# Temperature scales: Why "Degrees"? **URL:** \ **Category:** Factual Questions\ **Created:** [December 6, 2014, 1:54pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494 "2014-12-06T13:54:05Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [December 6, 2014, 1:54pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/1 "2014-12-06T13:54:05Z")
Why was the term “degree” chosen to refer to the units of the various traditional temperature scales? It seems a particularly inapt word. The several wiki articles I read were uninformative on this point. And yes, I’m aware the current SI unit of temperature is the “Kelvin”, not the “degree” or “degree Kelvin.” Although we all also know this is a relatively recent change and the unit \*was \*previously termed a “degree.” ---
**Author:** ![Novelty\_Bobble](https://avatars.discourse-cdn.com/v4/letter/n/a3d4f5/32.png) [@Novelty\_Bobble](https://boards.straightdope.com/u/Novelty_Bobble)\ **Post date:** [December 6, 2014, 2:11pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/2 "2014-12-06T14:11:38Z")
The word “degree” relates to varying levels. i.e. one can have different degrees of separation or Kevin Bacon, or maybe “degrees of freedom” in a statistical sense. So it makes sense to have degrees of temperature, or at least as much sense as any other term you choose to use. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [December 6, 2014, 2:51pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/3 "2014-12-06T14:51:38Z")
> [@Novelty\_Bobble](#): > > The word “degree” relates to varying levels. i.e. one can have different degrees of separation or Kevin Bacon, or maybe “degrees of freedom” in a statistical sense. > > So it makes sense to have degrees of temperature, or at least as much sense as any other term you choose to use. also, degrees Brix (sugar content in a solution) used by winemakers. Among others. ---
**Author:** ![orcenio](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/orcenio/32/1036_2.png) [@orcenio](https://boards.straightdope.com/u/orcenio)\ **Post date:** [December 6, 2014, 2:54pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/4 "2014-12-06T14:54:29Z")
nth degree burns ---
**Author:** ![Flywheel](https://avatars.discourse-cdn.com/v4/letter/f/eb8c5e/32.png) [@Flywheel](https://boards.straightdope.com/u/Flywheel)\ **Post date:** [December 6, 2014, 3:12pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/5 "2014-12-06T15:12:40Z")
> [@orcenio](#): > > nth degree burns and crimes. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 6, 2014, 3:22pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/6 "2014-12-06T15:22:10Z")
From [etymonline.com](http://etymonline.com) > [@](#): > > degree (n.) > early 13c., from Old French degré (12c.) “a step (of a stair), pace, degree (of relationship), academic degree; rank, status, position,” said to be from Vulgar Latin \*degradus “a step,” from Late Latin degredare, from Latin de- “down” (see de-) + gradus “step” (see grade (n.)). > > ``` > Most modern senses date from Middle English, from notion of a hierarchy of steps. Meaning "a grade of crime" is 1670s; that of "a unit of temperature" is from 1727. The division of the circle into 360 degrees was known in Babylon and Egypt. It is perhaps from the daily motion of the sun through the zodiac in the course of a year. > > ``` It’s the “hierarchy of steps” that lead to the notion of temperature being a slope that can be denominated by individual hotness, i.e. degrees. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [December 6, 2014, 3:34pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/7 "2014-12-06T15:34:39Z")
> [@Exapno\_Mapcase](#): > > From [etymonline.com](http://etymonline.com) To what degree do you rely on such obscure sources? 🙂 ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [December 6, 2014, 4:05pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/8 "2014-12-06T16:05:03Z")
> [@Amateur\_Barbarian](#): > > To what degree do you rely on such obscure sources? 🙂 > [@](#): > > obscure (adj.) > c.1400, “dark,” figuratively “morally unenlightened; gloomy,” from Old French obscur, oscur “dark, clouded, gloomy; dim, not clear” (12c.) and directly from Latin obscurus “dark, dusky, shady,” figuratively “unknown; unintelligible; hard to discern; from insignificant ancestors,” from ob “over” (see ob-) + -scurus “covered,” from PIE \*(s)keu- “to cover, conceal” (see sky). Related: Obscurely. Dark. Morally unenlightened. Obviously, I made a deal with the Devil for multiple degrees in Obscure knowledge from my alma pater, Lucifer U. 🆒 ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [December 6, 2014, 4:18pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/9 "2014-12-06T16:18:32Z")
> [@Exapno\_Mapcase](#): > > Dark. Morally unenlightened. Ah. So was a camera obscura used to shoot the earliest porn? > [@](#): > > Obviously, I made a deal with the Devil for multiple degrees in Obscure knowledge from my alma pater, Lucifer U. 🆒 Ah, yes, I remember their visiting games at Wassamatta U. ---
