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==Temperature problem==
The article states that the triple point of water is precisely 0.01 degrees centigrade, but the article on ], states that more accuately the triple point of water is 0.0098 cegrees centigrade.

I do not know which is correct, although one might assume the 'more accurate' figure would be correct.

Can someone with knowlege edit this please?

] (]) 17:49, 23 March 2008 (UTC)



There is an additional mistake at the "Kelvin temperature conversion formulae" on the right hand side: There it is written that 1 K = 1 C = ... it should be 274,15 K = 1 C = ... or 1 K = - 272,15 C but than F and all the other after it need to be changed too. <span style="font-size: smaller;" class="autosigned">— Preceding ] comment added by ] (]) 14:27, 8 January 2013 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

:No! You need to read it again. That part says specifically: "For temperature ''intervals'' rather than specific temperatures, ..." - ] (]) 14:59, 8 January 2013 (UTC)

== Inconsistency in this article and many linked to it ==

Is the plural form of the kelvin "kelvin" or "kelvins"?

"Ten million kelvin"
OR
"Ten million kelvins"

] 03:40, 19 January 2007 (UTC)

:Kelvin. Are we the only ones here? (-: ] 19:01, 5 February 2007 (UTC)

::Kelvins. The belief that it should be 'kelvin' dates from before 1968 when the SI system used the 'Kelvin scale'. There were then 'degrees Kelvin', just as there are still 'degrees Celsius'. People used to abbreviate 'n degrees Kelvin' to 'n Kelvin', just as they still do with the Celsius scale.

::The SI abolished the 'Kelvin scale' in 1967/68, and now states that the kelvin is just another unit. Therefore we now have 'n kelvins' just as we have 'n metres' and 'n seconds'. The SI brochure itself uses the term '273.16 kelvins' , and just in case you think this is a US/EU thing, here's the NIST saying the same thing: --] 22:01, 6 February 2007 (UTC)

:::Even if plausible examples of the use of "kelvins" can be found, it has in my view not been generally adopted. One reason for this might be that we do not talk about "fahrenheits" and "celsiuses" and never have. <small><span class="autosigned">—&nbsp;Preceding ] comment added by ] (] • ]) 16:10, 8 December 2015 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

::::This can be found explained in many books. In fact, some scientific books go into some length on this matter (just check google books). When referring to the scale, it's "Kelvin." When referring to the unit of temperature, it's "kelvins." When referring to the color temperature of a light, it's "kelvin." Scientifically, this helps avoid confusion between the meanings, but, in general use, either or all three can be found. Like most of the English language, there are no standardized rules for pluralizing units of measurement. Society in general just makes this stuff up as they go along, and all we can do is follow the language as it changes. ] (]) 23:50, 15 December 2015 (UTC)
----
It makes no sense to use capital letters in many instances of the entry, then claim lowercase is the SI standard when spelled out. Besides which, you claim a capital "K" when abbreviated is preferred. A person's name is ALWAYS capitalized. The River Kelvin is named for a person, and the Baron Kelvin was titled for it. If I get a majority of people to claim SI is no longer SI, but si, does that make it right? Tradition has its place, and if William Thomson would not recognize what you have done to his work, no majority can make it right. <small>—The preceding ] comment was added by ] (] • ]){{#if:{{{2|}}}|&#32;{{{2}}}|}}.</small><!-- Template:Unsigned -->
:See ], ], ], ], and the other ]s. - ]'']'' 12:37, 19 February 2007 (UTC)

==Colour vs. Color, and related spelling issues==
The issue of British English vs. American English has been a subject of heated debate. Misplaced Pages’s current policy seems to be the most equitable, encourages contributions, and settles conflict. Per ], the term originally used in the article by the first major contributor(s) should be retained. ] (''])'' 01:50, 1 April 2007 (UTC)

==Deleting the existence of the “Kelvin scale”==
Someone made on the novel and most original notion that of the 13th CGPM in 1967/68, which better defined the ''unit increment'' of thermodynamic temperature (as distinct from the ''scale''), somehow “abolished” the “Kelvin scale” out of existence. You know, the “scale;” that ''“thing”'' created in 1954 by wherein absolute zero equals zero kelvin and the triple point of water equals 273.16&nbsp;K. Perhaps the proponent of this theory should point this out to ] since (and repeated their error too). Encyclopedia Britannica even took the effort to capitalize the word “Kelvin” when referring to this imaginary scale.

OK, I’m done being facetious. I’ve gone out on a limb here and restored the article with the reality that the word “kelvin” refers to both the unit increment ''and'' the scale upon which kelvin temperatures are based. This contributor’s wild notion isn’t supported by any number of Web sites like or and or Note that all these sites also took care to ensure that “Kelvin scale” is capitalized.

And to any contributor desiring to erase the Kelvin scale from existence, <u>please</u> cite an authoritative source to buttress your claim rather than simply flat declaring the scale no longer exists. Merely citing Resolution 4 of the 13th CGPM doesn’t cut it. Resolution 4 doesn’t say <u>anywhere</u> that the temperature ''scale'' is abolished, only that the unit increment is ''better defined''. Oh, one other thing: please resist the temptation to declare that Encyclopedia Britannica and others like the NIST are wrong. You know, Encyclopedia Britannica actually hires and pays ''experts'' to write their articles. They also use professional (paid) editors to edit articles to make them flow well and to make them harmonious with articles on related topics. Though expensive, this way of making an encyclopedia does have its advantages.

Now, if you still can’t reconcile how the ''unit increment'' can peacefully coexist with the ''scale,'' just remember that the unit increment known as the ''kelvin'' is defined as 1/273.16th the difference between absolute zero and the triple point of water. It is a distinct noun; a ''thing'', like the kilogram or meter. The combined intended effect of the 13th CGPM’s two back-to-back resolutions ( and Resolution 4), was there was now a clear, consistent, rational basis established for why one could measure both temperatures and ''intervals'' (like a 30&nbsp;K temperature rise on a heatsink), without using a degree symbol (°) in front of the “K” symbol. However, the ''Kelvin <u>scale</u>'' still exists and its 1954 definition still holds whereby absolute zero is 0&nbsp;K and the triple point of water is 273.16&nbsp;K.

If you ''still'' feel that something in Resolution 4 of the 13th CGPM somehow abrogated the definition of the thermodynamic temperature scale, examine the wording at the beginning of the resolution:

{{cquote|'''considering''' that it is useful to formulate more explicitly the definition of the unit of thermodynamic temperature contained in <u>'''Resolution&nbsp;3'''</u> of the 10th CGPM (1954),}}

And what does does Resolution&nbsp;3 of the 10th CGPM say? It starts out with the following:

{{cquote|The 10th Conférence Générale des Poids et Mesures decides to define the thermodynamic temperature scale by choosing the triple point of water…}}

As you can see, ''far'' from abrogating Resolution 3 of the 10th CGPM, the 13th CGPM in 1967/68 was abundantly clear that they were <u>keeping</u> the thermodynamic temperature scale and were only “<u>more explicitly</u>” defining the unit comprising that scale. This is all sort of a '''Well…''' '''''DUHHH&nbsp;''''' thing. After all, without the scale, we couldn’t measure temperatures; we could only measure temperature intervals. Note too that the CGPM never named the thermodynamic temperature scale, not even back in 1954; they referred to it by ''description:'' “the thermodynamic temperature scale.” Why? you might ask. Going back even further, to the formal name of the unit increment of temperature on the “thermodynamic temperature scale” was also somewhat descriptive rather than a good, proper name: “degree absolute” (symbol °K). So it was obvious to everyone and ] what the scale’s name became when the unit increment got its new name in 1967/68. It was, of course, even more obvious that nothing the 13th CGPM did erased the scale from existence.

And last: while the edits in question certainly met Misplaced Pages’s advise to contributors to “''']'''” when making edits, a quick sanity check would have been helpful before deciding that the Kelvin scale “no longer exists.” Remember, Resolution 4 of the 13th CGPM (the one creating the unit increment called ''the kelvin'') dates back to 1967/68. This event preceded the ] by over 22 years. One should have asked: “Why then, are there so many Web sites that mention the existence of the Kelvin scale?” It’s not like the term could be some sort of legacy holdover from bygone days. ] (''])'' 03:18, 1 April 2007 (UTC)

:I seem to remember that I reworded the article to get rid of the clumsy first sentence - "Kelvin is, or relates to, a unit increment of temperature known as the kelvin (symbol: K)" - and various other minor style problems. My objection to that sentence is that its subject is the word "kelvin", not the kelvin or the Kelvin scale. Misplaced Pages articles are about things, not words, so this sentence needs to change.

:I do admit, however, that the statement I made in my edit summary that "there is no longer a Kelvin scale" was wrong, although it was based on my Google search of the BIPM's website which revealed eight instances of "thermodynamic temperature scale" and none of either "Kelvin scale" or "Kelvin temperature scale". That was my sanity check. I know that the phrase "Kelvin scale" is widely used, even in the hallowed and infallible EB, but I thought it might have been superseded by the BIPM's usage. --] 19:43, 2 April 2007 (UTC)

::Where do you get off declaring that “This article is about the kelvin “? Is there a separate Misplaced Pages article for the Kelvin scale? No, there isn’t. This one article must properly address both nouns. The Kelvin scale” is a noun. So too is “the kelvin” (the unit increment). The word "kelvin” is part of either noun. Unless there are to be ''two entirely different Misplaced Pages articles'', one titled “Kelvin (unit)” and another titled “Kelvin scale” (a <u>highly</u> inadvisable approach), it is important for readers to know that the word kelvin refers to two “things.” Further, this introductory format has been used successfully on the ] article for a long time with great success. A good indicator of the proper way to tackle this is how Encyclopedia Britannica handled it. They wrote in the introductory paragraph that the word applies to two different things. '''''Any''''' good encyclopedia would use this approach. What are you going to do, create a separate article for the Kelvin scale just to get your way? Give it up. Your logic makes no sense and is unsupportable. ] (''])'' 23:56, 2 April 2007 (UTC)

::Update: After sleeping on it, I understood better what your objection is over how the ''“subject is the word ‘kelvin’”''. I agree that the wording was rather dictionary-like than encyclopedia-like in nature. I hope you approve of the new wording. By making the first word in the sentence “The”, the following word “kelvin”, is lowercase (which is good when one is discussing the unit increment). As now revised, it deletes the ''“is, or relates to,”'' (which I suspect goes to the heart of what you felt was “clumsy”). And the new wording retains the important virtue of not deleting the Kelvin scale from existence; it addresses both nouns: the unit increment, and the scale. Peace? ] (''])'' 21:47, 3 April 2007 (UTC)

:::Yes, peace, Greg. I can find nothing to object to, factually, in the current wording, although having two successive sentences starting with 'The kelvin is...' is not ideal. Anyway, I'm not going to change them in case this starts to look like a tit-for-tat exercise. I'll let someone else take care of that. Thank you for accommodating my views, which is generous of you given my misinterpretation of Resolution 3/13th. I guess I must have seen the abolition of the term 'degree Kelvin' and jumped to the conclusion that the term 'Kelvin scale' had been abolished at the same time. You have convinced me with copious evidence that the latter term has not been abolished. --] 21:00, 4 April 2007 (UTC)

::::You’re right. Excessive redundancy fixed: second instance of ''“The kelvin is”'' replaced with ''“It is”''. ] (''])'' 21:24, 4 April 2007 (UTC)

==Conversion Chart==
::And to whoever <u>screwed up the conversion table</u>: Drag out a calculator and do the math yourself; it's not ''that'' complex. I checked the history log. At the exact moment I was actually ''making something'' (creating for the ] article), you were over here fouling things up when all you needed to do was take the time to perform a simple, calculator-based sanity check on what was already here. Just so someone doesn’t have to restore the chart again, I’ll step you through how the now-restored math is correct. Examine the fifth conversion down in the chart:

:::To find Fahrenheit, From kelvin: °F = (K &times; 1.8) − 459.67

:::Plug a number into it, the melting point of water for instance…

:::?? °F = (273.15 K &times; 1.8) − 459.67

::Try it. You’ll see it works as the answer is the correct 32 °F. Whatever you were copying elsewhere on the Web probably had different column headings on the chart (like, “To convert from…” or something like that).

::] (''])'' 00:25, 3 April 2007 (UTC)

I may be wrong (I haven't had my coffee yet) but I believe the equations for kelvin to celsius and celsius to kelvin are reversed in the chart. 0 degrees kelvin is absolute zero, 0 degrees celsius is the substantially higher melting point of water under standard conditions. The chart gives degrees celsius as "degrees kelvin MINUS the constant 273.15" and degrees kelvin as degrees celsius PLUS 273.15. Unless I am parsing this incorrectly, this places the freezng point of water at "absolute zero" and "absolute zero" at an impossibly lower temperature. I believe the constant 273.15 is correct, as kelvin and celsius use degrees of the same quantity, but it has been transposed in the chart. I don't want to chck out and correct the whole chart right now, but if I am right, and/or if the above poster is right, this chart needs substantial revision.
] (]) 18:51, 19 July 2010 (UTC)
: I think you need that coffee. From the chart: taking 0 degrees celsius on the top line, equates to + 273 Kelvin, +32 degrees Farenheit, etc, which is correct. From the Infobox (Kelvin temperature conversion formulae), if we take 273.15 kelvin, the Celcuis equivalent = (273.15 - 273.15) = zero Celcuis, which is what we expect. ] (]) 20:11, 19 July 2010 (UTC)


==Plural usage== ==Plural usage==
Line 114: Line 23:
::We don't say Celsiuses or Fahrenheits because we say degree'''s''' Celsius or degree'''s''' Fahrenheit. The plurality of '''degrees''' is what leads people to want to use a plural. I don't think it's a problem. As long as the abbreviated form doesn't get corrupt, e.g. as we sometime see in "kms/h" instead of "km/h", for example. ] (]) 04:22, 27 July 2009 (UTC) ::We don't say Celsiuses or Fahrenheits because we say degree'''s''' Celsius or degree'''s''' Fahrenheit. The plurality of '''degrees''' is what leads people to want to use a plural. I don't think it's a problem. As long as the abbreviated form doesn't get corrupt, e.g. as we sometime see in "kms/h" instead of "km/h", for example. ] (]) 04:22, 27 July 2009 (UTC)


:BIPM quote:
==Georgia peach==
"over a wide temperature range from a few '''kelvins''' to above 550 K."
This is a bad example, as Georgia is always capitalized, while kelvin is not always capitalized. --] 20:19, 16 July 2007 (UTC)
:from "SI-App2-kelvin.pdf"
:] (]) 13:51, 12 September 2022 (UTC) baden k.


