User talk:Chjoaygame

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Hello, Chjoaygame, and welcome to Wikipedia! Thank you for your contributions. I hope you like the place and decide to stay. Here are some pages that you might find helpful:

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thanks, Ancheta Wis

@Ancheta Wis. Thank you. Yes, that's what I intended. Somehow I messed it up!Chjoaygame (talk) 13:00, 28 February 2023 (UTC)

the editor of superior knowledge

@Dirac66:. As you may have noticed, the editor of superior knowledge has endorsed the definition of heat as energy transferred because of temperature difference. That may be good enough for the Encyclopaedia Britannica, but surely Wikipedia should do better. Today the editor of superior knowledge demonstrated his superior knowledge by correcting "Another kind of heat transfer is by radiation" into "Another kind of energy transfer is by radiation, performing work on the system." I am inclined to guess that laser light could be made to perform work directly in transfer, but not ordinary light from thermal sources; I am not sure about this. I think that Planck would say that the temperature of laser light is higher than the thermal temperature of the body that emits it. I do not try to do anything in response to the works of the editor of superior knowledge, because I am inclined to see him as likely to respond further.Chjoaygame (talk) 22:27, 2 June 2023 (UTC)

I presume that you are referring to the editor who made 3 edits yesterday on the Heat article? I believe that the definition as energy transferred due to T difference is the usual introductory definition in textbooks. If you want to go further, then you will need references to support any more advanced definiton. Dirac66 (talk) 00:42, 3 June 2023 (UTC)

Thank you for that clarification.

I am coming from a long-standing Wikipedia tradition of definition of heat. That definition was established by a lot of work by many editors on the article on heat and on its talk page. Nearly all of the Wikipedia editors who worked on it now seem to have retired or moved to other parts of Wikipedia. The work on it was based on careful selection of the best reliable sources. It was loosely agreed that perhaps the most standard source was F. Reif (Fundamentals of statistical and thermal physics, 1965, McGraw-Hill). Since you don't recognize that, I can see that, at least for the present, that tradition is abandoned. I don't have the strength of motivation to try to resurrect it all on my own. I will just observe that one of the new edits we are talking about, in the article on Work (thermodynamics) ("Another kind of energy transfer is by radiation, performing work on the system."), as I read it, seems to express the idea that radiative transfer is work, not heat. Do you read it that way too?

A primary motive of the Wikipedia traditional definition was to have a rigorously logical development of thermodynamics. That meant defining heat purely through the first law before stating the thermodynamic definition of temperature in the context of the second law, basing the definition on a relationship of heat and thermodynamic work. The present Wikipedia definition of heat defies that. Thermodynamics regards the current SI definition of temperature as a theory-based definition of an empirical temperature, not as a definition of thermodynamic absolute temperature as per Kelvin.Chjoaygame (talk) 09:39, 3 June 2023 (UTC)

I thought I would try to consider your above remark "I believe that the definition as energy transferred due to T difference is the usual introductory definition in textbooks." So I have started to look alphabetically at my textbooks. I am not clear about the difference between an "introductory definition" and a definition proper. Howsoever, in looking through my alphabetically first textbook (Adkins, C.J., 1983, Equilibrium Thermodynamics, 3rd edition, Cambridge University Press), I came across the following. I thought that it might be useful to quote it here. There are various approaches to thermodynamics, and I know that some Wikipedia editors and other physicists disagree with Adkins.

It is perhaps because thermodynamics is not concerned with fundamentals in the microscopic sense that it sometimes does not appeal readily to the physicist; but he will disregard it at his peril. It is precisely because it avoids microscopic theories that it is so valuable. It often yields answers to problems where an understanding of the fundamental processes involved might be difficult or impossible. It also helps to prevent mistakes; for any result which does not satisfy the requirements of thermodynamics must be wrong. But, perhaps more important, a physicist's training is not only concerned with learning fundamental theories but also with developing a sensibility to the way in which physical systems behave, and here thermodynamics has a peculiar contribution to make by providing a very general framework of ideas from which the understanding of particular systems may more readily be achieved.

end of part comment.Chjoaygame (talk) 01:10, 4 June 2023 (UTC)

I should clarify one of my above remarks as follows. I wrote

Today the editor of superior knowledge demonstrated his superior knowledge by correcting "Another kind of heat transfer is by radiation" into "Another kind of energy transfer is by radiation, performing work on the system."

This was done in the article Work (thermodynamics), not the article Heat. The edit was here https://en.wikipedia.org/enwiki/w/index.php?title=Work_%28thermodynamics%29&diff=1158226314&oldid=1158070006

There are two problems with this edit, one of them characteristic of the editor of superior knowledge. First, so far as I know, all reliable sources consider radiation to be a form of heat transfer, not of work. I find the edit to verge on the preposterous, but I didn't try to correct it because I have found it dangerous to try to correct the editor of superior knowledge. Second, the edit left intact the source of the previous statement, Prevost, who thought in terms of radiation as heat transfer; this is characteristic of the editor of superior knowledge, not to bother to check references, but just to copy them, apparently unread. Yet the editor of superior knowledge seems generally accepted as authoritative in these pages. Challenging him is often met savagely.Chjoaygame (talk) 12:17, 30 June 2023 (UTC)

Simply irreversible heat production

Friction, in rubbing, in viscosity, in electrical conduction, and in hammering, is simply irreversible; one cannot undo friction. It was the turning point in physicists' escape from the caloric theory.

In friction, there is conversion of work into heat. The process is a transformation of energy as well as a transfer of energy. The arriving form of energy, in the body or thermodynamic system, is different from the departing form of energy, in the surroundings.

Some of the heat generated by friction can be recovered as work, but not by simple reversal of friction.

