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Definition of Heat

The problem is that the definition of heat in the article is inconsistent in that it does not distinguish between heat and the transfer of heat. To assist in clarifying this I asked a question - would you .... explain what you accept as the proper name for the kinetic energy in vibrating or colliding particles?. This would help to clear up contradictions in the article. --Damorbel (talk) 09:50, 29 September 2012 (UTC)

Indeed the definition of heat in the article does not distinguish between heat and the transfer of heat. Indeed, the article explicitly says ″In physics, "heat" is by definition a transfer of energy and is always associated with a process of some kind. "Heat" is used interchangeably with "heat flow" and "heat transfer".″ I think editors who watch this page know well enough that you do not like that definition and interchangeable usage, from your many times repeated comments to that effect.

I do not see a good reason why I should try to comply with your gratuitous request that I "explain what accept as the proper name for the kinetic energy in vibrating or colliding particles", to use your words. I can say that your phrase does not give a good definition of heat in physics. In order to understand why this is so and to understand a sound physical definition of heat, one needs to have a fair understanding of thermodynamics, more than is likely to be expressed both adequately for your needs and briefly in this talk page. Your view that this article contains "contradictions" is due to your non-acceptance of the definition of heat that has been reached by consensus for this article.Chjoaygame (talk) 10:38, 29 September 2012 (UTC)

My question is simple, where in the article is the difference between heat (particle vibrations) and heat transfer? The matter is not difficult, particles at a high temperature vibrate with a geater energy than those at a lower temperature; when two (or more) samples matter with different temperature come into thermal contact (by whatever means) energy is transferred from the high temperature to the lower.

After a time the temperatures will equalise, which means that the vibrational energy of the particles is the same and heat transfer stops.

At present the article gives the impression that "heat has stopped" when the temperatures are equal; this can't be true because the particles are still vibrating with a common energy i.e. with a common temperature, even though the heating of the cooler body by the hotter has indeed come to a stop. --Damorbel (talk) 11:18, 29 September 2012 (UTC)

Dear Damorbel, you ask "where in the article is the difference between heat (particle vibrations) and heat transfer?" It seems to you that your question is simple, but in reality it is muddle-headedly posed, and so has no useful answer. Your muddle is of your own making. You find the article hard to understand because you insist on your own muddled approach to heat. By misdirecting your efforts to trying to force that muddled approach onto others, you distract yourself from getting a better understanding. You muddle yourself about a thermodynamic matter by prematurely dabbling in the kinetic theory that provides a microscopic explanation for it. Instead of that, if you spent some time trying to follow the approach of basic thermodynamics itself, you would find that things would become clearer to you.Chjoaygame (talk) 14:36, 29 September 2012 (UTC)

Chjoaygame, the article would be considerably improved if it contained a clear distinction between heat (energy - joules), heat transfer (power - watts or joules/second) and the role that temperature (joules/particle) plays in both. --Damorbel (talk) 06:03, 1 October 2012 (UTC)

Damorbel, you continue to express your view that "the article would be considerably improved if it contained a clear distinction between heat (energy - joules), heat transfer (power - watts or joules/second)..."

The article is based on a view different from yours, but found almost universally in reliable sources on thermodynamics, and accepted by the consensus on which the present article is based. It is that the idea of heat in thermodynamics refers to a quantity of energy transferred in a process. It is fundamental to thermodynamics that heat is a process quantity, not a state quantity. For a discrete process that carries an initial state of a closed system to a final state, with finitely separated initial and final states of thermodynamic equilibrium, the heat transferred is a quantity of energy. For a continuous-time process of a closed system, one can consider the rate of heat transfer as a power, energy transferred per unit time, provided a temperature exists throughout the process and provided some other conditions are satisfied. There is in thermodynamics no "state quantity of heat". The energy status of a closed system or body is described in thermodynamics by its internal energy. It is the message of the first law of thermodynamics that the internal energy is a state variable, and that it cannot in thermodynamics unconstrainedly be split into moieties which are also state variables. The notion of unconstrained splitting refers to the fact that different amounts of heat can be extracted from a body depending on the constraints under which the heat is to be extracted.

The reason for this is that energy of a body which might be available for extraction as heat, microscopically considered, is partly in the internal kinetic energy and partly in the mutual internal potential energy of the constituents of the body, and that the distinction between these two factors cannot be made without constraint for the process of extraction. This is another way of saying that the heat transferred in a process of a closed system is a function of the path of the process; the path of the process is specified in terms of constraints on it.

To judge from what you write, it seems clear that you do not accept the thermodynamic view that I have expressed just above, that is the basis of the present article.Chjoaygame (talk) 07:46, 1 October 2012 (UTC)

Chjoaygame, the concept of heat as the vibrational (kinetic) energy of fundamental particles is well established by kinetic theory, the heat article needs to recognise this, at present it doesn't, e.g. when it has ""

Up until now nothing you have written explains what name or function the article should give to the energy stored in the motions of particles. I would be much more inclined to agree with you if you could sort this this out. --Damorbel (talk) 09:22, 1 October 2012 (UTC)

Damorbel, you are insisting on your own personal viewpoint that is fundamentally contrary to the viewpoint taken by the article as it stands, which is the result of consensus of editors based on reliable sources. Your personal viewpoint is a very personal and private reading of the sources. You insist on giving conceptual priority to your reading in terms of "kinetic theory", contrary to the general principle that the thermodynamics of heat is about macroscopic measurements made on closed systems. While you insist on this personal and private reading, you will not be able to understand the consensus viewpoint in terms of thermodynamics, which is that of this article as it stands. Your personal viewpoint is muddled and inconsistent, though you are blind to its defects. The thermodynamic concept that you need to understand is called 'internal energy'. Microscopically it is explained by the internal kinetic energy and the internal mutual potential energy of the constituents of the system. The great discovery of Clausius was that macroscopically for thermodynamics the internal energy is a state variable that cannot be "sorted out" (as you wish) into parts so as to produce part that would be an unconstrained quantity of heat that would be a further state variable. The internal energy discovered, but not named, by Clausius was not recognized by him at first as a quantity of energy; it took him 15 years to come to understand that it was such. Your notion of "the energy stored in the motions of particles" is not a well defined quantity; however much you might wish it to be recognized as a physical quantity, it is just wishful thinking without physical understanding. In chasing "the energy stored in the motions of particles" you are chasing a will-o'-the-wisp invented by you in your own internal word games, without physical understanding. It is possible that you are not to blame for your misunderstanding, but were led to it by would-be self-judged "clever" teachers who thought that they could teach kinetic theory without a prior basis of thermodynamics; this was a regrettable fashion in teaching at one stage.

In order to understand the thermodynamics of heat, you need to abandon your present personal and private viewpoint in this, because it blocks your understanding of the thermodynamical viewpoint. No progress will occur until you grasp this nettle.Chjoaygame (talk) 11:09, 1 October 2012 (UTC)

Chjoaygame, you write (above) "the energy stored in the motions of particles" is not a well defined quantity", I understand from this that you do not accept that this energy is a function of the temperature of the particles i.e E = 1/2m/v = 1/2k_BT?

You seem to find Clausius slow "The internal energy discovered, ... by Clausius was not recognized .... as a quantity of energy; it took him 15 years to come to understand ...". Is his slowness important to your argument?

So when Clausius wrote an article “On the Nature of the Motion which we call Heat” (Über die Art der Bewegung die wir Wärme nennen - available in English from Google Books) was he wrong?

Clausius writes (on p127, after equ.(9)) "No constant need be added, since, as before remarked, the heat in the gas is proportional to the vis viva of the translatory motion, and hence to the absolute temperature" --Damorbel (talk) 12:39, 1 October 2012 (UTC)

As I already mentioned several times, while you insist on your personal reading of the matter, you will not be able to understand the thermodynamics of heat. You are now trying to distract attention from thermodynamics by arguing in terms of Clausius' understanding in terms of kinetic theory. You may feel that this is a clever debating move, and indeed it looks good. But it doesn't cut it, because the argument that Clausius is using does not take into account the internal mutual potential energy of the constituents of the body. So, yes, I am saying that Clausius' argument here, on which you rely, is wrong if taken as a general argument for the thermodynamic nature of heat. As I mentioned, Clausius' discovery of internal energy was not at first fully recognized for what it was even by Clausius. The reason I mentioned it was to soften the blow for you when you are eventually struck by the weight of the concept of internal energy, which reduces to nonsense your wishful thinking about heat as a state variable. You are not the only person to have difficulty grasping the concept of internal energy. The article by Clausius that you cite was written in 1857, some years before 1865 when he accepted the understanding of his quantity U as internal energy. Your relying on Clausius' 1857 article for your case shows that you will go to any length to hold to your personal and private reading of heat, so as to avoid your gaining an understanding of heat in terms of changes in the internal energy of a closed system, as held by thermodynamics. There are none so blind as those who will not see.

It struck me that perhaps an analogy may help you. Perhaps not; perhaps you will just use it as another distractor to help you hold to your personal view and protect you from physical understanding which you are so strenuously avoiding. The analogy likens the internal energy of a body to the water in a pond. The pond is filled from a stream and emptied by a pump. It also receives water from the rain and from snow and dew. It also evaporates. The analogy likens the stream and the pump to "work" and it likens the rain, dew, snow, and evaporation to "heat". It is not possible by ordinary macroscopic measurements to split the water in the pond into "work" water and "heat" water. You would like to make such a split, but it won't happen.