==SI prefixed forms of kelvin== == History of Kelvin scale ==


There seems to be an issue with the history of the Kelvin scale, which I reverted. The 1848 paper does deal with the need for an absolute thermometric scale, so I'm not sure what the point of the edit was. There were also some typoes present, and items removed without explanation. So, let's discuss what is thought to be needed before reinstating this change. ] (]) 03:16, 13 June 2019 (UTC)
What does this table listing everything from yoctokelvin (1e-24 K) to yottakelvin (1e+24 K) add to the article? I think it would suffice with a remark along the lines of ''as with other SI units, standard SI prefixes can be used with the K symbol, for example mK for millikelvin (1e-3 K) and MK for megakelvin (1e6 K). Temperatures of MK occur in <insert field of science here>''. The whole idea of SI prefixes is that you can use them for ANY unit. Why not add such tables to ], ], ], and every other SI unit in existence as well? It makes just as much sense to mention that the word "temperature" can be prefixed with "high", "low" and any other adjective. It does not add any new information. Note that yottaparsec makes as little sense as yottakelvin. Is there any notable scientific publication that actually uses yottakelvins? If not, it should not be mentioned on this page, since Misplaced Pages is not a place for ]. ] (]) 09:29, 23 August 2007 (UTC)
:Let me be specific about what I don't like:
:It doesn't add anything - it just bulks up the article a bit. --] 14:12, 23 August 2007 (UTC)
*Change of "engineer and physicist" to "physicist". He's remembered today primarily as a physicist, but recognition in his own time was for his engineering skills. So I think that description is appropriate.
::Agreed. The same argument holds for the articles on ], ], ], ], ], ], ], ], ], ], ], ]. Maybe it's good to build consensus about removing these tables. ] (]) 15:44, 23 August 2007 (UTC)
*Parenthetical statement in lead about why he was awarded the title. We generally prefer to avoid parenthetical statements in the lede.
::I've nominated ] for deletion. I think the deletion discussion could serve as a place to build consensus. ] (]) 16:02, 23 August 2007 (UTC)
*Celcius. It's tricky wording to begin with (we used to have the terms degree Celsius and degree Kelvin, now it's the kelvin alone), the mispelling doesn't help. I think we should leave it as is. The point is that one unit of Celsius (called a degree) is equivalent to a difference of one Kelvin, the question is the phraseology.
:::'''Hankwang''': You should read the article on ] as you don’t seem to understand what it means. The SI prefixes may be applied to any SI (or even non-SI unit of measure). The chart lists the full range of SI-prefixed forms of the kelvin. Further, it serves a purpose that a general link to ] can't do: it shows which prefixed versions of the kelvin (in bold) are the common one's that one might want to limit themselves to to avoid being too obscure. '''Yath''': Finally, as had been explained in the editors’ note imbedded within the ] section, other articles link directly to this table. For instance, the ] article might mention 450&nbsp;] and the link takes the reader to the table. Articles would become bloated if they each had to individually explain every prefixed form of the kelvin. This issue is addressed most efficiently by including tables in their respective units of measure for other articles to link to. When you delete referenced sections like you did, you break numerous links in other Misplaced Pages articles because the referenced section is '''''gone.''''' Most importantly, you should read and comprehend what editors notes are saying. Ill-considered, wholesale deletions of entire sections of articles—especially when an editors’ note advised of the ramifications—are disruptive to others. ] (''])'' 17:39, 23 August 2007 (UTC)
*In his 1848 paper, he made clear the need for an absolute scale. Maybe we need to reword it to avoid implying that he had it entirely worked out in 1848, but we don't need to complicate it with later 1851 paper which still didn't have all the details worked out. The point to get across is when the work started.
::::This is the second time we've met up in an article and your immediate response is to revert me. Have you considered that my edits improve the articles, and that I don't perform them without good reason? --] 18:38, 23 August 2007 (UTC)
:] (]) 03:23, 13 June 2019 (UTC)
:::::Don't play games. The last time you edited this article was nearly a year ago. Yet nine hours after I restored the table, you visit this article and ''delete the section.'' Perhaps this is shear coincidence; I doubt it. As regards "improving" articles, for the reasons clearly stated above, absolutely no; your deletion broke numerous other links. As I stated above, read and comprehend editors’ notes so you understand the ramifications of what you’re doing. If it can be convincingly demonstrated that you are just trying to be disruptive and are not making good faith edits, you might be blocked. ] (''])'' 18:44, 23 August 2007 (UTC)
:::Now let's keep a cool head, okay? Join the discussion on ] and contribute to a consensus for either keeping or deleting these tables. ] (]) 20:02, 23 August 2007 (UTC)
::::I am keeping a cool head. Your baseless insinuation that I’m not does not establish you as the wise voice of reason. I will, however, visit the provided link. ] (''])'' 20:07, 23 August 2007 (UTC) '''P.S.''': I added my comments to ]. ] (''])'' 20:52, 23 August 2007 (UTC)


I simply thought I would share what I have learned:
I'm in absolute agreement that a full table with all SI prefixes is completely unnecessary and unwanted. There should absolutely be a reference to the "SI prefixes" page in wikipedia, which explains the usage of the prefixes, but it makes no sense to have it in every article with SI units. And especially not right at the very beginning of the page in the introduction. ] (]) 00:13, 12 April 2008 (UTC)
* Kelvin thought of himself as a physicist, and the engineering got added in because the engineer initially running the project (Preece, if memory serves me) screwed up the Atlantic cable project; Kelvin was brought in to fix it, which he did. He was a physicist who for a time did engineering, but he was not an engineer. I don't know where you got that idea, but it is wrong.
* The writing is not perfect; I felt that correct information is more important that great wording (to which I am sensitive).
* Please feel free to revise. At least distinguish between recognizing the need for an absolute scale (I did explain what such a scale means) and actually finding one. <!-- Template:Unsigned --><small class="autosigned">—&nbsp;Preceding ] comment added by ] (] • ]) 04:48, 13 June 2019 (UTC)</small> <!--Autosigned by SineBot-->


::My two cents. The first thing to remember is that the article is about the unit of measurement, not about Kelvin himself, so details about his schooling and preferred rather than professional titles are really not germane here. (Technically, if one trains to be an engineer but doesn't make a living at it, they are not an engineer, but if one works as an engineer, they are one regardless of training. To some it just comes naturally.)
==SI table via template==
I've reverted the table back to its Wiki table form. That is, after all, what Wiki ''table syntax'' is for: creating ''tables.'' Whereas templates are nice tool to have (thank you for creating the template) when creating new articles or brand new tables, they can not serve every need for every article. The main disadvantage of templates is that ''templates can be deleted'' at a later date and this would delete the table, would it not? Attempts to do <u>precisely</u> this—delete a table-generating template—have been attempted in the recent past after certain users objected to the very existence of SI tables. I guess I can’t ignore the preceding discussion topic (see above): as a matter of fact, once such user ''was'' '''''you.''''' I’m very pleased to see that you’ve had a 180° change of heart. I’m actually somewhat surprised at this, given your well articulated arguments above as to why they had no value whatsoever. You also advanced a good argument as to why they have no value in (which was not affirmed by consensus). But I see that you now wholeheartedly embrace them. Unfortunately, the table you entered into this article had the symbols and names reversed. '''''' the original table, and '''''' what you replaced it with. Notice the mix up. I’m actually rather surprised you hadn’t noticed that when you placed it here.


::Great wording can be all the difference between something that is coherent and understandable, and something either incomprehensible or something that may mean multiple things depending upon how you look at it. With this particular topic, it's very difficult to avoid those dual meanings and make it fully understandable to the general masses. Great care should be taken to make sure of both.
Please allow other users to use your recently created template for new projects and don't replace existing tables. ] (''])'' 22:55, 27 September 2007 (UTC)
:I reversed to submultiples/multiples now and changed the headings. Please continue the discussion on ]. ] (]) 09:59, 28 September 2007 (UTC)


::Mostly, we need sources to verify what you learned. The info must come from somewhere, so it is always advisable to cite those sources for any info you add. I hope that helps. ] (]) 20:32, 13 June 2019 (UTC)
==Unicode use==
Someone wrote the following in the section titled ]:


== triple point of water ==
{{quotation|] includes the "kelvin sign" at U+212A (&#x212A;). However, the "kelvin sign" is ] into U+006B (the ordinary Latin letter K), and is thereby seen as a (pre-existing) encoding mistake. The ordinary K should be used directly.<ref>{{cite book |title=The Unicode Standard |url=http://www.unicode.org/versions/Unicode5.0.0/ |format=PDF |accessdate=2007-07-06 |edition=Version 5.0 |isbn=0-321-48091-0 |pages=493 |chapter=Symbols |chapterurl=http://www.unicode.org/versions/Unicode5.0.0/ch15.pdf }}</ref>}}


The redefinition of SI results in the triple point of water now becoming an empirically determined value. I think the current lead is perhaps misleading in that it could be read to indicate that the triple point of water is still exactly 0.01 Celsius, when this is no longer the case. Thus I changed the lead. Please let me know if you feel that this is incorrect. ] (]) 03:10, 7 July 2019 (UTC)
Note that the cited reference, ''The Unicode Standard, Version 5.0, Chapter 15: Symbols'' ( states precisely the following regarding the kelvin symbol:


== Potential new sections, Implications of 2019 revision and motivation for using an absolute scale ==
{{cquote|Three letterlike symbols have been given canonical equivalence to regular letters: U+2126 ohm sign, U+212A kelvin sign, and U+212B angstrom sign. In all three instances, the regular letter should be used. <u>'''''If''''' text is normalized</u> according to Unicode Standard Annex #15, “Unicode Normalization Forms,” these three characters will be replaced by their regular equivalents.}}


Do you think we should create a section on the mathematical implications of assigning an exact value the the Boltzmann constant?
(Emphasis added)


Do you think we should create a section on the the motivation for creating an absolute temperature scale at all, rather than sticking with scales that have some other starting point? This has the potential to get into puff piece territory, but I could also imagine this being one of the main questions people have when looking this subject up. ] (]) 07:29, 18 February 2022 (UTC)
The section as originally worded misrepresented the facts and cites a reference that doesn’t support the statement. In fact, any computer capable of displaying Unicode should—and usually will—display the Unicode kelvin character.


:I don't know much about the first part of your question, as I don't speak math very fluently. Possibly could be of value if you can translate it to English for all us non-mathematicians out here.
Shown below is what my browser (Safari under Mac OS X) shows when the kelvin character and the letter K are showed side-by-side:


:The second part of your question is something that interests me very much, as I'm always wanting to know why. It may be a little much or off topic for this article, but I think it would be perfect for the ] article. I know Kelvin was a pioneer in both deep cold and deep vacuum measurements, along with Edison and several others. (They each began using the ] scale very early in their research, so the concept was not new.) Both are quantities you can assign a known minimum to, and in both you start to get wonky readings at extreme lows without having a fixed zero-reference to compare against. It's not necessarily that an absolute scale is better than a relative one, because it all depends on what you're measuring for. (See discussion at ]) We live in a pressurized atmosphere at temperatures above freezing, so for day-to-day measurements a relative scale is better. For example, with things like tire pressure or blood pressure, the absolute pressure is not very critical. It's far more important to know the difference between them and atmospheric pressure, because that is a far better indication of burst pressure. With lighting, aeronautics, or barometry, an absolute scale is far more accurate for the necessary info. When it comes to deep cold or deep vacuum measurements, it starts to become really apparent that you need an absolute scale so you have a fixed reference point that doesn't change.
]


:Also, I think the section on orders of magnitude could be toned down a little. It would probably read better as a list, so it doesn't clutter up the table of contents as much. ] (]) 04:08, 2 March 2022 (UTC)
In fact, some browsers <u>can</u> display the kelvin character, which is coded in Unicode as '''&amp;#x212A;''' . And in fact, some old browsers <u>can’t</u> handle Unicode and display weird, box-like characters. And in fact, others <u>may</u> normalize them. It is however, '''''entirely''''' incorrect to state that ''“ is thereby seen as a (pre-existing) encoding mistake.”''


== 1 Kelvin ==
It is obvious on the face of it that if one specifies a Unicode character, many computers will properly display them; that’s what Unicode is ''for'' after all. For instance, when I measure four microvolts (4&nbsp;µV), the “&#x00B5;” symbol is a special Unicode ‘micro’ symbol, which is different from the Greek lowercase mu character (μ). If you can read these characters and see the difference between the two, then your computer is properly displaying Unicode.


I don't see why there should be a (rather lengthy) section on '''1 Kelvin''' in this article. More appropriately it should be in a separate article, much like ''']'''. <br>
The end conclusion in the text that used to be in the article is the same one as in my new text: one should use a regular uppercase K so it displays properly on all computers. This is also consistent with the advise given in ''The Unicode Standard, Version 5.0, Chapter 15: Symbols''.
—DIV (] (]) 03:47, 9 May 2022 (UTC))


== Bloat ==
] (''])'' 21:39, 10 October 2007 (UTC)


The user {{user|Ava Eva Thornton}} added a huge volume of content in this article, not all of it useful. vs. . While, some the content is mostly tangential, usually quantitative information. I have already deleted a section that was purely ] that added no useful information about the 2019 definition. The "Multiples" section is mostly ], and I recommend either converting it into a table like ], or deleting it outright; "1 kelvin" should probably be deleted for the same reason. –] (]]) 19:55, 13 July 2022 (UTC)
: It is actually entirely correct in saying that “ is thereby seen as a (pre-existing) encoding mistake.” That's exactly what canonical normalization means; that Unicode encoded a duplicate of an existing character, either as an error, or as in this case, for compatibility with a different standard, and therefore it should be treated exactly same as that existing character (in this case, K).--] (]) 03:33, 7 March 2008 (UTC)
:The {{tq|Multiples}} section should simply go away. The {{tq|1 Kelvin}} section has interesting information, but isn't specific to the Kelvin scale, so should probably be moved to another article. ] (]) 20:26, 13 July 2022 (UTC)
::The {{tq|1 Kelvin}} section probably belongs in the ] section, which it at least partially overlaps. ] (]) 20:33, 13 July 2022 (UTC)


== Conversion Table Placement ==
{{reflist-talk}}


The Conversion Table is placed in (adjacent to) the "Practical uses" section, but has nothing to do with the section's content. A better placement would be desirable.
== electronVolts ==


] (]) 13:16, 12 September 2022 (UTC) baden k.
Should we include eV in the table in this article? eV are a unit of energy, not temperature. While it may be convenient to use it as a unit of temperature in certain limited contexts, that's not generally the case, and this really will only confuse Misplaced Pages users. -] 07:51, 27 October 2007 (UTC)
: At least we should make it clear that without the Boltzmann constant the quantity calculus is inconsistent. --] (]) 17:16, 27 November 2007 (UTC)
:: I removed it, since it only complicates things (and after all, if we have eVs, then we should also have cm^-1, J and all other units that have some sort of temperature equivalent).--] (]) 21:53, 28 December 2007 (UTC)


== Make the range of Kelvin immediately clear ==
== Population Inversion ==


In the intro, can it be made immediately obvious that a characteristic of Kelvin is that its lowest possible value is 0, because it is tied to kinetic energy? i.e. Kelvin's values range from 0 on upwards; there is never a negative Kelvin value (if this is true). Such basic things about the nature and usage and consequences of concepts are nice to make immediately clear, for anyone who doesn't really need to know more than that, but does need to know and understand such implications for usage. And then anyone who wants to go further for the sake of knowledge or the nuances of those reasons can delve into the further details.
It's been over 20 years since I studied any statistical mechanics, but I believe that population inversions, which can occur inside lasers for instance, have "temperatures" measured in negative Kelvin.