Adkins

Adkins starts with a definition of temperature, partly based on the zeroth law. He uses the ideal gas scale, calling it 'thermodynamic temperature'. I wonder how Kelvin would feel about that? Buchdahl would call it an 'empirical temperature'.

Now, as to heat in Adkins, I didn't find what I could recognize as an explicitly 'introductory' definition. I found a general exposition of the move from the Laplace–Lavoisier doctrine of caloric to the current thermodynamical theory of heat.

One of the factors in the move was the cannon boring experiment of https://en.wikipedia.org/wiki/Benjamin_Thompson, in his article https://en.wikipedia.org/wiki/An_Experimental_Enquiry_Concerning_the_Source_of_the_Heat_which_is_Excited_by_Friction.

Thompson's idea was accepted by https://en.wikipedia.org/wiki/Julius_von_Mayer in 1842, as follows:

Without recognizing the causal connection between motion and heat, it is just as difficult to explain the production of heat by friction as it is to give any account of the motion that disappears.

Mayer gave a calculation of the mechanical equivalent of heat, relying on frictional generation of heat in paper pulp, and on calorimetry.

A further factor in the move to the current theory was the water paddle experiment of https://en.wikipedia.org/wiki/James_Prescott_Joule, another version of heat generation by friction. Another form of heat generation was examined by Joule, and described in his 'first law', https://en.wikipedia.org/wiki/Joule_heating.

Explicitly defining heat, Adkins writes on page 32:

... We call it the internal energy, $U.$ Thus, when a change of state is brought about by the performance of work alone, the work done on the system is simply the change in the internal energy in going from the initial to the final state:

$\Delta U=W.$           (3.1)

U is a function of state because W is independent of path.

3.4.    Heat

          Equation (3.1) applies to a thermally isolated system. However, we know that it is also possible to change the state of a system without doing work on it. We may use heat alone, or any combination of heat and work. Thus, when a system is not thermally isolated equation (3.1) is no longer valid. It must now be modified to

$\Delta U=Q+W$           (3.2)

We have thus defined heat as a form of energy entirely equivalent in its effect on the total energy of a system to energy communicated by the performance of some kind of work.

No mention of temperature here.

Eventually, Adkins is not quite clear about the definition of heat. He writes:

We have thus defined heat as a form of energy entirely equivalent in its effect on the total energy of a system to energy communicated by the performance of some kind of work. The distinction between heat and work is not always clear-cut in the sense that it is not always easy to decide whether a particular energy contribution should be classed as heat or work.

I think his unease in decision is due to his apparent failure to be clear, for a closed system, about the difference between work defined solely in the surroundings, and thermodynamic work defined by changes in the thermodynamic system's state variables other than temperature or entropy. An energy transfer as thermodynamic work done by the system on its surroundings is defined by both the changes in its state variables other than temperature and entropy, and the ordinary physically defined force × distance work. Apart from the idealization of an infinitely slow process, an energy transfer as work done by the surroundings on the system, defined through ordinary physical work in the surroundings, involves friction in the system, and is not identical with the associated thermodynamic work.

At this stage, Adkins is not considering transfer of matter.

Enough on Adkins for the moment.Chjoaygame (talk) 01:10, 4 June 2023 (UTC)

Anderson

Anderson, G., 2005, Thermodynamics of Natural Systems, Cambridge University Press, is rather chatty in his introductory chapters. He writes:

A chemical reaction involves the rearrangement of atoms from one structure or configuration to another, normally accompanied by an energy change.

....

It was discovered quite early that most chemical reactions are accompanied by an energy transfer either to or from the reacting substances. In other words, chemical reactions usually either liberate heat or absorb heat.

....

To change the temperature of the crystal, heat must be applied to it. This sets up a temperature gradient between the inside and the outside of the crystal, and heat travels into the crystal, raising its temperature.

....

In everyday conversation we use words like heat, work, and energy quite frequently, and everyone has a sufficiently good idea of their meaning for our ideas to be communicated. Unfortunately, this type of understanding is not sufficient for the construction of a quantitative model of energy relationships like thermodynamics. To get quantitative about anything, or, in other words, to devise equations relating measurements of real quantities, you must first be quite sure what it is you are measuring. This is not too difficult if you are measuring the weight of potatoes and carrots; it is a more subtle problem when you are measuring heat, work, and energy. Historically, it took several decades of effort by many investigators in the nineteenth century to sort out the difficulties that you are expected to understand by reading this chapter!

....

• Heat (q) is the energy that flows across a system boundary in response to a temperature gradient.

• Work (w) is the energy that flows across a system boundary in response to a force moving through a distance (such as happens when a system changes volume).

Apparently, Anderson, despite all his care, has forgotten about friction as a source of heat. Also, he is rather vague about what he means by "in response to a force moving through a distance." What is the cause of the force? It makes a difference whether the force is generated by the system in a process of spontaneous expansion, or by some factor in the surroundings. The force itself passes the work energy, which is therefore not a response to the force but is an aspect of the force itself.

In his next chapter, about the first law of thermodynamics, Anderson goes on to talk about water entering and leaving a pond, in an analogy that is almost shamelessly chatty, and lacking in thermodynamic insight. He goes on to say:

For “real” work processes, the work done is invariably less than the reversible work (Equation 3.7), usually much less, and usually of more interest to engineers than to geochemists.

Planck divided processes into natural, ideal, and unnatural: For him, natural processes can actually occur, and I guess correspond with Anderson's “real” work processes. Ideal processes occur in the notebooks of physicists. Unnatural processes violate the second law and do not occur.

... such as work done by frictional forces, that you can review in a physics text.

