Talk:International System of Units/Archives/01/2018

Derived units
We just throw these out there. Some are not obvious, and their applicability to anything, not relevant to the casual reader. The other article, metric system, doesn't explicitly describe the named derived units. Can they describe the 4 forces of nature? It's not so easy to quantify the strong and weak nuclear forces. Maybe that's tangential, but the gravitational relationship to mass is interesting enough. Can they relate mass to energy? Indeed they can: e=mc2. Some useful context for each of them seems warranted. Sbalfour (talk) 20:35, 20 December 2017 (UTC)


 * Retention of non-SI units is mostly superficial and superfluous versus Non-SI units accepted for use with SI. Maybe it can just be deleted? Sbalfour (talk) 22:26, 20 December 2017 (UTC)
 * Merged and deleted. Sbalfour (talk)

There's this expression Derived units are associated with derived quantities, for example velocity is a quantity that is derived from the base quantities of time and length, so in SI the derived unit is metres per second (symbol m/s). So, for example, foot (unit) is a quantity that is derived from the base quantity metre, so in SI the derived unit is .3048 metre. Yaa? Nay? So everything named or not is a derived unit of SI. Actually, unlike velocity, foot is a named derived unit (there's no such thing as "1 velocity" because it is only a figurative quantity. not a unit). Very confusing. I think the statement in the text needs to be rephrased. Sbalfour (talk) 01:35, 23 December 2017 (UTC)


 * What is meant here is derived units within the SI. So your example of a foot is excluded.  (As an aside, a named derived unit was proposed for velocity: the benz.)  The section does start with "The derived units in the SI ...", so I'm not sure what more you want here.  —Quondum 03:59, 23 December 2017 (UTC)

There's a lot of information that could be included in the table here: We need to also consider a separate list of unnamed derived quantities like velocity and acceleration so that readers don't have to flipflop between articles to get that info (full list could be long, but we're not an almanac - keep it usefully and informatively short). As the table grows, the details in it become progressively less important. In any case, the table isn't the article; in a printed document, that table would be in an appendix, and the text would say something readable and informative. We've let stultifying but easily composed detail take over the exposition. Sbalfour (talk) 18:04, 23 December 2017 (UTC)
 * date of adoption into SI;
 * the namesake of the quantity, i.e. Joseph Henry for the Henry;
 * the date the quantity was originally defined or came into use, i.e. volt ~1790's);
 * the legacy unit and its value in terms of the SI unit, i.e. 'rem';
 * its equivalent in English or Imperial units, i.e. meter = 3.28 feet


 * It is true that there is a lot of associated information, but I think that including that in this table would be problematic (too much detail that is only of historical interest). The split into base units and named derived units is how the SI is presented by the BIPM documents, and is useful for reference (in the sense of what it currently is and means).  Further detail (dates of introduction, units named after people, etc.; essentially all information of primarily historical interest) is best kept separate IMO, possibly in a main article devoted to the historical development of SI or at least in a historically oriented section.  One of the beauties of a richly hyperlinked medium as that something can be presented without clutter, but relevant detail is only a few clicks away: in a footnote, a linked section, another article or another internet resource.
 * Listing unnamed derived units seems to be an open-ended project – a bit like listing all possible integers. What would be the purpose?  SI provides a defined framework for deriving units as needed.  The International System of Quantities is a broader context into which this sort of question falls (i.e. outside of SI itself, which deals primarily with defining base unit and how to derive further units; named derived units are almost incidental).  The ISQ tries to identify many quantities, and the formulae that define them, along with the associated units.  —Quondum 19:16, 23 December 2017 (UTC)
 * I like the idea of including the date of first adoption in the SI, but that's where it should end. I agree with Quondum we should not expand the table to derived quantities not explicitly mentioned by the current BIPM brochure (8th edition). Dondervogel 2 (talk) 11:22, 7 January 2018 (UTC)

Degrees Celsius is NOT a "derived SI unit", nor is the Celsius scale associated with SI units in any way. The SI unit of temperature is kelvins (K). The Celsius scale is a metric unit, but NOT an SI unit. This is an error in the article, but I'm not going to bother fixing it, because Wikipedia is filled with errors like this. SimpsonDG (talk) 00:35, 7 January 2018 (UTC)
 * The degree Celsius is listed as a derived unit in the BIPM's SI brochure (8t edition). In what sense is it not a derived unit?