**Author:** ![Hail\_Ants](https://avatars.discourse-cdn.com/v4/letter/h/dc4da7/32.png) [@Hail\_Ants](https://boards.straightdope.com/u/Hail_Ants)\ **Post date:** [December 6, 2014, 4:18pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/10 "2014-12-06T16:18:53Z")
Fahrenheit and Celsius units are called ‘degrees’ for the exact same reason Kelvins are \*\*NOT \*\*called ‘degrees’. A Kelvin is a specific, measurable amount of heat energy, similar to BTUs or calories. Fahrenheit & Celsius are just arbitrary, made-up scales, like deciding a circle should have 360 degrees. The number 360 was just chosen because it’s easily divisible, it has no meaning or measurable relationship to a circle in the real-world (as opposed to [radians](https://en.wikipedia.org/wiki/Radian), which do)… ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [December 6, 2014, 4:20pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/11 "2014-12-06T16:20:07Z")
> [@LSLGuy](#): > > Why was the term “degree” chosen to refer to the units of the various traditional temperature scales? It seems a particularly inapt word. I think the question has been answered, but I’m curious as to why you think the word is particularly inapt. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [December 6, 2014, 6:13pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/12 "2014-12-06T18:13:11Z")
> [@Thudlow\_Boink](#): > > I think the question has been answered, but I’m curious as to why you think the word is particularly inapt. …and what might be or might have been used in its place - a specific term for the concept? A “fahrenheit” or a “celsius”? Or…? ---
**Author:** ![Earl\_Snake-Hips\_Tucker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/earl_snake-hips_tucker/32/3269_2.png) [@Earl\_Snake-Hips\_Tucker](https://boards.straightdope.com/u/Earl_Snake-Hips_Tucker)\ **Post date:** [December 6, 2014, 6:30pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/13 "2014-12-06T18:30:10Z")
BTW, the kelvin ‘degree’ is properly spelled lower case. ---
**Author:** ![Peremensoe](https://avatars.discourse-cdn.com/v4/letter/p/ce7236/32.png) [@Peremensoe](https://boards.straightdope.com/u/Peremensoe)\ **Post date:** [December 6, 2014, 6:54pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/14 "2014-12-06T18:54:30Z")
> [@Hail\_Ants](#): > > Fahrenheit and Celsius units are called ‘degrees’ for the exact same reason Kelvins are \*\*NOT \*\*called ‘degrees’. **A Kelvin is a specific, measurable amount of heat energy** , similar to BTUs or calories. Fahrenheit & Celsius are just arbitrary, made-up scales… Albeit an arbitrarily specific amount, based on the magnitude of the Celsius scale degree. ---
**Author:** ![Amateur\_Barbarian](https://avatars.discourse-cdn.com/v4/letter/a/59ef9b/32.png) [@Amateur\_Barbarian](https://boards.straightdope.com/u/Amateur_Barbarian)\ **Post date:** [December 6, 2014, 7:36pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/15 "2014-12-06T19:36:32Z")
> [@Peremensoe](#): > > Albeit an arbitrarily specific amount, based on the magnitude of the Celsius scale degree. Except that it’s referenced to absolute zero instead of the somewhat arbitrary standard of water freezing. (Which, by the way, is why people in cryogenic suspension are perfectly 0K.) ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [December 6, 2014, 10:21pm UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/16 "2014-12-06T22:21:17Z")
> [@Amateur\_Barbarian](#): > > Except that it’s referenced to absolute zero instead of the somewhat arbitrary standard of water freezing. It’s actually referenced to two “fixed points”: absolute zero, and the triple point of water. Absolute zero has been assigned the temperature 0 K. The triple point of water has been assigned the temperature 273.16 K. Or you if you prefer, absolute zero has been assigned the temperature 0.00000000000000000000000000 K, and the triple point of water has been assigned the temperature 273.1600000000000000000000000000 K. Thus there are two - and only two - _ **defined** _ temperatures. All other temperatures - including the temperatures of other “fixed points” (e.g. the freezing point of water), are measured _based_ on these two defined temperatures. As an example, the melt point of gallium has been measured based on these two defined temperatures, and the latest value is 302.9146 K. With better instrumentation available in the future, however, we may discover the melt point of gallium is 302.9147 K based on these two defined temperatures. A hundred years from now, we may discover it’s actually closer to 302.91475 K. We will never know exactly what it is, as there’s always uncertainly in the measurement. As another example, the freeze point of aluminum has been measured based on these two defined temperatures, and the latest value is 933.473 K. With better instrumentation available in the future, we may discover the freeze point of aluminum is 933.471 K based on these two defined temperatures. A hundred years from now, we may discover it’s actually closer to 933.4714 K. We will never know exactly what it is, as there’s always uncertainly in the measurement. This is true for all temperature measurements; there’s always some uncertainty, even with “fixed” melt and freeze points. There are only two exceptions: absolute zero, which has been rigidly defined to be 0 K, and the triple point of water, which has been rigidly defined to be 273.16 K. As mentioned, all other temperature measurements are based on these two defined temperatures. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [December 7, 2014, 4:15am UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/17 "2014-12-07T04:15:53Z")
