Why is the Celsius symbol not placed on the Kelvin unit?

[OMAR_ALQAM]

Homework Statement

Explain why the symbol of the degree Celsius ° is not placed on the unit of Kelvin, with a reference

Relevant Equations

K = °C + 273.15

I searched the internet for the topic but I did not find an answer or a reference.
* (Note): This is not a university assignment, but from the elementary class.

 

[berkeman]

Welcome to PF.

What search terms did you use? Did you read the article at Wikipedia?

 

[OMAR_ALQAM]

Welcome to PF.

What search terms did you use? Did you read the article at Wikipedia?

I looked up the question directly, and didn't find a convincing answer on Wikipedia.

 

[berkeman]

I looked up the question directly

Sorry, I don't know what that means. I typed some key phrases into the Google search box and it took me right to the answer.

 

[OMAR_ALQAM]

Sorry, I don't know what that means. I typed some key phrases into the Google search box and it took me right to the answer.

The problem is that I want a reference for the answer, the answer is worthless without the reference

 

[Ibix]

The Wikipedia article provides a link to the 1967 BIPM resolution that decided it was K and not °K. It doesn't get much more authoritarive than that.

 

[OMAR_ALQAM]

The Wikipedia article provides a link to the 1967 BIPM resolution that decided it was K and not °K. It doesn't get much more authoritarive than that.

Well we can say it is k and not k°, but I want to know why the ° sign is not put with a reference from a book or research .

 

[phinds]

Well we can say it is k and not k°, but I want to know why the ° sign is not put with a reference from a book or research .

As @Ibix pointed out, it's an agree upon DEFINITION. How do you get more authoritative than that?

 

[Ibix]

Well we can say it is k and not k°, but I want to know why the ° sign is not put with a reference from a book or research .

It's just a human choice, and the BIPM are the ones who make it. There's no more reason than that.

Read their resolution - I expect they explain the reasoning for their choice.

 

[OMAR_ALQAM]

It's just a human choice, and the BIPM are the ones who make it. There's no more reason than that.

Read their resolution - I expect they explain the reasoning for their choice.

@Ibix @phinds @berkeman Well, thanks everyone, I think the problem is with me, I am not used to searching for information, the good thing here is that I found this site. Sorry for the inconvenience

 

[berkeman]

No need to be sorry; we're here to help. We can't give out answers to schoolwork-type questions, but we can usually give good hints and ask the right questions to help you get to the answer yourself.

 

[Lnewqban]

I am not used to searching for information

Welcome, Omar!

This may help:
https://www.bipm.org/documents/2012...15e?version=2.2&t=1734626189691&download=true

 

[OMAR_ALQAM]

Welcome, Omar!

This may help:
https://www.bipm.org/documents/2012...15e?version=2.2&t=1734626189691&download=true

Thanks , this was helpful this helped me get to the reference
Proceedings of the 13th CGPM (1967), 1969, p104

 

[OmCheeto]

Thanks , this was helpful this helped me get to the reference
Proceedings of the 13th CGPM (1967), 1969, p104

Apologies, but I don't speak French very well. Can you translate the reason for me.
I've always been a bit annoyed by the omission of the '°' from the Kelvin temperature, as for about umpteen years I was confused by the 'cold' temperature of the cosmic microwave background, when it quite clearly stated it was 3000 something or another.

Hopefully, one day, they'll see their errant ways, and whatever society happens to be in charge of annoying pedantic matters will decide that the '°' symbol simply designates that we're talking about temperature, and not "many expletives deleted" something else.

 

[pines-demon]

Apologies, but I don't speak French very well. Can you translate the reason for me.
I've always been a bit annoyed by the omission of the '°' from the Kelvin temperature, as for about umpteen years I was confused by the 'cold' temperature of the cosmic microwave background, when it quite clearly stated it was 3000 something or another.

Hopefully, one day, they'll see their errant ways, and whatever society happens to be in charge of annoying pedantic matters will decide that the '°' symbol simply designates that we're talking about temperature, and not "many expletives deleted" something else.