I'll write what I might suggest for such an addition later, if I remember. ] (]) 23:25, 17 February 2023 (UTC)
I'd like to see some mentione of the existence and interpretation of negative Kelvin temperatures. See ].
:I have added that link to the "See also" section. ] (]) 13:41, 4 April 2009 (UTC)


:I agree. The lede is a little backwards in its presentation, which doesn't help really clarify immediately what this thing is. The most important information for building context is actually in the last sentence of the first paragraph, when it should really be the first. That it's an SI unit or who it's named after is really secondary to that. For all intents and purposes, Kelvin is just another name for Celsius (absolute), that is, it's based on the Celsius scale, but starts at absolute zero rather than the freezing point of water. If you want to try to improve it, you are most welcome to give it a shot. ] (]) 01:08, 18 February 2023 (UTC)
=="In Short"==
::I took a stab. I think the 0 K - 273.15 K - 273.16 K sentence should explain the range pretty well. Although maybe it's hard to understand? ] (]) 05:06, 24 April 2023 (UTC)


== Lead structure ==
I corrected the use of the degree symbol here, as well as making it marginally more informative. However, I question the need for this section at all. ] (]) 20:24, 24 January 2008 (UTC)


@] I don't think your lead structure is "much-improved". My two-paragraph structure has a simple, logical structure: one paragraph for the current definition and one paragraph for the historical definitions. This makes the key points clear. In contrast, your structure is fragmented - the historical context abruptly ends and then switches to discussing the 2019 redefinition in a new paragraph. Putting the 2019 redefinition using the Boltzmann at the start of a new paragraph is confusing to readers as they wonder why this is a new topic and how it is related to kelvins. In contrast, my second paragraph seamlessly integrates all of the historical definitions without disrupting the flow of the text. Two paragraphs is also more concise than 3 - following your logic, every sentence would be in its own paragraph because these "brief paragraphs" would somehow make it less intimidating. But of course this is flawed as breaking up paragraphs with random breaks makes it less readable and more intimidating.
==Heat vs. Temperature==


My structure introduces the precise, current definition of the scale early, following ]: "If its subject is definable, then the first sentence should give a concise definition." (Per ] it is actually two sentences with two definitions, as the kelvin and Kelvin scale are highly related topics). In contrast, if someone needs to identify the current definition of the Kelvin scale in your structure, they would have to look at the beginning and end of the first paragraph and also search through the end of the third paragraph. This disjointed definition is not suitable for grasping the concept of the kelvin. It is not accessible, not early, and not clear. ] (]) 18:36, 2 May 2024 (UTC)
The section labeled "Uppercase/lowercase, plural form usage, and written conventions" ends with the statement "an absolute unit of measure which can be manipulated algebraically (e.g. multiply by 2 to indicate twice the amount of heat)." This should read "multiply by 2 to indicate twice the amount of kinetic energy." As a change in the amount of heat does not necessarily correspond to a change in the temperature, even Kelvins, as in a phase change. ] (])
:I agree with that, but it's a very subtle point: the change in temperature (e.g. doubling its absolute value) does not imply at all doubling the energy in the system -- you can even change temperature along an adiabatic process!
:This is an old issue concerning the fact that temperature does not represent a fully-qualified physical quantity: in fact there is no sense in the statement "System A has twice the temperature of System B" in a unit-independent meaning. In contrast, for every other physical quantity Q like volume or mass, a statement like "System A has twice Q of System B" makes sense even without reference to any unit of measurement. Even more, it is just this property that make it possible to choose/define a physical unit for that quantity. Temperature is different, it is only a scale of comparison between systems which make order among them based on the heat flow direction: any ''non linear'' rescale of any good scale is good as well. (ok, absolute T is "more good" since it's linearly related to a physical quantity, namely energy...).
:To make a long story short, the change you propose is by far better that the current statement, so I'm going to change the sentence the way you suggested, but there should be a place where the story is explained in its full length (like I did for it.wiki . Ciao, ] (]) 09:44, 29 November 2008 (UTC)


:To address the concern about the 2019 definition not appearing immediately, the infobox to add a line "2019 definition" that gives out the Boltzmann constant in terms of J/K.
==color temp==
:I had done many of the edits to try to simplify the lead. I am afraid if we overload new readers by immediately in the first paragraph getting into very technical Boltzmann constant (which itself requires a large amount of explaining and background knowledge), then we risk loosing them completely.
I restored this section. It was deleted by a user without any discussion. This is a common and important usage of the Kelvin scale. I don't accept the assertion that color temperature has no relation to kelvin. ] (]) 10:33, 23 November 2008 (UTC)
:The historical definition using the melting point of ice is something that won't loose new readers because it is more relatable too. Even though the kelvin is no longer precisely defined by the melting point, that is still a good-enough and concise definition for practical purposes. As the "2019 definition" section now explains:
:"For practical purposes, the redefinition was unnoticed; enough digits were used for the Boltzmann constant to ensure that 273.16&nbsp;K has enough ] to contain the uncertainty of water's triple point<ref name="codata2017">{{cite journal |last1=Newell |first1=D B |last2=Cabiati |first2=F |last3=Fischer |first3=J |last4=Fujii |first4=K |last5=Karshenboim |first5=S G |last6=Margolis |first6=H S |last7=de Mirandés |first7=E |last8=Mohr |first8=P J |last9=Nez |first9=F |last10=Pachucki |first10=K |last11=Quinn |first11=T J |last12=Taylor |first12=B N |last13=Wang |first13=M |last14=Wood |first14=B M |last15=Zhang |first15=Z |date=29 January 2018 |title=The CODATA 2017 values of ''h'', ''e'', ''k'', and ''N''<sub>A</sub> for the revision of the SI |journal=Metrologia |volume=55 |issue=1 |pages=L13–L16 |bibcode=2018Metro..55L..13N |doi=10.1088/1681-7575/aa950a |bibcode-access=free |doi-access=free |collaboration=Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants}}</ref> and water will still freeze at 0&nbsp;°C<ref>{{cite web |title=Updating the definition of the kelvin |url=http://www.bipm.org/wg/CCT/TG-SI/Allowed/Documents/Updating_the_definition_of_the_kelvin2.pdf |url-status=dead |archive-url=https://web.archive.org/web/20081123043044/http://www.bipm.org/wg/CCT/TG-SI/Allowed/Documents/Updating_the_definition_of_the_kelvin2.pdf |archive-date=23 November 2008 |access-date=2010-02-23 |publisher=]}}</ref> to a high degree of precision." ] (]) 20:04, 2 May 2024 (UTC)
{{reflist-talk}}
::Upon rereading the intro a few times, I would suggest the name origin "It is named after ]-born ] scientist ] (1824–1907)" could be moved to the very end of the introduction instead of being in the first paragraph, because its name itself has little to do with what it is. ] (]) 20:11, 2 May 2024 (UTC)
:::Here's my advice. Shorter is not always better, and being too brief is always a problem with technical and scientific articles. Technicians and scientists invariably write for technicians and scientists, leaving out much of the background information necessary for the general reader to follow smoothly, hence the term "techniquese". There is such a thing as too brief.


:::Explaining complex things to people who have no background knowledge of it is one of the greatest challenges in writing. It shouldn't focus on the number of paragraphs as much as getting the point across as concisely yet precisely as possible.
== 273.15 vs. 273.16 ==


:::The lede should be written at around a 6th grade level, which doesn't mean dumbing it down or oversimplifying, but explaining it in terms that a 6th grader should be expected to understand. It doesn't need to be overly detailed, because it's just a summary of the body, but should give the basic gist of what the body contains in easily understandable terminology.
The article uses both the figures and 273.15 and 273.16. To the naive eye this looks like a typo or bad rounding; I found a forum thread elsewhere saying it's because the difference between the triple point and the freezing point. I think a few words on this distinction (if it truly exists) would be a good addition. --] (]) 00:50, 8 September 2009 (UTC)


:::Things like the history are not as important as what the subject is. That should be answered in the first paragraph. But what if I don't know what absolute zero means? If I have to click on that wikilink you've already lost me down the rabbit hole, so that doesn't work either. Imagine trying to explain it to a 6th grader in a way they'll comprehend precisely what the subject is.
: Kelvin is defined to use 273.16 K for the triple point of water. However the degree Celsius is defined (in terms of kelvin) to be: T_Celsius = T_kelvin - 273.15. The Celsius definition uses the ice point and not the triple point. So I think the text is correct? but it is a bit confusing.<br />—]&nbsp;(]) 06:23, 28 October 2009 (UTC)


:::For comparison, a very well-written article is ]. It's not overly technical in the lede, but saves that for the body, yet gives all the pertinent info needed to get a good understanding of the subject in a very logical order. Not too long and not too short either. I hope that helps. ] (]) 20:38, 2 May 2024 (UTC)
::] now modified. ] (]) 10:39, 13 November 2009 (UTC)
:::: and tried to explain just enough as to why things were done. Those are significant changes, so I understand if other editors revert it or make more changes. ] (]) 00:50, 3 May 2024 (UTC)
:::::I think it reads much better that way. By that, I mean it's more cohesive and flows a lot better, and those are important factors for both comprehension and in keeping the average reader's interest.


:::::That said, I would eliminate the first sentence of the second paragraph altogether. I had to read it twice to figure out what it was saying, and it seems redundant considering the following sentence says basically the same thing.
: As the triple point of VSMOW is at 273.16 K, the last sentence of ] should be: "water will still freeze at 0 °C (273.15 K)." and not 273.16 K. ] (]) 09:07, 24 April 2010 (UTC)


:::::For this sentence, ''"...the 2019 redefinition of the SI base units now defines the kelvin by setting the Boltzmann constant to exactly 1.380649×10−23 joules per kelvin"'', I would probably clarify that it's defining temperature as a product of energy, so I might change it to read: ''"...the 2019 redefinition of the SI base units now defines the kelvin in terms of energy by setting the Boltzmann constant to exactly 1.380649×10−23 joules per kelvin"'', or something like that. Just so the reader has enough context to connect the dots.
::The paragraph that you are refering to, was added on 22 February 2010, and as you correctly pointed it is was wrong. The triple point of water is not the same as the freezing point; the latter being 0.01 K lower than the former. ] (]) 17:08, 25 April 2010 (UTC)


:::::The only thing else I wonder is if a short sentence, maybe at the end of the second paragraph, comparing kelvin to other absolute scales (Rankine, which is the same principal but based on the Fahrenheit scale) would be helpful to the reader, or would it just confuse the issue? ] (]) 01:24, 3 May 2024 (UTC)
:::The triple point ''is'' the freezing point for that pressure which is not atmospheric pressure. ] 11:04, 17 May 2015 (UTC)


::::::Of course, there have been some changes while I was writing the above, so many of those suggestions may no longer apply, but it looks like you got the gist. ] (]) 01:36, 3 May 2024 (UTC)
== Removal of discussion regarding Thomson's calculation of absolute zero ==
:::::::Thanks, I've incorporated the "''now defines the kelvin in terms of energy"'' and sorry I did make quite more changes while you were typing. I'll sleep now and won't edit it for the next day or so to give others a chance to edit. ] (]) 03:24, 3 May 2024 (UTC)
I removed the sentence noting the accuracy of Thomson's estimate of absolute zero. Since Thomson's data only had three significant figures, he could only estimate absolte zero to three significant figures - the agreement in the fourth significant figure was a fluke. Furthermore, as no refernces was given to this, so I must assume a bit of well-intentioned, but poor ].
:Mathnerd314159, we're writing for one of the largest audiences in the world, and we don't know why our readers are here or how they got here. We do know that it's extraordinarily unlikely that they'll be reading Misplaced Pages in order to do anything that requires the value of the Boltzmann constant. Laboratories measuring temperature in their experiments, industries measuring process temperatures, manufacturers of temperature measurement equipment and others will at intervals want to ensure their instrumentation's good. For this, there's a worldwide system of certification ultimately traceable back to national and international standards - see ] - which since 2019 can if necessary be completely independently established. That's an extraordinary achievement, finally liberating international metrology from the ] and the isotopes of water, and it's quite rarefied; it makes no difference to those laboratories, industries and manufacturers. Likewise, what the Boltzmann constant is, how it's used to define the kelvin or what particular numeric constant is used in that definition aren't going to be at all meaningful to our readers until they understand a bit more about what the kelvin is. Indeed, once they've understood that bit more about the kelvin, they may well still not have the slightest interest in the Boltzmann constant, and we should respect that, not insist that they read all the digits before going further.
:Instead, we talk about the idea of absolute temperature, and about the close but shifting relationship between the kelvin and the more familiar degree Celsius. Especially in the lead, we can use paragraphs to make it easier for readers to judge what they might choose to read and what they might skip; in that way and others, we respect our readers and their various interests and abilities - they're not all mathnerds and that's fine. As ] says, {{tq|It is even more important here than in the rest of the article that the text be accessible. Editors should avoid lengthy paragraphs and overly specific descriptions – greater detail is saved for the body of the article.}} ] (]) 18:01, 3 May 2024 (UTC)
::I don't agree with you that the SI definition of the kelvin and its numerical constant is meaningless or useless to most readers. Looking at the other ]:
::* ] says "historically defined as 1/86400 of a day", then SI as the second paragraph (B-class)
::* ] gives SI as the second sentence (B-class)
::* ] alludes to the SI definition in a sentence in the second paragraph and explains that a Kibble balance can be used to realize this definition. (Good article)
::* ] says 1 coulomb/s and SI is the second paragraph (C-class)
::* ] has SI as the second sentence (C-class)
::* ] doesn't have SI in the lead, but its definition is complex (B-class)
::So the trend is that the SI definition is somewhere in the lead, generally the second paragraph. If the SI definition was lengthy or complex I could see omitting it but for kelvin it is actually shorter than e.g. the definition of the second so ] does not justify leaving it out.
::I am OK with what Em3rgent0rdr did, defining the Kelvin scale as "0 K = absolute zero and 1 K = 1 °C" is reasonable, historical, and it avoids duplicating the Boltzmann constant. It is sort of circular, since Celsius is now defined in terms of kelvins instead of the basic 0 = freezing 100 = boiling, but ampere/coulomb is viciously circular and ] seems to have left it that way. I did some rearrangement again since I still think the Kelvin scale should be explicitly defined with a sentence like "The Kelvin scale is...".
::You do bring up a good point with the traceability. There is some stuff . Expanding the article with how the kelvin is practically realized and used would bring the different definitions into context and make their relative importance more clear. ] (]) 21:56, 3 May 2024 (UTC)
:::Sadly, Misplaced Pages is not a good guide as to what's meaningful to readers! Our articles don't always develop with such a coherent view and as you've found (and thanks for that survey), most of our articles on base units aren't rated highly. Of course, it varies from one unit to another how much explanation of the concept's needed, roughly in the order you've given: the second is a familiar unit in common parlance and in other systems, while the very idea of the mole is unfamiliar to many and the candela is indeed complex.
:::Still, looking at ] - assessed as a GA in 2008, before the redefinition - I notice a three-paragraph lead with the middle paragraph describing the manner in which the kilogram's defined and the significance of such a definition without actually providing any of the constants or formulae involved. What's more, the reader can skip that paragraph after reading the first few words, carry on to the next paragraph and still gain from the article. In that way it's doing a good job of talking to a wide range of readers.
:::I'm sure we can improve on the current lead. At the moment, the first of two short paragraphs manages to repeat 273.15 three times, and the second then throws in 273.16. So many numbers don't make for easy reading, and as ] shows, we can communicate a great deal without supplying a lot of quantities. ] (]) 16:22, 4 May 2024 (UTC)