Dear Damorbel, you are a master of distraction and irrelevant rhetoric, but you are no good at sound reasoning about the physics of heat. I have mentioned before that you are challenged in the logic department. In this case, it seems to me that you are perhaps making the logical error of taking ordinary language as if it had the compositional property that mathematical formulations mostly have. Compositionality means that the meaning of a clause can be determined simply by considering it as a composition of units each of which separately has its respective fixed and definite meaning. That is to say, you are thinking that because one speaks of extracting heat from a body, it follows that it makes sense to think of the body as storing heat. The ordinary language construction makes that look plausible, on the assumption of compositionality, but it is nevertheless wrong in logic, because ordinary speech does not have the compositional property.

You have indeed this time till now succeeded in luring me into trying to have a rational conversation with you, an error which I have previously recognized as an exercise in futility. You are afresh showing your ability to avoid real understanding by admittedly clever rhetoric. I have had a good try at helping you here, perhaps foolishly, given your present characteristics. While I congratulate on so far luring me into a futile exchange, I don't want to continue with it. You are showing every sign that you are unable to bring yourself to attend to reason in this matter, and are hardly likely to change in that respect in this conversation. You can lead a horse to water, but you can't make it drink.Chjoaygame (talk) 15:47, 1 October 2012 (UTC)

Perhaps it may be useful to Damorbel to read exactly why the Clausius 1857 paper does not support Damorbel's view of things as he supposes it does. Clausius had at that time, in 1857, not yet come to call his state function U the internal energy. In that paper he still spoke of the "generation and consumption of heat" and used the concept of "interior work". That 1857 use of the word heat by Clausius is not that of present day thermodynamics; in many cases Clausius spoke of "heat" when today we would speak of internal energy, but it was not not till 1865, some years after the 1857 paper to which Damorbel refers, that Clausius started using the term energy for his state function U which we now call internal energy. "Interior work" corresponds to what we might today call the internal mutual potential energy of the constituents of the material. For gases, this is usually not as great as the kinetic energy of the molecules, but for liquids and solids it is usually greater. Damorbel wants us to forget about the internal mutual potential energy of the constituents of the material, and so he thinks mostly, it seems, in terms of ideal gases, which behave somewhat differently from real gases and very differently from solids. For ideal gases one can indeed forget the internal mutual potential energy of the molecules. But the thermodynamic concept of quantity of heat tranferred is intended to deal not only with ideal gases but also with real gases, liquids, and solids. So it takes into account not only the kinetic energy that Damorbel thinks about, but also the potential energy that he doesn't think about. Damorbel makes the basic error of building his conception of heat from the kinetic theory of gases, instead of the simpler and more general theory of macroscopic thermodynamics, which is needed to get a full understanding of the nature of heat. Damorbel is not the only person to make this mistake, and often those who make it think they are very clever, and are being more "fundamental". The result is that Damorbel, and sometimes others, get a muddled view of the nature of heat.Chjoaygame (talk) 20:11, 2 October 2012 (UTC)

Chjoaygame, internal energy, U has two components kinetic energy (Q) which is 'heat' and potential energy which has many different forms, chemical bonds, van der Waals forces etc. Potential energy is completely separate from kinetic energy because it, by definition, is about static forces, i.e. it does not involve particle motion; for that reason potential energy is irrelevant to the definition of heat. --Damorbel (talk) 07:30, 3 October 2012 (UTC)

Damorbel, now you have put your cards on the table. Thermodynamics is largely interesting because its definition of quantity of heat transferred is sensitive to internal mutual potential energy, which you say here is irrelevant to your definition of heat. In direct conflict with your view, in thermodynamics, internal energy U cannot be unconstrainedly split into two components, one of which would be a state variable that might attract your private label Q. This puts you thoroughly in direct conflict with the thermodynamic analysis. You can cite the name of Clausius as a specious rhetorical move, but you have missed understanding the main point of his discovery of U. You will remain beyond help until you try to see your mistake here.Chjoaygame (talk) 08:38, 3 October 2012 (UTC)

Chjoaygame, you do not mention temperature. According to Clausius heat (vis viva; energy in modern terms) in a given substance, is proportional to absolute temperature. The energy in different substances at the same temperature is not the same because not all substances have the same specific heat because different substances have differing numbers of (kinetic) DOF (degrees of freedom). Non-kinetic e.g. potential energy, degrees of freedom, have a variable effect on internal energy e.g. zero for a perfect gas, (3 DOF) (there is no potential energy in a (theoretically) perfect gas). Real gases have intermolecular (van der Waals) forces that make them change state (liquify, solidify etc.) at various temperatures. --Damorbel (talk) 09:13, 3 October 2012 (UTC)

In thermodynamics, temperature is related to heat transfer between bodies or closed systems. When two bodies with different temperatures are in contact through a connection permeable only to heat (as noted by Carathéodory), then heat is spontanteously conducted from the one with the higher to the one with the lower temperature. In physical reality, there is no immediate and simple one-to-one relation between the temperature of a body and its internal energy. In examination of the microscopic mechanisms of energy, one finds various indirect and complicated relations between the temperature of a real body and its internal energy. Only in a merely idealized explanation, such as of an ideal gas, does one find more direct and simple relations between the temperature of a body and its internal energy. Yet you are demanding that such merely idealized cases expressed by idealized microscopic models should define your term "heat in a body", as if it were a state variable. The point of the thermodynamic analysis of heat is (without consideration of the microscopic models, which are in general beyond the feasible practical reach of precise calculation) to deal with the non-idealities which you wish to ignore when you engage in wishful thinking in terms of your idealized examples. Your approach ignores and effectively contradicts that of thermodynamics. And you are trying to force its acceptance as a new basis for this article, contrary to the (admittedly not quite unanimous) consensus of editors, and contrary to the weight of reliable current sources.Chjoaygame (talk) 11:53, 3 October 2012 (UTC)

"temperature is related to heat transfer" How? For transfer of energy? For energy to be transferred there needs to two temperatures, the heat source (T₁) and the heat sink (T₂). Which of the two do you have with a fever of 98.4F? --Damorbel (talk) 13:47, 3 October 2012 (UTC)

Chjoaygame, what does temperature measure? --Damorbel (talk) 13:50, 3 October 2012 (UTC)

With a temperature of 98.4°F, you don't have a fever.

Temperature measures the partial derivative of internal energy with respect to entropy at constant volume and chemical constitution.Chjoaygame (talk) 13:09, 4 October 2012 (UTC)Chjoaygame (talk) 23:02, 5 October 2012 (UTC)

Chjoaygame, temperature is the energy per particle, as with the Boltzmann constant. Temperature can only be defined at maximum entropy (Thermal equilibrium), or don't you agree. BTW(1), the thermal equilibrium article describes the equilibrium state as existing with >1 temperature thus with entropy <Smax, I intend to correct this. BTW(2) since temperature can only be defined at Smax (dS/dt = 0) how can it be the partial derivative of internal energy with respect to entropy? --Damorbel (talk) 10:10, 5 October 2012 (UTC)

In order to find the answer to your question about the partial derivative, you will need to study thermodynamics.Chjoaygame (talk) 13:59, 5 October 2012 (UTC)

response by WFPM

With regard to the internal motion of a system of particles, The contained energy of the system of particles is considered to be equal to the integral of the sum 1/2 of the squared value of the speed of the individual particles. This is really the heat energy but is usually called the heat. In order to be able to detect and quantitatively measure this value, devices have been created that will read out a variable "temperature" value derived from some observed physical condition (like expansion) of the physical measuring device. This measured "heat" value is then used to infer the heat energy content of the measured system. And then the rules of "thermodynamics" are used to determine how the heat energy content of the system is interchanged with other forms of kinetic energy of motion by the various devices that use heat energy exchange processes as a means of doing work or other physical or chemical accomplishments. But the word "heat" is not a name of anything other than a indication of a "temperature differential" unless it is associated with organization of a specific physical system which can be assessed as to its quantitative physical and/or chemical properties.WFPM (talk) 22:37, 6 December 2012 (UTC)

There are other microscopic forms of energy besides the kinetic energies of translation of the individual particles. These other forms are also important.Chjoaygame (talk) 00:52, 7 December 2012 (UTC)

Well, unless you want to talk about the conversion of mass into energy, I can't think of anything else that the mass can do other than to have kinetic energy of motion. If its volume is confined, then we have the pressure-volume factors. But for the individual particle, about the only thing it can do is to have internal energy of motion. Of course if it is located within a physical force field it has potential energy of motion, and then we have to analyze it as part of a work energy accumulating force field system. But as to its "heat energy" content, we're back to an energy value that's related to some kind of motion. The complication is due to an inability to correctly determine the mass and speed of motion of the moving constituents of the particle.WFPM (talk) 18:44, 8 December 2012 (UTC)

Conservation of ' 'Heat ' ' ?

