Talk:International System of Units/Archives/04/2020

Lead

The lead prior to being reverted is quite a readable explanatory essay. I agree that the lead is way too long and with far too many specifics, even after the revert. However, this article is lacking a suitable introduction. Perhaps the essay-like lead could be inserted as an introductory section, after which the lead could be further stripped of the remaining excessive detail? (Reuqr, this might appeal to you. I would be interested in other opinions.) —Quondum 14:21, 14 April 2020 (UTC)

Quondum, I agree with everything stated above. The lead was and still is too long, and it should instead become an 'Introduction' section. I may actually implement this if I find the time today or tomorrow; my main problem is what the actual lead should look like instead.

(I also wish anyone considering reversions in the future would first read Wikipedia:Revert only when necessary…) --Reuqr (talk) 20:33, 14 April 2020 (UTC)

I think the lead is way too long and way too detailed. According to WP:LEAD, the lead should identify the topic and summarise the body of the article with appropriate weight. I think all it needs is a few sentences cohvering each top-level section in the article. Also, as the lead should not contain any information that is not already covered and sourced in the article body, it should not require any references or notes cluttering it. -- DeFacto (talk). 21:24, 14 April 2020 (UTC)

This could have been discussed before reverting (it is a friendlier way), but it also only takes seconds to put the pre-revert lead into a section. We should ideally not be putting the lead into an unnecessary state; there are other ways to create this content, so let's assume no-one is intending extra work for anyone. I'll start by doing so, then we can trim duplication from the lead. —Quondum 21:42, 14 April 2020 (UTC)

@Quondum: I don't think it was me who reverted or changed the lead. -- DeFacto (talk). 22:21, 14 April 2020 (UTC)

It wasn't; I didn't mean to suggest so, and the points you make are entirely valid. I was acknowledging Reuqr's evident (but gently expressed) frustration at being reverted without a preceding comment (one I had half a mind to make), while also trying to suggest to Reuqr that the action is not unreasonable amongst editors who understand the process and do not need to spend too much effort tiptoeing around each other (although on review, I see that my intended meaning was not at all obvious). I do not sense that there is much happening at cross-purposes here, which is fortunate. —Quondum 22:36, 14 April 2020 (UTC)

Prefixed units are SI units

A subtle point perhaps, but the current wording of the article (e.g. "It comprises a coherent system of units of measurement [...]") could be read to mean that prefixed units are units combined with prefixes, as opposed to being SI units themselves. The class of units without prefixes (kg excepted) forms the set of coherent units, but units together with metric prefixes (e.g. millimetre) are also SI units, albeit not coherent. —Quondum 18:31, 11 April 2020 (UTC)

Later, the lead states "Another characteristic feature of the SI system is that it provides twenty prefixes to the unit names and unit symbols that may be used when specifying power-of-ten (i.e. decimal) multiples and sub-multiples of SI units, ranging from 10^-24 to 10²⁴." Your argument, carried to its logical extreme, is that readers won't read further than the first sentence, or first word, or first letter of the article, so articles should say everything there is to say about a subject with one letter. Jc3s5h (talk) 18:37, 11 April 2020 (UTC)

Not quite. That example would be fixed by replacing the word "comprises" (which suggests/means that what follows is comprehensive) by something like "includes". My objection is made more acute by the fact that it does not answer the question "Is 'millimetre' an SI unit?", to which I can imagine that someone might reply "No, it is a combination of a prefix and an SI unit, but the combination is not an SI unit", which is not in contradiction to what you quote. This kind of ambiguity in the definition of whether a specific unit is an SI unit should not occur in an encyclopaedia article. I did note that it is subtle. —Quondum 20:29, 11 April 2020 (UTC)

The 9th SI Brochure itself makes this crystal clear: "The complete set of SI units includes both the coherent set and the multiples and sub-multiples formed by using the SI prefixes." I think we should do the same. —Quondum 20:47, 11 April 2020 (UTC)

This is now stated in International System of Units#Metric_prefixes (the end of the third paragraph in this version). --Reuqr (talk) 00:30, 16 April 2020 (UTC)

Metric units that are not recognized by the SI

I think it's reasonable to have a brief section with this heading, but the article is about the opposite of this, so I wonder how detailed it can be without extending beyond the article's scope. In particular, is there a risk of duplication with Metric units? Dondervogel 2 (talk) 13:30, 15 April 2020 (UTC)

That section grew out of a note whose purpose was to explain that, contrary to common contemporary usage, the terms the metric system and the SI system are not synonyms. I have finally reinserted a note that now links to the section ‘Metric units that are not recognized by the SI’, in the second sentence of International System of Units#Introduction. The note reads,

Although the terms the metric system and the SI system are often used as synonyms, there are in fact many different, mutually incompatible types of metric systems. Moreover, there even exist some individual metric units that are not recognized by any larger metric system. See the section Metric units that are not recognized by the SI, below.

