Talk:Heat/Archive 13

This is an archive of past discussions about Heat. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

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Proposal to community topic-ban User:Damorbel

After his latest efforts at Talk:Boltzmann constant I've made a proposal at WT:PHYSICS that User:Damorbel be community topic-banned from further editing articles and talk pages related to thermodynamics.

The views of those who've interacted with him on this talk page would be useful, since has edited extensively on this talk page as well. Jheald (talk) 21:47, 8 December 2012 (UTC)

What does matter do

Having got to the point of having a concept of a quantity of matter, The next question becomes "what can the matter do?" The answer is that it can contain "energy of motion". And a property of the amount of the "energy of motion" that can be measured by a temperature measuring device is called its heat energy or just heat. And since it's related to the motion value it must be considered to be a form of the "kinetic energy of motion", which is usually viewed as being equal to a "1/2 of the mass time the square of the speed" value. So the "speed" goes up as the square of the temperature. Which is suitable for most classical computations.WFPM (talk) 03:53, 9 December 2012 (UTC) Please note that in the article Latent Heat that heat is defined as being the thermal heat energy being transferred from a substance to its surroundings.WFPM (talk) 04:01, 9 December 2012 (UTC)

Inconsistency in opening section.

The 2^nd line has this:-

Heat is not a property of a system or body, but instead is always associated with a process of some kind, and is synonymous with heat flow and heat transfer.

While the 4^th para. begins:-

The SI unit of heat is the joule

Heat transfer etc. is measured in J/s (joules/sec) or Watts. Joules and Watts are not the same. This sort of contradiction has no place in a Wikipedia article.

Anybody have a solution to this? --Damorbel (talk) 07:50, 20 December 2012 (UTC)

PS In case anybody is wondering why I am repeating a previous observation; well neither the passage of time nor the pages of innaccurate physics written for these talk pages between 10:38, 29 September 2012 and 08:39, 27 November 2012 has provided any explanation for how the SI has the joule (energy) as the unit of heat and the article has heat transfer (Watts) as the unit of heat. --Damorbel (talk) 13:56, 20 December 2012 (UTC)

"Heat transfer etc. is measured in J/s (joules/sec) or Watts." No, it's not. The amount of heat transferred is (of course) measured in Joules. You could measure instantaneous heat transfer, or heat transferred/time, in Watts. There is no inconsistency. Waleswatcher (talk) 14:36, 20 December 2012 (UTC)

Waleswatcher, you write:-

You could measure instantaneous heat transfer

You are claiming instantaneous heat transfer?

Utter nonsense, no wonder the article is in a mess! --Damorbel (talk) 16:17, 20 December 2012 (UTC)

Damorbel, do you have a solution? RockMagnetist (talk) 17:25, 20 December 2012 (UTC)

Only in the model of Clausius where heat is the kinetic energy of particles (atoms, molecules, etc.). With this model everything falls into place, temperature, entropy, energy etc., etc.

I am all too aware of the 'heat is energy in motion' model but unfortunately it doesn't add up; the most obvious example is the inevitable contradiction I have pointed to in the units used to describe it. The 'energy in motion' model is widely taught in universities etc. but that still doesn't make it work! --Damorbel (talk) 18:02, 20 December 2012 (UTC)

How about proposing an alternate wording, then? RockMagnetist (talk) 18:48, 20 December 2012 (UTC)

How about using the term "heat energy" or "thermal energy" for the noun, and "heat", "heating", etc. for the verb.PAR (talk) 21:31, 20 December 2012 (UTC)

If you agree with the Clausius model:-

...motion of the particles does exist, and that heat is the measure of their vis viva... - Philosophical Magazine July 1851. p4.

then heat is the dynamic and kinetic energy of the particles in the system; it is proportional to the temperature of the particles in the system. Temperature is related to this (particle) energy by the Boltzmann constant.

N.B. Thermal energy does not correspond to heat since thermal energy is dispersed throughout the system. With the definition of Clausius heat is a function of the concentration "thermal energy" i.e. of the temperature.

Using Clausius' definition there is no need for a system to be in equilibrium to describe it, i.e. some of the particles can be much hotter than others!. --Damorbel (talk) 14:31, 21 December 2012 (UTC)

1st Line

The 1^st line has:-

...heat is energy transferred from one body to another by ....

This is an obvious lack of clarity; just what is the nature of this energy that is being transferred? Is it potential energy or kinetic energy, etc., etc.? This opening statement needs to be improved. --Damorbel (talk) 07:25, 21 December 2012 (UTC)

That "lack of clarity" is actually generality. Heat is defined by the laws of thermodynamics, not by the specific nature of the system in question. As for Clausius, things have moved on since 1851, and the concept of heat is far more general than that.

You don't seem to understand that wikipedia is an encyclopedia. It should reflect consensus knowledge, not idiosyncratic personal beliefs such as yours. In any case, discussions with you are quite pointless. If you make changes to articles along the lines you suggest, they will be reverted as they would violate wiki policy. Waleswatcher (talk) 15:09, 21 December 2012 (UTC)

"motions of the microscopic constituents"

I agree with Waleswatcher that "motions of the microscopic constituents" was poor or wrong expression. I was uncomfortable with it when I wrote it, but I did not dare to use the more natural wording, that I would prefer, that the explanation is in terms of the 'adventures of the microscopic constituents'. The word adventures is probably too adventurous for us? I don't think it wrong, but I accept that it is a bit unconventional in the present context. The problem with "motions" is that it underplays potential energies of various kinds and in a sense overplays kinetic energy. Can we find a more general word to do the job?

'Adventure' is a word of the ordinary language. At a terrible risk of being ridiculed by some well respected editors (shudder, shock, horror), I quote Alfred North Whitehead's Process and Reality at page 87 as follows; "But what Locke is explicitly concerned with is the notion of the self-identity of the one enduring physical body which lasts for years, or for seconds, or for ages. He is considering the current philosophical notion of an individualized particular substance (in the Aristotelian sense) which undergoes adventures of change, retaining its substantial form amid transition or accidents." I dare not quote more. In my defence, I will say that Whitehead cannot be dismissed as a fool. Principia Mathematica is not the work of a fool. According to the Wikipedia, which I accept is not a reliable source, "P[rincipia ]M[athematica] is widely considered by specialists in the subject to be one of the most important and seminal works in mathematical logic and philosophy since Aristotle's Organon.[1] The Modern Library placed it 23rd in a list of the top 100 English-language nonfiction books of the twentieth century.[2]" The co-author of such a book is hardly to be dismissed as a fool. I would say that Process and Reality is hard going, and I think very often more or less misrepresented. The references in the Wikipedia article on it do not include the one I think is perhaps most helpful, LeClerk, I. (1958), Whitehead's Metaphysics. An Introductory Exposition, George Allen and Unwin, London.

Heat is explained in terms of constituent kinds of energy, with special reference to microscopic particles, but also with reference to supply of internal energy from work done by external forces such as gravity, and motion is an essential part of the explanation, because the energy starts in one body and ends in another. According to some views, statistical mechanics is about equilibrium ensembles, and so a full explanation of heat needs a slightly different approach, that is sometimes referred to as the kinetic theory, particularly of gases, to account for transport.

I agree with Waleswatcher that "motions" did not do the job as well as we may desire.Chjoaygame (talk) 02:56, 22 December 2012 (UTC)

Thinking about it, I now think that "motions and intereactions of the microscopic constituents" would do.Chjoaygame (talk) 14:29, 22 December 2012 (UTC)

"especially in thermodynamics"

Waleswatcher proposes that the words "especially in thermodynamics" were redundant. But his next sentence reads "Heat is a primary topic in thermodynamics." The word 'especially' is neither exhaustively comprehensive nor exclusive. It just points to a particular instance, as it were, in apposition with the main words, physics and chemistry. But thermodynamics is an important instance, as is indicated by Waleswatcher's next sentence.Chjoaygame (talk) 03:23, 22 December 2012 (UTC)

"heat has only one meaning in physics and chemistry"

Waleswatcher's cover note to his recent edit reads: "... heat has only one meaning in physics and chemistry ...".

A praiseworthy sentiment.

I wish it were realized in all potential sources for our article here.

According to physics texts, transfer of energy as heat is recognized between two closed systems in thermal connection. In purely physical terms, that means connection by thermal conduction or by thermal radiation. Examples of such texts were until recently cited in the lead. The two cited ones were Kittel & Kroemer and Reif.

As defined by Reif, transfer of energy as heat can be thought of in two ways.

The officially correct thermodynamic way to think of it is that quantity of heat is to be defined as a virtual quantity of energy transferred as work that would have produced a specified change of state that was actually produced by some unspecified mechanism other than transfer of energy as work between closed systems; by deduction, this must have been energy transferred as heat, and by deduction, this must have been transferred by conduction or radiation because those are the only permitted mechanisms of transfer of energy other than as work between closed systems. The virtues of this officially correct reading are evident: simplicity, transparency, mathematical perfection. Experimentally it is hardly ever done. But it is carefully prescribed as the correct way by Reif and others of his mind, that includes most textbooks when they are on their good behaviour. They were led to this by the work of mathematician Constantin Carathéodory, who was put onto it by Max Born.

The officially wrong way to think of it is to recognize that calorimetry is the commonest source of thermodynamic data, and to measure transfer of energy as heat by calorimetry, the heat being conducted or radiated. Far too easy for the official viewpoint.

For the definition of flux of ""thermal energy"" (not a properly defined term here—just setting a trap for young players here), statistical mechanics and especially transport theory, and some textbooks of non-equilibrium but local thermodynamic equilibrium thermodynamics, consider open systems from the start. Textbooks of statistical mechanics and of transport usually, and of non-equilibrium thermodynamics sometimes, say they are defining "flux of heat", but if you read carefully, you find they are actually referring to what thermodynamics strictly calls flux of internal energy. Thus many texts of statistical mechanics and transport theory do not bother at all with the distinction between heat and work that so concerns Reif in his work with closed systems. They just jump to flux of internal energy and call it "flux of heat". There is a good reason for this. The distinction mentioned above, for closed systems, between work and heat does not work in general for all processes between open systems. [Münster, A. (1970), Classical Thermodynamics, translated by E.S. Halberstadt, Wiley–Interscience, London, ISBN 0-471-62430-6, pp. 45–51.] Some textbooks of thermodynamics deal with this just by not mentioning open systems with reference to work and heat. Some textbooks, especially engineering texts, but also some thermodynamics texts, do talk about heat transfer between open systems, but they do it without making it very clear that their distinction works only under special or restricted conditions, and does not work for general processes between open systems. The outcome is that in some important circumstances, statistical mechanics and transport theory and non-equilibrium thermodynamics do not distinguish between heat and internal energy: when they say "heat" they mean internal energy. Saves a lot of time and words, but doesn't agree with the idea that "heat has only one meaning in physics and chemistry". The fundamental physics here is that for open system processes in general, the relevant quantities that are transferred are entropy and internal energy.