Heat is not a conserved quantity so, in thermodynamic terms, it cannot be transferred. What is transferred is energy. The article should make clear that common usage does not explain subtle differences in language. The Heat article currently doesn't explain these subtle differences either; this is a serious deficiency because it contains statements such as :-

Heat flow from high to low temperature occurs spontaneously (Opening statement, 2para 1line)

which is thermodynamic nonsense because it does not respect the conservation of energy according to the 1 Law of thermodynamics. --Damorbel (talk) 08:47, 24 November 2012 (UTC)

Nope: 'work' and 'heat' are forms of _transfer_ of energy. Neither is conserved. What is conserved is _energy_ not 'work' and not 'heat'. Nobody is saying (only Darmobel) that "heat is conserved". Energy is conserved and for any thermodynamic process 'heat' must be released when doing 'work'. ΔE=Q+W. What flows spontaneously from high to low temperature is 'heat' which is _a_form_ of energy transfer. In that (when only heat is tranfered) case W=0 and ΔE=Q: the change in energy is exactly the ammount of heat released. But when work is also being done then ΔE=Q+W. Energy is used to do work _but_ some energy is transfered as heat _always_. What this means is that not all energy is avaiable to do work. The minimal ammount of heat released during a process is δQrev=TdS: in general ΔS>=Q/T. Notice that is not "ΔQ": there is not a "heat change" there is an "energy change" where energy is tranfered via 'heat' with no 'work'. There are two main phenomena for energy transfer: 'heat' and 'work', which are distinct and are not conserved in themselves: that which is conserved is energy (for an isolated system) ΔETOT=0. This is why the first law of thermodynamics is stated as ΔE=Q+W or as ΔU(T)=Q+W when only the internal energy of the system is used. This internal energy might have been at a time considered only as 'thermal energy' but nowdays we know there is also "chemical energy" and "nuclear energy", etc., involved. Darmobel is missing the basic point of the laws of thermodynamics entirely, especialy the second law. He wants "heat" to be "thermal energy", which it is not. The main point of the laws of thermodynamics is that, when you use energy to do work some of the energy is _always_ transfered but not used as work. These concepts arose from a generalization of real world observations of physical processes: it is by no means self evident, but it seems to be the truth in the universe we live in, similarly to the arrow of time or that the velocity of light in a vacuum is a constant. The laws of thermodynamics (as happened with Newton's laws of motion) _might_ be disproven for some generalized case, but that has not been the case (as per the quotes if somebody finds a case where the laws of thermodynamics do not hold he or she probably would win a Nobel Prize of physics and hailed as greater than Einstein, Newton Et.al. all together. Even when studying black holes the concepts of conservation and of the increase in entropy of the universe and conservation of information arise). What Darmobel is missing is not easy matter to understand: the need for 'heat' that arises when realising that, when using 'energy' for doing 'work', not all 'energy' that is transfered is used as 'work' but some is transfered and not transformed into 'work'. This is the quantity that in thermodynamics is called 'heat'. This means that perpetuum mobile of the second kind _does_not_exist_ Whenever you use 'energy' to do 'work' some 'energy' is transfered but not used to do 'work'. These concepts began as an analysis of thermal engines and thermal procecess but later ere generalized as laws for "the universe". The interesting thing is that these "laws" have never being disproved but actually seem to hold in one form or another for all physical processes. It seemed to be a bold move to generalize the laws of thermodynamics to _every_physical_process_in_the_universe_ but, up until this day and age, there is not a single process where the laws of thermodynamics are not obeyed. Darmobel: the concept of 'heat' in physics arises when it is realized that an energy change cannot be used only to generate work. The rest of the energy that is tranfered is then called 'heat' and it seems to be related to a gradient in the quantity called temperature. Even in the study of "heat transfer' the differences in temperature are an important part of the velocity at which heat transfer occurs. Depending of the mechanism the dependence is different. In conduction the quantity of heat flow is a function of the gradient of temperature (dQ=kAdT/dx in one dimmenssion), in convection it is a function of a generalized gradient of temperature(dQ=hAdT), in radiation a function of the fourth power of temperature (dQ=σεdAT^4). Actually here we have a distinction between convection and conduction, even more established by Nusselt's number Nu=(h/k)L, where L is a characteristic distance. Here we have a ratio of convective heat transfer over conductive heat transfer. In http://en.wikipedia.org/Nusselt_number One can find a derivation of Nusselt's number from Fourier's equation. When one delves into the details of dimenssional annalysis and convection one starts to realize that the mechanics of heat transfer through convenction are, indeed, distinct from conduction and radiation... --186.32.17.47 (talk) 15:47, 24 November 2012 (UTC)

Nameless 186.32.17.47 - You write:- " Nobody is saying (only Darmobel) that "heat is conserved"" I doubt if I ever wrote Heat was conserved I opened this section and it has the title Conservation of ' 'Heat ' ' ?, the question mark is important. If you did not realise that I have been arguing the importance of the consevation of energy, not heat, for some time, then you may be struggling with the whole matter.

Nameless 186.32.17.47, you write What flows spontaneously from high to low temperature is 'heat' which is _a_form_ of energy transfer. Well written" Why don't you open a section enttled Conservation of ' 'Heat ' ' ?

Nameless 186.32.17.47, you write Darmobel: the concept of 'heat' in physics arises when it is realized that an energy change cannot be used only to generate.... Which of course raises the question: do you have special evening for teaching your grandmother to suck eggs? --Damorbel (talk) 22:00, 24 November 2012 (UTC)

In the immediately foregoing, written I guess by Crio de la paz, good points are made, I think.Chjoaygame (talk) 17:46, 24 November 2012 (UTC)

I agree - heat and work are process functions, not state functions. They are not something associated with a state. Asking how much heat a system contains is like asking how much work it contains. It's nonsense. You must ask how much work has a system done, how much heating has it done, etc. A system may lose internal energy by doing work or by heating another system, or may gain internal energy by having work done on it or by cooling another system. This idea is at odds with the non-scientific use of the word heat, the idea that a hot body contains a lot of heat, a cool body not so much. If we are going to speak scientifically, then we must use the scientific definition of heat and not confuse it with the unscientific common-usage "definition". PAR (talk) 18:13, 24 November 2012 (UTC)

PAR, you write:- "heat and work are process functions, not state functions." Do you recognise any connection between heat and temperature? Or between temperature and energy? Or between temperature and state functions? --Damorbel (talk) 22:00, 24 November 2012 (UTC)

I do not understand what the whole "teaching your grandmother to suck eggs" reference is about. PAR and Chjoaygame are right but Darmobel seems only to be trying to pick a fight. If he already undertsand these subjects then: What is he arguing about? Where has _anybody_ argued that "heat is conserved" or that "some mysterious substance that appears when temperature differences exist" besides him? If he already understands all we are saying and he does not require any explanation on thermodynamics: What is he arguing about? For all I've read in these discussions he is arguing only with himself. --Crio (talk) 00:44, 25 November 2012 (UTC)

This is a confusion of the everyday usage of the word heat and the thermodynamic definition. In the thermodynamic definition, heat and work are mathematically similar. The problem is in the English. If "work" and "heat" were to be made as similar verbally as they are mathematically, we could write:

• A system transfers energy to another system by doing work on it.
• A system transfers energy to another system by doing heat on it.

• A system transfers energy to another system by working it.
• A system transfers energy to another system by heating it.

• Work is something that is done, it does not "exist".
• Heat is something that is done, it does not "exist".

• PdV represents the amount of energy transferred by work.
• TdS represents the amount of energy transferred by heat.

Some of these sentences sound odd - they conflict with everyday English usage. Damorbel has failed to realize that the problem with these sentences is not with the physics, it is with the English. The word "heat" was perhaps a bad choice for TdS, but we seem to be stuck with it, and we have to deal with it and not declare that the English language guides the physics. You don't "do heat" the way you "do work", but rather, you "heat". You don't say "heat is done, it does not exist", you say "heating is done, it does not exist". You don't say "TdS is the energy transferred by heat", you say "TdS is the energy transferred by heating". That's an unfortunate verbal mess, but it has nothing to do with the physics.

As regards "thermal energy", I don't know the rigorous definition. If I have a box with a piece of ice in it at the temperature of the triple point, and I then heat the system until all the ice turns to water, it is still at the triple point temperature. The temperature has not changed, but the internal energy has increased because entropy has increased. Has the "thermal energy" increased? I don't know. PAR (talk) 16:20, 25 November 2012 (UTC)

PAR referring to your , it is still at the triple point temperature...". In practical terms this wouldn't happen because the water would not turn to ice at the same instant. The triple point cell does not normally allow much heating or cooling, it is supposed to be an equilibrium cell, where energy exchanges occur only between the ice, the water and the vapour, the total cell energy should remain constant.

I am interested in this post, I hope to return later, you identify misunderstanding via language as a problem - I agree with you!--Damorbel (talk) 16:54, 25 November 2012 (UTC)

This is not correct. You can heat a fixed-volume system containing ice, water, and vapor at the triple point. Let it equilibrate. As long as you have not added enough energy to melt all of the ice, the temperature will still be at the triple point. There will just be more water and less ice. That's why a triple point cell is so useful - heat it, cool it, work it, make it work, thereby adding or subtracting from its internal energy. When it comes to equilibrium, it will still be at the triple point as long as the three phases still coexist. The internal energy will have changed because the entropy has changed, but the temperature will not have changed. PAR (talk) 19:10, 25 November 2012 (UTC)

What you said is "....until all the ice turns to water That means that the buffering effect of the ice is no longer working..... But I understand what you mean!

• A system transfers energy to another system by doing work on it.

