Talk:Vacuum permeability

From Wikipedia, the free encyclopedia

[edit] μ or μ₀?

I am confused by the statement, "The vacuum permeability μ = μ_rμ₀ is equal to μ₀." Taken out of context, the conclusion is that μ_r = 1. I suppose that the whole nomenclature section is confusing me. Ronstew (talk) 22:25, 19 November 2007 (UTC)

For the vacuum, μ_r = 1, as the relative magnetic permeability of substances is relative to the vacuum. /Pieter Kuiper (talk) 22:40, 19 November 2007 (UTC)

[edit] naming

As per WP:NAME, the title of this page should be determined by common usage, and common usage overwhelmingly favors "vacuum permeability" and its variants ("permeability of vacuum" or "of free space") over "magnetic constant", despite the fact that the latter seems to be favored by standards organizations these days.

On a Google search of arXiv.org, there are 784 hits for the former names, and only 89 hits for the latter. On Google scholar, there are 14750 hits for the former, and 1590 hits for the latter. On Google overall, there are 143480 hits for the former terms and only 9350 hits for the latter.

Moreover, many of the hits for "magnetic constant", if you look closely, seem to be for something completely different. For example, in the first page of Google scholar hits, as far as I can tell none of the papers are using it for μ0. Several papers are using it for the relative permeability (in apparent analogy to "dielectric constant" for relative permittivity). There are also a number of papers that use it for an apparently completely unrelated astrophysical quantity (e.g. [1]).

In fact, there appear to be so many alternate usages of "magnetic constant" in widespread use that it looks like we need a disambiguation page for that term. (And its ambiguity is another reason not to use it as the title for this page.)

—Steven G. Johnson (talk) 01:37, 14 February 2008 (UTC)

A guideline in resolving naming conflicts is to check scientific nomenclature as used by professional bodies: Wikipedia:Naming conflict#Identification of common names using external references. Also, if one looks at the interwiki links, the sudden move by Stevenj goes against what most of the other wikipedias are using. /Pieter Kuiper (talk) 20:29, 14 February 2008 (UTC)

Read the whole page: that page lists ways to test which names are the most common, but the criterion is still which name is the most common—the guidelines are just giving examples of places to look. In this case, there is a clear disconnect in that the name that is most common with standards organizations is not even close to being the most common in professional usage by practicing scientists. (As for other languages, we're talking about terminology in English here, so it's not clear why that's relevant.) —Steven G. Johnson (talk) 23:02, 14 February 2008 (UTC)

Stevenj omits relevant passages on what the guidelines says. Wikipedia:Naming conflict#Proper nouns: "If the common name conflicts with the official name, use the common name except for conflicting scientific names". That should be clear, I think. /Pieter Kuiper (talk) 23:11, 14 February 2008 (UTC)

(Interesting, none of the other naming pages lists that exception IIRC.) In any case, that passage is not applicable because we are not dealing with an "official" name vs. an "unofficial" name. (This is not like "brontosaurus" vs. "apatosaurus" where one name has been explicitly deprecated.) As we've extensively discussed, the standards bodies haven't said that the other names are "wrong", or "incorrect", or "deprecated" (unlike, e.g. "dielectric constant"), or that there is only one "official" name for this constant. They have merely quietly, with no explicit statement of explanation or preference, chosen a particular synonym to use in their own documents (and many of the documents continue to list other synonyms as well, as we've discussed).

(And in this page, "magnetic constant" has another big strike against it in that it is ambiguous in current usage. Remember that the policy is to choose the least ambiguous common name.) —Steven G. Johnson (talk) 23:43, 14 February 2008 (UTC)

Magnetic constant is as official as scientific nomenclature can be. Stevenj's suddenly moving this article away from the official name was against the longstanding policy on scientific nomenclature stated in Wikipedia:Naming conflict#Proper nouns. So how to deal with Stevenj? Edit wars over article names are particularly disruptive. I think I will ask an administrator to move the article back to where it belongs. /Pieter Kuiper (talk) 10:00, 17 February 2008 (UTC)

There is zero evidence that "vacuum permeability" is "unofficial", as we have discussed ad nauseam; the mere fact that the standards bodies have implied a preferences (and continue to list "vacuum permeability" parenthetically) is not the same as explicitly deprecating the older term or making it "unofficial." (This is very different from things like names of species, where standards bodies clearly state that there is one and only one official scientific name of the species.) Hence, by longstanding Wikipedia policy, we should use the more common name, which is the older name by a large margin in any search of the literature, textbooks, etcetera. You are the one who has been fighting tooth and nail against WP policy (here and in vacuum permittivity). —Steven G. Johnson (talk) 18:23, 17 February 2008 (UTC)

Put another way, Pieter wants Wikipedia to take the position that the terminology used by most current practitioners in the field, and by most popular textbooks, is "unofficial" and obsolete. This is not the type of linguistic battle that Wikipedia fights, by policy.

(Although my biggest concern at this point in the two articles is not the naming, but the implication that the linear permittivity and permeability of vacuum can differ from ε0 and μ0, which is impossible by definition of the units, any more than the vacuum speed of light can differ from c. More pertinently for Wikipedia, it is original research because it directly contradicts all the authoritative published references. See Talk:Vacuum permittivity. —Steven G. Johnson (talk) 18:44, 17 February 2008 (UTC))