Template talk:Infobox physical quantity

Comments from TimothyRias
I have updated the infobox with several parameters which may be useful.

I also have my reservations about the "derivations=" parameter. The type of formulas used here typically are dependent on the context. Most of the useful information added with this parameter can also be entered using the new "dimension=" parameter. (TimothyRias (talk) 09:08, 27 July 2009 (UTC))

Not merely for measurement, but for expression
I've changed the label that gets generated for the unit field from "Measured in" to "Expressed in." My sense of the semantics is that we do a lot more with, say, momentum than measure it: we also record it, we predict it, we describe it, ... And all of those involve expressing the quantity.

Note, too, that this is the way user:TimothyRias had done things in his first draft of the template (as documented here).—PaulTanenbaum (talk) 03:04, 28 February 2010 (UTC)

SI symbol --> Common symbol(s)
SI literature, as far as I can see, does not specify whether (for example), an electric charge quantity should be written using the symbol Q or q or x or ξ or anything else. Therefore there is no such thing as an "SI symbol" for a physical quantity. I am replacing it with "Common symbol(s)". The "(s)" is because often more than one symbol is commonly used, like q and Q for charge, or V and φ for electric potential. --Steve (talk) 14:34, 15 July 2012 (UTC)

No reason for "Name" to be mandatory
There's no reason "name" should be mandatory. If the infobox is at the top of the article, and the name of the quantity is the same as the title of the article, then there is no reason to rewrite it. I edited the template accordingly. --Steve (talk) 16:12, 15 July 2012 (UTC)


 * Thumb up for you. —Kri (talk) 22:53, 19 July 2012 (UTC)

Vector/Scalar
This template needs an option for specifying whether the physical quantity is a scalar or a vector. — Preceding unsigned comment added by Theemathas (talk • contribs) 05:45, 23 November 2013 (UTC)


 * Now there's "transformas", to indicate scalar, vector, tensor. fgnievinski (talk) 18:55, 30 August 2023 (UTC)

for SI dimension?
It seems that the "SI dimension" content is taken from wikidata, but its formatting is different there and here. For example, for pressure it is rendered using  formatting in wikidata, but as unprocessed TeX markup in WP. What controls this, and how the situation can be corrected (without breaking something else)? — Mikhail Ryazanov (talk) 00:50, 25 July 2017 (UTC)
 * , it seems to be your addition. Do you have any ideas how it is supposed to work? (For me, wikidata is something quite obscure) — Mikhail Ryazanov (talk) 00:57, 25 July 2017 (UTC)
 * So en:Pressure, now shows  here. In wikidata:  ,
 * In Wikidata: L&minus;1MT&minus;2
 * Try: &lt;math>: $$L^{-1}MT^{-2}$$ ✅
 * Looks like this is the way to go. Maybe try in the sandbox? For a while, it might be switched off (invisible in articles) until this is solved.


 * I note: the font is free (eg serifs allowed/not required). However, the letters should be upright (Roman), not italics: L&minus;1MT&minus;2 . To be changed in Wikidata. -DePiep (talk) 13:35, 25 July 2017 (UTC)
 * Example now spoiled, worse in infobox, but the general note stands: Wikidata format should be OK for all dimensions, not just one. -DePiep (talk) 15:39, 25 July 2017 (UTC)

propose deleting - or at least not auto-inserting - "SI dimension"
If I look at, for example Power (physics), the 3rd line is "In SI base units kg⋅m^2⋅s^−3", and the 4th line is "SI dimension L^2MT^-3". These two lines are obviously redundant, and indeed I think the 4th line is actively harmful to the article's pedagogy, because most readers would have to stop and ponder whether M means "meter" or "mass" or "metric" or whatever, and if they can't figure it out they'll click on the link to "SI dimension" which actually goes to Dimensional analysis, a long article in which these L,M,T abbreviations are deeply buried, and which also doesn't explain what "SI dimension" actually means (beyond a synonym of just "dimension").

The entries of this infobox are the most valuable real estate in the entire article—the only thing many readers will read—and it seems to me that we are wasting one of those lines to say something which is somewhere between useless and actively harmful to readers' being able to quickly and effectively learn about the article topic.