I’d like to tidy this up still further (and Crafter I think we had this conversation before a few years ago). I don’t think absolute zero is a defined temperature of zero, unless you consider that lengths are measured with two defined distances of 1 meter and zero meters, or masses with defined 1 kg and 0 kg (I know the meter and kilogram are the base units and not artifacts for defining but let’s not complicate things further). It really means something to double a temperature or take the square root or inverse of a temperature, when you’re doing it in kelvins. As an example temperature to the fourth power is important (for blackbodies this is proportional to energy radiated). An analogous example in distance would be, length to the third power is important (for rectangular solids this is proportional to the mass and volume). These are things that can be added, for instance. Temperature scales are different, like a musical scale or the Beaufort wind scale. They eventually wound up being linear with (though not proportional to) thermodynamic temperature, but they didn’t have to be. You could define a temperature scale by how fast it made a chemical reaction proceed. In this case you’d get a logarithmic scale (roughly, assuming an Arrhenius rate dependence). A scale is a much less ambitious statement about a quantity. We couldn’t see clearly that there was such a thing as zero temperature until way later than we could conceive zero length or zero mass. The triple point of water is defined at 273.16, yes, but I don’t think absolute zero is defined as 0 K any more than zero length is defined as the thickness of an infinitely thin sheet. You don’t need such things. We can count, and having none of something is well defined through math and philosophy already. At least, this is how I understand it. I understand that Kelvin’s role in conceptualizing thermodynamic temperature (the thing that the kelvin is a unit of) such that only one definition is needed is why he’s one of only two people with base units in the SI named after him. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [December 7, 2014, 4:15am UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/18 "2014-12-07T04:15:56Z")
Anyone think we need an SI unit for degree of separation? And if they make one, should it be called the **bacon** or the **erdős**? Or something else? ---
**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\ **Post date:** [December 7, 2014, 4:49am UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/19 "2014-12-07T04:49:53Z")
> [@Exapno\_Mapcase](#): > > Dark. Morally unenlightened. > > Obviously, I made a deal with the Devil for multiple degrees in Obscure knowledge from my alma pater, Lucifer U. 🆒 was that summa cum malum ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [December 7, 2014, 6:41am UTC](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494/20 "2014-12-07T06:41:06Z")
> [@Napier](#): > > … > It really means something to double a temperature or take the square root or inverse of a temperature, when you’re doing it in kelvins. As an example temperature to the fourth power is important (for blackbodies this is proportional to energy radiated). An analogous example in distance would be, length to the third power is important (for rectangular solids this is proportional to the mass and volume). These are things that can be added, for instance. > > Temperature scales are different, like a musical scale or the Beaufort wind scale. They eventually wound up being linear with (though not proportional to) thermodynamic temperature, but they didn’t have to be. > > You could define a temperature scale by how fast it made a chemical reaction proceed. In this case you’d get a logarithmic scale (roughly, assuming an Arrhenius rate dependence). A scale is a much less ambitious statement about a quantity. > > … Nicely made point. The nature of music pitch collections/modes (choosing equally problematic theoretical terms millennia apart) assigned out of the blur of sound is arbitrary. Performers and theorists–who may be descriptive or prescriptive-- create their own rationales. ETA: Props to **Exapno** , ahead of us on the Gradus ad Parnassum. [Next page](https://boards.straightdope.com/t/temperature-scales-why-degrees/706494.md?page=2)