I'm not well versed in the subject myself except for it's practical importance, in that, at very cold temperatures just as in very deep vacuums relative scales tend to break down, hence having an absolute scale becomes a necessity then. So I don't have have much input to give beyond advice about writing in general. But along those lines I would make this suggestion: the last few days the article has become very unstable, which can be confusing or even frustrating for the reader. Perhaps it would be better to finish this discussion and hammer out all the details first, and when everyone has come to a consensus, then implement the changes to the article. We can copy/paste it right here and do all the wordsmithing until it's just right, without disrupting all those readers out there. Not to mention, it's hard to discuss something when that something is in constant flux, (see my last comment). To discuss, it's important to give people time to respond.
== History is confusing ==


That said, it's refreshing to see people actually discussing a subject in a collaborative manner rather than a combative one, for a change, so thanks for that. ] (]) 22:15, 3 May 2024 (UTC)
The History section is confusing it seems to suggest there were two third revisions.
The second Revision 3, mentions a 4th revision.


:I agree - the recent speed of editing makes it hard to discuss issues and hard even to spot a version one might like; it's also difficult to see when to edit, as another editor might or might not be in the middle of a batch of little changes, even about to revert themselves. Also, let's not put each other under pressure to respond quickly, for fear something will seem to be agreed ''nem con''; we can take it easy. ] (]) 15:49, 4 May 2024 (UTC)
] (]) 00:13, 12 October 2010 (UTC)
Confused of Sydney


===Drafting===
== Verification of general statements ==
Combining some of the recent improvements with some earlier ideas, I'd like to float the following draft; it's not perfect (no Misplaced Pages lead is ever perfect) but you'll recognise some of the principles from the discussion above. I've removed the refs for two reasons: they make talk-page drafting awkward, especially as many will be unresolved, and it's not actually necessary to source a lead when it's summarising sourced content, so we may do without them anyway.
{| class="wikitable"
! style="width: 60em;" | Draft
|-
|The '''kelvin''', symbol '''K''', is the ] for ] in the ] (SI). The '''Kelvin scale''' is an ] ] that starts from 0&nbsp;K as the coldest possible temperature, ]. It is named after the nineteenth-century British scientist ] who first developed it, and was formally added to the International System of Units in 1954.


The Kelvin scale was developed from the ] scale (symbol °C). A change of 1&nbsp;K exactly equals a change of 1&nbsp;°C, but absolute zero, -273.15&nbsp;°C, is 0&nbsp;K. Any temperature in degrees Celsius can be converted to kelvin by adding 273.15.
This article is packed with very general statements, particularly about usages, such as abbreviations, capitalizations and the the like. None of those statements carry citations. Since I passionately hate the "citation needed" tag, I've not gone in and marked such spots. The number of such spots is so high that result of doing so would look like vandalism. But really, somebody either needs to back off on the general usage of unsupported generalizations such as:


The Celsius, ], and ] scales are now defined in terms of the Kelvin scale. The kelvin itself is now defined in terms of ] by setting the ] to exactly {{physconst|k|ref=no|symbol=no|unit=no}} ] per kelvin; every 1&nbsp;K change of ] corresponds to a ] change of exactly {{val|1.380649|e=−23|u=J}}.
"When reference is made to the unit kelvin (either a specific temperature or a temperature interval), kelvin is always spelled with a lowercase k unless it is the first word in a sentence. When reference is made to the "Kelvin scale", the word "kelvin"—which is normally a noun—functions adjectivally to modify the noun "scale" and is capitalized."
|}
] (]) 17:00, 4 May 2024 (UTC)


:i like that draft. I would change ". A change" into ", such that a change" ] (]) 17:30, 4 May 2024 (UTC)
or get busy on supporting them.
::Thanks! It would be grammatically jarring, even wrong, to use "such that" without a preceding noun or noun phrase. "in such a way that" would be grammatical but a bit longwinded, and "so" logically incomplete, but "so that" or a semicolon would work. ] (]) 12:58, 6 May 2024 (UTC)
] (]) 21:06, 23 September 2012 (UTC)
:I don't like splitting the definition of the Kelvin scale into pieces. You can't define a scale without two pieces of information, in this case the start and the increment. So I would keep ", then rises by exactly 1 K for each 1 °C" after "absolute zero".
:I don't like "it is named after". For one, it is passive voice. The 1954 CGPM meeting named it. That's why my version puts it down below, in line with the history.
:You stated you didn't like the duplication of 273.15, this does remove one instance but there are still 2 left. Personally I liked having it 3 times, I think some schoolchildren will need it to be repeated to get it through their heads that this number is important. But if avoiding duplication is really a goal then I would say to go further and remove the absolute zero = -273.15 °C, just have a sentence "Any temperature in degrees Celsius can be converted to kelvin by adding 273.15." Also, it is incorrect to say that the Kelvin scale was developed from the Celsius scale, as my recent additions of the history show. Rather, the Kelvin scale was developed from thermodynamic principles, and then the arbitrary increment parameter was chosen to agree with the Celsius scale. So I would change that mini-paragraph to "The Kelvin scale was designed to be easily converted from the Celsius scale (symbol °C). Any temperature in degrees Celsius can be converted to kelvin by adding 273.15."
:I added the "absolute Celsius" reference because it provides a third definition, besides "SI unit" and the scale start and increment - a simple mnemonic to remember what the Kelvin scale is. I think adding a redirect from "Absolute Celsius" to here would make sense and having a sentence in the lead would explain the context of that redirect to readers. So I don't see why you removed it.
:I also don't like the phrasing "are now defined" - it begs the question of "since when?". In my phrasing it is chronological, there is the definition of the kelvin in 1954 and the redefinition in 2019 and one can conclude that the scales were redefined between those two points and the 2019 definition is the current definition. I don't have sources handy but I would suspect that the range 1954-2019 for redefining Celsius is about as precise as one can get because it was a gradual process of updating the definitions book by book.
:And 273.16 K being the triple point of water is an important definition, it is probably more important than the 2019 one at present. As those NIST pages I linked say, there is essentially no realization of the new 2019 definition at this point, everyone still uses triple point cells and there are no plans to change over for the foreseeable future. So again I object to removing it.
:So after going through those, I put what we seem to be in agreement about into the article. It is not a huge change but it is a little improvement. ] (]) 05:59, 7 May 2024 (UTC)


== Add expression of kelvin in terms of SI defining constants h, ΔνCs, and k ==
== Kelvin is not better than Celsius ==
Celsius has a defined point. It's a constant. Kelvin doesn't have a constant or a base because it's point of "absolute zero" isn't defined, readable or able to be practically applicative. ] (]) 04:08, 9 December 2012 (UTC) Harlequin


The section on "2019 redefinition" said:
The kelvin is an interval on an absolute temperature scale, it is defined by the Boltzmann constant.--] (]) 08:14, 12 December 2012 (UTC)<br>
: One Ke·lvin is defined as the 1/273.16 water's triple point (you don't need to define zero meter, zero ampere ... and also zero kelvin; all you got to do is "to measure" ). e.g. Sun's radiative power is 400 YW, dividing by its surface (take average diameter 1.40 Gm, gives you ''S'' = 6.2 Gm<sup>2</sup> ) so its intensity, ''I'' = ''P''/''A'' would be 64.5 MW/m<sup>2</sup>, ''I'' /''σ'' (stefan's cons. = 57 (nW/m<sup>2</sup>):K<sup>4</sup>) gives ''T''<sup>4</sup>, so ''T''<sup>4</sup> = 1.13 P-K<sup>4</sup> and ''T'' = 5.80 KK (famous 6000 °C sun surface temperature) <br>
] (]) 23:28, 22 September 2017 (UTC)


"The unit J/K is equal to kg⋅m<sup>2</sup>⋅s<sup>−2</sup>⋅K<sup>−1</sup>, where the ], ] and ] are defined in terms of the ], the ], and the duration of the ] ground-state ] respectively. Thus, this definition depends only on ], and not on any physical artifacts as practiced previously."
:I'm not familiar with water's triple-point, but will take your word for it. At some point in history (if not today) Celsius was zeroed at the freezing point of water at sea level, and 100 degrees was supposed to be the boiling point. When Kelvin began doing his experiments with extreme cold, it became apparent that thermometers of the time were not accurate enough to get the precise readings he needed, because the freezing and boiling points of water vary with air pressure, and air pressure is constantly fluctuating. Absolute zero, on the other hand, never fluctuates, so having an absolute scale was the only way to get truly precise measurements at such low temperatures. For measurements that don't need such precision, Celsius works just fine.


(Note I did do some rearrangement and tweaks to that section, which is why I've copied that stable version here.)
:It's a very similar thing with pressure. When Kelvin, Edison and the others were experimenting with deep vacuums, normal gauges gave fluctuating readings, thus, like kelvin, torr was zeroed at total vacuum and redefined to equal 1/760 of a standardized atmospheric pressure. The only way to get precise, accurate reading was with an absolute scale. However, that is not always a better scale, because when measuring things like blood pressure, the differential pressure between the blood and the air is far more important than the absolute pressure, because the former determines the burst pressure.] (]) 23:47, 22 September 2017 (UTC)


Out of curiosity, I looked at ] which gives an expression of the kelvin in terms of the SI defining constants (''h,'' {{math|Δ''ν''<sub>Cs</sub>}}, and ''k'') to be:
::I understand what you're saying, but how do you define "zero ampere" when stray electrical currents are constantly moving around? How could you define an absolute zero speed without a completely stationary reference frame? Aside from meters, the measurements you speak of are not inherently absolute, so there is no way to apply such a scale to them. ] (]) 08:45, 24 September 2017 (UTC)


1 kelvin = {{sfrac|{{val|13.80649}}|{{val|6.09110229711386655}}}} ''h'' {{math|Δ''ν''<sub>Cs</sub>}}/''k''
== Plurals ==


I want to put this into the "2019 redefinition" section, because it gives exactly what kelvin is in terms of the defining constants. Currently kelvin's article only provides the indirect definition by putting kelvin in the denominator of ] ≝ 1.380649×10<sup>−23</sup> ]/K. So I'm thinking to make kelvin's article a little more about kelvin (this article is titled "kelvin" and not "Boltzmann constant"), I'd like to add this expression to the "2019 redefinition" section (and maybe also in the "extradata2" field of its infobox unit). But per ]'s request to slow down editing the page directly, I'm posting in this talk first. ] (]) 00:25, 4 May 2024 (UTC)
The scale is Kelvin, but can the units ever be Kelvins, plural? Should temperatures be cited as "42 kelvin" or "42 kelvins"? (and is there a style guide source for this?)


:I'm just making a note that the page 133 gives
I've never used kelvins in my life, but per . ] (]) 09:21, 10 May 2013 (UTC)
:1 kelvin = {{sfrac|{{val|13.80649e-23}}|({{val|6.62607015e-34}})({{val|9192631770}})}} ''h'' {{math|Δ''ν''<sub>Cs</sub>}} / ''k''
:yes it can indeed be plural (with lower case k). see . <span style="background:lightgrey;font-family:Courier;border:2px dashed #000;">]]</span> 10:14, 10 May 2013 (UTC)
::My understanding is that you can use the plural form of kelvin for expressing differences (it is 20 kelvins between freezing and room temperature), but a temperature is expressed as 293 kelvin (singular), since it defines a point on the scale, not a number of intervals. ] (]) 17:58, 10 May 2013 (UTC) :so could cite that part. (The rest of the derivation is just multiplying the denominator numbers to get 6.09110229711386655 and cancelling the exponents.) ] (]) 03:04, 4 May 2024 (UTC)
:It seems fine, I would use the SI brochure's version. Or maybe group the constants with their numbers like

:<math display="block">1 \text{ kelvin} = \frac{h}{6.62607015 \times 10^{-34}}\frac{\Delta\nu_\text{Cs}}{9192631770}\frac{13.80649\times 10^{-23}}{k}</math>

:Also, the main point of contention has been the lead, I for one appreciate your edits and I wouldn't interpret Zaereth's request to include edits to the rest of the article. ] (]) 05:15, 4 May 2024 (UTC)
== What's the most CLEAR Non-Ambiguous symbol of Kelvin temperature scale? (°K) or (K)? ==
::I spent some time trying to figure out a good way to do show this, and ended up with putting discussion of the dependencies as caption to the SI units diagram, using blackened arrows for the kelvin-specific dependencies so is easier to trace: https://en.wikipedia.org/search/?title=Kelvin&diff=1222200283&oldid=1222153908 ] (]) 14:52, 4 May 2024 (UTC)

I was taught using the degree mark symbol (°) when using Kelvin scale, and now I understand why my past teacher taught me the pre-"13th CGPM in 1967/68" symbolization of Kelvin scale, with the degree mark (°K), but he never mentioned of the possible misinterpretation to "Kilo" interval scale to us until I realize it now.