I feel strongly that "SI dimension" should be turned off by default. If the editors of a certain article think that it's very important, let them add it in! And then people can debate whether or not it's helpful in the context of that specific article. (Not just "helpful" but "so extremely helpful that it merits its share of the most prominent real estate in the entire article".)

I would be even happier with "SI dimension" deleted entirely from this template, which I believe was the status quo as recently as last year. I think "SI dimension" is no more than a pedagogically-inferior synonym of "in SI base units". But I don't feel too strongly on that point and I am OK with it as an off-by-default option.

(I don't know template syntax / wikidata well enough to turn it off by default myself.) --Steve (talk) 14:50, 11 January 2018 (UTC)


 * I concur with Steve. Jc3s5h (talk) 15:03, 11 January 2018 (UTC)
 * Just as a note for the tech folks, this is . Primefac (talk) 15:26, 11 January 2018 (UTC)


 * To me is not that severe, but I won't oppose eliminating the label. Is there another way to make it less ambiguous? --MaoGo (talk) 16:01, 11 January 2018 (UTC)


 * Keep, I say. -DePiep (talk) 01:38, 12 January 2018 (UTC)
 * 1. re the proposal to be "turned off by default". As proposed, this is a soft, indirect way of removing the parameter altogether. Sbyrnes321 clearly notes that to add this parameter in an article it should be discussed per article, while also claiming that adding the dimension is not good anyway anywhere.


 * 2. re: The label SI dimension links "to Dimensional analysis, a long article in which these L,M,T abbreviations are deeply buried". Indeed. However, this being Wikipedia, the solution is that the article Dimensional analysis should be improved. Even better, I strongly suggest we move it to SI dimension, rewriting the lede and first sections to better explain just what it is. (Wikidata: says there is no enwiki article!). The 'analysis' in the title could be in lower sections. I think we can agree that both in physics and in metrics (system of measurement) it is a fundamental concept.


 * 3. re "SI dimension" is no more than a [...] synonym of "in SI base units"": no, it is not. A unit has SI dimension. As has the quantity the unit is used in. The quantity definition looks like this:
 * quantity = number &times; unit
 * Now the requirement is that quantity and unit have the same dimension. For quantity length (dimension L) we can use any unit that has dimension L: meter, centimeter, lightyear, maybe foot. But not second (dim second = T).
 * So it is not "obviously redundant" (not redundant, and the 'obvious' is based on this mistake). The example you choose is an easy one, but when more compluicated units are involved or added, the simplicity is gone. What with watt, joule, Newton? See also d:Wikidata:Property proposal/dimension, where its background is descibed a bit fundamentally (maybe search for "Main pitfall").


 * 4. re "entries of this infobox are the most valuable real estate" (agree), "wasting one of those lines". Let's note first that this parameter does not take the place of an other paremeter. But more important: since this is about physical quantity, we cannot discard this fundamental property of that quantity.


 * 5. re "readers would have to stop and ponder whether M means "meter" or "mass" or "metric" or whatever". Well, they don't have to of course, but they could. Already I mentioned, that the link to SI dimension should be improved (not removed). Still then, isn't that the essence of an encyclopedia? That one can find answers to such questions? If I am reading a wiki article mentioning Tuva, and I don't click/lookup that or I assume it is a mountain in South America: why would the article be to blame? In this case it says "Dimension" (not "Unit"), so if a reader misuses that information -- why should we be to blame? We are not to prevent sloppy reading by removing the infomation.
 * 5b. re "harmful to the article's pedagogy", "pedagogically-inferior synonym" (with 5.): as illustrated here, this parameter provides correct, well defined and fundamental information. How is Wikipedia responsible for sloppy reading? The improvement I'd expect being proposed is, to improve the presentation & clarification.


