Talk:Kelvin

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[edit] Temperature problem

The article states that the triple point of water is precisely 0.01 degrees centigrade, but the article on triple point, 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?

Philip.t.day (talk) 17:49, 23 March 2008 (UTC)

[edit] 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"

67.171.43.170 03:40, 19 January 2007 (UTC)

Kelvin. Are we the only ones here? (-: 207.63.251.215 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' [1], and just in case you think this is a US/EU thing, here's the NIST saying the same thing: [2] --Heron 22:01, 6 February 2007 (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. —The preceding unsigned comment was added by 70.230.157.167 (talk • contribs).

See ohm, joule, coulomb, watt, and the other SI derived units. - mako 12:37, 19 February 2007 (UTC)

[edit] Colour vs. Color, and related spelling issues

The issue of British English vs. American English has been a subject of heated debate. Wikipedia’s current policy seems to be the most equitable, encourages contributions, and settles conflict. Per Wikipedia: Manual of Style: Disputes over style issues, the term originally used in the article by the first major contributor(s) should be retained. Greg L (my talk) 01:50, 1 April 2007 (UTC)

[edit] Deleting the existence of the “Kelvin scale”

Someone made this giganzo series of edits on the novel and most original notion that Resolution 4 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 Resolution 3 of the 10th CGPM wherein absolute zero equals zero kelvin and the triple point of water equals 273.16 K. Perhaps the proponent of this theory should point this out to Encyclopedia Britannica since those poor fools believe the Kelvin scale still exists! (and repeated their error in this article 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 this site by the National Center for Atmospheric Research, or this NIST site, and this NIST site too, or this NASA site. 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, please 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 anywhere 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 (Resolution 3 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 K temperature rise on a heatsink), without using a degree symbol (°) in front of the “K” symbol. However, the Kelvin scale still exists and its 1954 definition still holds whereby absolute zero is 0 K and the triple point of water is 273.16 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:

“ considering that it is useful to formulate more explicitly the definition of the unit of thermodynamic temperature contained in Resolution 3 of the 10th CGPM (1954), ”

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

“ 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 keeping the thermodynamic temperature scale and were only “more explicitly” defining the unit comprising that scale. This is all sort of a Well… DUHHH  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 Resolution 7 of the 9th CGPM (1948), 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 Koko the gorilla 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 Wikipedia’s advise to contributors to “be bold” 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 World Wide Web 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. Greg L (my talk) 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. Wikipedia 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. --Heron 19:43, 2 April 2007 (UTC)
Where do you get off declaring that “This article is about the kelvin [the unit]“? Is there a separate Wikipedia 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 Wikipedia articles, one titled “Kelvin (unit)” and another titled “Kelvin scale” (a highly 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 Celsius 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. Greg L (my talk) 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? Greg L (my talk) 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. --Heron 21:00, 4 April 2007 (UTC)
You’re right. Excessive redundancy fixed: second instance of “The kelvin is” replaced with “It is”. Greg L (my talk) 21:24, 4 April 2007 (UTC)

[edit] Conversion Chart

And to whoever screwed up the conversion table: 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 this image for the Close-packing 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 × 1.8) − 459.67
Plug a number into it, the melting point of water for instance…
?? °F = (273.15 K × 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).
Greg L (my talk) 00:25, 3 April 2007 (UTC)

[edit] Plural usage

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 Wikipedia 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)

[edit] Georgia peach

This is a bad example, as Georgia is always capitalized, while kelvin is not always capitalized. --Scottandrewhutchins 20:19, 16 July 2007 (UTC)

[edit] SI prefixed forms of kelvin

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 Tesla (unit), Pascal (unit), parsec, 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 Wikipedia is not a place for original research. Han-Kwang (t) 09:29, 23 August 2007 (UTC)

It doesn't add anything - it just bulks up the article a bit. --Yath 14:12, 23 August 2007 (UTC)
Agreed. The same argument holds for the articles on metre, joule, watt, kg, katal, coulomb, steradian, gray, radian, siemens (unit), henry (unit), weber (unit). Maybe it's good to build consensus about removing these tables. Han-Kwang (t) 15:44, 23 August 2007 (UTC)
I've nominated Template:SI multiples for deletion. I think the deletion discussion could serve as a place to build consensus. Han-Kwang (t) 16:02, 23 August 2007 (UTC)
Hankwang: You should read the article on original research 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 SI prefixes 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 Kelvin table section, other articles link directly to this table. For instance, the Absolute zero article might mention 450 nk 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 Wikipedia 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. Greg L (my talk) 17:39, 23 August 2007 (UTC)
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? --Yath 18:38, 23 August 2007 (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. Greg L (my talk) 18:44, 23 August 2007 (UTC)
Now let's keep a cool head, okay? Join the discussion on WP:TFD and contribute to a consensus for either keeping or deleting these tables. Han-Kwang (t) 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. Greg L (my talk) 20:07, 23 August 2007 (UTC) P.S.: I added my comments to your nomination for deletion. Greg L (my talk) 20:52, 23 August 2007 (UTC)

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. Bvis08 (talk) 00:13, 12 April 2008 (UTC)

[edit] 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 precisely 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 your nomination to have the SI table template deleted, (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. Here’s the original table, and here’s what you replaced it with. Notice the mix up. I’m actually rather surprised you hadn’t noticed that when you placed it here.

Please allow other users to use your recently created template for new projects and don't replace existing tables. Greg L (my talk) 22:55, 27 September 2007 (UTC)

I reversed to submultiples/multiples now and changed the headings. Please continue the discussion on Template talk:SI multiples. Han-Kwang (t) 09:59, 28 September 2007 (UTC)

[edit] Unicode use

Someone wrote the following in the section titled The special Unicode sign:

Unicode includes the "kelvin sign" at U+212A (K). However, the "kelvin sign" is normalized 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.[1]

Note that the cited reference, The Unicode Standard, Version 5.0, Chapter 15: Symbols (632 kB download, here) states precisely the following regarding the kelvin symbol:

“ 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. If text is normalized according to Unicode Standard Annex #15, “Unicode Normalization Forms,” these three characters will be replaced by their regular equivalents. ”

(Emphasis added)

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.

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:

In fact, some browsers can display the kelvin character, which is coded in Unicode as &#x212A; . And in fact, some old browsers can’t handle Unicode and display weird, box-like characters. And in fact, others may normalize them. It is however, entirely incorrect to state that “[it is normalized and] is thereby seen as a (pre-existing) encoding mistake.”

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 µV), the “µ” 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.

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.

Greg L (my talk) 21:39, 10 October 2007 (UTC)

It is actually entirely correct in saying that “[it is normalized and] 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).--Prosfilaes (talk) 03:33, 7 March 2008 (UTC)

[edit] electronVolts

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 Wikipedia users. -Nathan J. Yoder 07:51, 27 October 2007 (UTC)

At least we should make it clear that without the Boltzmann constant the quantity calculus is inconsistent. --DrTorstenHenning (talk) 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).--141.154.246.202 (talk) 21:53, 28 December 2007 (UTC)

[edit] Population Inversion

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'd like to see some mentione of the existence and interpretation of negative Kelvin temperatures. See Negative_absolute_temperature.

[edit] "In Short"

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. dclayh (talk) 20:24, 24 January 2008 (UTC)

[edit] Heat vs. Temperature

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. elle317K (talk)