Talk:List of physical quantities

Wrong dimension of Intensity

The dimension of Intensity is, as the unit W/m^2 suggests, L^2 M T^-3 / L^2 = M T^-3. Majortom777 (talk) 21:51, 6 June 2016 (UTC)

Symbol for velocity

The symbol for velocity is "v", not "V". UED77 22:21, 2004 Sep 12 (UTC)

Big change

Why not remove the SI-Units (since this is a list of physical quantities and not physical units) and use some more space on information regarding vector/scalar and intrinsic/extrinsic property, etc.?

That's actually a good idea. Karol 15:43, 1 January 2006 (UTC)

Agree, someone can make a new/improved table? Thechamelon 22:14, 2 January 2006 (UTC)

I just did. Karol 02:47, 3 January 2006 (UTC)

The SI units are WAY too related to the properties to move from here. Also, it'd be pretty ridiculous have a long table of just properties and their units. How useful would that be?
Seriously, just because a column heading isn't in the title of page does not mean it doesn't completely belong there. Besides, if readers really wanted to know more about the "Comments" stuff of a particular quantity, they could easily click the its link.--ArtifexCrastinus (talk) 07:27, 8 September 2008 (UTC)

Question

Question: Doesn't velocity require a vector, while speed does not?

Yes. Karol 08:38, 15 October 2005 (UTC)

A legend of dimensions symbols would be nice

It would be nice to let the reader what [M], [L], [T],... stand for. Headbomb {ταλκ – WP Physics: PotW} 13:03, 25 July 2008 (UTC)

Isn't that exactly what the first table does? (among other things.) (TimothyRias (talk) 14:19, 25 July 2008 (UTC))

If that's what it's supposed to do, then there are some major inconsistencies. 1 would be given as the "symbol" for both plane and solid angles. Then index of refraction is listed as being of dimensions 1 (which is accurate, as it is of unit dimension), but if that table is meant to define the [L], [T], etc... then this is saying that index of refraction are given in units of plane/solid angles. Headbomb {ταλκ – WP Physics: PotW} 14:32, 25 July 2008 (UTC)

Plane and solid angles are dimensionless quantities, and hence carry unit dimension 1, just like index of refraction. (TimothyRias (talk) 21:42, 25 July 2008 (UTC))

The second table is units that are derived off the first table (Thus it's the "Base" table). If you wanted, you could use only the first table and be able to describe any quantity / unit (although that would be cumbersome, which is why we have the second table). MysticMetal (talk) 09:19, 21 September 2010 (UTC)

Where's specific gravity?

I know it's dimensionless, but it should definitely be up here.--ArtifexCrastinus (talk) 07:31, 8 September 2008 (UTC)

Well feel free to add it. As it is this list is mostly a compilation of the various BIPM tables with physical quantities. Undoubtedly, there are still many quantities missing from this list. (TimothyRias (talk) 08:12, 8 September 2008 (UTC))

Using Symbols

Shouldn't there be something in the introduction about using symbols in such places as custom equations and column headings. I've often seen them with subscripts to right of them indicating the substance of which they describe. For example, the mass of a lead object can be represented as m_Pb. Is this not as common as I thought? --ArtifexCrastinus (talk) 07:43, 8 September 2008 (UTC)

Current is not a base quantity

Current is not a base quantity, charge (Coulombs) is. (Current is Charge / time). MysticMetal (talk) 09:19, 21 September 2010 (UTC)

Another sortable column

Should we add a sortable column that says what it's generally used for (Chemistry, Electricity/magnetism, Physics), so if someone's interested in Electrical properties, they can sort based on that column (I came upon this page wondering about physical quantities...)? MysticMetal (talk) 09:22, 21 September 2010 (UTC)

I think it would be impossible to unambiguously assign some quantities to one particular field.TimothyRias (talk) 09:33, 21 September 2010 (UTC)

Article organization

Should we have it generally sorted so chemical properties are before (<) electrical < physical < magnetic? So far it's just cobbled together... --MysticMetal (talk) 09:27, 21 September 2010 (UTC)

merge proposal

The articles defining equation (physics) and defining equation (physical chemistry) are essentially the same with formulae, units, and dimensions in excruciating detail but they lack the 1-phrase explanation style given in this article. What do people think of splitting and transferring content from this article into those? Maschen (talk) 08:00, 5 September 2012 (UTC)

I would agree. Njaohnt (talk) 17:53, 3 November 2012 (UTC)

ISO/IEC 80000

Since there is an international standard system of physical quantities (ISO/IEC 80000) why isn't this list page based on it? D.keenan (talk) 02:46, 11 May 2017 (UTC)

Plane Angle and Solid Angle on which table?