After I browsed all thru this Talk page length, almost none mentioned the misinterpretation possibility of the letter "K" misusage between units and scales defined in SI standard, specifically the Metric interval scale standard.

My point is, how can you differ the "6900 K" written statement is for "6900 Kilo" (6.9 Mega) or for "6900 (degree) Kelvin"? This is a good example of my past confusion when reading the lamp color temperature of "Cool White" light color. "Kilo of what unit?" Until I realized later, it's referring to Kelvin temp-scale unit.


By using a degree symbol (°) before "K" letter, people can understand it's referring to Kelvin temperature scale (regardless of temperature absolutism/relativism/whatever issue - people have shown it can be inter-related to degree Celcius so easily anyway, so why SI in the 1st place removed the degree scale symbol if this can cause a mix-up with its own "Kilo" symbol? Ambiguity with Rankine scale? How come? it's written in "R" letter and not "K", for godsake! Just like all SI temperature scale units such as Celcius ('C), Kelvin ('K) belongs to this one too: the "temperature-scale" unit, so why "Kelvin" must omit the degree symbol while "Celcius" use it?). If you omit this degree symbol (sometimes replaced by aposthrope/single quote symbol for chatting/fast-typing convenience, e.g: 'C for degree Celcius, 'K for degree Kelvin) people may mistake this with "Kilo" which is often abbreviated with uppercase "K" letter (in sync with SI recommendation itself) - even in practice, those who didn't know SI standard writings may mistakenly write it in lowercase letter "k" and think it refers to "Kilo" too (as mentioned in this Talk page debate, lower-cased "k" letter is used for Kelvin temp-scale too, making things worse).

FYI, SI defines all MAJOR/UP-SCALE intervals (multiple-upwards, e.g: 100x, 1000x) must be written in uppercase letter such as ilo, ega, iga, eta, and so on - and all MINOR/DOWN-SCALE intervals (multiple-downwards, e.g: 1/100x, 1/1000x) must be written in lowercase letter such as enti, illi, ano, iko, and so on. I'm sure at least one people remember this SI rule of its popular interval scale used throughout almost all the countries in the world (even USA mention their people wage/salary in "K" or "k" for shortening "Kilo", though along with UK, they are the last Imperial standard bastion/homebase).


-----
So, I highly protest about the degree removal of Kelvin temp-scale unit, then recommend, and humbly suggest SI people for scientific world and people sake to revert to pre-"13th CGPM in 1967/68" convention, which used the degree symbol for Kelvin scale (°K, or 'K) to avoid misinterpretation with its own world-wide popular multi-interval scale, specifically the uppercase "K" letter for "Kilo" (1000x by basepoint).
For this one, I agree with "Greg L" for using back the degree mark before "K" letter, but mainly for avoiding the misinterpretation reason, and nothing else (such as plural degree and lower/upper-case "K" letter issues).
-----


Just to add comment to the "pluralistic" usage issue: it shouldn't be SI case though which deals only to metric standards and not grammatical/vocabulary issue between world languages, since it's merely English (Anglo-Saxonian base) grammatical/vocabularic problem that any plural object must be suffixed by "s", and reference to human/object must be gender-based/bias (he/she/his/her, etc - i.e: why reference to a ship must be 'her' in first place? can't it just be 'it'? can we melt down the 'he/she' text into just 'it' or similar short genderless singular word to avoid gender-bias and too-long-to-type problems?), since some nations (other than UK/US) have no obligation to mention things in plural form, thus saves text space and brain utilization so much :).

For example, I would highly prefer "123 Kilo" rather than "123 Kilos", since both refers to the same idea, it states the unit name clearly/distinctly w/o possible misusage for some non-English speakers (e.g: "1 Kilos" instead of "1 Kilo"), and this will save much lines of programming codes needed to determine whether the number is over/below 1 and when it's true then append "s" letter after the "Kilo" text (only dumb can-not-count-number people can't figure out it's plural or not without the suffix "s" - only when a clearly-stated number is not involved/stated then the "s" suffix can be quite useful to mention the plural degree of object family/class).
It's also better (no mix-ups), shorter, and easier to write (273 'K), (273 °K), (273 Kelvin) instead of (273 K), (273 Ks), (273 degrees Kelvin), (273 Kelvins).
This way the unit name will stand out clearly and readable correctly w/o pluralistic thing involved, thus prevents possible unit name misuse/wrongly-used later on some non English-aware countries/nations.
What if the people in far far far Asia (for example) w/o plural-reference awareness think the unit name is "Kelvins" instead of "Kelvin" (or the scale name is "Kilos" instead of "Kilo")?
Does SI board/people ever consider that possible misuse also?


-----
"A global standard should be FREE from possible MIX-UPs/MisInterpretations/Misuses, especially with its own (already) defined units/scales/markings." - .
-----


If lowercase "k" letter would be used for Kelvin temp-scale then please do a cross-check 1st with SI own metric units/scales - has it defined yet already? If not, then it can be used as one of SI scale/unit standard, otherwise try other ways to define this clearly without possible mix-ups with SI own standard units/scales.

It's unbelievable how this misinterpretation/mix-up issue can arise on the global popularly-accepted SI metric standard, in form of terms/writings collision in its own defined standard - and no one (SI standard users) even mentioned about it a bit.

---> <span style="font-size: smaller;" class="autosigned">— Preceding ] comment added by ] (]) 08:36, 20 July 2013 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

:Misplaced Pages is about collating information that already exists, it is not a forum for personal viewpoints. I suggest that you visit the to see how best to progress your views, though I don't guarantee that it will be of any use. ] (]) 09:30, 20 July 2013 (UTC)

::Yes, I knew that "WP only gathers links and info from existing others (or not the primary original source of info)" stuff already. But please tell me, why people above/before me use this TALK page for expressing their views also just like me? If they were for article's editorial reasons, why using this TALK page instead of the special editorial board section? They use this TALK page for discussing the related article and forbid themselves from ruining the main article with comments (they know how to behave here) - this TALK page is like a mini discussion forum for them since Misplaced Pages doesn't provide other right media for discussing the article and expressing their views about the article contents. If you have read contents of many articles' TALK pages in Misplaced Pages, you know what I'm talking here. May be Misplaced Pages want to try to start as the first TRUE interactive online encyclopaedia in th world? In offline world, people are usually making sidemarks/sidenotes on their science bibles, the encyclopaedia books, or whatever they are for correcting things obsolete/contradictive to current views or standards - In online world, people now can interactively making online suggestions/corrections to their shared online encyclopaedia 'books' like Misplaced Pages here (in form of suggestions to board of editors or whatever it might be called). Why would Misplaced Pages restrict itself from being the BEST MOST TRUE INTERACTIVE shared online Encyclopaedia, and the #1 recommended and referenced by ALL scientists/knowledge-seekers in the world? "Want to advance your knowledge FAST and share your nerdy (constructive) opinions FREEly without those stupid (deconstructively-commenting) trolls? Simply quantum-jump yourself to Misplaced Pages!" - A good educational ad, eh? :) Have you ever think kind of the possibilities this far? Watch out, others may snatch this idea quickly and start it anyway, sooner or later! A brand new version of social-media in a TRUE scientifical/knowledge-base taste, and they have their own (#1) online encyclopaedia for global references/standards used by most scientists and teachers in the world, why not?!
Misplaced Pages is highly regarded as (quite reliable) source/resource of knowledges by some people inclined to science/education world. If those who think they are so clever and sitting on boards of standards never think about reading Misplaced Pages's TALK page for gathering people comments/expressions/whatever to make for better standards/whatever to the world, then they should step down and replaced by some clever people commenting here (or from editors board of Misplaced Pages). If I were one of those high board committee or whatever dealing with global/regional standards, I would read public/scientific forums related to the (open) standards, including this Misplaced Pages TALK page, for external source of informations, and for decision making, for current and future possible issues. As you said also, going to BIPM won't guarantee anything (is this also picturing how 'snob' they are like commonly assumed by people regarding boards of something? Only hear themselves and not others?), why would I bother going there on first place? At least one clever and honored by boards of standards like BIPM could carry these people comments and suggestions to the boards and discuss those for better CLEAR standards. But I might pay a visit there on my leisure time though, to see how many people visiting and commenting there and comparing to Misplaced Pages visits by people.
It's amazing to see how clever these people are commenting in Misplaced Pages, so smartly serious (as it should be here) and forgetting to trash this page with stupid short chat-like and/or deconstructive trolling comments (such as: "You imbecile luddite must..., etc, etc") just like other public forums (moderated/not) - they know how to behave/socialize here in a knowledge-base media. Thank you for not trashing and vandalizing this TALK page, all smart/clever people! Thanks again in my humble deep honor!
--->.

::Just in case someone else reads the rant at the top of this section and wonders if it should be taken seriously, please note a few errors made by that original poster. (1) SI symbols for multiples less than a million are LOWERCASE, e.g., kg=kilogram, hm=hectometer, etc. Above one million, they become capital: Mg=megagram, GW=gigawatt, etc. So, the OP is fundamentally confused about capitalization conventions for SI. "K" can never be mistaken for "kilo" because the abbreviation of "kilo" is lowercase "k". (2) "Kilo" is not a unit. In many countries, people say "kilo" when they really mean "kilogram," and the context is clearly about weight. But the standard SI symbol for that is ALWAYS kg, not k or K or anything else. (3) The OP worries that someone might think that "kelvins" is a unit. Well, it IS the plural of the unit "kelvin," as discussed in the article. (4) There are actually other examples of SI symbols which would be better examples of the OP's problem: G = Gauss as well as "giga," T = Tesla as well as "tera", etc. But the problem is, like "kilo," these are only PREFIXES and thus can never be encountered alone. So, "T" by itself as a derived unit MUST mean Tesla, not just "tera" -- tera... what? Similarly, "K" must mean kelvin.
::In sum, the OP requests that the SI system be free from misinterpretation, but it already is -- BY DESIGN. The people who created the standards thought long and hard just to avoid all the sorts of confusion the OP thinks exists... except it only exists because he/she doesn't understand that correct use of the SI system. ] (]) 21:27, 26 April 2014 (UTC)
:this unit is named after him (like volt, watt, etc) and he didn't inroduce it as Celsius and Fahrenheit did. so "degree" isn't needed.
] (]) 23:23, 22 September 2017 (UTC)

== Capitalisation in the table ==

The conversion table says "Kelvin" with a capital K. Shouldn't it be lower case?] (]) 09:23, 10 December 2013 (UTC)

=== Template ===

The conversoin template spells Kelvin instead of kelvin, due to the use of the page title as a parameter. ] (]) 12:48, 2 May 2014 (UTC)

=== Fixed ===

Well, "to/from Kelvin" could be interpreted as short for "to/from the Kelvin scale" but it's been to "to/from kelvins" anyway. ] 10:59, 17 May 2015 (UTC)

== Does "degree" really indicate an arbitrary reference point? ==

The article states:
<blockquote>The omission of "degree" indicates that it is not relative to an arbitrary reference point like the Celsius and Fahrenheit scales (although the Rankine scale continued to use "degree Rankine"), but rather an absolute unit of measure which can be manipulated algebraically (e.g. multiplied by two to indicate twice the amount of "mean energy" available among elementary degrees of freedom of the system).</blockquote>

That sentence implies that the term "degree" somehow distinguishes scales with an arbitrary reference point from scales with an absolute reference point. If that is true, it needs a citation. ] gives no indication that the term has any such meaning. -TC ] (]) 00:11, 11 February 2016 (UTC)

:I have seen that explained just that way in many different scientific books. (See my comments near the top of this page.) However, the thing to understand is that the English language is very fluid and constantly changing. The word "gear" is one of my favorite examples. In Old English this meant "habits and mannerisms." In Middle English it referred to "any goods, supplies or arms carried with a person." In the renaissance it became "any internal workings of a machine." It was only in the last century that a gear became "a wheel with interlocking teeth." Scientific words are adopted by the general population and altered all the time, and visa versa.

:This notion of removing the term "degree" is really an attempt to change the unit from a circular reference to a linear one. For instance, we don't speak of degrees of inches or meters, degrees of weight, pressure, etc... The term "degree" was adopted from measurements of arc, which are not specific to any actual distance. (The distance of one degree is dependent on the size of the circle, or the "defining parameters.") I have no idea why it became used in temperature measurements at all, but it did.

:In the scientific sense, removing the term "degree" gives it the sense that is fully defined measurement with a very specific "distance." (I'm using the term "distance" in a rather symbolic fashion here.) In contrast, the "length" of one unit of Celsius depends on both the freezing and boiling points of water. Because these points change ever so slightly depending on air pressure, the unit or "degree" of Celsius is not a fixed one. (The "distance" changes depending on air pressure.) Having 2 zero-points, one fixed and the other not, provides that circular parameter. Scientists wanted to make a distinction that the distance of one kelvin was always the same. They did the same thing with ], because mmHg was constantly fluctuating with air pressure, and made deep vacuum measurements nearly impossible. When working with extreme cold, the same problem became evident.