Anderson goes on to talk about temperature without having given a thermodynamic definition of it. What he says is pretty much covered by what Buchdahl calls 'empirical temperature', and makes sense in that light. Anderson is largely concerned with chemical reactions and enthalpy. He is aiming to define "chemical energy". His actual words are in the first paragraph of his chapter on the first law:

3.1.1 Temperature

One of the early triumphs of the study of thermodynamics was the demonstration that there is an absolute zero of temperature. However, there are several different temperature scales, for historical reasons. All you need to know about this is that the kelvin scale (named after William Thompson, Lord Kelvin) has an absolute zero of 0 K and a temperature of 273.16 K at the triple point where water, ice, and water vapor are at equilibrium together. The melting point of ice at one atmosphere pressure is 0.01 degrees less than this, at 273.15 K (Figure 3.1).

That is perhaps all that Anderson thinks the student needs to know about thermodynamic temperature at that point. Anderson goes on to postulate a state variable called 'entropy'. He says of it:

The central fact about entropy as used in science is that it involves the distribution of energy in a system. Energy tends to become “spread out,” or delocalized, if not prevented from doing so.

Soon, Anderson says:

... in fact the heat engine approach is very useful in the derivation of Equation (4.3), and also the kelvin temperature scale.

But he doesn't pursue this, saying that it is scarcely necessary for the purpose of his book.

Later, Anderson remarks:

Heat flows can be measured in various ways. One way is to observe some process in which heat is liberated under controlled conditions, resulting in a rise in temperature, and then duplicate that temperature rise using an electrical heater. The energy used by the heater can be measured exactly, and will equal the energy released by the process considered.

Evidently, an electrical heater can be used to generate heat, as noted by Joule.Chjoaygame (talk) 09:15, 4 June 2023 (UTC)

Ansermet & Brechet

Now to look at Principles of Thermodynamics by J.-P. Ansermet and S.D. Brechet, 2019, Cambridge University Press. They start with a picture of Joule, with a caption that says "In 1840, he stated the law that bears his name on power dissipated by a current passing through a resistance." Their actual text begins with 1839 work by Marc Séguin on the heat engine. They go on to mention that in 1842 Julius Robert von Mayer, in a treatise, asked "what is the change in temperature of a stone when it hits the ground after falling from a given height?" They remark that Joule actually measured that in 1845. I would say that the rise in temperature was due to friction of impact within the stone.

On the first law of thermodynamics, they say

• P_Q represents the thermal power associated with heat exchange with the environment through conduction.

• P_C represents the chemical power associated with matter exchange with the environment through convection.

Any physical process performing work is called a mechanical action. Any physical process in which heat is exchanged is called a heat transfer. A physical process in which matter is exchanged is called a matter transfer or mass transfer. When a heat transfer takes place through a matter transfer, it is called a heat transfer by convection. When a heat transfer occurs without matter transfer, it is called a heat transfer by conduction. In general, a matter transfer leads simultaneously to a mechanical action and to a heat transfer.

Perhaps following Prigogine and Defay, they are happy to talk of rates of energy flow, which does not respect the rule of classical thermodynamics, which refers situations of changes of state from one thermodynamic equilibrium to another. I do not like the confusion that is introduced by talking of heat transfer as well as of heat "exchange". I think that talk of heat "exchange" is slippery. Max Born is careful to say that the energy transfer that accompanies matter transfer in itself cannot be resolved into heat transfer and work. The two latter forms of transfer, if simultaneous with matter transfer, to be identified, must occur by pathways separate from matter transfer. For example, radiative transfer of heat can be distinguished from energy transfer accompanying matter transfer. Maxwell said that matter transfer by convection was not a form of heat transfer. There is no mention of radiative transfer nor of friction here.

Ansermet & Brechet go on to remark that

The chemical work could also be called convective chemical heat.

Soon they remark that

We consider two colliding object that remain attached after impact. It can be shown that this type of collision has the maximum kinetic energy change.

In such a collision, the colliding bodies exhibit conversion of the kinetic energy of their relative motion into internal energy. Since there is a temperature increase in the bodies, one might be tempted to say that this occurred due to the internal friction in the collision. One might even consider talking of generation of heat. But Ansermet & Brechet talk only of kinetic energy and of internal energy, not of friction, nor of heat in this process. To say that the product is internal energy is to avoid saying whether it is transferred as heat or as work; that is equivocation like that of Adkins.

Ansermet & Brechet consider a fan in a room. They consider a viscous frictional torque associated with the motion of the fan, and calculate it by considering entropy production, but do not mention heat in this scenario. Again, to say that the product is entropy is to avoid saying whether the energy transfer is as heat or as work; that is equivocation like that of Adkins.

They consider a damped harmonic oscillator, and ask the student to calculate the power P(t) due to the friction force, but they do not use the word 'heat' in this scenario.

In a section on heat in their chapter on the second law, they write:

Let us begin with our experience of everyday life to illustrates [sic] various forms of heat transfers. When a stone warms up because it is exposed to the sun, it receives ‘heat’ by a thermal process that occurs in the absence of any macroscopic external force. It is due to heat transfer by radiation. When two objects at different temperatures are connected to each other, heat transfer takes place by conduction until both objects reach the same temperature. A third type of heat transfer takes place through convection. It is due to matter transfer from one region of space to another, which is at a different temperature. It is clearly distinct from heat transfer by radiation or conduction, since in both of these no matter transfer occurs.

Maxwell and Born would have qualms about that. Benjamin Thompson and Planck would be unhappy that it does not mention friction or rubbing.

Ansermet & Brechet deal with what Benjamin Thompson and Planck would call generation of heat sometimes by talking of entropy production, other times of heat production. They write:

        Simple experiments points [sic] to the existence of entropy production, no matter in which way the process is carried out. For instance, entropy is produced in a fire or by rubbing hands together. It is also produced by an electric current flowing through a resistance. Many historical experiments, such as that of Earl Rumford (hollowing out of canons) or that of Humphry Davy (two ice blocks rubbed against each other), led to the conclusion that there are processes which cause an entropy production.