Plane Angle and Solid Angle were previously listed in the Base Quantities list. But now they are in Derived quantities list. I think they should be listed in the Base Quantities list. Che12PM 13:51, 6 June 2017 (UTC)

Yes plane and solid angle should be in the fundamental table. M∧Ŝc²ħεИ_τlk 15:55, 6 June 2017 (UTC)

BIPM classifies rad and sr as derived units (see NIST SP 330, Table 3); I guess this is an argument that they should not appear in the base quantities table. If one considers them to be dimensionless, as they typically are, this makes sense, in the same way that the zero vector cannot be an element of a basis. (Even in my own quirky view, where angle should be treated as a dimensionful quantity, sr = rad² would still be a derived unit). —Quondum 16:26, 20 June 2017 (UTC)

Isn't Information (i.e. bits and bytes) a Base Quantity?

NIST (at []) considers bytes/MB/GB/etc. to be SI units; a whole special system of binary prefixes has been created by IEC.

So, is information / data storage measured in a base quantity, or as a population (like people or moles) based on the base quantity "amount"? Casu Marzu (talk) 19:58, 8 June 2017 (UTC)

I don't see how you read that into the page you linked; it is talking about non-SI usage. SI is pretty clear: it defines seven base quantities, and information and data storage are not amongst them. Even though the edge cases may be debatable (the "dimensionless" angle, information/entropy, data storage capacity, and logarithmic quantities in general might be considered dimensionful, while amount of substance is apparently dimensionless, and luminance and temperature arguably are derived quantities), we do not have the scope on WP to argue against the standard and nearly universal approach. So, interesting as the debate might be, in this context, I think the answer is a pretty clear "no". —Quondum 17:09, 20 June 2017 (UTC)

Dimension

Adding the simplest formula of the physical quantity will make the dimension essey. If you will aggery my suggestion ,it must be better for it. Padmanabha Dhala (talk) 05:00, 29 June 2019 (UTC)

GM/c²

how about explaining GM/c² as a usual astrophysical unit (in the theory of black holes) including "G"? thanx! HilmarHansWerner (talk) 12:49, 17 February 2021 (UTC)

Electric Dipole Moment

I would like to add electric dipole moment. ScientistBuilder (talk) 17:01, 24 January 2022 (UTC)ScientistBuilderScientistBuilder (talk) 17:01, 24 January 2022 (UTC)

Consider it done. DWIII (talk) 22:35, 12 February 2022 (UTC)

Base quantities being highlighted

I'm inclined to merge the list of base quantities into the table of scalars. This is not the article to focus on the distinction between base and derived units, which, in any event, is purely a convention (not even the number of base quantities is fundamental). The only role of base quantities here is for interpretation of the 'Dimension' column. I'm mentioning this ahead of time in anticipation of a challenge by Misterpotatoman. —Quondum 17:17, 26 November 2025 (UTC)

I agree that this separation is not essential to the nature of this article (as opposed to one on SI). My suggestion would be to include "SI base unit" in the Comment column for each such entry. Johnjbarton (talk) 17:38, 26 November 2025 (UTC)

It is an editorial decision whether or not to list base quantitities separately, but it does appear that ISO 80000-1:2022 section 4.2 at least discusses the distinction between base quantities and derived quantities (I don't have access to that section's text). Certainly the current 9th edition of the SI Brochure lists them as base quantities (Table 2, p130) and on the previous page says "noting also that the ISO/IEC 80000 series of Standards specify base and derived quantities which necessarily correspond to the SI base and derived units defined here", confirming that the distinction is made in ISO 80000. If merging and commenting, how about "ISQ base quantity"? NebY (talk) 18:34, 26 November 2025 (UTC)

The ISQ needs to define base quantities in order to define the concepts of quantity dimension for purposes of defining and analyzing mutual dependencies, and that article seems to do a good job of that. However, the distinction is just irrelevant in an article such as this, which should merely list the dependencies on the conventional base dimensions, as it does in the column "Dimensions". I think Johnjbarton's suggestion works well.