:Nearly all of the scientific data has caught up to this distinction, but the general population has not, and may never. There are no set rules for how units of measurement must be written. Each unit has its own way of doing things, and that doesn't alter how the term "degree" is used in other units. Like all language, these things are something society as a whole just makes up as they go along through a process of groupthink. Some catch on and some don't, but that is a very condensed explanation of what you can find in most books. When I get some more time, I'll be glad to add sources and maybe a little clarification. ] (]) 01:21, 11 February 2016 (UTC)

::Thank you for the well-considered reply. I must agree with your persuasive argument that language is fluid and constantly changing, but I'm not sure that is relevant here. The bottom line is that if the article explains why "degree" is omitted from the unit name and symbol, then that explanation must either be intuitive or must be supported with a citation. The current explanation is neither intuitive nor supported. -TC ] (]) 20:34, 15 February 2016 (UTC)

:::These things are rarely intuitive. Just look at the etymologies of "moose," "bird" or "dog," or the scientific vs the general definition of glass, to name a couple. You are more than welcome to find some citations and make changes that will make the text more understandable and well defined. You can find lots of reliable stuff on google books. Personally, I'm extremely busy and only spend about ten minutes a day on the computer anyway (this is just something to do when I'm on hold) so I have no time to do it right now. I only have this article on my watchlist because I added a wikilink once and haven't de-watchlisted it yet, but etymology fascinates me, so I decided to answer your question. Like I said, I may be able to get back to this in the future, but not now. ] (]) 21:49, 15 February 2016 (UTC)

::::The issue with your explanation though Zaereth is that while it does make sense at a glance, celcius in practical usage is a set measure, kelvin itself is based upon celcius, what constitutes 1 increment in the measurement is thus abitrary (Why is the split between Absolute zero and the triple point 273.16 and not 200 or 500 for example) and both measures have changed and will change over time.
::::It seems more like a random and pointless change than anything... ] (]) 14:44, 8 September 2016 (UTC)

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==Lowercase kelvin==
According to the , the unit kelvin is lowercase, so I changed all references to it to lowercase in the article. That same reference used, e.g., 144 kelvins; I didn't realize the the plural form is indeed different, with that added "s".

The statement below seems dubious to me, so I removed it. If it is reinstated, I hope an appropriate reference is included.
::When reference is made to the "Kelvin scale", the word "Kelvin"—which is normally a noun—functions adjectivally to modify the noun "scale" and is capitalized.
In the context of referring to the scale ''proposed by Lord Kelvin'', that might be called the Kelvin scale. However, in the context of referring to a scale ''based on the kelvin unit'', that would surely be the kelvin scale. --] (]) 15:37, 12 May 2017 (UTC)
:I reverted it. The name of the scale is unaffected by that CIPM brochure, it refers specifically to the use of the unit itself. Common usage in current published material is to refer to it as the Kelvin scale. Whether the scale is named after the unit or the Lord is a angels-on-a-pinhead question, but current published material uses capitalization there. ] (]) 01:02, 13 May 2017 (UTC)
:: In which case the statement about capitalization should be cited to the "current published material". --] (]) 01:50, 13 May 2017 (UTC)
:::Possibly. The change in the unit name being lower case "kelvin" dates back to the 1980s (my recollection is that we changed from degree Kelvin (˚K) to kelvin (K) at the same time), and usage I see in the various recent textbooks all use "Kelvin scale" while using "kelvin" as the unit. The uncited statement could be removed, because its uncited - I restored it because it provided an explanation for a non-obvious typographical usage. Either way, there is no justification for changing the name of the scale, the literature doesn't seem to reflect it. ] (]) 02:24, 13 May 2017 (UTC)

== Temperance & temperation ==

temperance, T, is measured in Ke·lvins, while temperation, ΔT = T − T<sub>0</sub>, where T<sub>0</sub> = 273.15 Ke. so normal body temperance would be 310.15 Ke, while its temperation is 310.15 − 273.15 = 37 Ke. so we can easily use kelvin unit in everyday expressions such as weather predictions etc. e.g. my room "temperation" is 25 Ke.
<br>
] (]) 23:16, 22 September 2017 (UTC)

== Phraseology ==

{{Ping|Dondervogel_2}} just marked a sentence as dubious, with the edit comment: ''I don't buy this; "273 kelvin" is way more common than "273 kelvins"''.

I don't have a cite, but I'll comment that as a current student, but someone who grew up knowing kelvin used degrees, calling the triple point of water 273 kelvin or 273 kelvins is purely a matter of where I'm swallowing the "degrees". Is it "273 degrees kelvin", or "273 kelvin degrees", where I'm keeping the degrees silent? In the former, the plural gets eaten, but in the latter, it's natural to move the plural to the remaining word. Certainly in offsets (Nitrogen liquifies 13 kelvins cooler than oxygen) the plural tends to be used. Some people would prefer "degrees" be used in that sentence, but being in an a region where Fahrenheit is used, the term "degree" is avoided unless a qualifier is added. ] (]) 23:38, 25 February 2018 (UTC)

: In my experience (confirmed by ) people do not say "273 kelvins" when referring to zero degrees Celsius, but "273 kelvin", and this is my main point. There's no "degrees" to swallow because there are no degrees Kelvin, just kelvin (or kelvins). ] (]) 00:14, 26 February 2018 (UTC)

::There are a lot of over-conceptualized arguments for the use of non-pluralized "Kelvin" for temperature. Some would argue it's a unit and not a degree, while others say a degree is also a unit. Other units like Millimeters, Radians, or Pascals are pluralized, while still others like Torr, Bar, and Rankin are not. Like most language, this doesn't seem to have developed with any rhyme nor reason other than "that's the way it turned out." As far as I can tell it is simply a matter of convention amongst scientists to use the non-pluralized form for temperature and quite often the pluralized form for ] (possibly as a mere matter of convenience, who knows). Or possibly, as Tarl points out, for differential temperature as well, just because it flows off the tongue better. I don't have any sources that actually say this, I've just noticed in books that it is more common than not to use them this way.

::That's the trouble with English, because you can't always apply rules like pluralization to everything equally, across the board, and expect everyone else to follow. There are always exceptions to every so-called rule, because that's just the way we speak. (We could just as easily say "units Kelvin", but nobody does ... except I guess in cases of division, as in "per units Kelvin".) ] (]) 19:59, 26 February 2018 (UTC)

== kilowatt.hours? ==

A little off-topic, but has anyone come across kelvin as an historic synonym for kW.h, the unit of electrical energy used by electric supply companies for charging consumers? In this 1919 Australian (electricity for lighting purposes being charged at a higher rate) it is so used, and their equivalence noted . ] (]) 00:18, 13 May 2018 (UTC)
:Nope. It was certainly never standardized, and from the pointers you give, appears to have been a purely Australian usage, which fortunately disappeared almost without a trace. ] (]) 01:07, 13 May 2018 (UTC)

== Is there a name for the constant 273.15? ==
I wonder if there is a name for the constant, 273.15? So you don't need to utter the value, which is a bit cumbersome to do, each time when you need to mention it. --] (]) 06:37, 14 February 2019 (UTC)

:From everything I've read, that's called the "freezing point of water" ... at standard atmospheric pressure of course. The ] is slightly higher than that, which is where water can exist in all three states (solid, liquid, and gas, or as we Alaskans call it, slush) at the same time. (Slightly higher than the triple point is the melting point of ice.) ] (]) 19:22, 14 February 2019 (UTC)

== History of Kelvin scale ==

There seems to be an issue with the history of the Kelvin scale, which I reverted. The 1848 paper does deal with the need for an absolute thermometric scale, so I'm not sure what the point of the edit was. There were also some typoes present, and items removed without explanation. So, let's discuss what is thought to be needed before reinstating this change. ] (]) 03:16, 13 June 2019 (UTC)
:Let me be specific about what I don't like:
*Change of "engineer and physicist" to "physicist". He's remembered today primarily as a physicist, but recognition in his own time was for his engineering skills. So I think that description is appropriate.
*Parenthetical statement in lead about why he was awarded the title. We generally prefer to avoid parenthetical statements in the lede.
*Celcius. It's tricky wording to begin with (we used to have the terms degree Celsius and degree Kelvin, now it's the kelvin alone), the mispelling doesn't help. I think we should leave it as is. The point is that one unit of Celsius (called a degree) is equivalent to a difference of one Kelvin, the question is the phraseology.
*In his 1848 paper, he made clear the need for an absolute scale. Maybe we need to reword it to avoid implying that he had it entirely worked out in 1848, but we don't need to complicate it with later 1851 paper which still didn't have all the details worked out. The point to get across is when the work started.
:] (]) 03:23, 13 June 2019 (UTC)

I simply thought I would share what I have learned:
* Kelvin thought of himself as a physicist, and the engineering got added in because the engineer initially running the project (Preece, if memory serves me) screwed up the Atlantic cable project; Kelvin was brought in to fix it, which he did. He was a physicist who for a time did engineering, but he was not an engineer. I don't know where you got that idea, but it is wrong.
* The writing is not perfect; I felt that correct information is more important that great wording (to which I am sensitive).
* Please feel free to revise. At least distinguish between recognizing the need for an absolute scale (I did explain what such a scale means) and actually finding one. <!-- Template:Unsigned --><small class="autosigned">—&nbsp;Preceding ] comment added by ] (] • ]) 04:48, 13 June 2019 (UTC)</small> <!--Autosigned by SineBot-->

::My two cents. The first thing to remember is that the article is about the unit of measurement, not about Kelvin himself, so details about his schooling and preferred rather than professional titles are really not germane here. (Technically, if one trains to be an engineer but doesn't make a living at it, they are not an engineer, but if one works as an engineer, they are one regardless of training. To some it just comes naturally.)

::Great wording can be all the difference between something that is coherent and understandable, and something either incomprehensible or something that may mean multiple things depending upon how you look at it. With this particular topic, it's very difficult to avoid those dual meanings and make it fully understandable to the general masses. Great care should be taken to make sure of both.

::Mostly, we need sources to verify what you learned. The info must come from somewhere, so it is always advisable to cite those sources for any info you add. I hope that helps. ] (]) 20:32, 13 June 2019 (UTC)

== triple point of water ==

The redefinition of SI results in the triple point of water now becoming an empirically determined value. I think the current lead is perhaps misleading in that it could be read to indicate that the triple point of water is still exactly 0.01 Celsius, when this is no longer the case. Thus I changed the lead. Please let me know if you feel that this is incorrect. ] (]) 03:10, 7 July 2019 (UTC)

== Potential new sections, Implications of 2019 revision and motivation for using an absolute scale ==

Do you think we should create a section on the mathematical implications of assigning an exact value the the Boltzmann constant?

Do you think we should create a section on the the motivation for creating an absolute temperature scale at all, rather than sticking with scales that have some other starting point? This has the potential to get into puff piece territory, but I could also imagine this being one of the main questions people have when looking this subject up. ] (]) 07:29, 18 February 2022 (UTC)

:I don't know much about the first part of your question, as I don't speak math very fluently. Possibly could be of value if you can translate it to English for all us non-mathematicians out here.

:The second part of your question is something that interests me very much, as I'm always wanting to know why. It may be a little much or off topic for this article, but I think it would be perfect for the ] article. I know Kelvin was a pioneer in both deep cold and deep vacuum measurements, along with Edison and several others. (They each began using the ] scale very early in their research, so the concept was not new.) Both are quantities you can assign a known minimum to, and in both you start to get wonky readings at extreme lows without having a fixed zero-reference to compare against. It's not necessarily that an absolute scale is better than a relative one, because it all depends on what you're measuring for. (See discussion at ]) We live in a pressurized atmosphere at temperatures above freezing, so for day-to-day measurements a relative scale is better. For example, with things like tire pressure or blood pressure, the absolute pressure is not very critical. It's far more important to know the difference between them and atmospheric pressure, because that is a far better indication of burst pressure. With lighting, aeronautics, or barometry, an absolute scale is far more accurate for the necessary info. When it comes to deep cold or deep vacuum measurements, it starts to become really apparent that you need an absolute scale so you have a fixed reference point that doesn't change.

:Also, I think the section on orders of magnitude could be toned down a little. It would probably read better as a list, so it doesn't clutter up the table of contents as much. ] (]) 04:08, 2 March 2022 (UTC)

== 1 Kelvin ==

I don't see why there should be a (rather lengthy) section on '''1 Kelvin''' in this article. More appropriately it should be in a separate article, much like ''']'''. <br>
—DIV (] (]) 03:47, 9 May 2022 (UTC))

== Bloat ==

The user {{user|Ava Eva Thornton}} added a huge volume of content in this article, not all of it useful. vs. . While, some the content is mostly tangential, usually quantitative information. I have already deleted a section that was purely ] that added no useful information about the 2019 definition. The "Multiples" section is mostly ], and I recommend either converting it into a table like ], or deleting it outright; "1 kelvin" should probably be deleted for the same reason. –] (]]) 19:55, 13 July 2022 (UTC)
:The {{tq|Multiples}} section should simply go away. The {{tq|1 Kelvin}} section has interesting information, but isn't specific to the Kelvin scale, so should probably be moved to another article. ] (]) 20:26, 13 July 2022 (UTC)
::The {{tq|1 Kelvin}} section probably belongs in the ] section, which it at least partially overlaps. ] (]) 20:33, 13 July 2022 (UTC)

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Plural usage

As a mechanical engineer with a B.S. and M.S. from MIT with a specialization in Thermodynamics, I must emphatically assert that the usage of the Kelvin scale when spoken or written is always singular (e.g. "77 kelvin"). This is confirmed by Wiktionary "... (usually as postpositioned adjective) A unit for a specific temperature on the Kelvin scale. 

