Talk:Kelvin/Archive 1

message: I just had an edit of mine reverted and I'd like to explain myself.  The BIPM brochure on kelvin, which link I added to the article, states the following (emphasis is in the original):
:The 13th CGPM (1967-1968, Resolution 3) adopted the name kelvin (symbol K) instead of "degree Kelvin" (symbol °K) and defined the unit of thermodynamic temperature as follows (Resolution 4):
::The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.
:Because of the way temperature scales used to be defined, it remains common practice to express a thermodynamic temperature, symbol T, in terms of its difference from the reference temperature T0 = 273.15 K, the ice point. This temperature difference is called the Celsius temperature, symbol t, and is defined by the quantity equation
::t = T - T_0
I re-stated and summarized this as follows:
:The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. It is defined as the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. A temperature given in kelvins, without further qualification, is measured with respect to absolute zero, where molecular motion stops. It is also common to give a temperature (a so-called Celsius temperature) relative to the reference temperature of 273.15 K, approximately the melting point of water under ordinary conditions.
I think this is a fairly faithful rendering of the BIPM's description, but I'm open to discussion on the point.  Our prior (and, after the revert, our current) definition reads as follows:
:The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. It is defined by two facts: zero kelvins is absolute zero (when molecular motion stops), and one kelvin is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. The Celsius temperature scale is now defined in terms of the kelvin, with 0 °C corresponding to 273.15 kelvins, approximately the melting point of water under ordinary conditions.
The problem with this description is that it does not make any distinction between the kelvin unit of temperature versus the Kelvin thermodynamic temperature scale, which measures temperature relative to absolute zero.  For example, take the statement that "zero kelvins is absolute zero".  Consider the question: what temperature change is necessary in water at standard temperature and pressure in order to liquefy it?  The answer is "zero kelvins", but this most certainly does not indicate that the liquefied water would be at absolute zero.
My version of the definition used terms and phrases introduced by the BIPM brochure:
# a kelvin is 1/273.16 of the thermodynamic temperature of the triple point of water,
# it is common to measure relative to 273.15 kelvins, and
# such practice is referred to as "Celsius temperature".
It also includes some embellishments I thought were fairly benign (and were pre-existing):
* absolute zero is where (not "when") molecular motion stops, and
* 273.15 kelvins is approximately the melting point of water.
All in all, I think this is a fairly uncontrovercial definition of the kelvin, and I'd like to reinstate it, or something like it.  --Doradus 03:30, Dec 30, 2004 (UTC)
:No objections in almost 9 months; I have restored my paragraph with a slight modification to avoid the phrase "so-called Celcius scale". --Doradus 16:38, September 7, 2005 (UTC)
===Dispute - Definition of Kelvin===
When I look this up, there seems to be a descrepency between the definition of absolute zero with Zero Kelvin and what is provided by my Physics professor and my physics textbook. Here, it says ..."is measured with respect to absolute zero, where molecular motion stops (except for the residual quantum mechanical zero-point energy)." However, my physics professor and my textbook explicitly disagrees with that exact definition and the textbook says (emphasis mine):
"Absolute zero is not the temperature at which all molecular motion ceases."
As such, the book continues to describe it as: "One way to determine absolute zero is to graph the pressure of a fixed volume of gas as a function of temperature." So the book graphs the temperature of several gases' pressure as temperature drops, and they after many readings, you can then continue to "extrapolate the linear relationship, as described by the Ideal Gas Law." This results in a point in which this converges to a point called absolute zero. My textbook describes it as: "The absolute zero of temperature can also be described as that temperature at which all of the energy that can be removed from the object has been removed."
The textbook I used is: "The World of Physics: Mysteries Magic & Myth" by Dr. John W. Jewett, Jr., Published by: Harcourt College Publishters. . If someone can verify/support this (or disprove it) with other sources, it would be appreciated. -- Akosygin 22:43, 23 January 2006 (UTC)
replies: text: I don't understand your point.  The article only makes a qualified statement with respect to molecular motion, just as your textbook does.  Only difference is, your textbook doesn't spell it out as much. The "can be" vs. "has been" is just a different way of explaining the zero state energy zero-point energy explained at that link in the definition here, isn't it? Gene Nygaard 01:13, 24 January 2006 (UTC)
replies: text: Well, the article makes the exact statement in which the textbook specifically says it is not. "absolute zero, where molecular motion stops" is exactly the definition as stated by the textbook of what absolute zero is not. It specifically states that is not what it is, and yet the article says in a way that molecular motion stops. Therefore, it is rather contradictory to say that the article AND the textbook is correct when they are opposite statements. That is why I am requested either: A.) A rewording of the statement in the article; or B.) support for, or disprove, of what my textbook has said what absolute zero is specifically not. -- Akosygin 01:18, 24 January 2006 (UTC)
replies: text: It is only a qualified statement.  Sure, try to reword it if you like.  But this isn't an "accuracy dispute".  Your textbook's statement is at least as misleading, if not more so.  Remove those templates.  BTW, I fixed the link in my earlier reply above, so it's not a redlink but the one in the article.Gene Nygaard 01:28, 24 January 2006 (UTC)
replies: text: Before I take up on your offer to reword it, let me find additional support for this so that I may more appropriately provide the new wording. If anyone else has additional support either way, help in sheding some light in to this would be appreciated. -- Akosygin 04:24, 24 January 2006 (UTC)
thread_title:  Definition and comparison with Celsius 

