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English language (monolingual) [PRO] Tech/Engineering - Science (general) / Temperature
English term or phrase:kelvins / Kelvin
OK, in my little world we have degrees Fahrenheit, degrees Celsius and Kelvin for expressing temperature.
Has anyone come across 'kelvins' with lowercase K plus 's'? I'm talking about in an English-language textbook for A-level or university-level physics/chemistry.... ?
It was new to me, but google suggests it's not uncommon.
I've such a textbook to edit, and am wondering if changing the kelvins would be overcooking it.
Explanation: This issue has been debated extensively in the discussion box. Please have a look there to find more information compiled by my colleagues. The following is just a summary.
C) ...high school textbooks,... Holt Physics (Serway, Faughn, Holt McDougal) Conceptual Physics (Hewitt / Addison-Wesley) [two of the most widely used textbooks in the US up to 2009; both available as a Google Books preview]
A-Level Physics (Roger Muncaster) [also available as a preview]
...all seem to agree on lowercase k for kelvin, a regular plural form (kelvins), uppercase K for the abbreviated unit and Kelvin with an uppercase K if "scale" or similar is added (e.g., http://www.oxforddictionaries.com/definition/english/kelvin-... ).
On a side note: The description "degrees Kelvin" is obsolete. It fell out of favor at the latest in the 1980s - if not earlier (http://www.bipm.org/en/CGPM/db/13/4/ ).
In brief: If your textbook isn't funded by the IAEA, I'd recommend word usage as stated above.
At least my comments about Celsius were not to be taken seriously. The other matters - hyphenation, non-breaking space, and upper- or lowercase - were.
Both the UK and the US Metric Association are not official government institutions. NIST, however, is. There is more than just one UK government document refusing to acknowledge a kelvin plural (the one I referenced is called "Writing for Home Office Science"). The same is true for hyphenation where the BBC, UK and US official sources and the Guardian Style Guide can't seem to agree, really. I haven't looked through EU sources again, so I am not sure whether it has something to do with that, but as far as I recall, official SI unit documents are not necessarily in line with UK usage.
Are the Brits more prone to be a law unto themselves on such matters? Perhaps we are. The BBC certainly is on this. If they say 30 Celsius as a matter of policy it simply means that they've decided to use an ellipsis and omit the word "degrees". Nothing wrong with that; people do it quite often, but it's hardly a normative rule for anybody else. The unit is a degree Celsius. There is no unit called a "Celsius" and there is not likely to be in the future; there's no call for it. If there were, it would be spelt with a lower-case c (celsius). Whether the plural would be celsiuses or celsius (cf. siemens) is an intriguing point but is (fortunately) not worth debating.
...and you get a really good mash-up - or chaotic result may be more like it.
It is an unproven hypothesis, but it seems to me that based on all these discussions, the US seems to have a more straightforward answer to SI unit names and layout - after all, the Department of Commerce is directly involved here. In the UK, there seem to exist many different opinions (see also the gov.uk document I found.)
Wasn't there a similar discussion a few years ago?
21:44 Apr 18, 2016
Not about kelvins, but about spaces and degree symbol ° and Celsius/Fahrenheit/Kelvin? I seem to remember Tony mentioning the BBC weatherman there too. In fact, I'll see if I can find it. Just out of interest. Strange the things you remember. :-)
Not sure; I remember the BBC weatherman telling us the from now on temperature would be expressed in Celsius, and explaining that there were no degrees; I'm pretty sure I saw this on UK TV before I left the UK? i.e. prior to '96
Sorry for the late reply. I have entered the answer and hope that I have sufficiently incorporated most of the statements made here.
@B D Finch I don't like Wiki as a reference - my university professors wouldn't accept anything like it. I quoted Oxford instead to corroborate your usage of "Kelvin scale."
On a side note: There is one non-SI unit where you can threaten me all you want, I will continue using the singular form, albeit dictionaries may recommend a plural: bar.