Not so easy to check. I hope there has to be a document in English for you somewhere. I skimmed through it, it is long. There are whole transcripts of discussions. The whole issue seems to be that some people wanted degrees to mean temperature intervals, so °C means degrees with respect to 0°C. However for simplicity they decided on having a single symbol for SI for both temperature intervals and absolute temperatures given by K (note that we do not have a different symbol for "mass intervals"). However degrees °C is still authorized. Before the resolution you could find some documents that used °K for temperature differences.

 

[OMAR_ALQAM]

Apologies, but I don't speak French very well. Can you translate the reason for me.
I've always been a bit annoyed by the omission of the '°' from the Kelvin temperature, as for about umpteen years I was confused by the 'cold' temperature of the cosmic microwave background, when it quite clearly stated it was 3000 something or another.

Hopefully, one day, they'll see their errant ways, and whatever society happens to be in charge of annoying pedantic matters will decide that the '°' symbol simply designates that we're talking about temperature, and not "many expletives deleted" something else.

@OmCheeto
Well, I don't speak it fluently, nor English, it's not my native language. I searched for a document in English and couldn't find it.



*Note* I didn't do the translation, I used artificial intelligence.
-----------------------------------------------------------------------------------------------------------------------
Draft Resolution B

The Thirteenth General Conference on Weights and Measures,

CONSIDERING
the names "degree Kelvin" and "degree," the symbols "°K" and "deg," and their usage rules contained in Resolution 7 of the Ninth General Conference (1948), in Resolution 12 of the Eleventh General Conference (1960), and the decision made by the International Committee for Weights and Measures in 1962 (Proceedings, 30, p. 27),

that the unit of thermodynamic temperature and the unit of temperature interval are the same unit and should be designated by a unique name and a unique symbol,

DECIDES

1. The unit of thermodynamic temperature is designated by the name "kelvin," and its symbol is K;
2. The same name and the same symbol are used to express a temperature interval;
3. The unit of thermodynamic temperature shall no longer be referred to as "degree Kelvin," symbol °K;
4. A temperature interval may also be expressed in degrees Celsius;
5. The decisions mentioned in the first consideration concerning the name of the unit of thermodynamic temperature, its symbol, and the designation of the unit to express an interval or a temperature difference are repealed.
   Proceedings of the 13th CGPM (1967), 1969, p104 (page 19)

 

[pines-demon]

View attachment 356748
@OmCheeto
Well, I don't speak it fluently, nor English, it's not my native language. I searched for a document in English and couldn't find it.



*Note* I didn't do the translation, I used artificial intelligence.
-----------------------------------------------------------------------------------------------------------------------
Draft Resolution B

The Thirteenth General Conference on Weights and Measures,

CONSIDERING
the names "degree Kelvin" and "degree," the symbols "°K" and "deg," and their usage rules contained in Resolution 7 of the Ninth General Conference (1948), in Resolution 12 of the Eleventh General Conference (1960), and the decision made by the International Committee for Weights and Measures in 1962 (Proceedings, 30, p. 27),

that the unit of thermodynamic temperature and the unit of temperature interval are the same unit and should be designated by a unique name and a unique symbol,

DECIDES

1. The unit of thermodynamic temperature is designated by the name "kelvin," and its symbol is K;
2. The same name and the same symbol are used to express a temperature interval;
3. The unit of thermodynamic temperature shall no longer be referred to as "degree Kelvin," symbol °K;
4. A temperature interval may also be expressed in degrees Celsius;
5. The decisions mentioned in the first consideration concerning the name of the unit of thermodynamic temperature, its symbol, and the designation of the unit to express an interval or a temperature difference are repealed.
   Proceedings of the 13th CGPM (1967), 1969, p104 (page 19)

Does that solve your question? (You translated the draft of the resolution, but the final resolution is in page 104, other important discussions can be found in pp. 64-66).

 

[OMAR_ALQAM]

Does that solve your question? (You translated the draft of the resolution, but the final resolution is in page 104, other important discussions can be found in pp. 64-66).