The effect you get depends on how the work is done - if the system is a shell (in the barrel of a gun) work done is the propellant pushing the shell out of the barrel and the work gives the shell velocity. If you are forging a billet of steel the work is changing the shape of the billet and it gets hotter

• A system transfers energy to another system by doing heat on it.

The gun's propellant burns in the breech, producing hot gas that heats the barrel.

• A system transfers energy to another system by working it.

1/When forging a billet of steel the work is changing the shape of the billet and it gets hotter

2/When bending a nail stuck in a plank of wood the nail gets hot fron the internal friction resisting the force bending the nail,

• A system transfers energy to another system by heating it.

The gun's propellant burns in the breech, producing hot gas that heats the barrel.

• Work is something that is done, it does not "exist".

The work done by the propellant gas accelerates the (depleted uranium anti-tank) shell to 1500m/s, giving it a lot of kinetic energy. The (depleted uranium anti-tank) shell hits the enemy tank, deforming the tank and, by means of friction, the tank brings the shell's 1500m/s velocity to zero. This friction changes the kinetic energy of the shell into heat, and induces chemical change by cooking the people in the tank.

• Heat is something that is done, it does not "exist".

There is chemical (thus potential) energy in the propellant, waiting for someone to trigger its release. When burning, the propellant decomposes to gas which is very hot (flames and suchlike) and so at a high pressure, this hot gas forces the (depleted uranium anti-tank) shell out of the barrel. The potential energy in the propellant does a number of things 1/it raises the temperature and pressure of the combustion gases 2/ it heats the gun's barrel and 3/pushes the shell out of the gun at high speed; cooking the enemy in their tank. From this you will realise that the chemical energy, when triggered, is spread all over the place but it is not destroyed it just gets spread around to lower and lower concentrations, always lower than the orignal (chemical) energy in the propellant.

• PdV represents the amount of energy transferred by work.

Only if it is a gas that is worked on and only if the action is adiabatic.

• TdS represents the amount of energy transferred by heat.

Depends on what dS means. Is the system at maximum entropy. I assume there is only one source of energy, but it the energy doesn't have to be evenly distributed, perhaps there is (= there always is) a gravitational field.--Damorbel (talk) 21:49, 25 November 2012 (UTC)

I wrote above:-

the chemical energy, when triggered, is spread all over the place but it is not destroyed it just gets spread around to lower and lower concentrations, always lower than the orignal (chemical) energy in the propellant.

What I should have mentioned is that the total energy released by burning the propellant remains traceable i.e. it is conserved but it is continually changing its form: from chemical energy to heat: to kinetic energy of the gas and the shell: to low temperature energ in the gun barrel: back to heat energy, possibly hotter than the combustion products when the shell strikes the tank. Other energy products from triggering the propellant are sound and perhaps gravitational potential energy - I invite contributions! But also it should be noted that none of the combustion energy is transformed into another conserved quantity such as momentum. --Damorbel (talk) 07:04, 26 November 2012 (UTC)

The simple answer to your question is that "thermal energy" is undefined and is a bad term to use because it seems to have meaning when it does not. Likewise thermal internal energy which suggests we can identify what part of U came from heat and what didn't. If you have a sample of hot gas, did it get hot from compression PdV or heating TdS? No way to know. Either is possible or some combo. To pretend you know, perhaps by crystal ball, is fooling yourself and others. Thus there is no heat content. There is no latent heat content. Potential energy goes up in a phase change, and that's the way internal energy is stored, but you don't know how it got there or how that energy will come out, so you're kidding yourself if you think it's tagged by Mother Nature as "thermal" energy. It's just potential energy. It follows that heat cannot be advected. Heat is not, and cannot be, stored. Heat is not a noun! As declares a famous pedagogical paper. This all goes back to Mark Zemanski's opus of 1970, called "The Use and Misuse of the Word "Heat" In Physics". Still widely cited after 42 years (but still not online, alas). But also widely ignored by college text writing boobs, which makes well-nigh impossible to cover these topics on Misplaced Pages. Much as happened with "weight" and "matter". There are ten careless writers for every rigorous one. And WP editors would rather win an argument than think. SBHarris 17:15, 25 November 2012 (UTC)

SBHarris writes words of wisdom: "There are ten careless writers for every rigorous one." His next sentence I think needs a slight amendment, the addition of the word some: "And some WP editors would rather win an argument than think."Chjoaygame (talk) 18:51, 25 November 2012 (UTC)

definition of heat in this article

The present article starts by defining heat in a way not precisely that of any particular reliable source. The sources cited are Reif and Kittel & Kroemer, two student texts of statistical or thermal physics. They both come from a particular pedagogical viewpoint, that one should teach thermodynamics along with statistical mechanics. In his introduction, Reif makes the point that he thinks he is particularly clever to do this. Another well represented pedagogical viewpoint is that thermodynamics should be taught separately from and prior to statistical mechanics. The reason for the latter viewpoint is that it is good for the physicist to have a good grasp of what can be done with thermodynamics alone, without calling on the special notions of statistical mechanics.

The present article's precise wording is nearer to Reif's than to Kittel & Kroemer's definition. The article's definition omits the word "purely" from Reif's definition. Reif, like most sources, defines heat in a carefully constructed context, and does not intend his definition to make sense without that context. The present article's definition omits that context. It follows that the present article's definition of heat is original research.

Reif defines heat in a context of classical thermodynamics. There are two bodies which can interact by exchanging energy. There are, according to Reif here, two types of interaction available for them. Reif has already defined a system or body in specific terms; the terms point to the working body of a classical thermodynamic system, defined statically by external parameters. Regrettably, as a result of his pedagogical stance, Reif's definition is partly clouded by its inclusion of loosely worded ideas that refer vaguely to the quantum mechanical Hamiltonian, with the result that the context of his sentence that introduces the word heat on page 67 is complicated or even, one might say, cluttered.

Kittel & Kroemer are likewise practitioners of the mixed-teaching pedagogical persuasion. They do not use the same definition as Reif, though the difference does not amount to a significant conflict. They specify on page 227 that "Heat is the transfer of energy to a system by thermal contact with a reservoir." Their reservoir is assumed to possess a well-defined temperature.

The term "thermal contact" is worth examining. It comes from a tradition of rigorous classical thermodynamic thinking started by Bryan, and continued by Carathéodory, and blessed by the authority of Born. The tradition examines very simple assemblies of bodies of respectively homogeneous chemical constitution, in communication with each other through defined partitions. The partitions are considered to be permeable to or capable of transferring energy or matter in specific ways. Amongst the ways is the thermal way, in Carathéodory's translated words, "as heat". This refers to the case when matter cannot permeate the partition, and where the partition does not move so as to produce volume-related work, and where external long-range forces are invariant. Carathéodory is burning to obey Born's advice to follow up on Bryan's observation that if one relies on the principle of conservation of energy as a prior supposition, or if one imagines that one can perform reversible work, then one can simply define heat transfer as transfer of energy that is not as work. This thinking is often regarded with awe as brilliant physical insight. Carathéodory admits the existence of partitions permeable only to "heat", but he carefully words his definition of them so that the words heat and temperature are not explicit in them. Indeed, he continues his article without actually offering a definition of heat according to his scheme of development of the basic ideas of classical thermodynamics for closed systems. Nevertheless, his scheme has built into it, for its definition of the equilibrium states of parts of his systems (the only states defined in his development), a "non-deformation" variable, that other more traditional developments would regard as a potential measure of empirical temparature, Carathéodory's development carefully avoids explicit mention of empirical temperature. Thus for Carathéodory, the father of this very rigorous way of thinking, heat is transferred by conduction or by radiation, though, for the sake of the brillianct cleverness of the development, the wording is carefully constructed to hide this fact, a fact which appears clearly in other more traditional developments that do not consider themselves quite as brilliantly clever as Carathéodory.

Many texts, such as Reif and Kittel & Kroemer, in developing the notion of transfer of energy as heat, do not proceed to discuss the first law of thermodynamics for open systems, but restrict their systematic development to closed systems.Chjoaygame (talk) 17:40, 24 November 2012 (UTC)

Response by Crio

Quite an interesting exposition Chjoaygame! --Crio (talk) 00:50, 25 November 2012 (UTC)

Response by Damorbel

Looking at your sources (BTW, please don't cite sources without refencing some relevant passage(s)):- Kittel & Kroemer on the 1 law of themodynamics p49:- First law. Heat is a form of energy. This law is no more than a statement of the principle of the conservation of energy, Ch.8 discusses what form of energy heat is. Ch.8Has the heading :-

Energy and entropy transfer

Definition of Heat and Work

They open:- Heat and work are two different forms of energy transfer but heat is not a conserved quantity. Later they go on about entropy transferbut entropy is not a conserved quantity.

Thus form the beginning Kittel & Kroemer are mixing conserved and none conserved items and not drawing attention to the fact that only conserved items can be transferred, non-conserved items can appear or disappear, sometimes without trace, e.g. chemical energy and kinetic energy. Thus Kittel & Kroemer cannot be considered as a reliable source on the first law of thermodynamics, so the the rest of their arguments are necessarily quite doubtful.--Damorbel (talk) 10:43, 25 November 2012 (UTC)

Dear Darmorbel, contrary to your comment, they are not my sources; they are, as I wrote, the sources cited in the article, which gives the relevant page numbers, only p. 227 in the case of K & K, not the p. 49 to which you further refer. I am not proposing that these sources are, or are not, reliable. I am pointing that they are the ones cited in the article for its definition, though that definition does not follow them precisely, and is therefore original research.