Every time I read pressure and "100 bars" somewhere, the first thing that pops into my head is: of gold? chocolate?
for your time, thoughts, insight. I think I can safely leave the kelvins. I just couldn't recall ever seeing it written that way in a textbook, hence the Q. THanks again.
https://en.wikipedia.org/wiki/Kelvin "The kelvin is a unit of measure for temperature based upon an absolute scale. It is one of the seven base units in the International System of Units (SI) and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, ..."
Note their careful use of lowercase "k" for the unit of measurement and upper case for the "Kelvin scale". The unit of measurement must, as others have noted, be able to have a plural. So, you will have to check that the plural and lowercase are used in the correct contexts. Temperature may rise or fall by N kelvins or by N degrees Kelvin.
And if people want evidence of the use of these books they can simply search for "Krane" "physics" "reading list", for example (in this case the first results include Balliol Oxford, Queen Mary London, Salford, Edinburgh..., not to mention Princeton).
May I incorporate your references into my answer? I will point to the discussion box, but I know how people hate reading through all those entries usually.
Hugh D. Young & Roger A. Freeman, University Physics: With Modern Physics, 13th ed. (Addison Wesley), nearly 1600 pp, seems to be widely used in British universities. It has "kelvins".
I take your point, though I think the question of what is correct, as well as what is customary, is relevant. It would be quite a task to track down all the Physics textbooks used in UK universities and check them, since they are often not available online. But for example Kenneth Krane's Modern Physics, 3rd ed. (Wiley) which is on some UK university reading lists, uses "kelvins".
But my point is really that Cilian has to decide whether to change kelvins to kelvin in a text he is editing. And I say that kelvins is demonstrably and indisputably correct and that there are therefore no grounds for changing it. This is so, in my view, regardless of what other textbooks use, though as a matter of fact the ones we've looked at do seem to use kelvins. A more difficult decision would be whether to change kelvin to kelvins, because it depends on whether you think an incorrect form that is nevertheless widely used by professionals (and sanctioned by CERN, no less) should be corrected or left alone.
By the way, "degrees Kelvin" became effectively obsolete in 1968, when the name kelvin was adopted for the unit of thermodynamic temperature: http://www.bipm.org/en/CGPM/db/13/4/
I referenced this in the very first discussion entry: "In older material you’ll run across 'degrees Kelvin,' symbol °K, but that usage was officially declared obsolete in 1980."
@Charles The thing is Cilian asked about "university textbooks." Someone will have yet to provide a reference for those. I did it for high school textbooks in the US and I guess my last link for the UK, but I haven't had the time yet to check for university textbooks. I find it a bit difficult sometimes - German university courses are very different (at least in comparison with the US). There is no general education at the beginning and books are rarely given out (more like PowerPoints, etc.).
that not pluralizing kelvin is probably a throwback to the habit of saying "degrees Kelvin" (which I have from being taught physics at university in the late eighties).
What I mean is that not pluralising "kelvin" is completely illogical. There's no more reason to say "100 kelvin" than "100 amp" or "100 joule". The only possible justification is custom, and that's what the CERN rule must be based on: people don't pluralise it because they're not used to doing so and it sounds wrong to them (as it does to you, because people who taught and worked with you didn't say it). And this quite probably arose from the fact that when they stopped being called degrees people simply dropped the word "degrees" and started saying "100 kelvin", as a sort of ellipsis for "100 degrees Kelvin", without taking the further step of adapting the morphology.
My guess (and it's only a guess) is that "kelvin" as a zero plural is a hangover from the pre-1968 days when it was officially "degrees Kelvin". People were taught by people who had grown up talking about degrees Kelvin, and "kelvins" sounded wrong to them. But as far as I can see kelvin is no more a mass noun than any other SI unit. You can have a kelvin, can't you? If so you can have several kelvins.
If you check back you'll see that I had already quoted the CERN guidelines on this.
To my mind it seems pretty clear that "298 kelvin" and "298 kelvins" are both in common use, but given that "kelvins" is in line with general usage, which is to pluralise units (with very few exceptions: lux, hertz and siemens are just about the only ones and all for the obvious reason that they end in a sibilant, which is not true of kelvin), I firmly believe that it would not be justified to change "kelvins" to "kelvin" in a text you are editing. You should only change what's wrong, and this isn't.