        In an isolated system, entropy can increase, but it cannot decrease. All experiments lead to this conclusion. For instance, a drill produces heat while it is drilling.

Enough about Ansermet & Brechet for the moment.Chjoaygame (talk) 10:56, 4 June 2023 (UTC)

Atkins

Now to look at Atkins, P., de Paula, J., Keeler, J., 2018, Physical Chemistry, eleventh edition, Oxford University Press.

Their first sentence, for closed systems, that could be considered as a start to defining heat reads:

Experiments have shown that the energy of a system may be changed by means other than work itself.

This expresses the admirable ideas of Bryan (1907) and of Carathéodory (1909) that are prime ingredients of rigorous modern thermodynamics.

In my opinion, Atkins et al. then go overboard by writing:

The distinction between work and heat is made in the surroundings. The fact that a falling weight may stimulate thermal motion in the system is irrelevant to the distinction between heat and work: work is identified as energy transfer making use of the organized motion of atoms in the surroundings, and heat is identified as energy transfer making use of thermal motion in the surroundings.

I agree that thermodynamic quantities are always measureable through the surroundings. But that includes the internal state variables of the system. Atkins et al. demand that all features of a process of transfer of energy are defined by considerations that exclude the externally measured internal state variables of the system. They dismiss friction and rubbing, which Planck considered important; sad to say, it isn't easy to find English translations of Planck saying so. Atkins et al. use the notion of 'organized motion of atoms in the surroundings'. That is a notion foreign to thermodynamics proper, and hard to define in simple terms. Pressure in the surroundings is easily thought of as a manifestation of disorganized motion of atoms or molecules, but is able to do work as defined in the surroundings. In a real process, however, it will cause friction within the system, so that not all that work as defined in the surroundings will reach the system as thermodynamic work, which, for its definition, requires consideration of the externally measured internal state variables of the system. This is an example of what Adkins means by loss of clarity of thought when he talks about thermodynamics as a strictly macroscopic theory, as in his above quote.

Atkins et al. go on to remark that

... no work is done when a system expands freely. Expansion of this kind occurs when a gas expands into a vacuum.

When a gas expands into a vacuum, there is transfer of matter from the originally enclosed body of gas to the originally empty space. The process is set going by the thermodynamic operation of removal of the partition between the two spaces. In the view of Max Born, such a process does not allow a distinction between heat and work because it includes transfer of matter. This is one reason why the first law is mainly about closed systems. This seems to be forgotten by Atkins et al..

It is becoming evident that I am inclined to prefer the thinking of the best and most reliable sources, as distinct from less reliable sources.Chjoaygame (talk) 02:14, 5 June 2023 (UTC)

Attard

Attard, P., 2002, Thermodynamics and Statistical Mechanics: Equilibrium by Entropy Maximisation, Elsevier, Academic Press.

Because no dissipative mechanisms have been introduced to this stage, the simple harmonic motion of the piston continues forever, and one can only speak of the equilibrium state in a statistical sense as the average position of the piston. In practice energy is lost due to friction and to the internal viscosity of the system. Assuming that the latter dominates, then when the motion of the piston has died out, dK = 0 and dE₁ = — dE₂, so that all of the previous equilibrium analysis holds. Effectively the system has been heated by internal motion even though it is enclosed in adiathermal walls.

Many texts tell this story of friction. There is no mention here of microscopic factors such as unorganised motion of molecules. No mention of temperature here. Chjoaygame (talk) 19:09, 6 June 2023 (UTC)

Baierlein

Baierlein, R., 1999/2005, Thermal Physics, 6th printing, Cambridge University Press.

What are the common characteristics of these diverse means of heating and cooling? The following provides a partial list.

1. There is net transfer of energy (to or from the system, be it frying pan or muffin or soda).

2. The amount of energy transferred may be controlled and known at the macroscopic level but not at the microscopic level.

3. The transfer of energy does not require any change in the system's external parameters.

....

In a fundamental way, one distinguishes two modes of energy transfer to a physical system:

1. by heating (or cooling);

2. by changing one or more external parameters.

To be sure, both kinds of transfer may occur simultaneously (for example, if one irradiates a sample at the same time that one changes the external magnetic field), but the distinction remains absolutely vital.

Energy transfer produced by a change in external parameters is called work.

....

Elementary physics often speaks of three ways of heating: conduction, convection, and radiation. You may wonder, why is convection not mentioned here? Convection is basically energy transport by the flow of some material, perhaps hot air, water, or liquid sodium. Such "transport" is distinct from the "transfer" of energy to a physical system from its environment.

To summarize: think of "heating" as a process of energy transfer, a process accomplished by conduction or radiation.

Evidently, for Baierlein, thermodynamic work is defined in terms of the external parameters of the system itself, without mention of ordinary physical work in the surroundings. For a closed system, for Bairlein, heating is defined by exclusion of thermodynamic work. Baierlein here forgets Joule's experiments.

Later, talking about the Carnot engine, Baierlein mentions rubbing and friction, but doesn't mention hammering or heat when he does so:

(b) No dissipative processes, such as frictional rubbing or viscous damping of fluid motion, accompany the process.

Conduction more or less implies that the source of the transferred heat has a temperature. Laser radiation is an example of heat transfer when the temperature of the source is not counted. Baierlein doesn't tell us whether frictional rubbing, viscous damping of fluid motion, or hammering, are counted as work or as heat.Chjoaygame (talk) 20:12, 6 June 2023 (UTC)

Blundell

Blundell, S.J., Blundell, K.M., 2006, Concepts in Thermal Physics, Oxford University Press. Introductory comment:

• In Chapter 2 we explore the concept of heat, defining it as “energy in transit”, and introduce the idea of a heat capacity.

Formal definition:

We therefore make the following definition:

heat is energy in transit.