   Ice melts above 273.15 kelvin.
   Water boils above 373.15 kelvin."  — Preceding unsigned comment added by 2601:6:3280:483:4593:DD0:2C31:EA0D (talk) 19:27, 2 May 2015 (UTC)

I have a proposal and am interested in what others think. I note that the BIMP and the NIST seem to have both ducked the issue of plural usage of kelvin when reporting temperatures. This Kelvin article currently ducks the issue too and the conspicuous absence sticks out like sore thumb. This article tells that kelvin in its plural form is kelvins, but it currently entirely avoids the topic of plural usage. From what I can see, plural usage is currently a free-for-all. It seems that intervals, e.g., “the difference between our two readings was 50 kelvins” is most commonly expressed using the plural form. This makes sense to me and and seems consistent with the rules of English usage. However, it seems that both forms are used in the expression of specific temperature values. One can as easily find "a temperature of 300 kelvin" as one can find "a temperature of 300 kelvins." I just now googled on sun "5800 kelvin" and got 963 hits. I got 458 hits on sun "5800 kelvins". I'm sure Misplaced Pages contributors have opinions as to what is the “proper” way to express temperatures but personal opinions are a dime a dozen. I wonder if any prominent scientific journals have specific editorial guidelines on this issue. So…

I've got a suggestion and a question. Perhaps this article should address the issue of plural usage by noting that both forms are currently used and there is no officially endorsed form. As regards my question, does anyone know of a suggested editorial practice by a reputable scientific publishing organization regarding the expression of kelvin temperatures? Greg L (my talk) 05:22, 4 April 2007 (UTC)

We don't talk about "centigrades" or "Fahrenheits" when giving temperatures, so why should we say "Kelvins?" Seems to me that the unit in all of these cases is the degree; the terms centigrade, Fahrenheit, Kelvin, etc. simply give the point of reference from which the measurement of degrees starts. True, since the size of a centigrade degree is different from that of a Fahrenheit degree, there is some justification for recognizing that uniqueness in an abbreviated form by saying "Kelvins," but it comes down to a personal preference, I suppose, for the "degrees Kelvin" form. As to capital letters, I think it's good to remember that Kelvin, Ohm, Volta, etc., were people--yes, it's nice to honor them, but it's also helpful to recall that they were human, and we are dealing with results of human endeavors--i.e., they might have made some wrong assumptions, and we should always be careful of following blindly. Personally, I am dead set against counting instances and going with the majority on ANY question whatsoever. Remember, half the folks out there are by definition below average.  :) As a historian, I have NEVER tried to settle a dispute by counting the number of sources on either side of the question. The question is how good the sources are, not how many idjots took the easy way out and copied a bad source without checking it. Terry J. Carter (talk) 18:25, 4 July 2008 (UTC)

If you look at the documents mentioned in the following footnote on the meter page: Meter#cite_note-7, they write 273.16 kelvins.
The Metric Conversion Act of 1975 gives the Secretary of Commerce of the US the responsibility of interpreting or modifying the SI for use in the US. The Secretary of Commerce delegated this authority to the Director of the National Institute of Standards and Technology (NIST) (Turner, 2008). In 2008, the NIST published the US version (Taylor and Thompson, 2008a) of the English text of the eighth edition of the Bureau International des Poids et Mesures (BIPM) publication Le Système International d’ Unités (SI) (BIPM, 2006). In the NIST publication, the spellings "meter," "liter," and "deka" are used rather than "metre", "litre", and "deca" as in the original BIPM English text (Taylor and Thompson, 2008a, p. iii). The Director of the NIST officially recognised this publication, together with Taylor and Thompson (2008b), as the "legal interpretation" of the SI for the United States (Turner, 2008).
If there is any official guidelines I would expect the NIST and BIPM would be aware of it? I would guess you say 3.4 kelvins, and 0.9 kelvin.
—Apis (talk) 05:38, 30 January 2009 (UTC)
We don't say Celsiuses or Fahrenheits because we say degrees Celsius or degrees Fahrenheit. The plurality of degrees is what leads people to want to use a plural. I don't think it's a problem. As long as the abbreviated form doesn't get corrupt, e.g. as we sometime see in "kms/h" instead of "km/h", for example. Jdpipe (talk) 04:22, 27 July 2009 (UTC)
BIPM quote:
"over a wide temperature range from a few kelvins to above 550 K."
from "SI-App2-kelvin.pdf"
189.129.53.203 (talk) 13:51, 12 September 2022 (UTC) baden k.

History of Kelvin scale

There seems to be an issue with the history of the Kelvin scale, which I reverted. The 1848 paper does deal with the need for an absolute thermometric scale, so I'm not sure what the point of the edit was. There were also some typoes present, and items removed without explanation. So, let's discuss what is thought to be needed before reinstating this change. Tarl N. (discuss) 03:16, 13 June 2019 (UTC)

Let me be specific about what I don't like:
  • Change of "engineer and physicist" to "physicist". He's remembered today primarily as a physicist, but recognition in his own time was for his engineering skills. So I think that description is appropriate.
  • Parenthetical statement in lead about why he was awarded the title. We generally prefer to avoid parenthetical statements in the lede.
  • Celcius. It's tricky wording to begin with (we used to have the terms degree Celsius and degree Kelvin, now it's the kelvin alone), the mispelling doesn't help. I think we should leave it as is. The point is that one unit of Celsius (called a degree) is equivalent to a difference of one Kelvin, the question is the phraseology.
  • In his 1848 paper, he made clear the need for an absolute scale. Maybe we need to reword it to avoid implying that he had it entirely worked out in 1848, but we don't need to complicate it with later 1851 paper which still didn't have all the details worked out. The point to get across is when the work started.
Tarl N. (discuss) 03:23, 13 June 2019 (UTC)

I simply thought I would share what I have learned:

  • Kelvin thought of himself as a physicist, and the engineering got added in because the engineer initially running the project (Preece, if memory serves me) screwed up the Atlantic cable project; Kelvin was brought in to fix it, which he did. He was a physicist who for a time did engineering, but he was not an engineer. I don't know where you got that idea, but it is wrong.
  • The writing is not perfect; I felt that correct information is more important that great wording (to which I am sensitive).
  • Please feel free to revise. At least distinguish between recognizing the need for an absolute scale (I did explain what such a scale means) and actually finding one. — Preceding unsigned comment added by WMSwiki (talk • contribs) 04:48, 13 June 2019 (UTC)
My two cents. The first thing to remember is that the article is about the unit of measurement, not about Kelvin himself, so details about his schooling and preferred rather than professional titles are really not germane here. (Technically, if one trains to be an engineer but doesn't make a living at it, they are not an engineer, but if one works as an engineer, they are one regardless of training. To some it just comes naturally.)
Great wording can be all the difference between something that is coherent and understandable, and something either incomprehensible or something that may mean multiple things depending upon how you look at it. With this particular topic, it's very difficult to avoid those dual meanings and make it fully understandable to the general masses. Great care should be taken to make sure of both.
Mostly, we need sources to verify what you learned. The info must come from somewhere, so it is always advisable to cite those sources for any info you add. I hope that helps. Zaereth (talk) 20:32, 13 June 2019 (UTC)

triple point of water

The redefinition of SI results in the triple point of water now becoming an empirically determined value. I think the current lead is perhaps misleading in that it could be read to indicate that the triple point of water is still exactly 0.01 Celsius, when this is no longer the case. Thus I changed the lead. Please let me know if you feel that this is incorrect. 2601:184:407F:8921:646B:30F2:10C3:559E (talk) 03:10, 7 July 2019 (UTC)

Potential new sections, Implications of 2019 revision and motivation for using an absolute scale

Do you think we should create a section on the mathematical implications of assigning an exact value the the Boltzmann constant?

Do you think we should create a section on the the motivation for creating an absolute temperature scale at all, rather than sticking with scales that have some other starting point? This has the potential to get into puff piece territory, but I could also imagine this being one of the main questions people have when looking this subject up. Ava Eva Thornton (talk) 07:29, 18 February 2022 (UTC)

I don't know much about the first part of your question, as I don't speak math very fluently. Possibly could be of value if you can translate it to English for all us non-mathematicians out here.
The second part of your question is something that interests me very much, as I'm always wanting to know why. It may be a little much or off topic for this article, but I think it would be perfect for the absolute scale article. I know Kelvin was a pioneer in both deep cold and deep vacuum measurements, along with Edison and several others. (They each began using the Torr scale very early in their research, so the concept was not new.) Both are quantities you can assign a known minimum to, and in both you start to get wonky readings at extreme lows without having a fixed zero-reference to compare against. It's not necessarily that an absolute scale is better than a relative one, because it all depends on what you're measuring for. (See discussion at Talk:Absolute scale) We live in a pressurized atmosphere at temperatures above freezing, so for day-to-day measurements a relative scale is better. For example, with things like tire pressure or blood pressure, the absolute pressure is not very critical. It's far more important to know the difference between them and atmospheric pressure, because that is a far better indication of burst pressure. With lighting, aeronautics, or barometry, an absolute scale is far more accurate for the necessary info. When it comes to deep cold or deep vacuum measurements, it starts to become really apparent that you need an absolute scale so you have a fixed reference point that doesn't change.
Also, I think the section on orders of magnitude could be toned down a little. It would probably read better as a list, so it doesn't clutter up the table of contents as much. Zaereth (talk) 04:08, 2 March 2022 (UTC)

1 Kelvin

I don't see why there should be a (rather lengthy) section on 1 Kelvin in this article. More appropriately it should be in a separate article, much like absolute zero.
—DIV (137.111.13.4 (talk) 03:47, 9 May 2022 (UTC))

Bloat

The user Ava Eva Thornton (talk · contribs) added a huge volume of content in this article, not all of it useful. Compare what the article used to look like vs. what it looks like now. While, some the content is mostly tangential, usually quantitative information. I have already deleted a section that was purely WP:OR that added no useful information about the 2019 definition. The "Multiples" section is mostly WP:IINFO, and I recommend either converting it into a table like Metre#SI prefixed forms of metre, or deleting it outright; "1 kelvin" should probably be deleted for the same reason. –LaundryPizza03 (dc̄) 19:55, 13 July 2022 (UTC)

The Multiples section should simply go away. The 1 Kelvin section has interesting information, but isn't specific to the Kelvin scale, so should probably be moved to another article. Tarl N. (discuss) 20:26, 13 July 2022 (UTC)
The 1 Kelvin section probably belongs in the Absolute zero#Very low temperatures section, which it at least partially overlaps. Tarl N. (discuss) 20:33, 13 July 2022 (UTC)

Conversion Table Placement

The Conversion Table is placed in (adjacent to) the "Practical uses" section, but has nothing to do with the section's content. A better placement would be desirable.

189.250.250.12 (talk) 13:16, 12 September 2022 (UTC) baden k.

Make the range of Kelvin immediately clear

In the intro, can it be made immediately obvious that a characteristic of Kelvin is that its lowest possible value is 0, because it is tied to kinetic energy? i.e. Kelvin's values range from 0 on upwards; there is never a negative Kelvin value (if this is true). Such basic things about the nature and usage and consequences of concepts are nice to make immediately clear, for anyone who doesn't really need to know more than that, but does need to know and understand such implications for usage. And then anyone who wants to go further for the sake of knowledge or the nuances of those reasons can delve into the further details.

I'll write what I might suggest for such an addition later, if I remember. GabeGibler (talk) 23:25, 17 February 2023 (UTC)

I agree. The lede is a little backwards in its presentation, which doesn't help really clarify immediately what this thing is. The most important information for building context is actually in the last sentence of the first paragraph, when it should really be the first. That it's an SI unit or who it's named after is really secondary to that. For all intents and purposes, Kelvin is just another name for Celsius (absolute), that is, it's based on the Celsius scale, but starts at absolute zero rather than the freezing point of water. If you want to try to improve it, you are most welcome to give it a shot. Zaereth (talk) 01:08, 18 February 2023 (UTC)
I took a stab. I think the 0 K - 273.15 K - 273.16 K sentence should explain the range pretty well. Although maybe it's hard to understand? Mathnerd314159 (talk) 05:06, 24 April 2023 (UTC)

Lead structure

@NebY I don't think your lead structure is "much-improved". My two-paragraph structure has a simple, logical structure: one paragraph for the current definition and one paragraph for the historical definitions. This makes the key points clear. In contrast, your structure is fragmented - the historical context abruptly ends and then switches to discussing the 2019 redefinition in a new paragraph. Putting the 2019 redefinition using the Boltzmann at the start of a new paragraph is confusing to readers as they wonder why this is a new topic and how it is related to kelvins. In contrast, my second paragraph seamlessly integrates all of the historical definitions without disrupting the flow of the text. Two paragraphs is also more concise than 3 - following your logic, every sentence would be in its own paragraph because these "brief paragraphs" would somehow make it less intimidating. But of course this is flawed as breaking up paragraphs with random breaks makes it less readable and more intimidating.

My structure introduces the precise, current definition of the scale early, following MOS:LEADSENTENCE: "If its subject is definable, then the first sentence should give a concise definition." (Per Misplaced Pages:Wikipedia_is_not_a_dictionary#Good_definitions it is actually two sentences with two definitions, as the kelvin and Kelvin scale are highly related topics). In contrast, if someone needs to identify the current definition of the Kelvin scale in your structure, they would have to look at the beginning and end of the first paragraph and also search through the end of the third paragraph. This disjointed definition is not suitable for grasping the concept of the kelvin. It is not accessible, not early, and not clear. Mathnerd314159 (talk) 18:36, 2 May 2024 (UTC)

To address the concern about the 2019 definition not appearing immediately, I have just edited the infobox to add a line "2019 definition" that gives out the Boltzmann constant in terms of J/K.
I had done many of the edits to try to simplify the lead. I am afraid if we overload new readers by immediately in the first paragraph getting into very technical Boltzmann constant (which itself requires a large amount of explaining and background knowledge), then we risk loosing them completely.
The historical definition using the melting point of ice is something that won't loose new readers because it is more relatable too. Even though the kelvin is no longer precisely defined by the melting point, that is still a good-enough and concise definition for practical purposes. As the "2019 definition" section now explains:
"For practical purposes, the redefinition was unnoticed; enough digits were used for the Boltzmann constant to ensure that 273.16 K has enough significant digits to contain the uncertainty of water's triple point and water will still freeze at 0 °C to a high degree of precision." Em3rgent0rdr (talk) 20:04, 2 May 2024 (UTC)