Neither Reif nor Kittel & Kroemer discuss convection, restricting their discussion to transfer of energy as heat between two bodies or closed systems, that is to say by conduction and by radiation. But our present Wikipedia article on heat has it that a three-body transfer mechanism called convection is also a form of transfer of energy as heat. Convection includes a step that transfers energy as internal energy, by bulk movement of matter, without necessarily involving in that step heat transfer as defined by Reif and by Kittel & Kroemer which is by conduction and radiation, not convection. Reif and Kittel & Kroemer have written whole books about the physics of heat, in terms of conduction and radiation, but have apparently not bothered to examine this third mechanism. Were they just careless? Or did they know that talk of convection would take them into talk about open systems which they did not think helpful? Many engineers do not bother to say that what is transported by bulk flow is internal energy, because they are interested only in the effects on the other two bodies, the source and the sink, in the three-body convection process, and their input and output quantities of interest are quantities of heat. One may ask, does the physical and chemical meaning of heat include convection? It is clear enough in physics texts on thermodynamics, but not in some engineering texts, that convection is not a pure form of transfer of energy as heat; it is a compound process with some of its components involving transfer of energy as heat as defined by physics and chemistry, but at least one component essentially and necessarily involving a different kind of transport of energy.

I will not here go into other possible doubts about the meaning of heat in physics and chemistry because I see them as not helpful right now. For the present I just want to point to the existence of reasonable questions about the laudable and desirable idea that "heat has only one meaning in physics and chemistry."Chjoaygame (talk) 12:26, 23 December 2012 (UTC)

Waleswatcher's recent edit

Waleswatcher has responded to the talk page comments of Count Iblis, and of PAR, just above, in the section Definition of heat given in the first sentence is wrong by restoring a previous version of his choice.

Count Iblis's comment was careful and reasonable, and clear enough, and it is hard to avoid the idea that PAR's comment was in agreement with that of Count Iblis, and that PAR was inviting not Waleswatcher, but rather was inviting Count Iblis, to make a re-write.

But Waleswatcher's uninvited edit to the previous version that he chose, ostensibly in response to the common commentary of Count Iblis and PAR, does not at all reflect that common commentary. The natural inference is that either

(1) Waleswatcher fails to understand the common commentary of Count Iblis and PAR; or

(2) Waleswatcher does understand the common commentary of Count Iblis and PAR, but rejects its intent.

If (2) Waleswatcher does reject the intent of the common commentary of Count Iblis and PAR, then it is incumbent on him to explain his new edit on fresh grounds, including his reason for rejecting the intent of the common commentary of Count Iblis and PAR, which he has not attempted to do. This lack of attempt to explain would make Waleswatcher's new edit improper.

If (1) Waleswatcher fails understand the common commentary of Count Iblis and PAR, that would call for him to improve his understanding, and would make his new edit unsubstantiated, and therefore fit to be undone.Chjoaygame (talk) 06:19, 24 December 2012 (UTC)

This is mere comment, replace it with something that will imrove the article, please. --Damorbel (talk) 07:38, 24 December 2012 (UTC)

Definition of heat given in the first sentence is wrong

Heat is in principle not energy transfer due to X, Y or Z. By definig heat in this way, it looks like whether some energy transfer is heat is some arbitrary definition where it matters if it is due to these factors. Count Iblis (talk) 14:48, 23 December 2012 (UTC)

I don't like that first sentence either. Could you please rewrite it? PAR (talk) 16:56, 23 December 2012 (UTC)

Me either. I'l restore it to what it was, which was more or less verbatim the definition from K&K. Waleswatcher (talk) 17:06, 23 December 2012 (UTC)

This is all very fine, but it is not quite spot on. Waleswatcher says that the sentence was "more or less verbatim" the definition from K&K. I would say that we established that it was more or less verbatim from Reif, but omitting a crucial word "purely". I would say that this is not spot on. In a matter like this, near enough is not good enough.

The three objections here are not mutually concordant. So far as I can see, the Waleswatcher definition is not the one being demanded by Count Iblis, and would by Count Iblis' definition also be wrong, because of its vagueness. PAR I suppose is writing more or less in agreement with Count Iblis, though he is not explicit about that.

I have made it clear enough above that I recognize the official correctness of the Carathéodory definition, the one followed by Reif, and by other reliable sources. I note that the latter has not been present in the lead for quite some time. I wonder why it is just now that it is objected to. Is it because the new version was more explicit and clear than the one that has been there for some time, that used the unsourced and defined term "thermal interactions". I am not opposed to making the Carathéodory definition primary, as proposed by Count Iblis, and I suppose by PAR. But I note that it definitely disagrees with a definition that allows convection, because the Carathéodory definition refers to closed systems, when convection refers to open systems.

I think it fair to say that if the Carathéodory definition is to be primary, it should be recognized that it is rather sophisticated and does not make its physical meaning obvious to a layman. Its physical meaning is clear, that it refers to transfer of energy through a wall that permits the passage only of heat, and that physically that means that it refers to conduction or radiation. The layman needs this to be made abundantly clear.

It seems that a careful statement above, in the section "heat has only one meaning in physics and chemistry", about this definition does not qualify for editors' attention or reply. I think this is not right, when no detailed and precise source and no consistent rational discussion is offered in the present section, even though a rational discussion has been offered immediately above.Chjoaygame (talk) 23:38, 23 December 2012 (UTC)

Well, at least say what a "thermal interaction" is. Saying only that heat energy transfered by "thermal interactions" and just leaving it hanging, is like saying that morphine induces sleep by means of its dormative properties. "Thermal" can MEAN something to do with heat. But in this case we mean more. A "thermal interaction" is an interaction wherein net internal energy is transfered from one place to another by means of a temperature difference, and wouldn't be transfered if there was no temperature difference. We specifically mean something that has to do with a temperature difference, so say that.
And while I'm at it, I fail to see why people are insisting on some purist approach to thermodynamics that doesn't take into account microscopic things like the mean kinetic energy of particles or the modal energy of a distribution of thermal photons. Both of which translate naturally into temperature, the difference in which is what drives heat transfer. Very simple. Trying to talk about all this without mentioning atoms or photons is like trying to talk about bulk chemistry without mentioning ye olde hypothesis of Mr. Dalton, regarding ye atomic corpuscles. You can talk about bulk chemistry without ever mentioning ye atoms, but it's not very satisfactory. S B H arris 04:21, 24 December 2012 (UTC)

On further thought, I see that Count Iblis' comment above is perhaps clear only to those who have followed this article for some time. With all respect to Count Iblis, I would like here to say what I think he intends in a more explicit way, for the benefit of those who have not followed this article for some time. Please would he correct me if what I write is a misrepresentation of his intention? Likewise, with respect, for the comment of PAR.

Count Iblis intends to refer strictly to the Reif definition of transfer of energy as heat. Reif takes some pages to do this, and his definition is made in the context of those pages. My take on the Reif definition is as follows.

The internal energy of a body in an arbitrary state

X

can be determined by amounts of work adiabatically performed on the body when it starts from a reference state

O

, allowing that sometimes the amount of work is calculated by assuming that some adiabatic process is reversible. Adiabatic work is defined in terms of adiabatic walls, which allow the frictionless performance of work but no other transfer, of energy or matter. In particular they do not allow the passage of energy as heat. Passage of energy as heat is allowed, according to Carathéodory 1909, the template on which Reif is based, by walls which are "permeable only to heat". It is envisaged that another arbitrary state

Y

is reached from state

O

by a process with two components, one adiabatic and the other not adiabatic. For convenience one may say that the adiabatic component was work done by volume change through movement of the walls while the non-adiabatic partition was excluded, so that only adiabatic change occurs in this component. Then the non-adiabatic component is performed by a process of energy transfer through the now opened wall that passes only heat. The change in internal energy is the sum of the two amounts of energy transferred. The quantity of energy transferred as heat is defined by Reif as the change in internal energy minus the amount of work done on the body by the adiabatic process. The quantity of energy transferred as heat is not specified directly in terms of the non-adiabatic process. It is defined through knowledge of precisely two variables, the change of internal energy and the amount of adiabatic work done, for the combined process of change from the reference state

O

to the arbitrary state

Y

. It is important that this does not explicitly involve the amount of energy transferred in the non-adiabatic component of the combined process. It is assumed here that the amount of energy required to pass from state

O

to state

Y

, the change of internal energy, is known, independently of the combined process, by a determination through a purely adiabatic process, like that for the determination of the internal energy of state

X

above.

Consequently, the mechanism of transfer of energy in the non-adiabatic component of the combined process is not explicitly specified in this definition given by Reif, adverted to and I think recommended by Count Iblis and by PAR. If I have taken their names in vain, I have done so with all good will, and I hope they will correct me about this.

I would say about this that although this Reif-Carathéodory definition does not explicitly specify the mechanism of transfer of energy in the non-adiabatic component of the combined process from

O

to

Y

, this definition lacks physical definiteness, and indeed for just that reason. It is part of the set-up, specified explicitly by Carathéodory, and by context and example by Reif, who writes of "purely thermal interaction" and immediately gives an example of cold beer in a refrigerator. The set-up involves walls "permeable only to heat". It also involves a "non-deformation variable". This variable is not obtrusively noted by Reif to be capable of interpretation as an empirical temperature, but implicit in his context is that it is common knowledge that beer left out of the refrigerator is not kept cold. The passage of energy as heat between one closed system and another requires difference of the equivalent values of the non-deformation variable, and a partition "permeable only to heat" (Carathéodory 1909). It is evident enough that the quantity of energy transferred as heat as defined by Reif is transferred by the mechanisms that determine transfer of energy through a partition permeable only to heat. The only physical mechanisms offered for that are thermal conduction and radiation. That Reif refrains from mentioning this is an impressive feat of presentation, pleasing especially to mathematicians; nevertheless, the physics is plain enough. Reif defines absolute thermodynamic temperature after stating the second law, but his whole presentation rests on the existence of empirical temperature, alias the "non-deformation variable" right from the start.