By the way, you are utterly mistaken to say that only conserved quantities can be transferred. In systems which can gain or lose bulk potential energy by long-range forces with the surroundings, internal energy is not conserved, but can be transferred. It is customary in the field theory of non-equilibrium thermodynamics to say that entropy can be transferred, though at least one writer, B.C. Eu, uses a specially invented word, "calortropy", to deal with the concern that "entropy" can be created as well as transferred, which should make you happy.

Above, you say that you are "arguing that Kinetic theory ... is ... at the base of thermodynamics and statistical mechanics". You are missing a main point there. No one is denying that kinetic theory or statistical mechanics can be considered to be "at the base of thermodynamics"; I think it clearer to say that they explain thermodynamics, though many people, including you, like to say that the explanation is "basic", relegating thermodynamics proper to a derivative or secondary status. What is being said, and is the consensus here, is that for the definition of quantity of energy transferred as heat, thermodynamics provides the primary definition, which is then exported to statistical thermodynamics, there to provide the target propositions that it aims to derive and thus explain in terms of the microscopic picture. How many times do we need to repeat this to you, before you hoist it in? One problem here is that much of the time you are arguing against straw men of your own making, misrepresenting what we try to tell you.Chjoaygame (talk) 11:47, 25 November 2012 (UTC)

Chjoaygame, you write they are not my sources; Who cares whether they are your sources? The article is not "your article". Kittel & Kroemer are in the article, they are being used to support unsupportable 1 Law assertions (heat flow.)

Further you write:- B.C. Eu, uses a specially invented word, "calortropy" Possibly related to caloric? Chjoaygame without explaning its relevance to the Heat article. This comment is utterly irrelevant and is time wasting. Usng this kind of logic you must not be surprised when your contributions get reversed. Please stop this kind of disruptive editing.

As regards reliable references WRT kinetic theory and thermodynamics you will find that the Royal Society and Sir Humphry Davy denied that heat was a property of molecules and deliberately obstructed publications on the matter (see here) so the aricle in distinguished company with Kittel & Kroemer as references!

Further you write:- By the way, you are utterly mistaken to say that only conserved quantities can be transferred. Really?

You go on toexplain with:- In systems which can gain or lose bulk potential energy by long-range forces with the surroundings, internal energy is not conserved Who is saying internal energy should be conserved? Please explain, this idea cannot possibly be supported in Misplaced Pages. --Damorbel (talk) 13:06, 25 November 2012 (UTC)

Damorbel, you write tetchily: "Chjoaygame, you write they are not my sources; Who cares whether they are your sources?" Damorbel, you care, as is shown by your gratuitously attributing them to me, a straw man of your own creation. In fact I had written: "... contrary to your comment, they are not my sources." Dear Damorbel, you now misrepresent my response to a previous misrepresentation by you of what I wrote previously. Previously you inaccurately wrote that they were my sources; I was just observing that I had written that they are the article's sources; I was just corrrecting your inaccurate statement about what I wrote. Now you try to make out that this means that I am engaging in disruptive editing. And next you write further erratic and irrational remarks. Your misrepresentations are too much. I don't have time for your antics. Why do we reply to you at all? We know from painful experience that trying to discuss physics with you is futile because of the way you behave. You have a current invitation by other editors, to put into the section on the statistical mechanical explanation what you want to about the Boltzmann constant, your heart's desire, but instead of doing so, you turn aside to behave so as to make another editor write just above here: "... Damorbel seems only to be trying to pick a fight." Chjoaygame (talk) 14:08, 25 November 2012 (UTC)

Comment by Chjoaygame

No one has responded to my statement at the beginning of this section, that the present article's definition of heat is original research. A reasonable response would be that the lead is a summary and cannot be required to be limited to exactly sourced material; it should accurately summarize the properly sourced material of the body of the article.Chjoaygame (talk) 22:04, 25 November 2012 (UTC)

I don't have it here to check, but the definition in the first line of the article is nearly verbatim K&K's definition of heat, isn't it? If so, how in the world can you construe that as "original research"? Are you familiar with the meaning of the phrase? Waleswatcher (talk)

No, it isn't "nearly verbatim K&K's definition of heat". When you wrote the above, you were not in a position to ask any rhetorical questions, let alone insulting ones. Please come back to us when you have done your homework.Chjoaygame (talk) 02:34, 26 November 2012 (UTC)

"Homework" - you have a very bizarre idea of what this talk page is for, don't you? Anyway, I checked. According to K&K, "heat is the transfer of energy to a system by thermal contact with a reservoir". Doesn't quite coincide with our first sentence, but "original research"? As I suspected, you clearly have no idea what that phrase means. Now why don't you go do your "homework" and get us Reif's definition, Chjoaygame. Waleswatcher (talk) 04:15, 26 November 2012 (UTC)

Good of you to do at least half of your homework; thank you. As I remarked above, Reif's definition includes essential context, which takes nearly a page, but is not supplied in the lead definition in the article. It cannot be copied safely here without copyright problems, I think.Chjoaygame (talk) 04:52, 26 November 2012 (UTC)

Waleswatcher, there is no way Kittel & Kroemer can be considered a reliable source on thermal physics. They are both highly qualified and have published an interesting book but neither have a background in teching the matter, Kittel is a solid state physicist and Kroemer a solid state engineer. In no way does it rule out their book but it does mean that, when citing it, it is necessary to examine what they have written. I regard reliable sources papers by people like Fourier, Einstein and Clausius. Such people have defended their theories and we may attack them (if we dare!). The problem with Kittel & Kroemer is over the first law of thermodynamics; on p49 they have:-

Heat is a form of energy This law is no more than the principle of conservation of energy.

It isn't, it is the energy that is conserved, but it need not be as heat, it may well be (and frequently is) chemical energy.

The arguments put forward by Kittel & Kroemer for their "Thermal Physics" fall down badly on the fundamentals, they treat thermal energy as a conserved quantity, it isn't. What is conserved is the energy of the heat but the whole of modern physics revolves around the fact that energy has many different forms, Heat, potential energy, chemical energy, sound energy, electrical energy etc.etc. None of these forms are conserved, that is why Heat flow (in the article) is not a scientific concept. I am not saying that Heat flow should not appear in the article, it should, but it must be put in the category of practical but unscientifc ideas about heat. --Damorbel (talk) 09:58, 26 November 2012 (UTC)

The immediately above comment by Damorbel is mostly drivel. I would say that Waleswatcher has no need to respond to such drivel.Chjoaygame (talk) 11:01, 26 November 2012 (UTC)

Good morning Chjoaygame. I would like to know why you think my contribution is drivel. Also I think you owe it to the other users of Wiipedia to show them you can manage better than simple abuse. --Damorbel (talk) 11:55, 26 November 2012 (UTC)

Damorbel, K&K is plainly a reliable source for this article. If you don't believe me, please go and read wiki's guidelines for reliable sources. You might note that K&K is one of the standard texts for undergraduate and Ph.D. level courses in thermal physics and statistical mechanics. Regarding the physics in your comment, I've decided to stop engaging you (and to a lesser extent, everyone else here) on physics unless it is directly related to a specific edit of the page. Waleswatcher (talk) 13:26, 26 November 2012 (UTC)

So if Kittel & Kroemer say that heat is a conserved quantity that is right is it? And if Richard Tolman - Principles of Statistical Mechanics. p 528 section 118. 1 para p529 section 119 says it isn't then he is somehow just - wrong?

Waleswatcher, there are some things in life that you have to be able to work out for yourself; I invite you to read Kittel & Kroemer and Tolman and explain which is the better argument. --Damorbel (talk) 14:00, 26 November 2012 (UTC)

Further comment

This section is relevant because Waleswatcher wants to put convection in the lead on the same status as conduction and radiation as modes of transfer of energy as heat. The definition that he adverts to just above, "heat is the transfer of energy to a system by contact with a reservoir", is taken from the student text by K&K in which the exact word "convection" does not appear at all, and in which the nearest to it is the term "convective isentropic equilibrium of the atmosphere"; the rest of the book concentrates on conduction and radiation. The other cited source, Reif, mentions convection only in order to exclude it, while the rest of Reif's book concentrates on conduction and radiation. Waleswatcher here is minimizing the departure of the article definition from its cited sources, that is to say, minimizing its aspect of original research. Apparently this minimizing of the aspect of original research is in order to bolster his effort to put convection in the lead on same status as conduction and radiation. I would describe this as spinning by Waleswatcher.Chjoaygame (talk) 08:19, 26 November 2012 (UTC)

As is his nature, Waleswatcher has now made a trivial edit that he thinks further minimizes the problem with the lead. He has replaced the word body with the word system, which is vague as to the important point that it is a closed system that is being considered. He is referring to the definition of Reif. He continues to omit the important word "purely" used by Reif; it is hard to be sure, but it seems perhaps that his cover note intends to excuse this omission by appeal to something about Wiki style? He writes an unusually long cover note because it is beneath his dignity to reply here on the talk page. But not long enough to actually deal clearly with the problem. And as for context in K & K, Waleswatcher omits their "contact with a reservoir", which for them has a temperature. Thus Waleswatcher continues to omit the important contexts indicated by K & K and by Reif. He also avoids mention of the important absence of convection from either K & K or Reif. He is a master of spin, but not of physics.Chjoaygame (talk) 16:35, 26 November 2012 (UTC)Chjoaygame (talk) 16:46, 26 November 2012 (UTC)

Your problem, Chjoaygame, is that you are an atrocious writer. You are incapable of writing coherently even here on talk pages, let alone in articles. You persist in embellishing, qualifying, decorating, and otherwise festooning your prose with so many unnecessary and overly elaborate semantic details that even an expert in the topic can barely follow them, let alone some innocent layperson that simply wants to know what "heat" is. When I read articles you've edited, I can see right away what part you wrote and what anyone else wrote. If you get nothing else from this discussion, at least understand that you need to learn how to write. Learning how not to insult and antagonize anyone that disagrees with you or prunes your bloviations would help, too.

