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Discuss. Dondervogel 2 (talk) 09:54, 6 February 2020 (UTC)
There is a scientific relationship, but not a legal relationship. No doubt the scientists and engineers who were behind the creation of SI had in mind scientific and mathematical principles which were eventually standardized as ISQ, but at a later date.
On the other hand, the CGPM is a treaty organization, and various governments sent representatives to periodic conferences. The resulting agreements are incorporated into national and sub-national laws. The local implementation is weights and measures inspectors who visit local retail outlets, impose fines for violations, seize inaccurate measuring devices, and seize packaged goods with inaccurate mass or volume claims on the label. If the shop keeper resists, the inspectors will call the police and the police will use violence to enforce the law.
I don't think we should be too quick to say that ISQ underlies SI, because you can violate the ISQ to your heart's content, and no one will put you in handcuffs. The same is not true for SI. Jc3s5h (talk) 01:51, 25 February 2020 (UTC)
The SI was named in 1960, the ISQ was named in 2009, which doesn't mean that length, mass, time, current, temperature, amount of matter and luminous intensity were unknown before that. On the contrary, AFAICT both the SI and the ISQ were “in the making” when the MKSA system was born in 1946, based on four quantities and their respective units, with two more “dimensions of measure” added no later than the SI's birth in 1960, and the mole added as the seventh unit even 11 years after that; and if they hadn't yet “solidified” before 1946, it was because there was a lot of hesitation about exactly which electromagnetic quantity to regard as fundamental and what exactly to use as its unit. IMHO the “ISQ naming” event in 2009 simply consisted in formalising the system of separate measurable and macroscopically independent magnitudes which had underlied the philosophy of the system of units all the way since the acceptance of the MKSA system; IMHO the fact that three additional quantities and their respective units were added since then is secondary to that philosophy: if someday a new physical quantity is discovered which is (macroscopically) independent of the current seven, and if some way is found to compare measurements of it with a small enough experimental error, I don't doubt that this new quantity will be added to the ISQ and a unit chosen from it and added to the SI; neither of these additions would change anything to the philosophy of how physicists (and lay people) measure quantities.
Now how should we formulate all this to make it clear without using the kind of long-worded jargon which would sound like gobbledygook to a lay person? What do you think of the following?
(About the mole officialy becoming part of SI in 1971 and no earlier, see Giovanni Giorgi#The Giorgi system and the reference mentioned there in fine.) — Tonymec (talk) 14:59, 29 February 2020 (UTC)
I've now had a go at fixing this, by specifying that the SI is based on a set of fundamental quantities, (something that has always been true), and that that set of quantities is now known as the International System of Quantities. This also gives the opportunity to link the fundamental quantities in the first section of the article, separately from the units that measure them. -- The Anome (talk) 15:13, 29 February 2020 (UTC)