Even the 9th SI Brochure has this to say (Appendix 4 Part 2), which seems seems to be suggesting that the choice of base units (and hence base quantities) is retained for historical reasons only, and may even be hinting that the separation would have been discarded were it not that they are already so established:

• The SI was previously defined in terms of seven base units and derived units defined as products of powers of the base units. The seven base units were chosen for historical reasons, as the metric system, later the SI, evolved and developed over the last 130 years. Their choice was not unique, but it has become established and familiar over the years, not only by providing a framework for describing the SI, but also for defining the derived units. This role for the base units continues in the present SI even though the SI itself is now defined in terms of the seven defining constants. In this brochure therefore, definitions of the seven base units can still be found but are henceforth based on the seven defining constants: [...]

I am, however, not committed to any course of action. I keep noticing misconceptions around "fundamental" and base units from editors who seem to have been educated that there is something inherently different about these quantities compared to derived units, and placing undue emphasis on the base/derived distinction reinforces the misconception, which is why I would prefer to de-emphasize this. If more than one other person objects, I will leave it be for the time being. —Quondum 20:42, 26 November 2025 (UTC)

I'd be fine with that de-emphasis. Moving away from base/derived distinctions is going to be a slow process for SI, let alone WP, but simply not dividing into separate tables is entirely appropriate. I still worry about exactly what we might put in the comments column. In a table of quantities, commenting "SI base unit" will read as if we're calling a quantity like length a unit, and so cast doubt on our credibility, hence my suggestion of "ISQ base quantity". We may well be able to do better than that too. NebY (talk) 22:02, 26 November 2025 (UTC)

Ah, sorry, I was not paying attention and the the unit/quantity distinction slipped past me. I totally agree with you on this. —Quondum 22:35, 26 November 2025 (UTC)

Well, I did rather slip it in without explanation. Thanks. NebY (talk) 22:42, 26 November 2025 (UTC)

I support de-emphasis of any link with SI base units. While the link is of historical interest, I see little fundamental relevance to a list of physical quantities. Dondervogel 2 (talk) 10:32, 27 November 2025 (UTC)

why is there no base quantities!?!?

after disappearing from the measurements section of wikipedia for a while, i came back to see that base quantities is for some reason gone!?, there's multiple sources that directly reference base quantities that are reliable like nist and bipm, i don't get it, can someone explain why they're gone!?!? Misterpotatoman (talk) 10:09, 1 December 2025 (UTC)

Maybe we can flip that around: you have not made any argument for them to be here, so there is nothing to answer. We talked about it in the section above, so don't expect much response until you have shown that you have understood that. But to give a very short answer: this is not the article to address them, and in reality the "base quantities" are no different from the others, as they too are derived from quantities. Their labeling as base quantities of the ISQ has been retained in the 'Comments' column. —Quondum 12:51, 1 December 2025 (UTC)

well, i make the argument that base quantities are distinct because they are fundamental and can't be described by other means, i think enough sources reference it directly and it to be useful and important enough to be separate, many sources cover them and it's quite useful, also we can set aside logic and rules for a second and think about user usefulness, it would be quite inconvenient for a someone's who wants to know the base quantities to figure it out by themselves, especially considering that the list is in alphabetical order and not notoriety order which in that case would have the base units on the top, but having notoriety order would be very subjective and having a base quantities row would be better, also considering that the list is quite large, we could do a thing i haven't seen before where we have multiple different wikitables for different thing's link wikitable for spacial based units separated by a super space then another wikitable for something else like energy units, what in suggesting here isn't new sections but just slight alterations to the list and a bring back to the base units, Misterpotatoman (talk) 18:55, 1 December 2025 (UTC)

The second sentence of the article is

• The International System of Quantities, which underlies the International System of Units, defines seven base quantities in terms of which any quantity dimension may be expressed, used in dimensional analysis, and which are associated with the SI base units.

Thus anyone keen on the base quantities can easily get them.

You might be interested in a different point of view concerning how fundamental the fundamental constants are:

• Duff, M. J. (2015). How fundamental are fundamental constants?. Contemporary Physics, 56(1), 35-47.
• Uzan, J. P. (2025). Fundamental constants: from measurement to the universe, a window on gravitation and cosmology. Living Reviews in Relativity, 28(1), 1-330.