It may be right to insist, as I think Count Iblis would like, that the article should present the Carathéodory-Reif definition of transfer of energy as heat, but I think it presents only one point of view, the mathematical point of view. They physical point of view is championed by (if I may quote him with respect) SBHarris, that transfer of energy as heat is determined by temperature difference acting across a wall permeable only to heat, or in Reif's terms, by difference in the non-deformation variable, otherwise recognizable as the empirical temperature, and a "purely thermal interaction". An empirical temperature is a strictly monotonic function of the thermodynamic or absolute temperature; this is very carefully set out by Truesdell and Bharatha (1977); this is a secondary source, the first author of which is a recognized expert writing in his area of expertise, contested by no one on this point, so far as I know. The Reif definition strictly requires a proper account of the internal energy as determined by purely adiabatic changes, and may take some effort to fit into the lead; indeed the charge of "walls of text" is lurking here!

Again, I hope I have rightly represented the view of Count Iblis and of PAR, and I trust they will correct me if I have not.

SBHarris is right to say that "purely thermal interaction" reminds one of the mediaeval 'dormitive virtue of morphine', a classic example for students, of deficient reasoning.Chjoaygame (talk) 12:33, 25 December 2012 (UTC)

Some more comments

Some more comments. I do largely support the view by Reif as Chjoaygame points out above. Now, my view here is that heat is a more fundamental concept than temperature, that's clear if you read the treatment by Reif. Another important thing to note is that "work" is "macroscopic work", and this is actually the key to understanding that heat is. You can always consider all energy transport as work. Once you define what your external parameters you can start to define what macroscopic work is. Energy transfer that is invisible at the coarse grained level where you describe the macroscopic object in terms of a few macroscopic variables is, by definition, heat.

While Reif does not mention the "non-deformation variable" what he does instead is mention that the quantities of interest, like energy transfer are obtained after averaging over an ensemble of macroscopically idential systems. These systems are in different microstates. If one were to assume that the system has some temperature than that alone would fix that ensemble to be descibed by the canonical ensemble. So, Reif's treatment is far more general than the approaches that follow classical thermodynamics. The reason why this is important for this article is because heat only starts to flow when you are slightly away from thermal equilibrium, so the definition of heat ahould not build on concepts that are exactly valid only at thermal equilibrium. Instead you need to consider general states that are arbitrarily far away from thermal equilibrium. From there one can look at quasistatioc changes and make contact with practical situations like that heat flows from hot to cold, but one should not make the mistake of attempting to define heat from such examples. Count Iblis (talk) 00:36, 27 December 2012 (UTC)

As noted by Count Iblis, Reif does not use Carathéodory's term "non-deformation variable". But Reif he does use a variable corresponding to Carathéodory's "non-deformation variable", under various other names. For example, on page 66 Reif writes: "The ″macroscopic state″ or ″macrostate″ of the system is defined by specifying the external parameters of the system and any other conditions to which the system is subject." Such other conditions are necessary as noted by Reif, and are summarized by Carathéodory's one "non-deformation variable". On page 67, Reif writes: "All systems in the ensemble are characterized by the given values of the external parameters and of the total energy." The total energy would do as a non-deformation variable for Carathéodory.

Classical thermodynamics, as for example that of Carathéodory, admits compound systems, each component of which is defined in its own initial equilibrium state, separated from the other component systems by walls of defined character. To initiate a process, the walls are considered to change, for example so as to change component system volumes and thereby pass energy as work. Eventually the states of the component systems are defined again, after the change, as final equilibrium states. The changes are not required to be quasi-static, though quasi-static changes are most informative.

Classical thermodynamics does not rely on or mention the microstates. Specification of more detail, such as microstates, makes a theory more particular, less general. In that sense, classical thermodynamics is more general than a scheme that does rely on specification of microstates. Reif does not consider time-varying Hamiltonians in this discussion.Chjoaygame (talk) 01:42, 27 December 2012 (UTC)

Count Iblis is right that the conceptual definition of absolute thermodynamic temperature is founded on the concept of quantity energy transferred as heat, which he expresses by saying that "heat is a more fundamental concept than temperature, that's clear if you read the treatment by Reif."

It remains the case that every system that is fully defined by Reif in physical fact has a temperature, whether one puts it into words or not, because all Reif's fully defined physical systems are in stationary states, indeed thermodynamic equilibrium states, stated though they are as ensembles of quantum mechanical systems. Reif's presentation does not verbalize the fact of the existence of temperature for his systems till he has formulated the second law, which provides a definition of absolute thermodynamic temperature. But the fully defined physical system right from the start of its equilibrium state has its temperature sitting physically in it, waiting for Reif's presentation to get around to verbalizing it. The Carathéodory-Reif presentation just doesn't mention this physical fact till late in its development. Carathėodory delays the verbal expression of the existence of temperature in the system by talking about the "non-deformation variable", while Reif does it by using the total energy or some other such variable to complete the specification of the system with the extra variable that is needed beyond the external mechanical variables. Their common plan is to hide the physical existence of temperature in the system from the start, by not mentioning it, so that they can seem very clever and produce the absolute thermodynamic temperature like a rabbit out of a hat when they have developed their presentation to the statement the second law. The physical existence of temperature in the system is indicated by the need for the "non-deformation variable" or the total energy, right from the start; these variables are empirical temperatures, though Carathéodory and Reif do not say so.

The Carathéodory-Reif presentation postulates the existence of walls "permeable only to heat" as part of the initial physical set-up. It's just that they don't talk about the transfer of energy as heat till late in the piece. Indeed Carathéodory in fact does not actually define transfer of energy as heat in his presentation at all; he leaves it to the reader to work out.

Count Iblis says that "you need to consider general states that are arbitrarily far from thermal equilibrium." But Reif only vaguely adverts to the possibility of non-equilibrium ensembles; he doesn't produce any calculations about them, or say how he would explicitly define them; it is a matter of words whether that vague adversion constititutes 'considering' non-equilibrium states. The classical approach also admits non-equilibrium states, that arise when the partitions between the component subsystems are changed; like Reif it does not try to produce calculations about them; like Reif, it waits till equilibrium is re-established and then does its calculations.

Reif and Kittel & Kroemer are both exponents of "thermal physics" pedagogy, that teaches thermodynamics and statistical mechanics more or less simultaneously. But they differ in their approach to heat. Reif is a strict Carathéodory man, while Kittel & Kroemer, as discussed below, regard heat and work as defined independently of one another, disregarding Carathéodory's rigorous approach. The pedagogical question of whether to teach thermodynamics simultaneously with statistical mechanics is distinct from the theoretical physical question of whether to regard heat and work as independent basic concepts or to define the concept of heat as a derivative from the concept of work. Kittel & Kroemer put it very briefly: "Heat is a form of energy" (page 49). They are not concerned with the logically careful Carathéodory development that so concerns Reif, because they feel that it is rendered trivial by their statistical mechanical, alias "thermal physics", approach.

Count Iblis is right to emphasize that here, by 'work', we mean macroscopic work.Chjoaygame (talk) 14:46, 27 December 2012 (UTC)

Thinking it over, I now think perhaps I see what Count Iblis wants to emphasize. That the non-deformation variable should be an average over an ensemble of microscopically defined objects. It should not be a macroscopic variable such as the internal energy, which is defined by work, which he emphasizes as a macroscopic variable, defined by changes in the macroscopic external parameters.

I don't see why he isn't saying that the macroscopic external variables and the work should also be averages over ensembles of microscopically defined objects. I don't see a compelling reason why the non-deformation variable should be treated differently from the external parameters, ensemble average versus macroscopic variable.Chjoaygame (talk) 20:37, 27 December 2012 (UTC)

some purist approach

SBHarris writes: "I fail to see why people are insisting on some purist approach to thermodynamics that doesn't take into account microscopic things like the mean kinetic energy of particles or the modal energy of a distribution of thermal photons". I have an idea that some other editors would more or less share this sentiment.

To be fair, I don't think that it would be accurate to say that those who think that the thermodynamic definitions of temperature and of quantity of heat transferred are primary would say they don't want to "take into account things like ..." Their position, as I understand them, is simply that some definition should be primary, and that the thermodynamic definition is most suited for that. The advantage of the thermodynamic approach is its generality, not depending on which particular microscopic model one is dealing with. Microscopic models for gases are often different from microscopic models for solids. One does not want to have to use a different definition of temperature every time one looks at a different microscopic model. Microscopic definitions of temperature are easy enough for ideal gases, but for solids in general they are not so easy to frame. The thermodynamic definition is a reliable guide to the framing of microscopic definitions, but the converse is not so easy.Chjoaygame (talk) 04:58, 24 December 2012 (UTC)

The temperature of a solid is the mean kinetic energy of its particles, just the same as it is, in a gas. If it weren't so, there would be some heat energy flow between solids and gases of the same temperatures, and there isn't. Sure, solids have other particle potential energies that take up internal energy, but their temperatures are in the kinetic energies which are the tip of the energy iceberg (while kinetic energy is the entire thing in ideal gases). That's not hard. Photon frequencies couple to particle kinetic energies, not particle velocities, frequencies, or vibrations. That's a quantum mystery, but must be the case. Lighter atoms vibrate at higher frequences at the same temperature, yet give off the same thermal photon spectrum, all the same. All that is required is that they have the same mean (RMS) kinetic energy per atom. S B H arris 05:26, 24 December 2012 (UTC)

It would be required that each atom have a well defined kinetic energy, but that condition is not always fulfilled. That was one of the reasons for the invention of the quantum theory.Chjoaygame (talk) 06:22, 24 December 2012 (UTC)

Chjoaygame, you write:-

a well defined kinetic energy

This isn't true, it is the total energy that is conserved.

Further, to understand quantum theory one must realise that quantum theory incorporates:-

1/ conservation of energy (in general)

2/ conservation momentum, both angular and linear;

3/ the uncertainty principle which is also fundamental to the conservation laws.

These laws must be taken into account rigorously, otherwise your are firmly in to fantasy physics.

If this what you mean by but that condition is not always fulfilled then you should say so, do not leave such a question hanging as if it was some sort of defence for the fantasy physics (heat is energy transferred from one body to another by thermal interactions )(!) found in the article. --Damorbel (talk) 06:59, 24 December 2012 (UTC)

I'm a purist in the sense that I want to maintain the distinction between macroscopic "classical" thermodynamics and the microscopic statistical mechanics explanation of classical thermodynamics. But I don't reject the enormous understanding of classical thermo provided by stat mech. Classical thermo provides operational definitions for all the thermo functions. Stat mech illustrates but does not supersede those definitions. Maintaining this point of view stops you from making false statements like "temperature is (proportional to) the mean kinetic energy per particle". That's a true statement, until the translational degrees of freedom start to freeze out, in the Bose-Einstein condensate temperature regime, for example. The classical thermo definition is then the only one left standing. PAR (talk) 17:24, 25 December 2012 (UTC)

If I qualify that as saying temperature is proportional to kinetic energy in excess of the (unavailable) zero point kinetic energy of atoms at absolute zero, it hardly destroys the argument, or somehow makes it irrelevant. It just means we now know threre is some energy you can't get at. This energy is not thermal , doesn't contribute to temp or heat capacity, can't be transferred by thermal contact, and might as well not exist. It's as thermodynamicaly relevant as nuclear binding energies or inner electron kinetic energies. Big deal. Sure vibrational excitations freeze out, leaving you only non-available zero point motion. That can't happen to pure translation unless you confine your particles in a box or potential somehow, and then you get the same phenomenon of a confined wave with a minimal ground state energy. Temp is zero there, no matter how high the ground state energy. What's the temp of nucleons in a nucleus? We're not talking of those unavailable energies. It's understood without saying they don't have anything to do with temperature.