Heating by transfer of heat from one thermodynamic system to another, and heating by rubbing a thermodynamic system with something in the surroundings:

To see this, consider your cold hands on a chilly winter day. You can increase the temperature of your hands in two different ways: (i) by adding heat, for example by putting your hands close to something hot, like a roaring fire; (ii) by rubbing your hands together. In one case you have added heat from the outside, in the other case you have not added any heat but have done some work. In both cases, you end up with the same final situation: hands which have increased in temperature. There is no physical difference between hands which have been warmed by heat and hands which have been warmed by work.

....

    Notice in this last example that the power in the heater is supplied by electrical work. Thus it is possible to produce heat by doing work. We will return to the question of whether one can produce work from heat in Chapter 13.

The conversion of ordinary physical work into heat occurs in the process of transfer.

In the section on the first law, some historical information. Lavoisier's 1789 notion of caloric. Thompson's 1798 heating by friction. Mayer's 1842 frictional generation of heat in paper pulp. Joule's frictional paddle experiment (1840 to 1845).Chjoaygame (talk) 06:14, 7 June 2023 (UTC)

Bridgman

Bridgman, P.W., 1943, The Nature of Thermodynamics, Harvard University Press.

.... the spontaneous appearance of temperature differences, as for example generation of heat by friction or collision, ...

....

When the bodies are thus in contact it is an experimental fact that there is a transfer of heat if there is a temperature gradient in the material of the two bodies in the directions normal to the surface of separation. This sort of heat transfer is said to be by conduction.

....

The second method by which heat transfer may take place occurs when two bodies are not in contact, but confront each other across a vacuous space, with their opposing surfaces at a difference of temperature; this method of transfer is "radiational" transfer.

Considering the first law, Bridgman analyzes heat production by friction:

We have the paradoxical result that the work received by the block from the pavement across the surface of separation is not equal to the work done on the pavement by the block. This failure of equality of direct and reaction work always occurs at a surface where there is tangential slip and there are forces in the direction of slip. This sort of thing does not occur very often in the conventional thermodynamic analysis; I think that many physicists have a sort of instinctive feeling that direct and reaction work are always equal. Obviously this can be the case only when there is no discontinuity in the motion at the surface, as at a piston which is compressing a gas.

I suppose the last phrase refers to the interface between the piston and the gas, not to that between the piston and the cylinder where there is friction. The difference between work done on the system, and work received by the system, by such a thing as a rotating paddle, was observed long ago by Bryan to be due to friction, and is the basis of the original experiments, by Davey, Thompson, Mayer, and Joule, that blew away the caloric theory and measured the mechanical equivalent of heat, but Bridgman is right to remark that this sort of thing does not occur very often in the conventional thermodynamic analysis. Perhaps the reason for this is that friction is not quite so easy to account for mathematically? Chjoaygame (talk) 06:41, 7 June 2023 (UTC)

Bryan

Bryan, G.H., 1907, Thermodynamics: an Introductory Treatise dealing mainly with First Principles and their Direct Applications, B.G. Teubner, Leipzig.

Bryan was writing when thermodynamics had been established empirically, but people were still interested to specify its logical structure. The work of Carathéodory also belongs to this historical era. Bryan was a physicist while Carathéodory was a mathematician.

Bryan started his treatise with an introductory chapter on the notions of heat and of temperature. He gives an example of where the notion of heating as raising a body's temperature contradicts the notion of heating as imparting a quantity of heat to that body.

He defined an adiabatic transformation as one in which the body neither gains nor loses heat. This is not quite the same as defining an adiabatic transformation as one that occurs to a body enclosed by walls impermeable to radiation and conduction.

He recognized calorimetry as a way of measuring quantity of heat. He recognized water as having a temperature of maximum density. This makes water unsuitable as a thermometric substance around that temperature.

His second chapter started with the recognition of friction as a source of heat, by Benjamin Thompson, by Humphry Davy, by Robert Mayer, and by James Prescott Joule.

He stated the First Law of Thermodynamics, or Mayer–Joule Principle as follows:

When heat is transformed into work or conversely work is transformed into heat, the quantity of heat gained or lost is proportional to the quantity of work lost or gained.

He wrote:

If heat be measured in dynamical units the mechanical equivalent becomes equal to unity, and the equations of thermodynamics assume a simpler and more symmetrical form.

He explained how the caloric theory of Lavoisier and Laplace made sense in terms of pure calorimetry.

Having rationally defined quantity of heat, he went on to consider the second law, including the Kelvin definition of absolute thermodynamic temperature.

In section 41, he wrote:

         41. Physical unreality of reversible processes. In Nature all phenomena are irreversible in a greater or less degree. The motions of celestial bodies afford the closest approximations to reversible motions, but motions which occur on this earth are largely retarded by friction, viscosity, electric and other resistances, and if the relative velocities of moving bodies were reversed, these resistances would still retard the relative motions and would not accelerate them as they should if the motions were perfectly reversible.

He then stated the principle of conservation of energy.

He then wrote:

In connection with irreversible phenomena the following axioms have to be assumed.

         (1) If a system can undergo an irreversible change it will do so.

         (2) A perfectly reversible change cannot take place of itself; such a change can only be regarded as the limiting form of an irreversible change.

On page 46, thinking of closed systems in thermal connection, he wrote:

We are thus led to postulate a system in which energy can pass from one element to another otherwise than by the performance of mechanical work.

On page 47, he wrote:

When energy flows from on system or part of a system to another otherwise than by the performance of work, the energy so transferred i[s] called heat.