Googling for "Langmuir" (one of the leading papers in physical chemistry) + "measured in kelvin" > 8900 hits "Langmuir" + "measure in kelvins" > 1400 hits
You can try the same with other leading physics/chemistry publications.
FWIW - "kelvins", in plural sounds very odd to me. I spent 4 years in a physical chemistry lab where temp was always quoted in kelvin - no plural. "298 kelvins" sounds wrong, like an error one of the non-anglophones in the lab would say. But I see from the difference between standards and guidelines that there is no standard - ho-hum, when is there.
I will leave you with the CERN's usage advice:
kelvin
"Spell out on first mention; note the lower-case k (all SI units are lower case when spelled out); can be abbreviated to K in subsequent mentions. And note that it is always kelvin, even when plural (not kelvins or degrees kelvin)." http://writing-guidelines.web.cern.ch/entries/kelvin
As my second reference says, "degrees Kelvin" went out in 1968 and they started to be called simply kelvins. It also points out that if you were writing for CERN you would use a zero plural, but still lower case. CERN is out of step here:
"kelvin Spell out on first mention; note the lower-case k (all SI units are lower case when spelled out); can be abbreviated to K in subsequent mentions. And note that it is always kelvin, even when plural (not kelvins or degrees kelvin)." http://writing-guidelines.web.cern.ch/entries/kelvin
Official SI practice is kelvins, apart from other considerations:
"The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. It follows that the thermodynamic temperature of the triple point of water is exactly 273.16 kelvins, T<sub>tpw</sub> = 273.16 K. [...] A difference or interval of temperature may be expressed in kelvins or in degrees Celsius (13th CGPM, 1967/68, Resolution 3, mentioned above), the numerical value of the temperature difference being the same." http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf
take a lowercase initial letter when written in full, even when a capital letter is used for the unit itself when abbreviated (many of which units were derived from people's names: V(olt), T(esla), A(mpère), W(att), etc.) I believe there is one exception to this rule, but can't remember which it is now; I had a feeling it was Ohm, for which the abbreviation is a Greek capital omega, but I may be wrong on that point.
So 'kelvin' with a l/c 'k' is no exception to the standard rule; likewise, it is normal practice to add the plural 's' on units when spelled out (which of course would NOT be added when abbreviated!) — so 'kelvins' also follows standard SI practice.
AFAIK, the only thing special about 'kelvins' is (as has already been noted) they are NOT 'degrees kelvin' — note in passing that if they had been, then it would have been the 'degrees' that took the plural!
The second and fourth one have no preview in Google Books. But the first and third one have a snippet view. If you type in "kelvins" as plural, both Holt and Conceptual Physics will show you examples.
"Thus temperature intervals or temperature differences may be expressed in either the degree Celsius or the kelvin using the same numerical value." http://www.nist.gov/pml/pubs/sp811/sec08.cfm
As you can see, the abbrevation is capital K, but the spelled-out one starts with a small letter.
2 days 20 hrs confidence: peer agreement (net): +3
kelvins / kelvin
kelvins or K
Explanation: This issue has been debated extensively in the discussion box. Please have a look there to find more information compiled by my colleagues. The following is just a summary.
C) ...high school textbooks,... Holt Physics (Serway, Faughn, Holt McDougal) Conceptual Physics (Hewitt / Addison-Wesley) [two of the most widely used textbooks in the US up to 2009; both available as a Google Books preview]
A-Level Physics (Roger Muncaster) [also available as a preview]
...all seem to agree on lowercase k for kelvin, a regular plural form (kelvins), uppercase K for the abbreviated unit and Kelvin with an uppercase K if "scale" or similar is added (e.g., http://www.oxforddictionaries.com/definition/english/kelvin-... ).
On a side note: The description "degrees Kelvin" is obsolete. It fell out of favor at the latest in the 1980s - if not earlier (http://www.bipm.org/en/CGPM/db/13/4/ ).
In brief: If your textbook isn't funded by the IAEA, I'd recommend word usage as stated above.
Björn Vrooman Local time: 21:25 Works in field Native speaker of: German PRO pts in category: 4
peer agreement (net): +3