Look, I'm not pushing this idea for my own esthetics. The mechanism of what happens in mechanical thermal contact is the atoms of two substances hit each other and in that process compare and trade available kinetic energies. That's it. It would be really stupid if this article on heat didn't mention that this is how heat moves. Don't annoy me with scholasticism. What I just said is what actually happens . You disagree? S B H arris 19:38, 25 December 2012 (UTC)

The article has a section headed Microscopic origin of heat. It does already say "that this is how heat moves". I hardly need say that of course editors are free to expand that section. I makes me happy to see you write about the mechanism of what happens. Heat transfer also in general involves microscopic potential as well as microscopic kinetic energy.Chjoaygame (talk) 20:02, 25 December 2012 (UTC)

In general heat transfer doesn't care about microscopic potentials, which are ignored. Helium gas at 300 K will transfer heat to bismuth metal at 299 K which has twice as much thermal energy per atom and all kinds of potential where the helium has essentially none. The process doesn't care about potential, but only 1/2 mv^2. S B H arris 03:31, 26 December 2012 (UTC)

By "essentially none" I think you mean 'very nearly none'? Even if your example worked as you intend, it is still a specially chosen example, not a general case.Chjoaygame (talk) 04:51, 26 December 2012 (UTC)

And all the Helium molecule has to do is to transfer a portion of its kinetic energy of motion to the slower motion of some component of the bismuth atom via a momentum transfer process, which is then presumably redistributed an a manner such as to slightly increase the contained kinetic energy (absolute temperature) characteristic of the bismuth. And the question remains as to how much contained internal kinetic energy does the bismuth (and particularly the OO9F18) atom have at O degrees Kelvin? And if all we have to think about are namely: 1 Matter, and 2 Motion, then how did we ever arrive at the concept of motion without matter?WFPM (talk) 22:44, 27 December 2012 (UTC)

It's a general case of a general rule that only linear kinetic energies "count" as temperature since only these participate in transferring net energy between molecules on impact. Consider deuterium D₂ gas and helium at the same temp and pressure (low enough for ideal behavior). Let us make it 400 K. You'll find D2 rotation affects heat capacity, but rotational KE of atoms does not show as temperature. The D2 molecules translate (center of mass) at the same speeds as He, even though the individual D atoms are moving 29% faster, and have 5/3 times more energy in total (though 83% as much individually, as there are twice as many). Their extra rotational kinetic energy is hidden, so far as temperature goes. It might as well be potential, for all it shows as temperature. It's only seen as heat capacity and that's it. This is typical of non translational motions. S B H arris 06:38, 26 December 2012 (UTC)

The point I was trying to make is that it is also typical of translational motions within a few degrees of absolute zero. The translational motions begin to freeze out also. When that begins, the mean energy per particle is no longer 3kT/2. This may be annoying scholasticism to room-temperature people, but not to people working with, e.g. a Bose-Einstein condensate. PAR (talk) 17:08, 27 December 2012 (UTC)

The kinetic theory temperature definition works when the particles obey Maxwell-Boltzmann statistics, but not in general when they don't. Another problem is that for the kinetic theory temperature definition, one has to pick and choose what one will consider to be a particle. Is a bound electron a particle for this purpose? How to decide?Chjoaygame (talk) 20:51, 27 December 2012 (UTC)

First of all, kinetic energies of translation doesn't freeze out for QM reasons at any temps we've been able to achieve. See the second problem here. Energy spacing for molecules at any reasonable volume correspond to a temp of 10^-15 K, which nobody has ever seen. At all temps anybody has ever seen, molecular translation is a classical not a quantum system. BE condensation has nothing to do with any of this, and has nothing to do with freezing out of translational modes. Vibrational modes are mostly frozen out at a few K, but BE condensation here is effect not cause. In those circumstances BE condensates can happen if you have bosons and not many phonons (so most of the bosons are sitting in the same ground vibrational state), but this doesn't affect the thermodynamics. He-3 at 0.1 K is a nice fluid, but not a superfluid. He-4 at that temp is a superfluid. They look the same, they can sit side by side (or mix) and not tranfer heat, and in each one the average atom has the same kinetic energy above zero-point (which isn't much). Of course the He-3 atoms are moving 15% faster. The zero point KE in both systems is enough to break atom-atom London force attractons, so fluid behavior is seen (but increase pressure and both fluids freeze to a crystal). Transition between quantum states in He-3 allows atoms to individualize, slow down, speed up, cause friction. I suppose there's a bigger velocity spread in He-3. None of this is germane.

As for the question of what particles "count", the bound ones don't. If electrons are free as in a plasma, their kinetic energy counts as they are free particles. Otherwise, no. Kinetic energy of vibration in diatomics doesn't increase temperature. It just absorbs heat and contributes to heat capacity. As for non-Bolzmann distributions, there exist of course non-equilibrium situations that do not even HAVE a well defined temperature. So worrying about kinetic energy definitions is to put the cart before the horse. First, you have to have a definable temperature in your collection of particles, and then when you do, it's a simple function of available KE (over zeropoint KE) per particle. If the collection hasn't yet settled down to a uniform temp, then all bets are off. But without defined temps there is no "thermal interaction" and you therefore can't transfer heat, or even see energy as "heat" (all this requires these things) so all this has to be in place, before we even get to the subject of this article. Again, I can fire a bullet a 0 K at an object and transfer a lot of energy to the object when it fragments. But that's not a thermal interaction, and it's not heating, and no heat is involved. Lots of internal and kinetic energy, sure, but no distribution of that motion in phase space before the bullet hits, and thus no heat. It's a bit like friction, which isn't heat transfer either. S B H arris 03:42, 28 December 2012 (UTC)

Thanks for that link, It was a good one. I understand the argument but have not verified the numbers. My argument was based on the fact that the internal energy of an ideal Bose gas begins to drop from 3NkT/2 towards zero as you approach the critical temperature, which is nowhere near as small as 10^-15 K which tells me that the energy per degree of freedom is no longer kT/2, and I have assumed that was due to freezing of the translational degrees of freedom. I will try to sort this out. If you have any suggestions as to the explanation of this BE behavior, please let me know. PAR (talk) 21:37, 28 December 2012 (UTC)

In fairness that link cheats a bit by calculating E-level spacing for just ONE atom in a 1 cm box. In a real gas, the volume each atoms gets is the volume/atom. And indeed at the BCE transition temp, that's more or less the atomic thermal wavelength cubed (up to a small pure numeric factor). So this is related to quantum lowest mode that will fit into a volume. In a gas it's a lot larger than the atomic volume, but is rather the gas volume/atom. In a liquid like He-4 where the atoms are practically touching, the thermal wavelength is about 1.6 A, which indeed is about the size of a helium atom. So all these are particle-in-box problems, though you can't call it translational freeze-out in a solid or liquid. Perhaps it's fair to do so in a diffuse BCE gas. But it's nothing unusual, as these correspond with phonon-freeze out in liquids and solids, and all we've said about KE applies. BCE atoms (in a gas or liquid) are just atoms that have no energy except zero-point energy, and no entropy, and don't participate in heat capacity. They have zero-point KE but that doesn't "count."

The reason I didn't want to get into BCEs is that they aren't magic. Think (for example) of what atoms would look like if electrons were bosons. They'd all be sitting in the 1s orbital, no matter how many! But they'd still repell each other, and that would probably be just about compensated by the atomic charge, so all atoms would still be about the same size, albeit a smaller size (about the size of helium atoms). But they would all still HAVE a size. The BCE phenomenon doen't collapse anything to zero volume; it just gets rid of Pauli-exclusion forces. So, as noted, the "freeze out" of higher modes in BCE gases is nothing special that doesn't already happen in crystals made of (say) fermions. It affects heat capacity, but temperature is still non zero-point mean kinetic energy. S B H arris 03:20, 29 December 2012 (UTC)

That's about the conclusion I came to, but I think the deviation of the mean kinetic energy from 3kT/2 is nevertheless due to freezing of the translational degrees of freedom. In the link you gave, I interpreted 10^-15 K as the temperature at which the translational degrees of freedom are practically completely frozen, but what we are looking for is the temperature at which they are practically completely UNfrozen. Above that, the mean kinetic energy is practically equal to 3kT/2. The critical temperature of a Bose gas is roughly where the thermal wavelength is equal to the average interparticle distance, and is the center of the "partially frozen" regime. The temperature at which the translational degrees of freedom are practically completely unfrozen is, I would guess, a few multiples of the critical temperature. Then, the thermal wavelength is much less than the average interparticle distance, and they behave as classical particles. The statement that "temperature is proportional to the mean kinetic energy of the particles" MUST be qualified by stating that it is only true above a certain temperature, where the particles behave classically. PAR (talk) 00:22, 30 December 2012 (UTC)

treatment of heat by Kittel & Kroemer 1980

Kittel & Kroemer (1980) in their preface announce that they will present their material in a new way.

They introduce transfer of energy through thermal contact in their introduction, chapter 0 if you like. They use the term 'closed system' without explicit definition, and slightly confusingly, perhaps not in accord with present-day Wikipedia definitions. In chapter 0 they let closed systems come into thermal contact and exchange energy, but do not there actually use the word 'heat'. At that stage there is no mention of work. The thermal transfer of energy is attributed to difference of temperature.

Chjoaygame you write:-

perhaps not in accord with present-day Wikipedia definitions.

Um, "Wikipedia definitions"? Are you suggesting here that, for you, Wikipedia is a reliable source? --Damorbel (talk) 16:51, 26 December 2012 (UTC)

In Chapter 1, on page 7, they say that mechanics tells us the meaning of work and that thermal physics tells us the meaning of heat. They say that their "point of departure for the development of thermal physics is the concept of the stationary quantum states of a system of particles."