 * TL;DR: "SI dimension" and "SI base unit" are not synonyms. Dimension is a fundamental concept in quantities. This is an encyclopedia, the "pedagogy" argument can not be used to solve/prevent sloppy reading or misusing correct information. Issues with presentation should lead to improvements, not removal (I propose article SI dimension ). -DePiep (talk) 16:42, 11 January 2018 (UTC)


 * DePiep, I agree that a dimension is not literally the same as a unit, merely redundant, in the sense that dimension can be trivially inferred if the template also has an "SI base units" line. For example, if we tell a reader that the SI unit of power is equivalent to kg⋅m^2⋅s^−3, then they can immediately infer that the dimension of power is mass⋅length^2⋅time^−3. Do you understand that part? If so, my question is: Can you give an example article where the Dimension entry conveys new useful information beyond what can be trivially inferred from an "SI base units" line? Or can you otherwise help me understand what type of reader we're trying to serve here? For example, do you expect there to be readers capable of solving dimensional analysis problems but who are unaware that kg is a unit of mass? Or something else? Just trying to understand, thanks in advance, --Steve (talk) 01:55, 12 January 2018 (UTC)
 * a dimension is not literally the same as a unit, merely redundant: no, no no!. Don't say 'not literally', don't say 'redundant' at all: they are actually, by definition, and for all understanding and purposes: Not The Same. Read the manual of physics. And from there it is you misunderstanding, so I can't go into 'can you ...'. This is about "physical quantity", and you need to accept & understand that, and follow its consequences. -DePiep (talk) 02:11, 12 January 2018 (UTC)


 * I'm not sure we agree on what "redundant" means, and what should be the bar for putting something in a prominent top infobox. You mentioned something being "correct, well-defined and fundamental", but you didn't say anything about "important" or "useful for readers". Take the infobox for Michael Jackson. Here are a couple things I could add to it:
 * Number of letters in last name:  7
 * Species:  Human
 * I hope you agree that these would not be wise additions to the Michael Jackson infobox. (Do you?) If so, why? Here's what I would say. The fact that Michael Jackson is human is something that's correct, well-defined, and very much fundamental to who he is. But it's also blindingly obvious. The fact that there are 7 letters in his last name is a correct, well-defined, and fundamental aspect of Michael Jackson. But it is completely useless to almost every reader, and those few readers who want to know that information can figure it out themselves. So, is it "redundant" for the infobox to say both (1) that his name is "Michael Jackson" and also (2) that the number of letters in his last name is 7? The statements (1) and (2) are not literally the same. But I would still call it redundant, because it's so very easy to figure out (2) from (1). That's how I use the word.
 * One more time: What's so bad about saying that Michael Jackson is human? The issue here is editorial discretion. The number of true things you can say about any topic is infinite, but readers' time and attention is not. So we must prioritize the most important information—i.e., the information which is most useful to the most readers. It's too low a bar to say "This thing is true, and at least a few readers would derive nonzero benefit from knowing it, therefore it is a good thing to add it." The most visible parts of the article need to be overwhelmingly important to almost every reader, and then as the article goes on, it should move on to the stuff which is extremely important to most people, and then the stuff that's very important to many people, and so on. That's why I keep bringing up the fact that this type of infobox is typically placed very prominently right at the top of the article, and that the entry in question is kinda hard to parse for many readers (because the meanings of L,M,T in this context are not widely known, in my experience), and thus claim a disproportionate amount of reader time and attention.
 * Being a professional physicist, I actually do dimensional analysis from time to time (and FYI I've always done it with "kg,m,s" instead of "M,L,T"! It works just fine, I promise!), but I think most people do it roughly zero or one time in their life, e.g. in a unit in high school physics. Think of all the people reading the Power (physics) article—not just physics students but mechanics, nurses, writers, etc.—just how important is it for them to understand what an M,L,T decomposition is in general, and what the particular decomposition is for power? I think practically everything else in the article is more important than that. I want the readers to be spending their limited time and mental energy understanding the other parts of the article, like mechanical power and electrical power and mechanical advantage and so on. --Steve (talk) 20:38, 13 January 2018 (UTC)
 * Also, here are two reasons that I don't think the L,M,T decomposition is a particularly important or fundamental aspect of a physical quantity:
 * (1) Two physical quantities can have the same L,M,T decomposition but have virtually nothing to do with each other: Torque vs Energy; Susceptance vs Transconductance; "Density of trucks on a highway" vs Light attenuation coefficient (both are 1/length); etc. None of these pairs have a significantly closer relation to each other than any pair of randomly-chosen physical quantities.
 * (2) Two physical quantities can have different L,M,T decompositions but are describing more-or-less exactly the same physical quantity: "Resistivity in Gaussian units" vs "Resistivity in SI units" (the former is T^1, the latter is M⋅L^3⋅T^−3⋅I^−2, but they are describing the same physical quantity!); "Power" vs "Power expressed in dBm"; Absolute permittivity vs Relative permittivity; etc.
 * The moral is that knowing the L,M,T decomposition of a physical quantity contributes almost nothing to your understanding of what that quantity is or means. Conversely, in my opinion, someone can be a world expert on the topic of (say) capacitance, publishing textbooks and papers and teaching courses on it and inventing new capacitors and analysis techniques, without knowing the M,L,T,I decomposition of capacitance off the top of their head, or indeed ever using that decomposition in their life. --Steve (talk) 20:06, 14 January 2018 (UTC)
 * (Will write replies later on). -DePiep (talk) 20:09, 14 January 2018 (UTC)
 * Unfortunately I have no time to reply carefully to these posts now. I just moved this "Dimensions" data row to the bottom of the infobox, understanding that less prominence is OK for everyone here (as an intermediate improvement; no prejudice wrt any outcome of this discussion). - DePiep (talk) 10:11, 16 January 2018 (UTC)