The first sentence of the lead of a wiki article is supposed to succinctly introduce the subject. It should have the title of the article in bold, preferably as the first word or phrase of the sentence. It is not the place to insert caveats, details, or if at all possible terms with a meaning that won't be clear to the average reader. That's what the rest of the article is for, to explain the details.

As for your patently absurd assertion that the first line is "original research", there's no point in even commenting on it further. From this point on, I will no longer respond to you on the talk page, as it is a clear waste of my time. The only exception will be if you have a specific objection or suggestion to a specific passage in the article. If you think "purely" is important, why haven't you edited it in rather than wasting everyone's time? Waleswatcher (talk) 21:10, 26 November 2012 (UTC)

Comment by Count Iblis

Thermodynamics is part of physics, and in physics we tend to put things in a broader context. Physics is, after all, about describing Nature and there are no imaginary boundaries between subjects such as electromagnetism, relativity, thermodynamics etc. etc. in Nature. When you do an experiment, you are dealing with all of Nature, not some aspect of it that only exists in some limit. This is why I support he way Reif treats this subjects. He approaches the topic from the point of view of physics, he motivates what he is doing, justifies approximations etc. etc. Count Iblis (talk) 23:30, 25 November 2012 (UTC)

The reason that I said there is a departure from sources, that warrants the technical term own research, is that the definition in the article departs from that of Reif, its closest source, by omitting the careful setting of context that Reif offers, and by omitting the word "purely" that he puts in front of "thermal". I further pointed out that Reif's book does not have the word convection in its index; I may now add that a computer search through Amazon reveals just one use of the word in its text, as follows. On page 492, in problem 12.15, Reif considers an experiment. He writes: "In the absence of any convection in the gas, make a rough estimate ..." I also pointed out that Kittel & Kroemer do not write the exact word 'convection' at all; they pose one problem in which they write of "convective isentropic equilibrium of the atmosphere".Chjoaygame (talk) 02:28, 26 November 2012 (UTC)

Reif does consider some specific examples, but the main definition is based on the definition of macroscopic work. The First Law is then taken to be the definition of heat, I think Reif makes that very clear. So, the question is then how Reif defines macroscopic work. This is done in terms of external parameters which define some macroscopic properties (constraints) of a system, such as the volume. A change in these external parameters will lead to a change in the internal energy. The work done by a system is the decrease in the internal energy due to the change in the external parameters. And here you always have to consider an ensemble of systems and take mean values to make this well defined. Count Iblis (talk) 03:42, 26 November 2012 (UTC)

It seems you and I agree here, in the major point that Reif states his definition carefully, referring explicitly to a context of closed systems, allowed only to exchange heat, through a diathermic partition, when the adiabatic partition is removed. Reif also follows the Bryan-Carathéodory-Born tradition of considering heat as strictly defined as a residual from work transfer, with respect to a strict requirement for conservation of energy and a well-defined internal energy, work being defined, as you note, by changes in external parameters under an adiabatic constraint.

Reif does indeed consider an ensemble of systems, because his context is that of quantum statistical mechanics. The present article takes instead the point of view of thermodynamics in its plain sense. I think you would like the article to change its point of view to that of quantum statistical mechanics.Chjoaygame (talk) 05:22, 26 November 2012 (UTC)

Thermodynamic and mechanistic explanations

Statements above like: " A proper explanation of heat has to be based on the energy contained in the motion of particles, not on the transfer of that energy between particles" by Damorbel ilustrate the problem with some of these approaches. Even though the laws of thermodynamics predate statistical mechanics and do not require it in order to be formulated (but are explained, in some cases, by it) when texts rely on statistical mechanics in order to explain thermodynamics they create confussion. The basic laws and concepts of thermodynamics were well under way before being "explained" by statistical mechanics and are compatible also with, i.e., Von Neuman entropy, Shannon entropy, Balck hole entropy, the entropy of gravitational fields, etc. That the mechanistic approach of statistical mechanics is compatible with classical thermodynamics is true, as are Newton's laws of motion, regarding work, in a non relativistic framework. But classical thermodynamics does not "need" statistical mechanics to be formulated, anymore that it need's Fourier's law of conduction, or Newton's laws of motion, or general relatitivy, or information physics theory. --Crio (talk) 01:18, 25 November 2012 (UTC)

Response by Damorbel

Crio I have previously explained to Chjoaygame what I am arguing as the nature of heat:

From what you write above (...your idea that heat is the energy of vibrating particles...) I understand your argument to be that heat is not the energy of vibrating particles, OK?

In that case would you care to explain what you accept as the proper name for the kinetic energy in vibrating or colliding particles?

This is not a trivial question because it is some of this kinetic energy that is transferred between material at different temperatures. It is entirely necessary that this energy is preserved, in one form or another, during and after the transfer; were this not so the 1st law of thermodynamics would not be valid ( 28 September 2012 (UTC))

I am arguing that Kinetic theory, as extended to solids by phonons, is the only sucessful theory at the base of thermodynamics and statistical mechanics. Am I wrong? If you think I'm wrong, would you care to say where? --Damorbel (talk) 07:45, 25 November 2012 (UTC)

Comment by Crio

'Heat', in a classical thermodynamic explanation of it, does not require a mechanistic explanation of either the system nor 'heat transfer'. Classical thermodynamics do not require, in principle, mechanistic explanations for it's formulation. Statistical mechanics provide _a_ framework that_explains_ (mechanistically) what does happen with _some_ of the internal energy of a 'body' and what does happen where conduction occurs. Radiation is exlained (mechanistically) in the terms of electromagnetic radiation. These two are forms of 'heat transfer', one explained by 'statistical mechanics' (conduction) the other by electromagnetic radiation (radiation). When one deals with turbulence in a fluid there are other complications: gases _do_ have a conductive heat transfer coefficient and, for specific transfer phenomena, different convective heat transfer coefficients, which are related through Nusselt's number. Nusselt's number is a function of Reynolds number and Prandtl number. The main problem of turbulent flow, specially in compressible fluids, is the lack of a proper mathematical framework that is _usable_ (since the existence and smoothness of Navier Stokes has not even been proven). There are other issues that arise with the modelling of 'heat' and 'internal energy' of systems when gravitational phenomena and 'gravitational waves' are taken into account, when dealing with 'informational physics' 'black holes' 'quantum theory' other mechanistic relations regarding thermodynamics arise. One interesting thing is that (from what I understand) some of these mechanistical interpretations of entropy and other quantities are compatible (entropy in statistical mechanics, Von Neumann's entropy, Shannon's entropy). Other's might not be compatible as the general theory of relativity has not been 'unified' with quantum mechanics. Thus entropy in regard to gravitational waves or black holes might not be (as of yet) related to entropy ina quantum mechanics.

Still, one can see that the laws of thermodynamics are used without regard of the internal mechanics of the system, the mechanism of heat transfer or the mechanism for doing work. The concepual framework of thermodynamics is more abstract than that. --Crio de la Paz (talk) 15:19, 25 November 2012 (UTC)

But, I _do_ agree that, as far as mechanisms to explain classical thermodynamics go, for a mayority of cases (cases that do not deal with gravitational waves or black holes and those kind of things), statistical mechanics is fundamental and of great importance, since it derives macro thermodynamic formulations from the atomic structure of matter. This is _remarkable_. But there is also the concept of entropy in information theory and in informational physics which might be another example of a physical theory that is compatible with classical thermodynamics. Classsical thermodynamics theory seems to hold in regard to the atomic structure of matter (statistical mechanics), quantum theory (Von Neumann's entropy), information theory (Shannon's entropy), and, as far as I understand, the general theory of relativity (gravitational waves and the entropy of gravitational fields).

I agree with Darmobel in that the kinetic theory of gases, solids and liquids (including phonons)is a fundamental development that explains a lot of the phenomena studied in classical thermodynamics and heat transfer. But I do think he is wrong stating it is "the only theory" since, i.e. Shanon's model of informational entropy is compatible with thermodynamics too (and with statistical mechanics, in as much as I know). There are also theories of entropy related to the gravitational field (where this is the predominant form) and gravitational waves, as far as I know.

Now as per the question of what is the kinetic energy of the particles that constitute a system: it is 'thermal energy' or (part of) the 'internal energy' of the 'system' (not 'heat'). The internal energy of the system includes all forms of energy of the system that do not include energy related to moving the system as a whole (kinetic energy of the whole system) nor the potential energy of the system implied in it's position in a force field.