On page 48, he wrote:

Another important exception occurs when sliding takes place between two rough bodies in contact. The algebraic sum of the works done is different from zero, because, although the action and reaction are equal and opposite the velocities of the parts of the bodies in contact are different. Moreover, the work lost in the process does not increase the mutual potential energy of the system and there is no intervening medium between the bodies. Unless the lost energy can be accounted for in other ways, (as when friction produces electrification), it follows from the Principle of Conservation of Energy that the algebraic sum of the quantities of heat gained by the two systems is equal to the quantity of work lost by friction.

I don't know whether Max Born knew of Bryan's work when he persuaded Carathéodory to undertake a mathematical investigation of the foundations of thermodynamics, or whether Carathéodory knew of Bryan's work, as he prepared his celebrated 1909 paper.

In my opinion, Bryan's definition of heat is the best available, and has been accepted by many thermodynamicists, and by the preponderance of past editors of this Wikpedia article. I regard Bryan's Treatise as a Wikipedia reliable source.Chjoaygame (talk) 04:48, 23 June 2023 (UTC)

Callen

Callen's first edition (1960), talking about closed systems (no transfer of matter), says on page 7:

Energy can be transferred to a mechanical mode of a system, such a flux of energy being called mechanical work. Similarly, energy can be transferred to an electrical mode of a system. Mechanical work is typified by the term $-P\ dV$ ($P$ is pressure, $V$ is volume), and electrical work is typified by the term $-E\ d{\mathcal {P}}$ ($E$ is electric field, ${\mathcal {P}}$ is electric dipole moment). These energy terms and various other mechanical and electrical work terms are treated fully in the standard mechanics and electricity references. But it is equally possible to transfer energy to the hidden atomic modes of motion as well as to those which happen to be macroscopically observable. An energy transfer to the hidden atomic modes is called heat.

Callen's second edition (1985, with material about statistical mechanics) is practically the same here.

No mention of temperature there. He is talking about an energy transfer into the system from its surroundings.Chjoaygame (talk) 06:44, 22 June 2023 (UTC)

Çengel

Çengel, Y.A., Boles, M.A., Kanoğlu, M., Thermodynamics: An Engineering Approach, 9th edition, 2019. Talking first about the zeroth law, on page 17:

It is a common experience that a cup of hot coffee left on the table eventually cools off and a cold drink eventually warms up. That is, when a body is brought into contact with another body that is at a different temperature, heat is transferred from the body at higher temperature to the one at lower temperature until both bodies attain the same temperature (Fig. 1–34). At that point, the heat transfer stops, and the two bodies are said to have reached thermal equilibrium. The equality of temperature is the only requirement for thermal equilibrium.

In my opinion, this really belongs to the preliminary statement that thermodynamics deals with bodies in their own states of internal thermodynamic equilibrium, and in equilibrium with connected bodies. The authors then proceed to talk about temperature, not waiting for the second law to tell them how to define thermodynamic temperature.

On page 56, the authors write:

An energy interaction is heat transfer if its driving force is a temperature difference. Otherwise it is work, as explained in the next section.

On page 60, they write:

Heat is defined as the form of energy that is transferred between two systems (or a system and its surroundings) by virtue of a temperature difference (Fig. 2–15). That is, an energy interaction is heat only if it takes place because of a temperature difference. Then it follows that there cannot be any heat transfer between two systems that are at the same temperature.

....

Heat is energy in transition. It is recognized only as it crosses the boundary of a system.

On page 62, they write:

Work, like heat, is an energy interaction between a system and its surroundings. As mentioned earlier, energy can cross the boundary of a closed system in the form of heat or work. Therefore, if the energy crossing the boundary of a closed system is not heat, it must be work. ... More specifically, work is the energy transfer associated with a force acting through a distance.

On page 65, they write:

In an electric field, electrons in a wire move under the effect of electromotive forces, doing work.

They do not explain precisely how these electromotive forces act through a distance.

On page 66, they focus on mechanical work, writing:

There are several different ways of doing work, each in some way related to a force acting through a distance (Fig. 2–28).

...

There are two requirements for a work interaction between a system and its surroundings to exist: (1) there must be a force acting on the boundary, and (2) the boundary must move. Therefore, the presence of forces on the boundary without any displacement of the boundary does not constitute a work interaction.

They apparently feel no need to remark that their aforementioned electrical work violates their second requirement for "work": the boundary doesn't move. This is, however, a mere pedagogical convenience, or perhaps oversight, for they subsequently treat electrical separately from mechanical work.

On page 66, they write:

Energy transmission with a rotating shaft is very common in engineering practice (Fig. 2–29).

They do relate this to the distance moved by a point in the rotating parts, measuring distance moved in a suitable way. But the boundary of the system is not displaced and doesn't move.

No mention so far of friction, but on page 68, they write:

This discussion together with the consideration for friction and other losses form the basis for determining the required power rating of motors used to drive devices such as elevators, escalators, conveyor belts, and ski lifts.

On page 70, they discuss other forms of work, including electrical work:

Some work modes encountered in practice are not mechanical in nature. However, these nonmechanical work modes can be treated in a similar manner by identifying a generalized force $F$ acting in the direction of a generalized displacement $x$.

These engineers have discarded the foundational idea that friction generates heat. Thus, they reverse the thermodynamic tradition expounded by Bryan and by Carathéodory of defining heat by its not occurring through thermodynamic work, nor through transfer of matter. These engineers define thermodynamic work by its not occurring through heat.Chjoaygame (talk) 13:16, 22 June 2023 (UTC)

The reversal of the orthodox thermodynamic tradition is an example of circular reasoning. Quantity of energy transferred as heat is defined in terms of "work", while "work" is defined in terms of heat. This might be resolved by giving "work" two distinct and logically unconnected definitions, committing an act of logical equivocation. Wikipedia should avoid logical equivocation in its presentations.