In Chapter 2 they explicitly define a closed system as having a constant energy and a constant volume and a constant number of particles, and they exclude gravity and other long range external forces. This terminology is different from that in the present Wikipedia, which would say that K & K's 'closed system' is a present-day 'isolated system'. In this chapter, again they talk about systems, not explicitly determined as closed, in thermal contact, with different temperatures, exhanging energy thereby, without mention of the systems being able to exchange energy as work. Temperature is defined as the reciprocal of the partial derivative of entropy with respect to internal energy. Without saying so, these authors are using what thermodynamicists call the entropy representation. There is, however, at this stage, no mention of a partial derivative of entropy with respect to volume, and no mention here of heat or work.

In Chapter 3 they introduce entropy as a function of internal energy and of volume, continuing to work in what thermodynamicists call the entropy represenation. They here define pressure as the partial derivative of internal energy with respect to volume, at constant entropy. Although they cite Callen (1960) in a list of references, these authors give the student no hint of the difference between the energy representation and the entropy representation that is so well set out by Callen. The quantities here are just quantities to be manipulated, not systematically presented in terms of characteristic functions, as in thermodynamic texts. In a one sentence comment, they note that "Heat is defined as the transfer of energy bewteen two systems brought into thermal contact", and refer the reader to their Chapter 8. There they do not use Reif's phrase "purely ″thermal interaction″".

These authors give no sign of recognition of the definition of heat as derived from that of work, that is so important for Reif. They consider heat and work as defined independently of one another.Chjoaygame (talk) 16:31, 26 December 2012 (UTC)

Chjoaygame, you are trying to justify text books as reliable source; your contribution here is a fair example of why they are not! --Damorbel (talk) 16:51, 26 December 2012 (UTC)

Damorbel, what do you consider a reliable source? RockMagnetist (talk) 17:39, 26 December 2012 (UTC)

Somewhere above I gave a link to Clausius On the Nature of the Motion which we call Heat, but the writings of J C Maxwell, L. Boltzmann, A. Einstein, M. Planck are also reliable. Writers of text books are not generally reliable, often hey are more interested in supplementing their income by selling books to students - witness the number of editions these books sometimes run to! Clausius & Co. made real contributions to the science of heat; lecturers on the other hand generally copy from their academic masters to avoid embarrassment and avoid arguments. Finally, citing any author is not itself a guarantee of reliablity, it is obvious that contributors to the Heat article in Wikipedia do not always properly understand the authors they are citing. --Damorbel (talk) 18:17, 26 December 2012 (UTC)

I am not here trying to define a reliable source in general. Wikipedia is not a reliable source. Here I am simply discussing one contestable source without prejudice.Chjoaygame (talk) 19:20, 26 December 2012 (UTC)

To put it in a nutshell, I am here saying that, according to the definition of heat nowadays considered to be rigorously correct and right, the definition of heat offered by Kittel & Kroemer is incorrect and wrong. But there doesn't seem to be on this talk page very widespread criticism of, or concern about, their being cited for the definition of heat in the lead of the article.Chjoaygame (talk) 22:58, 29 December 2012 (UTC)

Sorry Chjoaygame, I am not prepared to let you assert:-

according to the definition of heat nowadays considered to be rigorously correct and right

without asking you what this definition actually is? --Damorbel (talk) 09:45, 30 December 2012 (UTC)

Here.Chjoaygame (talk) 12:27, 30 December 2012 (UTC)

I see one reference each to Kittel and Kroemer and to Reif - both for the first sentence of the lead. The lead is supposed to summarize the body of the article. Are these issues discussed properly in the body? RockMagnetist (talk) 17:27, 30 December 2012 (UTC)

What is heat

Chjoaygame, since heat is defined by temperature (that is what thermometers measure!) and temperature is a an intensive property, it isn't dependent on the size of the system, a system may well have many different temperatures!

So heat cannot possibly be measured as energy because energy is an extensive property i.e. it depends on the amount of substance in the system i.e. it depends on the size of the system.

It doesn't matter a toss what Reif, Kroemer et al say; if that is how citations of their publications worm their way into Wikipedia then the citation is wrong. Either Reif, Kroemer et al are wrong or you are wrong in your citation. But to have "heat as energy" is clearly contradictory; if it was right then temperature would, in some mad way, be measured in Joules! --Damorbel (talk) 14:54, 30 December 2012 (UTC)

Don't be silly. Temperature is like voltage, pressure, or concentration--all intensive. Heat is like charge transfered or amount of fluid down a pipe or how much oxygen gets from the air into blood. All these things are the extensive conjugates of the "potential" variables. Temperature is a sort of potential-- it's energy per entropy unit. Heat is the energy moved by that potential, purely in the service of decreasing it so as to increase entropy, so total entropy per energy in the universe will be more. There you are. S B H arris 20:53, 30 December 2012 (UTC)

Ho Hum!

Temperature is like voltage, pressure, or concentration--all intensive

Yes indeed. And which of these is measured in joules? None of them! Neither is heat, heat is measured by temperature; a single particle can be very, very hot!

To get electrical energy to move there has to be a potential difference (read gradient). A current of some measurable size must flow for energy to transfer.--Damorbel (talk) 21:28, 30 December 2012 (UTC)

Heat is measured in joules. Not by temperature. It takes heat to melt ice and the temp doesn't change. It takes more heat to warm a bathtub than boil a teaspoon so clearly heat is energy not temperature. It's understood that each heat joule has been transfered due to a temp difference, but that doesn't show in the units. Temperature is in kelvins or if you like, in joules PER basic entropy unit per particle. And that DOES show up in the units since converting entropy bits to joules per kelvin to make this come out takes a conversion factor that depends arbitrarily on what scales you use for temperature and energy. It is Boltzmann's constant and its value would be 1 if we used the right T and E units. For historical reasons we don't. Only one of the three needs to be fixed to a physical process by measurement and the others are derived from that.

It's like length, time, and the speed of light c. We used to define L and t and measure c . Now we define t, fix c, and use the two to define L. Similarly we define T and E by physical process and measure k, but soon will define E physically, fix k at some exact value like we did with c, then content ourselves with using E and k to define our T scale. S B H arris 00:11, 31 December 2012 (UTC)

Sbharris, you write above:

Heat is measured in joules. Not by temperature.

So what, then, does a thermometer measure? --Damorbel (talk) 07:51, 31 December 2012 (UTC)

Temperature. In kelvins. A sort of "heat concentration" although the heat is gone as soon as it stops. Anyway what do you think a thermometer measures? It takes a lot more heat to warm a bathtub one degree than a teaspoon to boiling. The thermometer doesn't measure heat. S B H arris 15:48, 31 December 2012 (UTC)

Sbharris, you write:-

Temperature. In kelvins. A sort of "heat concentration" Then what sort of heat concentration? This is supposed to be a scientific matter !

the heat is gone as soon as it stops

These are the questions I have - Just what " is gone "? And Just what " Stops "?

You are making arbitrary statements that cannot be related to energy because energy is conserved. Energy cannot "be gone", or just somehow "stop", it must be accounted for, all the time.--Damorbel (talk) 16:11, 31 December 2012 (UTC)

Not at all. Heat is like electric current. Charge is conserved is it not? So what happens to current when it stops? Heat is internal energy in motion due to thermal contact--just like voltage. Stop voltage stop current. No problem. Current becomes static charge and heat becomes static internal energy. S B H arris 03:05, 1 January 2013 (UTC)

Further you ask:-

Anyway what do you think a thermometer measures?

No problem. A thermometer measures the energy of the particles in a system; the energy of the particles is related to the temperature by the Boltzmann constant.

Different thermometers do this in different ways, some materials expand linearly as their particle energy increases, mercury is very good in this repect. Gas thermometers come in two types, constant volume - the pressure rises as the particle energy increases; and constant pressure - the volume increases with temperature. A third type measures the energy of electrons free to move in the conduction band by measuring the associated electrical (Johnson) noise.

Other, less common, thermometers use the melting points of substances with well defined melting points. These can be very accurate if the material has high isotopic purity (one dominant isotope). Obviously the range of such a thermometer is non-existant but the deformation associated with melting means the temperature has been exceeded. Such thermometers often use a range of different materials with diferent melting points to give better coverage.

In every case these thermometers give an output proportional to the energy in their active components. --Damorbel (talk) 16:52, 31 December 2012 (UTC)

Nope. In no case does the thermometer see but a fraction of the energy except in ideal monatomic gases. In all other substances heat and energy goes in that doesn't appear as temperature. Latent heat does not change temp therefore is not seen by thermometers. Also heat capacity not due to molecular translation. Hydrogen at room temp has 60% more energy than the same volume and temp. That extra is not seen by the thermometer. So, you're just wrong. S B H arris 03:02, 1 January 2013 (UTC)

Yes I'm wrong! I should have written:-

thermometers give an output proportional to the linear kinetic energy in their active components.

However,it is well known that the rotational energy, as you point out for Hydrogen, is not exchanged between molecules by linear collisions but indirectly through equipartition thus Hydrogen has a higher mole specific heat than Helium.

Further, what you refer to as latent "heat" (a truly great misnomer!) is due to intermolecular forces that are not kinetic in origin in that it is they that, at low temperatures, overcome the particle kinetic forces and aggregate atoms and molecules in to liquids and solids; and, being potential energy, these intermolecular forces do not affect temperature.

So a thermometer measures the translational (linear) kinetic energy of particles; i.e. the free movement of gas particles, and the vibrational motion of liquids and solids. OK? --Damorbel (talk) 08:31, 1 January 2013 (UTC)

new links

The newly added links highlight the defects of the lead, but do not remedy them.Chjoaygame (talk) 13:29, 12 January 2013 (UTC)

Baierlein 1999 on transfer of energy as heat

According to R. Baierlein (1999), Thermal Physics, Cambridge University Press, Cambridge UK, ISBN 0521590825, on page 2: "Elementary physics often speaks of three ways of heating: conduction, convection, and radiation. You may wonder, why is convection not mentioned here? Convection is basically energy transport by flow of some material, perhaps hot air, water, of liquid sodium. Such ″transport″ is distinct from the ″transfer″ of energy to a physical system from its environment. For our purposes, only conduction and radiation are relevant."

Other texts on thermal physics simply do not discuss convection, but do not bother to do what Baierlein does here, explain explicitly why they do not do so.Chjoaygame (talk) 21:29, 9 January 2013 (UTC)

When a system is not in equilibrium, why exclude one particular method of achieving equilibrium? No logic in that. --Damorbel (talk) 22:00, 9 January 2013 (UTC)

No one is excluding convection in general. They are just saying that they call it transport, not transfer, and that they are here interested in transfer, not transport. Baierlein signals this by his phrase "For our purposes".Chjoaygame (talk) 14:58, 10 January 2013 (UTC)

So you are excluding convection, not because it doesn't involve energy transfer but because it is called "transport", and not "transfer"?