Moreover, I added a {{main|Metric units}} to the subsection ‘Metric units that are not recognized by the SI’. I hope all this is within the scope of the article and that the amount of duplication is acceptable. --Reuqr (talk) 22:22, 15 April 2020 (UTC)

I haven't looked in too much detail, but I do get the sense that some organizing is needed. There are a few different top-level sections scattered about that have a similar discursive character and have duplication: Introduction, Realisation of units, Evolution of the SI, History, Metric units that are not recognized by the SI. It may be sensible to group several of these and to rationalise their content. It is a skill to get the balance of conciseness, readibility, explanatoriness, completeness, lack of repetition or undue detail, tone, etc. right in an article such as this: there is a lot of information that an average reader might benefit from, but it should not even vaguely seem to ramble or lose the attention of the reader. The sections that are accessible to a high-schooler should be early near the start. —Quondum 22:38, 15 April 2020 (UTC)

To be sure… --Reuqr (talk) 00:33, 16 April 2020 (UTC)

the most widely used system of measurement?

“the most widely used system of measurement” - this is true, of course. But there is more: it is the only system used worldwide, right? — Wassermaus (talk) 21:54, 1 April 2020 (UTC)

No, "it is the only system used worldwide" can be interpreted as no other system is used anywhere in the world, which is wrong. Jc3s5h (talk) 22:04, 1 April 2020 (UTC)

One could make the language more precise. A more complete form of the sentence: It is the only system that is in use (recognized officially) in every country in the world. I don't see how that could be interpreted incorrectly. And to the original point: yes, I suspect that there is no other system that is officially recognized in every country, though one might want to source such a claim. —Quondum 22:35, 1 April 2020 (UTC)

AFAIK, SI units are used everywhere (including in the USA) for electricity and magnetism, except in quantum mechanics where some other units such as the electron-volt are also in use; for other purposes, they are known everywhere, but in the USA Imperial units are still in everyday use while in some other countries some pre-SI units may survive in a role that varies from “folkloric” to “borderline official” to “co-official with SI” depending on the country. Of course, non-SI units are used everywhere for time (year, week, day, hour, minute), for angles (turns, degrees, minutes, seconds and in France possibly still grades and decimals for ordnance survey) and for temperature (degrees Celsius, now regarded as SI-derived; and in some countries including the USA degrees Fahrenheit). Astronomers use non-SI length units such as the astronomical unit, the parsec and the light-year, and some non-SI mass units such as the solar mass. Meteorologists used to measure pressure in millibars but (at least in my country) they are now calling it hectopascals, which is the SI name for the millibar. So yes, I would agree with Quondum's formulation in broad lines, with possibly some refinements concerning the very large, the very small, and some retarded :-P countries like the USA. — Tonymec (talk) 07:09, 2 April 2020 (UTC)

Concerning a bit narrower question of whether the SI system has an official, government-recognized status in every country in the world: a number of sources claim that Liberia and Myanmar (but also possibly the Federated States of Micronesia, the Marshall Islands, Palau, and Samoa) haven't officially adopted the SI system. These sources include this blog entry on metricviews, this engineering.com article on Myanmar (maybe finally) going metric, this reddit/Metric thread on nonmetric countries, and the CIA Factbook Appendix on weights and measures. Myanmar officials have over the past few fears on a few occasions said that they would adopt it soon, but so far I have been unable to find a confirmation that they have actually done so. For what it's worth, all this is also discussed here on Wikipedia in Metrication#Overview. True, this Quora answer claims that Liberia and Myanmar have officially adopted the metric system, but the answerer does not cite his sources or indeed gives any indication where he got his information… and there is another answerer that says the opposite. Absent further information, I don't think this article should claim that the SI system has official status in every country. --Reuqr (talk) 23:02, 14 April 2020 (UTC)

Totally agreed. It should be toned down to "almost all", or "with possible exceptions", at the least, without referenced confirmation. My reformulation above was of the statement in question to address interpretation of language only, not correctness of the claim of the sentence. —Quondum 23:25, 14 April 2020 (UTC)

"While it’s true that metric use is mandatory in some countries and voluntary in others, all countries have recognized and adopted the SI, including the United States." Reference: NIST [1] -- Wassermaus (talk) 16:57, 16 April 2020 (UTC)