Darmobel seems to state that in a physical process, what is dubbed above, by me, as 'thermal energy' _has_ to be conserved. This is wrong: it is not an specific "form" of energy that is conserved, is energy as a whole. If there is a chemical reaction within the system that releases heat and rises the temperature of the system, thermal energy`is "created". So 'thermal energy' is not conserved: total energy for an isolated system is conserved.

To clearify: Darmobel states above: "

From what you write above (...your idea that heat is the energy of vibrating particles...) I understand your argument to be that heat is not the energy of vibrating particles, OK?

In that case would you care to explain what you accept as the proper name for the kinetic energy in vibrating or colliding particles? This is not a trivial question because it is some of this kinetic energy that is transferred between material at different temperatures. It is entirely necessary that this energy is preserved, in one form or another, during and after the transfer; were this not so the 1st law of thermodynamics would not be valid "

Heat is _not_ the energy of vibrating particles. The energy of the vibrating particles of the system is 'thermal energy'. 'Thermal energy' is part of the 'internal energy' of a system. Total energy is conserved, not 'thermal energy'. 'Internal energy' includes all forms of energy contained in a system, but it does not contain the kinetic energy of the system as a whole nor it's potential energy as a whole system in the presence of a force field. It does contain 'thermal energy', but also 'chemical energy', 'nuclear energy', energy related to the formation of Van der Waals interactions, hydrogen bonds, etc. Even when the system is considered to expand one must make room for the pressure related work to make room for the substance and enthalpy comes into play. When (some) of the energy of a system is dispersed as heat and only heat it is true that energy is conserved and, thus, all energy exchanged is used as 'heat' and there is no work production. But when a system does _work_ there is always _some_ energy that is dispersed as heat, no matter if the energy is 'thermal energy' or 'electrical energy' or 'chemical energy'. The concepts of 'heat' and 'work' and the first and second laws of thermodynamics deal mostly to the ammount of energy that _must_ be rejected as heat in order to change a system from one state to the other.

ΔETOT=0 for an isolated system.

dE=δQ+δW. dS>=δQrev/T For a reversible (ideal) process dE=TdS+δW δW=dE-TdS So the ammount of work avaiable for an ideal process of maximum efficiency is dE-TdS because there is a minimal ammount of energy that _must_be dispersed as heat. Of course a molecular explanation of conductive heat transfer involves kinetic energy of the particles involved. In the case of radiation it is electromagnetic waves and photon exchange which explains how heat is tranfered (so, in this case, 'heat' is _not_ the kinetic energy of the particles involved at all...) The case for convection is more complex and solutions for problems are expresed via dimensional annalysis since modelling turbulent flow, specially for compressible fluids, is not something easily done (Navier Stokes smoothness and continuity have not even been proved yet, and they are not solvable in a lot of cases, with any practicallity). Energy and entropy related to gravitational waves must also be considered. I do believe that explaining conductive heat transfer with the kinetic theory is similar to explaining electrical work via the electrical field. It explains an specific form of 'heat transfer' but not all of them. And in a similar fashion the general theory of relativity is not compatible with non gravitational forces of nature in it's formulations, in as much as I undertand ,since no grand unified theory is amongst us. --Crio de la Paz (talk) 05:25, 26 November 2012 (UTC)

Crio you write above:-

Heat is _not_ the energy of vibrating particles. The energy of the vibrating particles of the system is 'thermal energy'.

This is not correct. Heat is energy with a temperature - the basis of the 2 law of thermodynamics. Thermal energy is all kinetic energy above zero K; the distinction is subtle but, because of the 2 law requirement, scientifically and practically very important indeed. --Damorbel (talk) 06:32, 26 November 2012 (UTC)

No: Darmobel is _completely_ wrong in this last statement. heat _is_not_ 'energy with temperature'. The second law of thermodynamics does not state this. The second law of thermodynamics states that, when using energy to do work, some energy is always transfered that does not do work. This ammount of energy transfered that does not do work is what is called 'heat'.

Alternatively a quantity called 'entropy' is introduced as a function of state such as dS=δQrev/T. For an isolated system ΔS>=0 for any given process. Alternatively permetual motion machines of the second kind: that is there is _not_ a machine _in_the_unvierse_ that transforms energy into work without releasing 'heat'. Nowhere in the source provided by Darmobel does it say this afirmation of his that 'heat is energy with temperature'. Darmobel insist in confussing thermal energy with heat.

He should take a basic course in thermodynamics.

--Crio de la Paz (talk) 23:21, 26 November 2012 (UTC)

first paragraph of the lead

See my edit comments. In addition to what I wrote there, heat transfer by radiation, conduction, and convection all involve mass transfer in the literal sense that the object being heated will end up being slightly more massive than it was. So "closed system" is misleading both to lay readers and as a matter of fact (not to mention that it does not appear in the definition of heat given in Reif, the source for that sentence). As for "purely", if we include that term we need to explain what is meant by it - namely, that heat is not work. Otherwise, it clashes with the next sentence. Waleswatcher (talk) 01:51, 27 November 2012 (UTC)

closed systems

Indeed the word 'closed' does not appear in the particular sentence of Reif to which you refer, nor indeed in the relevant section. But the context and full meaning of the sentence to which you refer are for closed systems. Reif writes: "Let us now consider two macroscopic systems A and A′ which can interact with each other so that they can exchange energy. ... The first kind of interaction is that where the external parameters of the system remain unchanged. This represents the case of purely ″thermal interaction″." Reif is talking about closed systems. Misplaced Pages entry that cites him should reflect this because it is important here. You are right to use the term 'body' here, I think.Chjoaygame (talk) 02:16, 27 November 2012 (UTC)

Closed is correct, anyway. "Closed" means no matter transfer, not no mass-energy transfer. The last (no kind of transfer) is called an "isolated system." Closed systems go up (or down) in mass as they go up or down in energy (since mass is energy), but neither of these things happens as a result of a gain or loss in matter. Matter and mass are not the same thing, and this causes great confusion in relativity theory teaching. Matter (a poorly defined word, but usually means particles with rest mass) is not conserved. But mass is conserved. Mass and matter are equivalent to energy, but while all energy is mass (and has mass), not all energy is matter. Energy transmitted by heat is a good example-- mass goes with it, but matter does not. SBHarris 02:22, 27 November 2012 (UTC)

          conduction of heat in metals

Conduction of heat in metals can occur through electrons, which are matter by any definition. In any case, such distinctions are far too subtle for the first sentence of a wiki article. "Exchange of energy between closed system" is a very confusing phrase, and gains nothing in terms of accuracy. Waleswatcher (talk) 02:30, 27 November 2012 (UTC)

Yes, but the total number of electrons in the metal that is your "system" stays the same, even if some go in and others go out. So nobody cares, as one electron is pretty much like another. The point is not so much that matter is allowed in or out, but whether NET matter is allowed in or out (number of each kind of atom or particles changes). The reason we specify a closed system is the first law of thermodynamics demands it if you state that law in terms of only two RHS terms (work and heat). If you use the first law form that says dU = dq + dw (pretend I put in the deltas) and if you allow net atoms or electrons in or out of your system that has an internal energy U, that changes dU without being either dq or dw, so this equation is wrong. So if you're going to use that equation to define heat, you have to specify "closed". Adding the terms for mass in or out gives you another set of terms, a different equation, and now you have the first law of thermo for open systems, which you've seen with the sigma and the particle numbers and chem potentials, etc. If you want to know how an electric current into and out of your system counts, most texts define this as a sort of "work" (it's potential*dC) where C is the charge that goes in and comes out with DC, or the charge that wiggles back and forth in AC.

By the way, "convection" doesn't necessessarily require an open system, since heat may be transfered into and out of your system to the surroundings by diffusion, even in convection. Mass moves (is advected) in the surroundings. If you want to analyze energy tranfer within the fluid plume, only then are you looking at an open sytem. As far as the system transfering heat to the fluid, that can remain closed in analysis. SBHarris 03:49, 27 November 2012 (UTC)

It improves communication and saves time to carefully specify the formalism one intends. Electric current carried by electrons can be considered as a whole discrete body macroscopic process, when one may think of it as doing work. Or it can be considered at a phase boundary, or in a continuous medium, or both at once, when it is connected with the Seebeck and Thomson and Peltier effects. Considerations like this apply also to convection.Chjoaygame (talk) 05:31, 27 November 2012 (UTC)

Okay, here's a problem that is fun. We stick one electrode in an object or even a person on an insulated stand, and ground the other. Now we connect them to a potential, letting their own self capacitance allow them to take a one-way current and build up a charge. Open system. How does their 1/2CV^2 energy compare with internal energy change just from gaining net electrons? And to what potential would you need to charge them before the two kinds of net internal E increase are comparable? Hint--it's comparable to e rest energy in eV. A reminder of how important closing the system is. SBHarris 07:14, 27 November 2012 (UTC)

Okay, here's another problem that is fun: guess what I'm thinking?Chjoaygame (talk) 08:39, 27 November 2012 (UTC)

          matter

Just in case, the article on matter on the wiki says " Matter is generally considered to be a substance (often a particle) that has rest mass and (usually) also volume.".

It also states (correctly ) that "Albert Einstein showed that ultimately all matter is capable of being converted to energy, by the formula:

${\displaystyle E=mc^{2}\,\!}$

where E is the energy of a piece of matter of mass m, times c the speed of light squared"

Also "An example is positrons and electrons (matter) which may transform into photons (non-matter). However, although matter may be created or destroyed in such processes, neither the quantity of mass or energy change during the process".