But these issues and their discussion belong in Physical constant. The purpose of this article is simply to provide a list.

There are different ways to present the list. The current way is scalar/vector/tensor which emphasizes that these are "quantities" rather than units. So for example, acceleration is a vector quantity but it has units of m/s² which is a scalar. Johnjbarton (talk) 19:14, 1 December 2025 (UTC)

Misterpotatoman, amplifying on what Johnjbarton said above, I'll give some examples for you to think about:

• In the SI, measurement of time is defined in terms of a frequency. So which is more fundamental, time or frequency? I would say frequency, if definition sequence is to be considered.
• Electric current is defined by the SI in terms of the electric charge of an electron and a second. Electric charge is arguably more fundamental than electric current. It is even fundamentally a conserved quantity; electric current is not.
• Temperature is defined in terms of energy (per degree of freedom) using a prescribed constant, the Boltzmann constant. It could be (and often has been) argued that temperature is a fictitious dimension, i.e. that it is essentially a relabelling of energy for convenience of use in a different context, hardly what one would consider to be "fundamental".
• Luminosity is defined in terms of, amongst other things, a curve that is intended to represent the sensitivity of the human retina to different wavelengths of light. How fundamental is that?

And so on. Every single one of the base units, and like them, the base quantities, is ultimately defined in some way in terms of something else. Since the base quantities are defined in the SI and ISQ in terms of other quantities, I cannot reconcile this with your statement "base quantities are distinct because they are fundamental and can't be described by other means". To quote ISO 80000-1:2022 §4.2:

It is convenient to consider some quantities of different kinds as mutually independent. Such quantities are called base quantities. [...] It is a matter of choice how many and which quantities are considered to be base quantities. [...]

If you want to rely on NIST/BIPM and ISO as sources, then you should accept when they say that base quantities are a matter of convenience and choice (and hence, by implication, not fundamental in any sense). Nowhere have I seen anything to suggest that any quantity "can't be described by other means", i.e. in terms of other quantities. That is rather like saying that longitude based on a meridian other than through Greenwich would not have been as fundamental. —Quondum 20:37, 1 December 2025 (UTC)

ok, so my second argument is that something doesn't have to be meaningful to exist, higher and lower case have no reason to exist yet they do, and what will a school child do when they're teacher asks for them to write the names of the base quantities, the point im trying to make here is that base quantities are too popular to be removed because it's vital information, so they should be brought back. Misterpotatoman (talk) 23:40, 1 December 2025 (UTC)

No one ever suggested they should be removed, and they were not removed. As far as I can see they are all still there. If you think they should be presented in a different way, make a case for a change, and your proposal will be treated the same way as any other respectful proposal - with respect. Dondervogel 2 (talk) 00:13, 2 December 2025 (UTC)

should we bring back base quantities?

i think base quantities should be brought back, as many sources reference them directly and they could be useful to people, im suggesting that base quantities should be separate from from other quantities because even if they don't follow any strict logic they're to popular and important to be removed, what's the school boy gonna do when tommorrows test features features the base units? what im saying is regardless of anything else, the base units are too popular to be just another unit besides magnetic flux density. Misterpotatoman (talk) 00:35, 2 December 2025 (UTC)

Oppose We have a complete article on base quantities. Johnjbarton (talk) 01:53, 2 December 2025 (UTC)

did you mean we should have a separate article for base quantities, it looks like you typed a bit quickly... Misterpotatoman (talk) 02:02, 2 December 2025 (UTC)

We already have content for base quantities under that name. Johnjbarton (talk) 02:06, 2 December 2025 (UTC)

Note – The proposal appears to be suggesting that the base quantities should be separated out as a table of their own again. The words "brought back" and "removed" are undermining the proposal since they do not apply. What is entirely unclear is why this article should list the base quantities in a separate table, since the more obvious searches Base quantity and Base unit go to more directly appropriate and informative material. The proposer has not indicated that they have understood this or that they have noticed that the material is available in these more obvious locations. To engage in a productive discussion, you need to show that you have heard and understood what others are saying. When others repeat themselves as has been happening here, this can be a indication that they have the impression that you have not understood what has been said. Respond to the specific observations made. —Quondum 14:24, 2 December 2025 (UTC)