommerfeld_Model. This was what I was remembering when I made my edits. My point still stands - the Bohr magneton arises directly from the Bohr model for the hydrogen atom, yet this article still never mentions the hydrogen atom (or Bohr model). Bdushaw (talk) 10:28, 20 February 2023 (UTC)

You're welcome to add whatever you think is relevant to the article about the (one-century-as-obsolete) old Bohr model. But it has absolutely no relevance for the modern interpretation of QM. As to the angular momentum–angle uncertainty: if you are really interested in the subject, please read https://journals.aps.org/rmp/abstract/10.1103/RevModPhys.40.411, Sec.4 in particular. The article you mentioned fails even to cite this, so... Evgeny (talk) 11:23, 20 February 2023 (UTC)

You say: "My point still stands - the Bohr magneton arises directly from the Bohr model for the hydrogen atom, yet this article still never mentions the hydrogen atom (or Bohr model)."

Why, in the "History" section, it is mentioned:

"In the summer of 1913, the values for the natural units of atomic angular momentum and magnetic moment were obtained by the Danish physicist Niels Bohr as a consequence of his atom model." Evgeny (talk) 12:03, 20 February 2023 (UTC)

I've restored the changes I made, and revised them per our discussion and your intervening corrections. The basic issues are the proper origins of the Bohr magneton (the hydrogen atom in the Bohr model) and what was a confusion in the previous version between orbital and spin angular momentum and the Bohr magneton. Bdushaw (talk) 12:59, 20 February 2023 (UTC)

Also as originally mentioned, the content of the lead has to reflect the content of the article. Bdushaw (talk) 13:01, 20 February 2023 (UTC)

And I again undid it. Please stop the editing war. You're decreasing the quality of the article with your "improvements". There is "history" section of this article, which contains a link to a large detailed article about the Bohr model. You want more details? Add them there, not here. Further, your statement about the spin resulting in the Bohr magneton is just wrong. Read about the anomalous magnetic dipole moment of electron. The article has a proper link, BTW, to it. Evgeny (talk) 13:42, 20 February 2023 (UTC)

"Edit warring"??? No. You said: "You're welcome to add whatever you think is relevant to the article about the (one-century-as-obsolete) old Bohr model."??? and we discussed what the issues with your objections were. I corrected my original text per those discussions, as I said. "Spin resulting in the Bohr magneton" was not my statement, but in the previous text. I'll stand down; I am not perceiving "good faith" here - others can sort out the issues and the valid points that I've made and tried to correct. Bdushaw (talk) 14:00, 20 February 2023 (UTC)

The article about "the (one-century-as-obsolete) old Bohr model" is Bohr model, not this one. I'm sorry if my sentence was confusing. Or, if you really feel it should be explained here as well, it can be done in the "History" section, but not in the intro part. I believe the introduction is where the topic is explained in a succinct way, with no historic details - and especially when these historic interpretations are wrong. Evgeny (talk) 14:18, 20 February 2023 (UTC)