Please, could you explain what is the significant difference?

Further, does this distinction also apply to other heat transfer (transport?) processes such as diffusion?--Damorbel (talk) 16:40, 14 January 2013 (UTC)

Convected materials do not transfer heat (read heat energy) from one body to another, but merely "transport" themselves from one location to another, and thereby function under a different set of physical rules for the dissemination of heat energy.WFPM (talk) 18:38, 14 January 2013 (UTC)

I think you will find that, on reflection, convection takes place in fluid bodies that are not in equilibrium, how else could convection take place?

What you appear to be doing above is to confuse the physical phenomenon (convection) with your description of it (thereby function under a different set of physical rules . . . ) --Damorbel (talk) 21:08, 14 January 2013 (UTC)

PS Why is this guy (R. Baierlein) and his (text)book even mentioned in Wikipedia? There is no online access to the book, the only recommendation for a reference is that his name is mentioned by an anonymous editor together with a microscopic quotation. --Damorbel (talk) 21:26, 14 January 2013 (UTC)

Baierlein is not cited in the Wikipedia article. This is a talk page, in which it is proper to mention potential reliable sources without prejudice even when they are not cited in the parent article. As explicitly stated in the initial post of this section, the reason the Baierlein is mentioned here in the talk page is that he offers an explicit rational explanation for something important and notable that is left unexplained by other potentially reliable sources that are cited in the article. That important and notable something is that, in most texts of thermodynamics, transfer of energy as heat is discussed only for conduction and radiation. They do not discuss, or in some cases do not even mention, convection. Mostly they do not explicitly point this out or explain it. But Baierlein does. That is why Baierlein is quoted as online here, as explicitly stated in the initial post of this section.Chjoaygame (talk) 12:37, 15 January 2013 (UTC)

Baierlein is being discussed here. Thanks for the link. Have you checked his item on temperature? Page 178? Baierlein introduces a term called 'hotness' (p3) which turns out to be another word for temperature. He explains further (p85) by introducing entropy. But entropy is an extensive property, it only has relevance to temperature when (entropy) is at a maximum i.e, the system is in (thermal) equilibrium. It gets worse on p85 (subsection 4.3 entitled "A general definition of temperature") when he introduces the 2nd Law, which by definition is about sytems with more than one temperature.

On p178 his problems with 'hotness' reappear when he refers to 'Boson' (Bose-Einstein statistics) and 'Fermions'(Fermi-Dirac statistics). The distinction between these involves the way particles can occupy quantum states, basically because of allowable spin states. It is a fundamental tenet of physics that quantum considerations cause deviations from classical mechanics which requires particles to interact randomly, leading to Maxwell-Boltzmann statistics. On p178 Baerlein does not draw attention to this while trying to explain temperature.

A book on thermal physics having such defects is not suitable for any purpose whatsoever. --Damorbel (talk) 15:14, 15 January 2013 (UTC)

classical ideas on transfer of energy as heat

The section that has been deleted uses the word 'primitive', in the phrase 'primitive concept'. This usage is part of the ordinary language of scientific discourse, and is not used in an exceptional way in the deleted section. A complaint that it is 'new' is unfounded. A typical ordinary-scientific-discourse usage is as follows, written by James Serrin: "In the following section, we shall use the classical notions of heat, work, and hotness as primitive elements, ... That heat is an appropriate and natural primitive for thermodynamics was already accepted by Carnot. Its continued validity as a primitive element of thermodynamical structure is due to the fact that it synthesizes an essential physical concept, as well as to its successful use in recent work to unify different constitutive theories."[Serrin, J. (1986). Chapter 1, 'An Outline of Thermodynamical Structure', pages 3-32, in New Perspectives in Thermodynamics, edited by J. Serrin, Springer, Berlin, ISBN 3-540-15931-2, p. 5 .] Serrin continues with statements like this about 'hotness', and he comments that "Ernst Mach carefully notes that ″temperature″ is ... nothing else than the characterization, the mark of a hotness level by a number". Serrin is a recognized authority in the field of axiomatics of thermodynamics. A variant of this ordinary language usage is found in Herbert Callen's introduction to his widely cited text. Callen uses the phrase 'primal concepts': "Certain primal concepts of thermodynamics are intuitively familiar."[Callen, H.B. (1960/1985). Thermodynamics and an Introduction to Thermostatistics, (1st edition 1960) 2nd edition 1985, Wiley, New York, ISBN 0-471-86256-8, p. 2.]

As for 'empirical temperature', editors are referred to the following:

Adkins, C.J. (1968/1983). Equilibrium Thermodynamics, (first edition 1968), third edition 1983, Cambridge University Press, ISBN 0-521-25445-0, pp. 18–20.
Bailyn, M. (1994). A Survey of Thermodynamics, American Institute of Physics Press, New York, ISBN 0-88318-797-3, p. 26.
Beattie, J.A., Oppenheim, I. (1979). Principles of Thermodynamics, Elsevier Scientific Publishing, Amsterdam, ISBN 0-444-41806-7, p. 28.
Buchdahl, H.A. (1966), The Concepts of Classical Thermodynamics, Cambridge University Press, London, pp. 30, 34ff, 46f, 83.
Haase, R. (1971). Survey of Fundamental Laws, chapter 1 of Thermodynamics, pages 1–97 of volume 1, ed. W. Jost, of Physical Chemistry. An Advanced Treatise, ed. H. Eyring, D. Henderson, W. Jost, Academic Press, New York, lcn 73–117081, p. 8.
Landsberg, P.T. (1978). Thermodynamics and Statistical Mechanics, Oxford University Press, Oxford, ISBN 0-19-851142-6, p. 7.
Lavenda, B.H. (2010). A New Perspective on Thermodynamics, Springer, New York, ISBN 978-1-4419-1429-3, pp. 29, 43, 169, 175.
Münster, A. (1970), Classical Thermodynamics, translated by E.S. Halberstadt, Wiley–Interscience, London, ISBN 0-471-62430-6, p. 22.
Pippard, A.B. (1957/1966). Elements of Classical Thermodynamics for Advanced Students of Physics, original publication 1957, reprint 1966, Cambridge University Press, Cambridge UK, p. 10.
Truesdell, C.A. (1980). The Tragicomical History of Thermodynamics, 1822-1854, Springer, New York, ISBN 0-387-90403-4, pp. 307,321–328.
Waldram, J.R. (1985). The Theory of Thermodynamics, Cambridge University Press, Cambridge UK, ISBN 0-521-24575-3, pp. 1, 8.
Wilson, H.A. (1966). Thermodynamics and Statistical Mechanics, Cambridge University Press, London UK, pp. 4, 8, 68, 86, 97, 311.

The section was valid, notable, and useful as it stood. The deletion of the section was improper and unethical.Chjoaygame (talk) 17:32, 15 January 2013 (UTC)Chjoaygame (talk) 15:22, 17 January 2013 (UTC)

Primitive?:-

'primitive', in the phrase 'primitive concept'. This usage is part of the ordinary language of scientific discourse

You do not give even one link.

Further, an on-line search for 'empirical temperature' - yields only - empirical temperature scale ; a very different matter.

Temperature, as compared to temperature scales is not 'empirical'

Temperature scales are quite arbitrary; there are many. Notoriously Celsius had 0 (zero) for boiling water and 100 for the ice point! But the scalar relation of particle translational energy is definitely not empirical. In all scales zero energy is the same whatever number is given, the same applies to the triple points of water, mercury or sulphur; the numbers given are only needed to ensure consistency but the translational energy at these various points is not empirical, it is always the same for each substance, what ever scale is used.

--Damorbel (talk) 18:21, 15 January 2013 (UTC)

Primitive notion.Chjoaygame (talk) 20:37, 15 January 2013 (UTC)

Well? What am I supposed to learn from your link?

Chjoaygame this article is about heat, which is all about translational kinetic energy of particles. The concept of heat and primitive thermometers is lost in the mists of prehistory. The reliable measurement of temperature goes back to Fahrenheit in the early 18th century. The concept of heat as the motion of microscopic particles (do you now accept this?) is also pre-19th century, the difference being that Rumford demonstrated the connection between heat and work, Joule and Mayer measured it. And Clausius, Boltzmann, Kelvin and Maxwell showed how heat was explained as the energy of particles. On these matters the battle was all over when Carathéodory was working.

This is not to say the work Carathéodory did not do valuable work, but it is your idea that he advanced the theory of thermodynamics. By 1909 radiation was king (Planck, Einstein (1905)) with the saturnian atom and the electron and quantisation, not mentioned by Carathéodory in 1909.--Damorbel (talk) 21:44, 15 January 2013 (UTC)

These sections belong to thermodynamics

These sections:-

Examples of singularly simply specified and standard paths

and

Chemical reactions

are about Thermodynamics, they are far too extensive to be included in a section entitled "Heat"; therefore I have deleted them. For the moment the option of including them in 'Thermodynamics', if desirable, I leave to another contributor. --Damorbel (talk) 06:52, 17 January 2013 (UTC)

Rigorous mathematical definition of quantity of energy transferred as heat?

This section:-

Rigorous mathematical definition of quantity of energy transferred as heat

relies only on the work of Carathéodory. No attempt is made to show how Carathéodory's work, a single paper written in 1909, is to be distinguished from the works of reliable sources such as Maxwell, Clausius, Boltzmann and Kelvin.

Further, I am deleting it because the section is about Heat Transfer and an article on this already exists. If desirable this material should be edited into the Heat Transfer article. --Damorbel (talk) 07:18, 17 January 2013 (UTC)

Do you not read books as all? A simple Google Books search for Carathéodory thermodynamics returns 10,000 hits. Look at a serious book on thermodynamics, and you will inevitably find discussion of Carathéodory, and the "rigorous axiomatic mathematical framework for thermodynamics" he was the first to attempt to provide.

Attempting to portray Carathéodory's work as "a single paper written in 1909" with the implication that nobody has seriously paid any attention to it since shows a disturbing ignorance of the subject. Jheald (talk) 13:17, 17 January 2013 (UTC)

...with the implication that nobody has seriously paid any attention to it... As yet I have seen no demonstration that his 1909 paper materially advanced the science of thermodynamics. Many, many people have written papers on thermodynamics, throughout the 18^th and 19^th centuries and also in the 20^thC, many papers were published by excellent people that contained unsustainable ideas. Think of Joseph Priestly, went to his grave convinced of the merits of the Phlogiston theory; the Royal Society actually suppressed ground breaking papers on Kinetic theory by Herapath and Waterston for 50 yrs. History is littered with far more unsuccessful ideas than successful ones!