RFC: merger of Metric system and International system of units articles

 * The following discussion is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

These articles, both GA and of significant merit, have substantially duplicate content, titles and focus. While Metric system is not quite synonymous with International System of Units, surely, with a paragraph or section to detail one from the other, the articles are the same. A lot of hard working editors have a stake in each article, and their contributions should not be lost. But I think it irrational that the information should not be one place, and be the best article quality that we can produce. These could be a combined Featured Article. Sbalfour (talk) 00:34, 19 December 2017 (UTC)

Agree. Attic Salt (talk) 04:33, 20 December 2017 (UTC)

Agree. The content is largely duplicated, and the ubiquity of the metric system makes it likely that individuals searching for either it or SI units would want the same info. Balon Greyjoy (talk) 04:48, 20 December 2017 (UTC)

I object to an RFC that lacks links to the relevant articles. Dicklyon (talk) 05:24, 20 December 2017 (UTC)
 * Ok; the other article is Metric system. We may also wish to consider Introduction to the metric system. Sbalfour (talk) 05:28, 20 December 2017 (UTC)

Agree, merge International System of Units and Metric system. The content is largely duplicated. Better to have a single article with all the material of both, and no duplication. Maproom (talk) 08:10, 20 December 2017 (UTC)

Comment: Metric system has been taken in that article to be, essentially, a synonym for SI. It nevertheless then goes into other metric systems in §Variants. I think there is scope for a repartitioning of content, without undue duplication. International System of Units should not mention the variants, except in its history section, which it already does; that content should not be merged. To avoid a repetition of this hijacking of meaning, we could have an article named Metric systems instead of Metric system with content that does not belong in International System of Units. —Quondum 18:49, 21 December 2017 (UTC)

Comment: The current content of the articles is indeed the same. However my understanding (not necessarily reflected in everyday usage of the terms) is that metric system is any system that has length as a base quantity and uses metres as a unit. The SI is a very specific system of units based on the International System of Quantities. Thus the two in principle have very little in common. If my understanding is correct, I would oppose the merge and rewrite Metric system to inlude historic systems like MKS, MKSA as well as cgs and derived natural units e.g. using fm "fermi" as a base units.--Debenben (talk) 17:15, 23 December 2017 (UTC)

Comment: (bot-summoned) basically, I agree with Quondum and Debenden; the subjects are slightly distinct, though the desirable result is mostly emptying the current content of MS into ISU and focussing the MS system on the historical content.

This being said, I am not sure deciding this is really in the scope of an RfC. Don't get me wrong, it is a good idea to put the question to an RfC before starting to do heavy work in GA, and We the Community may certainly decide that merging or redistributing content in such or such general direction is the objective. However, actually implementing the objective is going to need heavy work, which I will most probably not provide, and I would not put too strict a bind on whoever does it. If someone can exhibit a draft of what the "metric system(s)" article could look like after the content change, we could have a brutal up-or-down vote, but that version will take some editorial work to produce, and it is hard to decide without seeing it. Tigraan Click here to contact me 17:10, 25 December 2017 (UTC)

Oppose - Merge is not the place to start here. Start by eliminating duplicated content through edits to both articles. Once that is done it should be more clear whether or not a merge is appropriate. I will put these articles on my watch list and try to help out with this. ~Kvng (talk) 15:44, 26 December 2017 (UTC)

Oppose (but rename 'Metric system'): It seems to me that two separate articles are needed. The term "metric units" is broad enough to include units like hectare, kiloton as well as (eg) the CGS unit systems. The SI is a specific incarnation of the metric system that deserves an article in its own right. I do agree there's way too much duplication of the SI in the present article entitled "Metric system". Dondervogel 2 (talk) 17:26, 26 December 2017 (UTC)
 * Clarification: I think Metric system should be renamed as Metric units.  The term 'metric system' (whatever that means) seems to imply a specific system of units, but that article, if it wants to complement this one, needs to be broader, covering all metric units (whatever that means). Dondervogel 2 (talk) 22:01, 4 January 2018 (UTC)

Oppose merge: they are not synonyms and there is nontrivial differing text. Merge could have been possible if the difference were trivial and easily covered in a subsection as a redirect target. In our case the articles must be rewritten to avoid duplication. Staszek Lem (talk) 01:53, 28 December 2017 (UTC)

Oppose merge: "SI units" are a writing and editing standard; I would not search on "metric system" for a guide to the use of SI units. Please keep the articles separate, with generous links between them. Of particular interest are the "derived units," not all of which can be found in official International System of Units sources, to which, by the way, there should be links in both articles. Claire Marie-Peterson (talk) 18:21, 04 January 2018 (UTC) — Preceding unsigned comment added by 137.78.111.221 (talk)

Oppose merge. I would disagree with Claire Marie-Peterson, and would not describe SI as "a writing and editing standard". Some units within the metric system depend on different experimental measurements that the units of SI. For example, to work with calories, one must experimentally determine the specific heat of water. To measure blood pressure in millimeters of mercury, one must experimentally determine the density of mercury. More examples exist. Jc3s5h (talk) 20:12, 4 January 2018 (UTC)

Oppose merge. The metric system dates to the 18th century. SI unites were adopted in 1960, and this article should concentrate on the history, definition, and usage of SI units. There is enough material available on SI for a separate article, but the development of the metric system itself should be left to the metric system articles. StarryGrandma (talk) 21:37, 5 January 2018 (UTC)

Oppose merge. They may be similar in some parts, but they also have their differences. But cleanup to remove duplicate content would be a good idea. --Info-Screen::Talk 22:28, 8 January 2018 (UTC)

Oppose merge in favor of Dondervogel's solution. — SMcCandlish ☏ ¢ 😼  18:16, 19 January 2018 (UTC)


 * The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.