More should be said. While it is possible to define empirical temperatures and so to define quantity of energy transferred as heat when it is between two bodies that each possess its respective temperature, it is convoluted and undesirable to need to redefine thermodynamic temperature after the acceptance of the second law. One might argue that the second law precedes the first law in logic, though that would be a hard road to hoe: how to define entropy without a prior definition of the distinction between heat and work transfers. A further problem with defining heat in terms of temperature difference is that not all sources of radiation, nor all sources of conducted heat, have a definite and uniquely defined temperature, so that the two-body definition of heat transfer doesn't work. From the orthodox thermodynamic viewpoint, the two-body temperature difference definition is merely a special case of the proper general definition by exclusion of thermodynamic work. The solution to the latter problem is to stay with the traditional thermodynamic base case of a system and its surroundings: the system has properly and uniquely defined thermodynamic state variables; but the surroundings are not so constrained; in the surroundings, from the viewpoint of thermodynamics, anything goes.

These points were, over several years long ago, established in this talk page, but they seem to have been discarded recently. The article should perhaps thoroughly explain this logic.

For Wikipedia, a good resolution is to avoid circular and convoluted reasoning, and to stay with the orthodox thermodynamic position, and to declare, solely for this specific purpose, that Çengel, Boles, and Kanoğlu 9th edition is not a reliable source.Chjoaygame (talk) 03:16, 23 June 2023 (UTC)

Denbigh

Denbigh K., The Principles of Chemical Equilibrium: with Applications in Chemistry and Chemical Engineering, 4th edition, 1981, Cambridge University Press.

On page 10, Denbigh wrote:

... we shall speak of any change taking place inside an adiabatic wall as being an adiabatic process.

This is thinking in terms of calorimetry, not so much in terms of the idea of Locke, Thompson, Mayer, and Joule, that friction generates heat.

On page 18, Denbigh wrote:

In the discussion of Joule's experiments we were concerned with the change in state of a body contained within an adiabatic enclosure. It would have been wrong to have spoken of the temperature rise of the water as having been due to heat (although this is sometimes done in a loose way); what we were clearly concerned with were changes of state due only to work. However it is also known from experience that the same changes of state can be produced, without the expenditure of work, by putting the body into direct contact (or through a non-adiabatic wall) with something hotter than itself. That is to say the change of internal energy, $U_{A}-U_{B}$ can be obtained without the performance of work. We are therefore led to postulate a mode of energy transfer between bodies different from work and it is this which may now be given the name heat. Our senses and instruments provide us with no direct knowledge of heat (which is quite distinct from hotness). The amount of heat transferred to a body can thus be determined, in mechanical units, only by measuring the amount of work which causes the same change of state.

Denbigh is thinking of heat as defined by calorimetry, relying on two bodies, each with a defined temperature. This thinking seems to show that, after all, Joule did not measure the mechanical equivalent heat, because he did not heat the water in the vat. Denbigh would perhaps reply that, nevertheless, the water changed its internal energy by the same amount as it would change if the process had been one of heating by conduction and radiation. That reply, however, relies on the Joule experiment having converted all the externally applied work into heat. If only some of the externally applied work were transformed into heat, more complicated reasoning would be necessary, as indicated by Bryant and by Bridgman. This may explain why Planck talks of surface rubbing as distinct from internal friction.

Denbigh on page 19 wrote:

... it follows from the above definition of heat that the heat gain of the first body is equal to the heat loss of the second.

This might be called 'the principle of calorimetry', and is the main basis of the caloric theory of heat. Bryant and Bridgman would reply that they do not accept such an equality as a general principle. It does not cover friction in such processes as drilling, rubbing, grinding, or hammering.

Denbigh made some concessions to the idea of thermodynamic work as defined by changes of state variables other than thermal, i.e., other than entropy and temperature. For discussion of heat, the internal energy is always one such state variable. Denbigh mentioned Joule's measurements of the energy changes due to friction between iron blocks, but he did not elaborate. He also wrote the following:

Similarly, in the irreversible process of friction, the kinetic energy of a body as a whole is converted into the random energy of its component molecules.

For example, in hammering. This didn't deal with rubbing. Apart from the latter two brief mentions, Denbigh conveniently ruled out discussion of friction.

For the definition of work, however, Denbigh wrote:

Similar expressions may be obtained for the stretching of wires, the work of magnetization, etc.‡

‡ A very clear account of work terms is given by Zemansky, Heat and Thermodynamics (New York), McGraw-Hill, 1968, and by Pippard, loc. cit.

The 'work' terms are sometimes taken to exclude 'chemical work'.

Eventually, Denbigh disallows the heat produced by friction. He relies on a roundabout calorimetric definition, supposing that heat comes from a convenient "heat bath" of water at its temperature of maximum density, and writing:

            Consider now a type of process $A\rightarrow B$ in which a body $X$ both absorbs heat and has work $w$ done on it. In this process let its change of internal energy be $U_{B}-U_{A}$. We shall suppose that the heat comes from a heat bath, that is, a system of constant volume which acts as a reservoir for processes of heat transfer, but performs no work (e.g. a quantity of water at its temperature of maximum density). Let its change of internal energy in the above process be $U_{B}^{\prime }-U_{A}^{\prime }$. Then for the body $X$ and the heat bath together we have,

$w=[(U_{B}-U_{A})+(U_{B}^{\prime }-U_{A}^{\prime })],$

the right-hand side being the total change of internal energy. But according to the above definition $U_{B}^{\prime }-U_{A}^{\prime }$ is equal to the negative of the heat lost by the bath and is equal therefore to the negative of the heat gained by $X$. If we denote this heat by $q$, we therefore have $q=-(U_{B}^{\prime }-U_{A}^{\prime })$. Substituting in the previous equation we obtain

$U_{B}-U_{A}=q+w$                            (1·8)

as a statement of the first law for a body which absorbs heat $q$ and has work $w$ done on it, during the change $A\rightarrow B$. This law therefore states that the algebraic sum of the heat and work effects of a body is equal to the change of the function of state, $U$, i.e. the algebraic sum is independent of the choice of path $A\rightarrow B$.