I didn't know there were discussions on the subject in the file! I barely knew where they were talking about the Kelvin unit (the file is in French) and I saw the results and their translation.
Thank you for alerting me @pines-demon

 

[D H]

The whole issue seems to be that some people wanted degrees to mean temperature intervals, so °C means degrees with respect to 0°C. However for simplicity they decided on having a single symbol for SI for both temperature intervals and absolute temperatures given by K (note that we do not have a different symbol for "mass intervals"). However degrees °C is still authorized. Before the resolution you could find some documents that used °K for temperature differences.

An interval scale means both more and less than what you wrote. It does not mean "with respect to 0 °C". An interval scale instead means that the ten degree change from -5 °C to +5 °C has the same meaning as does the ten degree change from 10 °C to 20 °C. The zero point is arbitrary in an interval scale. The meaning of the intervals is anything but arbitrary. That intervals are consistent means that one can (for example) compute the arithmetic mean of a collection of temperature samples. However, computing the geometric mean is not possible. That would require that temperatures be able to undergo multiplication as well as addition.

The reason we do not have a different symbol for "mass intervals" and "mass" is that (at least until relativity and quantum mechanics came along) was that we had a fairly good idea of what "mass" was. If mass was like temperature (degrees Celsius or degrees Fahrenheit), we would have the zero point of mass being something like the mass of a long-dead king. But we don't use the mass of a long-dead king as the zero point of mass. People everywhere (except perhaps merchants with intentionally bad scales) have long measured mass on an absolute scale that is also a ratio scale. Zero mass has real meaning.

That it is also a ratio scale means that things like doubling the mass or the ratio of two masses or the product of two masses makes sense. In comparison, doubling a temperature expressed in degrees Celsius or the ratio or product of two temperatures with both expressed in degrees Celsius does not make sense. In an interval scale (but not absolute scale) such as degrees Celsius, the difference between two temperatures does make sense, as does the ratio or product of a pair of temperature difference.

That was the point behind eliminating the degree symbol from the Kelvin scale. On the Kelvin scale, there is no difference between temperature and temperature difference. They are the same thing. Values on an interval scale can be added or subtracted, but cannot be multiplied or divided. An absolute scale is a different kind of scale than is a non-absolute scale.

 

[pines-demon]

An interval scale means both more and less than what you wrote. It does not mean "with respect to 0 °C". An interval scale instead means that the ten degree change from -5 °C to +5 °C has the same meaning as does the ten degree change from 10 °C to 20 °C. The zero point is arbitrary in an interval scale. The meaning of the intervals is anything but arbitrary. That intervals are consistent means that one can (for example) compute the arithmetic mean of a collection of temperature samples. However, computing the geometric mean is not possible. That would require that temperatures be able to undergo multiplication as well as addition.

The reason we do not have a different symbol for "mass intervals" and "mass" is that (at least until relativity and quantum mechanics came along) was that we had a fairly good idea of what "mass" was. If mass was like temperature (degrees Celsius or degrees Fahrenheit), we would have the zero point of mass being something like the mass of a long-dead king. But we don't use the mass of a long-dead king as the zero point of mass. People everywhere (except perhaps merchants with intentionally bad scales) have long measured mass on an absolute scale that is also a ratio scale. Zero mass has real meaning.

That it is also a ratio scale means that things like doubling the mass or the ratio of two masses or the product of two masses makes sense. In comparison, doubling a temperature expressed in degrees Celsius or the ratio or product of two temperatures with both expressed in degrees Celsius does not make sense. In an interval scale (but not absolute scale) such as degrees Celsius, the difference between two temperatures does make sense, as does the ratio or product of a pair of temperature difference.

Yes temperature is an intensive quantity.

Maybe I was ambiguous with the use of interval, but I did not spoke about "interval scales", I said that deg K was reserved for differences (intervals) in temperature that appear in some equations like thermal expansion of metals.

That was the point behind eliminating the degree symbol from the Kelvin scale. On the Kelvin scale, there is no difference between temperature and temperature difference. They are the same thing. Values on an interval scale can be added or subtracted, but cannot be multiplied or divided. An absolute scale is a different kind of scale than is a non-absolute scale.

Unclear from the text (the interval scale part), maybe you can cite a passage, I was discussing what I found in the text (p. 65).