Are you able to point to to any part of Carathéodory's 1909 paper that significantly altered thermodynamics? From what I read his arguments are about heat exchange through adiabatic walls; I would like to know why this is not a contradiction. --Damorbel (talk) 14:37, 17 January 2013 (UTC)

Carathéodory's 1909 paper was a bold attempt to construct a mathematical model of what is a strictly a random process, the interaction of free particles. He merely imposes some adiabatic restrictions on random events, how can he do that? In thermodynamics there are very, very few restrictions on the available states, in fact I can't think of any. --Damorbel (talk) 14:55, 17 January 2013 (UTC)

Whether you think the paper is worthwhile or not is neither here nor there. What is clear is that it is taken seriously in the secondary literature, therefore you cannot dismiss it. Jheald (talk) 21:46, 17 January 2013 (UTC)

I agree with Jheald. PAR (talk) 06:42, 18 January 2013 (UTC)

Please, can we have some order in the Talk pages? Does it really help that PAR agrees with Jheald? This kind of contribution is exactly what Wikipedia is NOT about. I do not offer an opinion on Carathéodory's 1909 paper. What I want to read is a clear explanation of why it should be mentioned.

Jheald and PAR, you must understand, Wikipedia is not a vehicle for your opinions on anything, least of all on each other's thoughts, but it should be a way of informing Wiki users about the merits of important matters. --Damorbel (talk) 17:16, 18 January 2013 (UTC)

The integral continuously follows the path . . .

I have removed this edit (introduced without any discussion) [1] The text is:-

The integral continuously follows the path of the process of transfer of energy as heat to the body.

No, the integral is not to be evaluated as a path integral. Such integrals are equal to the difference between the initial and final value. --Damorbel (talk) 06:47, 18 January 2013 (UTC)

The foregoing comment by Damorbel cannot usefully be answered by a rational response.Chjoaygame (talk) 13:58, 18 January 2013 (UTC)

Perhaps you can clarify what you mean by:-

The integral continuously follows the path of the process of transfer of energy as heat to the body.

Do you mean an integral according to the Gradient theorem or the integral along the length of a curve? Or do you mean something else? --Damorbel (talk) 15:45, 18 January 2013 (UTC)

Principal specific heats

I made deleted this [2] The article is about Heat but the section is about specific heat. Wikipedia already has far better article, more general and shorter, i.e, suitable for an encyclopedia; Wikipedia is not a text book. In this contribution the editor is quoting selectively from his cited text book(s), such an approach does not make sense without all the text. --Damorbel (talk) 19:51, 18 January 2013 (UTC)

Primitive?

I have deleted this section primitive concepts it is nothing but a very wordy explanation for a 'new' concept called a primitive. Wikipedia is not the place to introduce such a concept, and what makes it much worse is the vague assertions such as:-

heat transfer is purely due to spatial non-uniformity of temperature

And :-

Maxwell first considered what he called "temperature", that would nowadays stricty be called 'empirical temperature'.

Please, from where do you get the idea of 'empirical temperature' ? --Damorbel (talk) 15:45, 15 January 2013 (UTC)

I have posted another attempt to present the older traditional view of heat for calorimetry and thermodynamics of closed systems, taking into account all the comments just above. The concept of a primitive notion is shown not to be new. The reference to empirical temperature is removed. The summary that "heat transfer is purely due to spatial non-uniformity of temperature" is not unduly vague for a summary, and it accurately expresses a notable and essential element of the traditional view. The traditional viewpoint should be presented because it is often used for initial or introductory presentations in present-day textbooks, before they expound the far more sophisticated Carathéodory viewpoint.Chjoaygame (talk) 21:19, 18 January 2013 (UTC)

I find nothing in Carathéodory's 1909 paper that is rigorous or 'primitive'. What he is trying to do and with only limited success. is explain a adiabatic energy exchange in mathematical terms, he was of course primarily a mathematition. His success can be estimated by how much his methods and arguments are used i.e. not very great.

If you consider his paper to be valuable then please say why it is valuable. For example, why do you say the far more sophisticated Carathéodory viewpoint? (above)? That is merely your opinion, not appropriate for an encyclopedia. What would be appropriate is an explanation of how Carathéodory's paper improves the general understanding of thermal physics.

In the article it says:-

Although Carathéodory himself did not state such a definition, following his work it is customary in theoretical studies to define the quantity of energy transferred as heat, Q, to the body from its surroundings, in the combined process of change to state Y from the state O, as the change in internal energy, ΔUY, minus the amount of work, W, done by the body on its surrounds by the adiabatic process, so that Q = ΔUY − W.

Do you not find it redundant to observe that "Carathéodory himself did not state such a definition"? Then why is his paper cited?

Further, you are treating the '=' sign in mathematical terms, just like Carathéodory. The fault in this logic is that work and heat are equivalent, not equal. The equivalence of work and heat was the discovery Rumford with his cannon boring experiment and the measuring of it by Joule. The equals sign is a bit of mathematical exageration. Heat and work ar both forms of energy but they are not the same in a mathematical sense. --Damorbel (talk) 07:33, 19 January 2013 (UTC)

U = Q - W ?

In the section Internal energy and enthalpy the following mathematical expression appears

\Delta U=Q-W\quad {\rm {(first\,\,law)}}.

with the explanation:-

This can also be interpreted as that $Q$ makes contributions to the internal energy and to the work done by the system

This is incorrect because $Q$ certainly does not make a contribution to the work. One may well ask "Which work"? Converting heat to work requires something like a heat engine. Converting work to heat is mainly done by friction, frequently and undesireably friction arises spontaneously. So I am replacing the above explanation with this one:-

N.B. This, and subsequent equations, are not a mathematical expressions, the '=' sign is to be read as 'equivalent', not 'equals'. The expressions ' $Q$ ' and ' $W$ ' represent amounts of energy but energy in different forms, heat and work. It is fundamental to the science of heat that conversion between heat ( $Q$ ) and work $W$ is never 100% efficient so the '=' sign does not have its mathematical meaning.

--Damorbel (talk) 08:20, 19 January 2013 (UTC)

This replacement is invalid and should be undone. The symbols refer to numbers that denote quantities of energy, and are properly dealt with as numbers, as is done in the subsequent equations. Denotation is not equivalence. The intended 'logic' of the replacement is therefore wrong. The above objection to the replaced sentence is faulty in logic for like reasons. The equation can be interpreted to describe energy transfers for the working material of a heat engine.Chjoaygame (talk) 02:36, 20 January 2013 (UTC)

" The symbols refer to numbers " Indeed they would if it was just arithmetic or algebra, but this is physics and the two sides of the equation are equivalent, but not directly interchangeable i.e. equal or identical as in maths.

Please argue the physics, work (W) and heat (Q) are quite distinct in physical terms. Work is any force, mechanical, electrical, gravitational, intermolecular, etc., etc. integrated over distance, it may result in a temperature change or a change in electrical potential, potential energy etc., etc. --Damorbel (talk) 10:28, 20 January 2013 (UTC)

I sadly regret that I cannot see how to make a useful response to your comment.Chjoaygame (talk) 17:06, 20 January 2013 (UTC)

Complex?

Chjoaygame, what do you mean by "complex" processes? Is it like, um, Complex numbers? If not, will you be so kind as to explain what you mean by complex - please.

In the article it says also:-

Heat flow from hotter to colder systems occurs spontaneously, and is always accompanied by an increase in entropy

Which is rubbish (as it stands). Suppose the heat (that flows(!)) arises from a chemical reaction; this may well cause an decrease in entropy but is actually undefined because the reason for the heat (flow!) is not specified. Perhaps you are thinking of a new state of equilibrium, then why don't you say so? --Damorbel (talk) 14:59, 8 March 2013 (UTC)

Damorbel writes just above: "Chjoaygame, what do you mean by ″complex″ processes? Is it like, um, Complex numbers? If not, will you be so kind as to explain what you mean by complex - please."

The word 'complex' in this context has just been effectively defined in the article, just previous to the sentence from which Damorbel's edit deleted it, in the sentence: "In this sense, it can be said that convective circulation is a mechanism of transfer of energy as heat, but in this case, the transfer of energy as heat is complex, because in a general process of transfer of energy of heat there may be change of internal energy and temperature of the wall." In the sentence from which Damorbel's edit deleted the word 'complex', the word 'such' indicates that the meaning refers back to that just previous sentence.

In other words, when a partition has solid containing walls but a fluid interior, and can thus sustain convective circulation within itself, the phrase 'complex process' here refers to transfer of energy as heat through that partition allowing that the process may include convective circulation within the partition, and that the partition then has an appreciable internal energy of its own, and may have a temperature of its own. This is not the simple kind of transfer of energy as heat found in pure conduction and radiation, as usually considered in thermodynamics; a wall that simply conducts is often assumed for convenience to have negligibly small internal energy, so that its own temperature does not need to be considered.

I regret that I cannot see how to make a useful response to the rest of the above comment by Damorbel.Chjoaygame (talk) 16:10, 8 March 2013 (UTC)

Diathermal wall

The statement " Transfer of energy as heat is uniquely defined only between closed systems, and so it does not make sense to speak of transfer of energy as heat through a wall that allows transfer of matter; such a wall, however, does allow transfer of internal energy." is false. See Beris, "Thermodynamics of Flowing Systems..." page 146 (googlebooks and search on "flexible, permeable, diathermic"). There is no reason why a wall cannot conduct both heat and material.PAR (talk) 04:31, 6 March 2013 (UTC)

This comment by editor PAR says that the statement in the article is false. The comment offers a reference to a quote found in a googlebooks. The comment says that there is no reason why a wall cannot conduct both heat and material. The point here is that the statement in the article admits that a wall can pass matter and internal energy, but does not admit that the internal energy passed can be properly described simply as heat with the current Wikipedia definition of heat. The statement in the article relies on the definition of heat used in the present Wikipedia articles, not on other definitions or understandings of heat, which are variously different from the Wikipedia definition.

The cited source writes: "Let us consider an adiabatic, closed system,

Ω

, composed again of two subsystems,

Ω A

and

Ω B

, separated by a flexible, permeable, diathermic partition. ... In general, there will be a flow of heat between the two subsystems,

dΞ

, and a flow of mass,

d N i B = - d N i A = d N i

. ... The quantity

d U B + p B d V B

is obviously just the total heat change in

Ω B

, which we define as

dΞ

."