References

  1. Newell, D B; Cabiati, F; Fischer, J; Fujii, K; Karshenboim, S G; Margolis, H S; de Mirandés, E; Mohr, P J; Nez, F; Pachucki, K; Quinn, T J; Taylor, B N; Wang, M; Wood, B M; Zhang, Z; et al. (Committee on Data for Science and Technology (CODATA) Task Group on Fundamental Constants) (29 January 2018). "The CODATA 2017 values of h, e, k, and NA for the revision of the SI". Metrologia. 55 (1): L13 – L16. Bibcode:2018Metro..55L..13N. doi:10.1088/1681-7575/aa950a.
  2. "Updating the definition of the kelvin" (PDF). BIPM. Archived from the original (PDF) on 23 November 2008. Retrieved 2010-02-23.
Upon rereading the intro a few times, I would suggest the name origin "It is named after Belfast-born University of Glasgow scientist William Thomson, 1st Baron Kelvin (1824–1907)" could be moved to the very end of the introduction instead of being in the first paragraph, because its name itself has little to do with what it is. Em3rgent0rdr (talk) 20:11, 2 May 2024 (UTC)
Here's my advice. Shorter is not always better, and being too brief is always a problem with technical and scientific articles. Technicians and scientists invariably write for technicians and scientists, leaving out much of the background information necessary for the general reader to follow smoothly, hence the term "techniquese". There is such a thing as too brief.
Explaining complex things to people who have no background knowledge of it is one of the greatest challenges in writing. It shouldn't focus on the number of paragraphs as much as getting the point across as concisely yet precisely as possible.
The lede should be written at around a 6th grade level, which doesn't mean dumbing it down or oversimplifying, but explaining it in terms that a 6th grader should be expected to understand. It doesn't need to be overly detailed, because it's just a summary of the body, but should give the basic gist of what the body contains in easily understandable terminology.
Things like the history are not as important as what the subject is. That should be answered in the first paragraph. But what if I don't know what absolute zero means? If I have to click on that wikilink you've already lost me down the rabbit hole, so that doesn't work either. Imagine trying to explain it to a 6th grader in a way they'll comprehend precisely what the subject is.
For comparison, a very well-written article is Honey. It's not overly technical in the lede, but saves that for the body, yet gives all the pertinent info needed to get a good understanding of the subject in a very logical order. Not too long and not too short either. I hope that helps. Zaereth (talk) 20:38, 2 May 2024 (UTC)
I've tried taking your advice and tried to explain just enough as to why things were done. Those are significant changes, so I understand if other editors revert it or make more changes. Em3rgent0rdr (talk) 00:50, 3 May 2024 (UTC)
I think it reads much better that way. By that, I mean it's more cohesive and flows a lot better, and those are important factors for both comprehension and in keeping the average reader's interest.
That said, I would eliminate the first sentence of the second paragraph altogether. I had to read it twice to figure out what it was saying, and it seems redundant considering the following sentence says basically the same thing.
For this sentence, "...the 2019 redefinition of the SI base units now defines the kelvin by setting the Boltzmann constant to exactly 1.380649×10−23 joules per kelvin", I would probably clarify that it's defining temperature as a product of energy, so I might change it to read: "...the 2019 redefinition of the SI base units now defines the kelvin in terms of energy by setting the Boltzmann constant to exactly 1.380649×10−23 joules per kelvin", or something like that. Just so the reader has enough context to connect the dots.
The only thing else I wonder is if a short sentence, maybe at the end of the second paragraph, comparing kelvin to other absolute scales (Rankine, which is the same principal but based on the Fahrenheit scale) would be helpful to the reader, or would it just confuse the issue? Zaereth (talk) 01:24, 3 May 2024 (UTC)
Of course, there have been some changes while I was writing the above, so many of those suggestions may no longer apply, but it looks like you got the gist. Zaereth (talk) 01:36, 3 May 2024 (UTC)
Thanks, I've incorporated the "now defines the kelvin in terms of energy" and sorry I did make quite more changes while you were typing. I'll sleep now and won't edit it for the next day or so to give others a chance to edit. Em3rgent0rdr (talk) 03:24, 3 May 2024 (UTC)
Mathnerd314159, we're writing for one of the largest audiences in the world, and we don't know why our readers are here or how they got here. We do know that it's extraordinarily unlikely that they'll be reading Misplaced Pages in order to do anything that requires the value of the Boltzmann constant. Laboratories measuring temperature in their experiments, industries measuring process temperatures, manufacturers of temperature measurement equipment and others will at intervals want to ensure their instrumentation's good. For this, there's a worldwide system of certification ultimately traceable back to national and international standards - see Traceability#Measurement - which since 2019 can if necessary be completely independently established. That's an extraordinary achievement, finally liberating international metrology from the International Prototype of the Kilogram and the isotopes of water, and it's quite rarefied; it makes no difference to those laboratories, industries and manufacturers. Likewise, what the Boltzmann constant is, how it's used to define the kelvin or what particular numeric constant is used in that definition aren't going to be at all meaningful to our readers until they understand a bit more about what the kelvin is. Indeed, once they've understood that bit more about the kelvin, they may well still not have the slightest interest in the Boltzmann constant, and we should respect that, not insist that they read all the digits before going further.
Instead, we talk about the idea of absolute temperature, and about the close but shifting relationship between the kelvin and the more familiar degree Celsius. Especially in the lead, we can use paragraphs to make it easier for readers to judge what they might choose to read and what they might skip; in that way and others, we respect our readers and their various interests and abilities - they're not all mathnerds and that's fine. As MOS:INTRO says, It is even more important here than in the rest of the article that the text be accessible. Editors should avoid lengthy paragraphs and overly specific descriptions – greater detail is saved for the body of the article. NebY (talk) 18:01, 3 May 2024 (UTC)
I don't agree with you that the SI definition of the kelvin and its numerical constant is meaningless or useless to most readers. Looking at the other base SI units:
  • Second says "historically defined as 1/86400 of a day", then SI as the second paragraph (B-class)
  • Metre gives SI as the second sentence (B-class)
  • Kilogram alludes to the SI definition in a sentence in the second paragraph and explains that a Kibble balance can be used to realize this definition. (Good article)
  • Ampere says 1 coulomb/s and SI is the second paragraph (C-class)
  • Mole (unit) has SI as the second sentence (C-class)
  • Candela doesn't have SI in the lead, but its definition is complex (B-class)
So the trend is that the SI definition is somewhere in the lead, generally the second paragraph. If the SI definition was lengthy or complex I could see omitting it but for kelvin it is actually shorter than e.g. the definition of the second so MOS:INTRO does not justify leaving it out.
I am OK with what Em3rgent0rdr did, defining the Kelvin scale as "0 K = absolute zero and 1 K = 1 °C" is reasonable, historical, and it avoids duplicating the Boltzmann constant. It is sort of circular, since Celsius is now defined in terms of kelvins instead of the basic 0 = freezing 100 = boiling, but ampere/coulomb is viciously circular and the discussion seems to have left it that way. I did some rearrangement again since I still think the Kelvin scale should be explicitly defined with a sentence like "The Kelvin scale is...".
You do bring up a good point with the traceability. There is some stuff . Expanding the article with how the kelvin is practically realized and used would bring the different definitions into context and make their relative importance more clear. Mathnerd314159 (talk) 21:56, 3 May 2024 (UTC)
Sadly, Misplaced Pages is not a good guide as to what's meaningful to readers! Our articles don't always develop with such a coherent view and as you've found (and thanks for that survey), most of our articles on base units aren't rated highly. Of course, it varies from one unit to another how much explanation of the concept's needed, roughly in the order you've given: the second is a familiar unit in common parlance and in other systems, while the very idea of the mole is unfamiliar to many and the candela is indeed complex.
Still, looking at Kilogram - assessed as a GA in 2008, before the redefinition - I notice a three-paragraph lead with the middle paragraph describing the manner in which the kilogram's defined and the significance of such a definition without actually providing any of the constants or formulae involved. What's more, the reader can skip that paragraph after reading the first few words, carry on to the next paragraph and still gain from the article. In that way it's doing a good job of talking to a wide range of readers.
I'm sure we can improve on the current lead. At the moment, the first of two short paragraphs manages to repeat 273.15 three times, and the second then throws in 273.16. So many numbers don't make for easy reading, and as Kilogram shows, we can communicate a great deal without supplying a lot of quantities. NebY (talk) 16:22, 4 May 2024 (UTC)

I'm not well versed in the subject myself except for it's practical importance, in that, at very cold temperatures just as in very deep vacuums relative scales tend to break down, hence having an absolute scale becomes a necessity then. So I don't have have much input to give beyond advice about writing in general. But along those lines I would make this suggestion: the last few days the article has become very unstable, which can be confusing or even frustrating for the reader. Perhaps it would be better to finish this discussion and hammer out all the details first, and when everyone has come to a consensus, then implement the changes to the article. We can copy/paste it right here and do all the wordsmithing until it's just right, without disrupting all those readers out there. Not to mention, it's hard to discuss something when that something is in constant flux, (see my last comment). To discuss, it's important to give people time to respond.

That said, it's refreshing to see people actually discussing a subject in a collaborative manner rather than a combative one, for a change, so thanks for that. Zaereth (talk) 22:15, 3 May 2024 (UTC)

I agree - the recent speed of editing makes it hard to discuss issues and hard even to spot a version one might like; it's also difficult to see when to edit, as another editor might or might not be in the middle of a batch of little changes, even about to revert themselves. Also, let's not put each other under pressure to respond quickly, for fear something will seem to be agreed nem con; we can take it easy. NebY (talk) 15:49, 4 May 2024 (UTC)

Drafting

Combining some of the recent improvements with some earlier ideas, I'd like to float the following draft; it's not perfect (no Misplaced Pages lead is ever perfect) but you'll recognise some of the principles from the discussion above. I've removed the refs for two reasons: they make talk-page drafting awkward, especially as many will be unresolved, and it's not actually necessary to source a lead when it's summarising sourced content, so we may do without them anyway.

Draft
The kelvin, symbol K, is the base unit of measurement for temperature in the International System of Units (SI). The Kelvin scale is an absolute temperature scale that starts from 0 K as the coldest possible temperature, absolute zero. It is named after the nineteenth-century British scientist Lord Kelvin who first developed it, and was formally added to the International System of Units in 1954.

The Kelvin scale was developed from the Celsius scale (symbol °C). A change of 1 K exactly equals a change of 1 °C, but absolute zero, -273.15 °C, is 0 K. Any temperature in degrees Celsius can be converted to kelvin by adding 273.15.

The Celsius, Fahrenheit, and Rankine scales are now defined in terms of the Kelvin scale. The kelvin itself is now defined in terms of energy by setting the Boltzmann constant to exactly 1.380649×10 joules per kelvin; every 1 K change of thermodynamic temperature corresponds to a thermal energy change of exactly 1.380649×10 J.

NebY (talk) 17:00, 4 May 2024 (UTC)

i like that draft. I would change ". A change" into ", such that a change" Em3rgent0rdr (talk) 17:30, 4 May 2024 (UTC)
Thanks! It would be grammatically jarring, even wrong, to use "such that" without a preceding noun or noun phrase. "in such a way that" would be grammatical but a bit longwinded, and "so" logically incomplete, but "so that" or a semicolon would work. NebY (talk) 12:58, 6 May 2024 (UTC)
I don't like splitting the definition of the Kelvin scale into pieces. You can't define a scale without two pieces of information, in this case the start and the increment. So I would keep ", then rises by exactly 1 K for each 1 °C" after "absolute zero".
I don't like "it is named after". For one, it is passive voice. The 1954 CGPM meeting named it. That's why my version puts it down below, in line with the history.
You stated you didn't like the duplication of 273.15, this does remove one instance but there are still 2 left. Personally I liked having it 3 times, I think some schoolchildren will need it to be repeated to get it through their heads that this number is important. But if avoiding duplication is really a goal then I would say to go further and remove the absolute zero = -273.15 °C, just have a sentence "Any temperature in degrees Celsius can be converted to kelvin by adding 273.15." Also, it is incorrect to say that the Kelvin scale was developed from the Celsius scale, as my recent additions of the history show. Rather, the Kelvin scale was developed from thermodynamic principles, and then the arbitrary increment parameter was chosen to agree with the Celsius scale. So I would change that mini-paragraph to "The Kelvin scale was designed to be easily converted from the Celsius scale (symbol °C). Any temperature in degrees Celsius can be converted to kelvin by adding 273.15."
I added the "absolute Celsius" reference because it provides a third definition, besides "SI unit" and the scale start and increment - a simple mnemonic to remember what the Kelvin scale is. I think adding a redirect from "Absolute Celsius" to here would make sense and having a sentence in the lead would explain the context of that redirect to readers. So I don't see why you removed it.
I also don't like the phrasing "are now defined" - it begs the question of "since when?". In my phrasing it is chronological, there is the definition of the kelvin in 1954 and the redefinition in 2019 and one can conclude that the scales were redefined between those two points and the 2019 definition is the current definition. I don't have sources handy but I would suspect that the range 1954-2019 for redefining Celsius is about as precise as one can get because it was a gradual process of updating the definitions book by book.
And 273.16 K being the triple point of water is an important definition, it is probably more important than the 2019 one at present. As those NIST pages I linked say, there is essentially no realization of the new 2019 definition at this point, everyone still uses triple point cells and there are no plans to change over for the foreseeable future. So again I object to removing it.
So after going through those, I put what we seem to be in agreement about into the article. It is not a huge change but it is a little improvement. Mathnerd314159 (talk) 05:59, 7 May 2024 (UTC)

Add expression of kelvin in terms of SI defining constants h, ΔνCs, and k

The stable (April 30th) section on "2019 redefinition" said:

"The unit J/K is equal to kg⋅m⋅s⋅K, where the kilogram, metre and second are defined in terms of the Planck constant, the speed of light, and the duration of the caesium-133 ground-state hyperfine transition respectively. Thus, this definition depends only on universal constants, and not on any physical artifacts as practiced previously."

(Note I did do some rearrangement and tweaks to that section, which is why I've copied that stable version here.)

Out of curiosity, I looked at Caesium standard#Summary which gives an expression of the kelvin in terms of the SI defining constants (h, ΔνCs, and k) to be:

1 kelvin = ⁠13.80649/6.09110229711386655⁠ h ΔνCs/k

I want to put this into the "2019 redefinition" section, because it gives exactly what kelvin is in terms of the defining constants. Currently kelvin's article only provides the indirect definition by putting kelvin in the denominator of kB ≝ 1.380649×10 J/K. So I'm thinking to make kelvin's article a little more about kelvin (this article is titled "kelvin" and not "Boltzmann constant"), I'd like to add this expression to the "2019 redefinition" section (and maybe also in the "extradata2" field of its infobox unit). But per Zaereth's request to slow down editing the page directly, I'm posting in this talk first. Em3rgent0rdr (talk) 00:25, 4 May 2024 (UTC)

I'm just making a note that the SI brochure page 133 gives
1 kelvin = ⁠13.80649×10/(6.62607015×10)(9192631770)⁠ h ΔνCs / k
so could cite that part. (The rest of the derivation is just multiplying the denominator numbers to get 6.09110229711386655 and cancelling the exponents.) Em3rgent0rdr (talk) 03:04, 4 May 2024 (UTC)
It seems fine, I would use the SI brochure's version. Or maybe group the constants with their numbers like
1  kelvin = h 6.62607015 × 10 − 34 Δ ν Cs 9192631770 13.80649 × 10 − 23 k {\displaystyle 1{\text{ kelvin}}={\frac {h}{6.62607015\times 10^{-34}}}{\frac {\Delta \nu _{\text{Cs}}}{9192631770}}{\frac {13.80649\times 10^{-23}}{k}}}
Also, the main point of contention has been the lead, I for one appreciate your edits and I wouldn't interpret Zaereth's request to include edits to the rest of the article. Mathnerd314159 (talk) 05:15, 4 May 2024 (UTC)
I spent some time trying to figure out a good way to do show this, and ended up with putting discussion of the dependencies as caption to the SI units diagram, using blackened arrows for the kelvin-specific dependencies so is easier to trace: https://en.wikipedia.org/search/?title=Kelvin&diff=1222200283&oldid=1222153908 Em3rgent0rdr (talk) 14:52, 4 May 2024 (UTC)
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