 * Just as a side comment, we could very easily pipe the link to point to Dimensional_analysis, which I assume is the best place in the article to point. Primefac (talk) 16:58, 11 January 2018 (UTC)
 * Looks like International System of Quantities is a better hit to pipe to. First section already lists these symbols! The #Natural_units does not look very related. btw, could you weigh in in the discussion? Opinions wantyed ;-) -DePiep (talk) 17:21, 11 January 2018 (UTC)
 * "SI-dimensions" is nonsense, in as much as ML2T&minus;3 are the dimensions of power in ANY systems of units. Headbomb {t · c · p · b} 17:57, 11 January 2018 (UTC)
 * No, not nonsense. One can also construct a dimension set with volume, energy (as in: E = mc2), ... Just as long as they are independent. However, I don't mind omitting the SI prefix. -DePiep (talk) 18:15, 11 January 2018 (UTC)
 * I suppose, but that wouldn't be the "non-SI dimensions". Power has dimensions of ET−1 (E being energy), or ML2T−3 in any system of units. You might argue that ML2T−3 is expressed in base SI dimensions, and that'd be fine, but ML2T−3 is still valid in any other basis. Much like current has dimensions of QT−1, even if the hardcore SI people would express this as 'I'. Headbomb {t · c · p · b} 00:39, 12 January 2018 (UTC)
 * Whatever. Why not spend your smart time on arguing the issue? -DePiep (talk) 01:13, 12 January 2018 (UTC)
 * In Gaussian units, current has dimension length^(3/2)·mass^(1/2)·time^(−2). :-P --Steve (talk) 01:55, 12 January 2018 (UTC)
 * ... and in my own system (by volume (V), energy (E), ...,) I can express that same current dim as: like V-2/3E2... Being both correct and not SI. Also, I can transpose your every quantity into my system. BTW, meanwhile Headbomb could have excused for their "nonsense" claim. -DePiep (talk) 02:27, 12 January 2018 (UTC)
 * What's your point here? Headbomb {t · c · p · b} 02:54, 12 January 2018 (UTC)
 * My point here is,, that you crying "SI-dimensions" is nonsense is wrong. I illustrated that there are viable non-SI dimensional sets (VE...), that you admitted that E is a dimension while not being SI, etc etc, and while your were splitting hairs and claiming sense yourself (against & disproving your own non-sense statement) you did not contribute a single syllable to the discussion. No a single syl-la-ble. -DePiep (talk) 03:07, 12 January 2018 (UTC)
 * "that you admitted that E is a dimension while not being SI" not sure I "admitted" that. That was my position from the outset. There are many valid bases, dimensions are not an SI property and apply regardless of the system of units. Now if you don't have anything of value to add, I suggest you go do something more productive than write orders of magnitudes more about my own writings than I ever wrote here in the first place. Headbomb {t · c · p · b} 03:13, 12 January 2018 (UTC)
 * Number of syllables contributed: 0. Cumulative: 0. E lost: immesurable. DePiep (talk) 03:31, 12 January 2018 (UTC)