But, also, it says "Scientifically, the term "mass" is well-defined, but the term "matter" is not. For this reason, none of the uses of the word "matter" in this article should be considered definitive.".

And then "Matter therefore is anything that contributes to the energy–momentum of a system, that is, anything that is not purely gravity. This view is commonly held in fields that deal with general relativity such as cosmology".

There is also the concept of "strange matter", "antimatter", "dark matter", and "dark energy", that complicate matters even more.--Crio de la Paz (talk) 16:21, 27 November 2012 (UTC)

Particle physicists tend to define "matter" as the fermions of the standard model, with the possible exception of neutrinos. So that includes electrons, muons, etc. and composites like the proton and neutron, but not for instance the W and Z bosons (even though they're massive) or the photon. Anyway, a system that allows electrons to flow in or out is obviously not "closed" by any sensible definition. If in some specific process the net flow of electrons is close to zero one can ignore the chemical potential terms, but calling such a system "closed" is very confusing, and I think we should avoid using the term in this article. Instead, we can simply explain that energy is conserved, and net matter flowing in or out contributes to the energy balance, which is hence simplest when the net flow is zero. Waleswatcher (talk) 16:52, 27 November 2012 (UTC)

Waleswatcher writes: "Anyway, a system that allows electrons to flow in or out is obviously not ″closed″ by any sensible definition", and "calling such a system ″closed″ is very confusing, and I think we should avoid using the term in this article. Instead, we can simply explain that energy is conserved, and net matter flowing in or out contributes to the energy balance, which is hence simplest when the net flow is zero." Thermodynamicists are not in general particle physicists, and this article is more about thermodynamics than about particle physics. Thermodynamicists may not use a "sensible definition", but for purposes like the present they often regard the flow of electricity as just that, without concern about whether particles carry it, and do not regard it as flow of matter. It it is true that K & K (1969/1980) and Callen (1960/1985) use the term 'closed' when more recent writers, including the Misplaced Pages and Reif, would use the term 'isolated'. It is clear from reading p. 227 that there K & K are referring to what more recent writers call 'closed systems'; they do not need to use the more recent terminology because they do not consider the thermodynamics of what more recent writers would call 'open systems' as distinct from 'closed systems'Chjoaygame (talk) 17:23, 27 November 2012 (UTC)Chjoaygame (talk) 02:27, 28 November 2012 (UTC)

Anyway, I agree with Waleswatcher that the word 'body' is convenient here. It did not strike me that SBHarris disagreed with that usage. I had the impression that he was just confirming that Reif and K & K are talking about closed systems, not that he was trying to insist on those very words 'closed system'?Chjoaygame (talk) 17:51, 27 November 2012 (UTC)

          open systems

Actually for an _open_ system we have a balance of energy of the form:

dEk/dt+dEp/t+dU/dt=SUM(mi(Hi+vi^2/2+gzi))+q+w

Where: dEk/dt is the increase of kinematic energy of the system, Dep/Dt is the increase of the potential energy of the system and dU/dt is the increase of the internal energy of the system through time. This has to be equal to the sumatory of the enthalpies, kinetic energy and potential energy of the flows of matter into and out of the system, plus the net heat flow into the system plus the net work done on the system . mi is flow of matter "i", Hi it's enthalpy by unit of mass, vi it's velocity and zi it's position in a gravitational field (this can be even generalized more if it is allowed for potential energies that are not gravitational: in that case these potential energies must be taken into account). Of course q might be decomposed in different 'heat flows' either involving differents forms of heat transfer or and w in different forms of power done on the system or done by the system.

The important aspect for a conservation law is that the rate at which a given quantity varies for the system is equal to the net flows of the quantity plus net generation of the quantity within the system (this is useful for, i.e., a balance of mass of an specific susbstance in the mist of a chemical reaction.

As some oher users have pointed above entropy is another quantity that, for all processes that are not 'reversible' or 'ideal' actually might be 'generated' as far as I understand.--Crio de la Paz (talk) 22:51, 27 November 2012 (UTC)

For a simple introduction to an entropy balance see: https://ecourses.ou.edu/cgi-bin/ebook.cgi?doc=&topic=th&chap_sec=06.6&page=theory--Crio de la Paz (talk) 22:57, 27 November 2012 (UTC)

purely thermal interaction

Waleswatcher writes: "As for ″purely″, if we include that term we need to explain what is meant by it - namely, that heat is not work. Otherwise, it clashes with the next sentence." Indeed, otherwise, it clashes with the next sentence. "Purely" is repeated by Reif and is important for his presentation. It is also implicit in that of K & K.Chjoaygame (talk) 03:05, 27 November 2012 (UTC).

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 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 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 Misplaced Pages 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 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)

categories

R.C. Tolman (1938, The Principles of Statistical Mechanics, Oxford University Press, Oxford) on page 9 writes: "...we discuss the application of statistical mechanics to the problem of obtaining a mechanical explanation for the phenomena of thermodynamics ... The explanation of the complete science of thermodynamics in terms of the more abstract science of statistical mechanics ... the more fundamental character of statistical mechanical considerations ... the desired mechanical interpretation and explanation of the first and second laws of thermodynamics."

W.T. Grandy, Jr (1987, Foundations of Statistical Mechanics, volume 1, Equilibrium Theory, D. Reidel Publishing Company, Dordrecht, ISBN 90-277-2489-X (v. 1), writes on page1: "Thus, one of the objectives of what Gibbs first called statistical mechanics is to provide an acceptable and fundamental explanation of phenomenological thermodynamics."

I am here on about a trivial point. The origin of something is a matter of where or what it came from. The destination of something is about where it will go or what it will become. I feel that the origin and destination of heat is internal energy. "Dust I am, to dust and bending." So it seems to me that thermodynamics already knows the origin of heat, without needing statistical mechanics to say so. But thermodynamics is lacking in explanatory power. That's how I see statistical mechanics coming in. I see a theory as belonging to one category of existence and heat as belonging to another. I see heat as a concept that is part of a theory, and for me that puts the two into distinct categories of existence. I suppose I might say that for me, a thing and its origin are in the same category of existence. So I feel uncomfortable with talk of a theory as the origin of one of its constituents. I would be happier with the wording that the theory provides the basis or ground or context of the constituent. But origin seems more dynamic that ground or basis.

A section heading of the article as it now stands is "Microscopic origin of heat". The heading as it stands, and the first sentence of the section, seem to imply that the origin of heat is in statistical mechanics, and I suppose the wording in the lead could reasonably, though not necessarily, be read that way too. I do not feel comfortable with the idea of a microscopic notion being an origin of a macroscopic notion.

For me, thermodynamics and statistical mechanics, in some fair sense, belong to the same category of existence: they are both theories. For example, Prigogine & Defay (1954) write on page xix: "Thus, phenomenological thermodynamics and statistical mechanics are complementary to one another." Callen (1960/1985) writes on page viii: "... statistical mechanics and thermodynamics ... I have attempted neither to separate them completely not to meld them into the undifferentiated form now popular under the rubric of "thermal physics". But heat belongs to the category of physical quantities, not to that of theories. I would find it odd to read, for example, that 'heat and statistical mechanics are complementary', because I feel heat to exist in a category distinct from that of statistical mechanics, in the same way that I feel the part to differ from the whole, or the trees from the forest.

I am uncomfortable with the wording that heat has properties. Most of us here, I think, agree that the notion 'transfer of energy as heat' refers to a kind of process. One can say that processes have properties I suppose, but more often a property seems to belong to a more static kind of substantive, I feel; one very often says that water has properties, but not usually that heating has properties. One is more inclined to say that heating has mechanisms and characteristics. To say that 'heat has properties' seems to me to lead, admittedly unconsciously, but still too easily for a general reader, to thoughts such as that 'heat is a substance'; I accept that this is a trivial point. But since we are here partly on about rhetoric, presentation, and consideration of a non-specialist readership, trivial doesn't mean nugatory.

In short, I prefer the Tolman wording, that statistical mechanics interprets and explains the laws of thermodynamics. In the same way, I prefer to say that statistical mechanics explains the nature of heat rather than to say it is gives an understanding of the origin and properties of heat. The word 'nature' can also be elided by simply saying that statistical mechanics explains the processes.Chjoaygame (talk) 02:06, 22 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 Misplaced Pages, which I accept is not a reliable source, "PM 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. The Modern Library placed it 23rd in a list of the top 100 English-language nonfiction books of the twentieth century." 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 Misplaced Pages 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. 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 Misplaced Pages 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)

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. SBHarris 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 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. SBHarris 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? SBHarris 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. SBHarris 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)

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 and He at the same temp and pressure (low enough for ideal behavior). Lets 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, even though the 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 do far as temp goes. It might as well be potential for all it shows as temp. It's only seen as heat capacity and that's it. This is typical of non translational motions. SBHarris 06:38, 26 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)

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 Misplaced Pages 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 Misplaced Pages definitions.

Um, "Misplaced Pages definitions"? Are you suggesting here that, for you, Misplaced Pages 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 Misplaced Pages, 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 Misplaced Pages do not always properly understand the authors they are citing. --Damorbel (talk) 18:17, 26 December 2012 (UTC)

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