The context of these statements is that "the simple ideas presented above, though thermodynamically correct, are inadequate for an experimental description of simultaneous heat and mass transfer between two subsystems because of the "unmeasurable (non-sensible) heat" associated with the enthalpy of the transferred mass." After the above partly quoted discussion, the source goes on to say "Yet it is apparent that the total heat change embodied by

dΞ

is composed not only of the "measurable heat" which we commonly recall, but also of heat associated with the enthalpy of the transferrred mass. This enthalpy change during the process between the two subsystems may be unequal, and hence so will the change in the measurable heat." This is just the very point, stated in other words, that is intended to be made by the statement in the article. This source supports the present statement in the article and is not a contrary to it. This source spells out in explicit detail what happens when one ignores Münster's and others' warning about the inapplicability to open systems of the definition of heat in terms of adiabatic work, the one used by Wikipedia. In effect, this source uses three definitions of heat, one being "sensible heat", and another being "heat" associated with enthalpy of transferred mass, which is not covered by the present Wikipedia definition of heat, and the third being a quantity that is the sum of the other two kinds of "heat".

I conclude that the statement in the article, using the Wikipedia definition of heat, asserted to be false by the above comment, is not false. Indeed, it is true, as supported by the source cited by the above comment.Chjoaygame (talk) 04:47, 7 March 2013 (UTC)

Lets forget about the Wikipedia definition of heat, for the moment. The question is whether a wall can be permeable to both heat transfer and matter transfer. In the Beris reference, yes, he refers to the change in "sensible heat". He refers to the "total heat" which includes the "enthalpy of the transferred mass", and it is this "total heat" that he is using to specify the entropy created. The rest of the discussion aims at expressing the creation of entropy in terms of "sensible heat" transfer and particle transfer, which finally results in Eq. 6.4-46. Basically this equation expresses the transfer of what is commonly called heat and the transfer of particles across the "flexible, permeable, diathermic partition". Why would Beris use the words "permeable" and "diathermic" to describe the partition if such a partition cannot exist?

Now lets return to the Wikipedia definition of heat. From what I can see, it makes no mention of whether the system is open, or, more precisely, its boundary is "permeable". In fact it seems to assume that the system is closed to particle transfer, in which case the Wikipedia definition of heat is incomplete, and needs to be expanded. PAR (talk) 04:46, 8 March 2013 (UTC)

Thank you for this response.

You propose for the sake of argument to temporarily forget the Wikipedia definition of heat. But you don't offer a replacement definition. You go ahead and ask whether a wall can be permeable to both heat transfer and matter transfer. I can only reply that I can't answer that without a definition of transfer of energy as heat. I am making the point that Beris uses three different definitions of heat. This is not too unusual, but is not rigorous. Much of the discussion about the definition of heat here for these Wikipedia articles has been to the effect that we want to define it rigorously. For one, Count Iblis is very particular about this. It would seem odd then to follow someone such as Beris who is not rigorous in his use of the word 'heat'. To say that "basically" something is so, is to invite questions about what "basic" might mean.

You ask why Beris talks of walls that are "permeable" to matter and to "heat". I would say that he is referring to walls that are permeable to matter and to internal energy, which might be transferred partly as driven by a temperature difference and partly by a concentration difference (including thermal diffusion, when a temperature difference drives diffusion of matter in the absence of a concentration difference), but what is at issue here is whether it is proper to label the internal energy transfer as "heat". It is not at issue, I think, as to whether we have walls available that are permeable to matter and to internal energy; yes, we do. In other words, Beris is not defining 'heat' rigorously with a single definition; that's enough to account for why he doesn't make a fuss about having used the word 'diathermal'. I don't think a fuss is warranted about it. I don't see too much problem with admitting that a wall that can pass internal energy partly driven by temperature difference, as well as passing matter with its associated internal energy, is 'diathermal and permeable to matter'.

It is true that the textbooks that use the residual definition of transfer of energy as heat (the one insisted upon by the consensus here, derived from the work of Carathéodory) do not make a big thing at that point of their expositions that they are referring to systems closed to the transfer of matter. But they have always some time earlier in the text said so. They just don't feel the need to remind the reader of it at the time of defining transfer of energy as heat; they haven't so far mentioned transfer of matter. That doesn't mean that the walls have without notice suddenly become permeable to matter, and that we are now dealing with open systems.

You propose that if indeed the Wikipedia definition of transfer of energy as heat is restricted to systems closed to transfer of matter, then it is incomplete and needs to be expanded.

This idea has long been considered in the literature. No unique general definition has been found. By 'unique general' here one means 'not arbitrarily restricted'. The most rigorous experts tell us explicitly that this is because none exists. The Gibbs presentation of thermodynamics starts right away with the postulate that

U = U (S, V, N)

without mention of work or heat. In this presentation, the ideas of heat and work have been entirely superseded by the ideas of entropy and internal energy. This is a real generalization of the Clausius-Kelvin-Carathéodory theory on which the Wikipedia definition of heat is based. A definition of heat that went beyond that would undoubtedly be original research, truly and seriously original research, research that would need proper peer review; I am not optimistic that it would pass muster; if it were published it would still be a primary source until it found its way into reliable secondary sources. There is a small literature about this. It is true that various arbitrary definitions are offered for arbitrarily restricted kinds of process, and in some cases, the definition of heat transfer turns out to be identical with the transfer of internal energy, as if all internal energy were heat. The most rigorous workers simply say it cannot be done without arbitrary restrictions or choices. Many texts just say little about it, and use the formula

d U = T d S - P d V + Σ i = 1 i = K μ i d N i

without a worry. Callen spends some pedagogic effort in producing special cases that may give the student some feel for what the formula might mean; many texts don't.Chjoaygame (talk) 11:55, 8 March 2013 (UTC)

This discussion is about the statement " Transfer of energy as heat is uniquely defined only between closed systems, and so it does not make sense to speak of transfer of energy as heat through a wall that allows transfer of matter; such a wall, however, does allow transfer of internal energy." I still do not understand why the TdS for the system does not represent the energy transferred across the wall as heat. For the system, with an immovable wall, the change in internal energy is dU=TdS+µdN, so µdN is the energy transferred across the wall attributable to particle transfer alone. PAR (talk) 06:46, 9 March 2013 (UTC)

You are positing an immovable wall. This precludes adiabatic pressure-volume work being reflected in the form

P d V

. But it does not preclude energy being put into the body of interest through the permeable wall, accompanying the matter that is forced in. How much energy goes in depends on how matter is forced into the body of interest from the surroundings. There is no unique partition of that accompanying energy into heat and work.Chjoaygame (talk) 12:08, 9 March 2013 (UTC)

None of the transferred energy is work, since the work is PdV and PdV is zero. There is a unique partition of the transferred energy into two terms: TdS and µdN. The TdS term represents the heat (what Beris calls the "sensible heat"), and the µdN term represents the rest of the energy transfer which is attributable only to particle transport. PAR (talk) 12:28, 9 March 2013 (UTC)

The work is not defined as

P d V

alone. That is only the pressure-volume part of the work, not including isochoric work, which is said by reliable sources to be significant. You are arbitrarily making things up off the top of your head, in this case by claiming that all work is pressure-volume work, and ignoring the possibility of isochoric work. The surroundings are losing volume to the phase of interest and so the surroundings feel that they are doing work; this is how the work is decided, what the surroundings feel, not just the deformation coordinates of the phase of interest. The amount of energy depends on how fast the surroundings surrender volume and the process goes. You are setting your own intuition against the reliable sources on this point, and not producing reliable sources to support you.

You have pushed me far enough. There are rules to this game and you are breaking them persistently. You seem to intend to simply wear me down by endless nagging, on the same point here and in the talk page for the article on Conservation of energy.

I have seen something like this before, over the zeroth law of thermodynamics. That time I decided to let you have your way. You feel entitled to own the article on the zeroth law and to dictate what goes into it. I can see that that article is very dear to your heart, and so in that isolated case I decided not to go on trying to insist on compliance with reliable sourcing because I did not see a pay-off in doing so. I don't think that set a precedent that means that every time you decide to break the rules I should give way to you.

The rules of the game are that reliable sources decide, and that private intuitions, such as you are persistently pushing here, do not decide. My case is properly supported by reliable sources. Your case is of the form that you don't see why the reliable sources are right, therefore they should give way to your private intuition that they are not right, and you try to put the burden of proof on me to explain to you why your private intuition doesn't agree with what the reliable sources say, and to accomodate that you don't like the definitions that have been agreed upon here.

You need proper reliable sourcing to progress with your case. Without that it would be wrong for you to persist further. Perhaps I have been foolish in trying to appease you so far. It would be wrong for you to persist any more along the lines which you have been following so far, and wrong for you to try to enforce your view by violent editing.Chjoaygame (talk) 15:08, 9 March 2013 (UTC)

Please don't take it that way. I am not, or really trying not to wear you down, or nag you, or break the rules. I am honestly trying to understand your statements and respond to them. From your point of view, I am substituting my own private intuitions while ignoring reliable sources. From my point of view, I read the sources, try to understand them, form a coherent picture in which I can consistently solve concrete problems in the subject and then edit an article based on this understanding, with references pointing to examples where the particular points are discussed. To my mind, you are reference-bound, your idea of editing an article is to quote various sources without attempting to bring coherence to the quotes. A paragraph should not begin with "Beris says...." or "Munster says...", and then ponder the differences in presentation and the confusion that might result, it should attempt to bring coherence to what they say, say it, and refer the reader to them for further reading, and to determine if the attempt at coherence has succeeded.

The zeroth law example is a good example. Different authors make different statements, after a bit of study it is clear they are all saying, or trying to say the same thing. I write down what they are trying to say, with pointers to the various references. You on the other hand, cannot or refuse to contemplate the unity of what they are trying to say, and prefer to offer the various quotations without venturing into a discussion of what they are aiming at, and then feel it is your duty to convey a sense of discord and confusion to the reader.

To me, this has been a productive discussion, because by attempting to answer your points, I have clarified my thinking on what properties a wall or partition may or may not have. Let's stop this conversation and I will carefully read what you have written and in a few days will respond. I have suspicions that you are trying to make a valid point, but it is very difficult for me to determine what it is, since you prefer a blizzard of quotes, rather than engage in a discussion of the meaning or logical consequences of those quotes. Again, I see no bad faith in your discussion and I assure you that there is none in mine. PAR (talk) 17:44, 9 March 2013 (UTC)

Ok, perhaps I went too hard with the admonitions in my last comment.Chjoaygame (talk) 20:56, 9 March 2013 (UTC)

Please see Talk:Zeroth law of thermodynamics for further comment on the zeroth law.

I cannot be the only one who finds these rambling discourses make no contribution to the article. In fact I suspect they are merely designed to promote their writers POV. --Damorbel (talk) 12:36, 8 March 2013 (UTC)