message: When I look this up, there seems to be a descrepency between the definition of absolute zero with Zero Kelvin and what is provided by my Physics professor and my physics textbook. Here, it says ..."is measured with respect to absolute zero, where molecular motion stops (except for the residual quantum mechanical zero-point energy)." However, my physics professor and my textbook explicitly disagrees with that exact definition and the textbook says (emphasis mine):
"Absolute zero is not the temperature at which all molecular motion ceases."
As such, the book continues to describe it as: "One way to determine absolute zero is to graph the pressure of a fixed volume of gas as a function of temperature." So the book graphs the temperature of several gases' pressure as temperature drops, and they after many readings, you can then continue to "extrapolate the linear relationship, as described by the Ideal Gas Law." This results in a point in which this converges to a point called absolute zero. My textbook describes it as: "The absolute zero of temperature can also be described as that temperature at which all of the energy that can be removed from the object has been removed."
The textbook I used is: "The World of Physics: Mysteries Magic & Myth" by Dr. John W. Jewett, Jr., Published by: Harcourt College Publishters. . If someone can verify/support this (or disprove it) with other sources, it would be appreciated. -- Akosygin 22:43, 23 January 2006 (UTC)
replies: text: I don't understand your point.  The article only makes a qualified statement with respect to molecular motion, just as your textbook does.  Only difference is, your textbook doesn't spell it out as much. The "can be" vs. "has been" is just a different way of explaining the zero state energy zero-point energy explained at that link in the definition here, isn't it? Gene Nygaard 01:13, 24 January 2006 (UTC)
replies: text: Well, the article makes the exact statement in which the textbook specifically says it is not. "absolute zero, where molecular motion stops" is exactly the definition as stated by the textbook of what absolute zero is not. It specifically states that is not what it is, and yet the article says in a way that molecular motion stops. Therefore, it is rather contradictory to say that the article AND the textbook is correct when they are opposite statements. That is why I am requested either: A.) A rewording of the statement in the article; or B.) support for, or disprove, of what my textbook has said what absolute zero is specifically not. -- Akosygin 01:18, 24 January 2006 (UTC)
replies: text: It is only a qualified statement.  Sure, try to reword it if you like.  But this isn't an "accuracy dispute".  Your textbook's statement is at least as misleading, if not more so.  Remove those templates.  BTW, I fixed the link in my earlier reply above, so it's not a redlink but the one in the article.Gene Nygaard 01:28, 24 January 2006 (UTC)
replies: text: Before I take up on your offer to reword it, let me find additional support for this so that I may more appropriately provide the new wording. If anyone else has additional support either way, help in sheding some light in to this would be appreciated. -- Akosygin 04:24, 24 January 2006 (UTC)
thread_title: Dispute - Definition of Kelvin

message: The symbol '°' is used when refering to a specific temperature (except for the absolute scale when the unit is used directly without any further symbol).  However when refering to the temperature interval, the term 'deg' is used to avoid confusion.
Thus 1 deg Celcius = 1 deg Kelvin. But 1 °Celcius <> 1 Kelvin.
:Nonsense.  Why in the world should we believe someone who doesn't know how to spell Celsius and who doesn't know, even after editing (almost slipped up and said reading, but obviously that didn't happen) this article, that "degrees Kelvin" were thrown out nearly 40 years ago?  
:There is of course, a grain of truth behind this notion—it may have been the recommendation for a brief period, only a few years.  But that silliness was specifically disavowed by the CGPM in 1967, at the same time the degrees Kelvin were abolished.  Gene Nygaard 00:01, 10 March 2006 (UTC)
replies: text: Furthermore, the degree symbol should only be used for temperatures with a letter symbol identifying the scale, not with the spelled out word, and kelvins are not capitalized, if you are really interested in following the rules.  Gene Nygaard 00:05, 10 March 2006 (UTC)
thread_title:  Terminology 

message: I made some changes in the convoluted explanations which included "Notwithstanding the naming convention historically used for the other temperature scales, SI unit names are never capitalized."
One of the biggest problems, of course, with this explanation is that the "degree Celsius" is an SI unit, a "derived unit with a special name", listed in "Table 3 SI derived units with special names and symbols" in the BIPM's SI brochure, for example.
The change isn't due to some inherent difference between kelvins and various other kinds of degrees.  It remains "degrees Celsius".  Furthermore, though the CGPM doesn't concern itself with the non-metric units, it also remains not only "degrees Fahrenheit" but also "degrees Rankine" in the other absolute temperature scale.  Gene Nygaard 12:42, 14 June 2006 (UTC)
replies: text: Furthermore, "degree Kelvin" was the name of the SI unit for over seven years after the SI was introduced in 1960. So it has nothing to do with "SI unit names are never capitalized". Gene Nygaard 13:29, 14 June 2006 (UTC)
replies: text: Note also that the SI rules generally deal mostly with the internationally uniform symbols, and that the spelled-out versions are not subject of uniform, worldwide rules, but rather their spelling and usage is language-specific.  In German, for example, it the unit is now the "Kelvin" with a capitalized K as with other nouns in German, unchanged in plural as other measurements such as "2,5 Meter"  and remain unchanged in the plural in the German language.  Gene Nygaard 14:09, 14 June 2006 (UTC)
thread_title: Capitalization explanation

message: I think this unit being named after Baron Kelvin should be mentioned earlier than it is now, perhaps even in the first sentence as it is with Celsius.  I think finding out who a unit is named after is often important to readers.  What do others think?  --Allen 06:19, 12 September 2006 (UTC)
replies: text: No response; I made the change.  I also removed the reference to the River Kelvin; that's more relevant to the article on the person, where it's already mentioned.  --Allen 02:15, 20 September 2006 (UTC)
thread_title:  mentioning namesake earlier