A chemist is hardly interested in friction at this stage of thinking, and this perhaps explains why Denbigh defies Thompson, Mayer, and Joule, and rules out friction as a generator of heat. Friction is more the province of physicists such as Planck.Chjoaygame (talk) 11:46, 1 July 2023 (UTC)

Dugdale

Dugdale wrote on page 4:

To this day calorimetry requires 'the most scrupulous attention to many circumstances which may affect the result'. A great deal of scientific effort still goes into the accurate measurement of heat capacities over a wide range of temperatures and indeed this is still one of the primary measurements in thermodynamics.

On page 20, he wrote:

We now define the difference between $\Delta U$ and $W$ (this difference is zero in adiabatic changes) as a measure of the heat $Q$ which has entered the system in the change. We shall treat the heat entering a system as positive. Thus

$Q=\Delta U-W.$

On page 21, he wrote:

Let me emphasise again that in the approach outlined here (due originally to Born) the thermodynamic concept of quantity of heat has been introduced and defined in terms of purely mechanical quantities.

Dugdale gives plenty of detail on Thompson's and on Joule's experiments, described by them as production of heat by friction, but he interprets them as occurring through work. Nevertheless, he gives much attention to calorimetry, as noted above.

On page 21, he wrote:

... heat is a form of energy in transit and cannot be said to exist except when changes of state are occurring.

...

Note that the thermodynamic concept of heat conflicts, in some important ways, with the common usage of the word. We say that heat is transferred from one body to another and that, for example, the heat lost by one body is gained by the other. There is thus a strong implication that the heat was originally inside the first body and ended up after the transfer inside the other body. It is precisely this notion that we have to get rid of in order to think clearly about heat, work and internal energy.

Dugdale is not interested in friction, and puts his faith in a principle of calorimetry, that the heat lost by one body is gained by the other. He defines work in terms of what happens in the surroundings, apparently not in terms of the change it produces in the state variables of the system. Yet, for the interpretation of experiments, he also relies on the definition of the state of the system in terms of 'work' variables, including internal energy.Chjoaygame (talk) 10:24, 30 June 2023 (UTC)

Dunning-Davies

Dunning-Davies, J., 2011. Concise Thermodynamics: Principles and Applications in Physical Science and Engineering, 2nd edition, Woodhead Publishing, Oxford UK.

On page ix, Dunning-Davies wrote:

Thermodynamics is concerned with heat. Notions of "hot" and "cold", of one body being warmer than another, and the idea of the "flow of heat" are all central to the subject and, in science, all retain the meanings they have in our everyday lives. Initially, curiously enough, it is probably this latter point which is most difficult for many to accept but that is the absolute truth, thermodynamics is concerned with notions and concepts which are, in a non-scientific way, familiar to everyone. If this seemingly trivial point is borne in mind always, academic study of thermodynamics takes on a whole new perspective and is not a difficult subject to understand and appreciate.

Evidently, Dunning-Davies is not too concerned or overfamiliar with the cave man's ability to generate heat by friction between sticks, or with the coachman's concern that sometimes the heat generated by friction of his axle with it bearing can set the coach on fire, or with the blacksmith's heating of his work by hammering. Those primitive fellows are not overfamiliar with the caloric theory of heat. Apparently, Dunning-Davies is happy with the ordinary language word 'heat' as a scientific term. He sees no need to explicitly define it in this context. He will remain content to talk of two systems being brought into thermal contact. Does that include mutual radiative exposure?

On page 1, Dunning-Davies, without explicitly defining it, introduces a term 'thermal properties' as follows: he remarks that "...the laws of thermodynamics ... are simply expressions of common experience of the thermal properties of matter and radiation." On page 2, again without explicitly defining it, in the context of the caloric theory, he uses the term "thermal contact".

On page 5, Dunning-Davies focuses on two bodies that each possess a temperature, not worrying about the general approach to thermodynamics that requires the system to have a temperature, but does not impose any such requirements on the surroundings. He wrote:

As has been mentioned already, everyone is familiar with such elementary notions as 'A is warmer than B', 'B may gain heat from A', and the qualitative notion of the 'flow of heat'. Also, everyone knows that, when the flow of heat between two systems has ceased, those systems are said to be in thermal equilibrium.

On page 13, Dunning-Davies wrote:

               Now consider an isolated system in which there is no thermal interaction with the surroundings. It is a 'fact of experience' that, if work is done on the system in some way, the system attains a new equilibrium state and it does not matter how the work which achieves this is done: for example, a gas may be compressed, or stirred, or have an electric current passed through it. It was one of Joule's great contributions to thermodynamics to demonstrate experimentally that this is the case. The result is that energy is given to the system during the process and, since no thermal interaction is involved, the process is said to be adiabatic.

...It follows that, if a system is caused to change from some initial state to a final state by adiabatic means, the work done is the same no matter how it is done.. Hence, there must exist a function of the coordinates of the system whose value in the final state minus its value in the initial state equals the work done in going from one state to the other. This function of state is called the internal energy and is denoted by $U$. For the isolated system

$W_{\text{a}}=U_{2}-U_{1}$                         (3.1)

where $U_{2}$ and $U_{1}$ are the final and initial values respectively of the internal energy and $W_{\text{a}}$ is the work done in this adiabatic process; the suffix ${\text{a}}$ indicating that the process is adiabatic.

               Suppose now that the system is not isolated as above but that thermal interaction between the system and its surroundings is allowed. In this case, the system may be taken from the state with internal energy $U_{1}$ to that with internal energy $U_{2}$ by a process which is not necessarily adiabatic. Such a process may be achieved by performing work which may be mechanical – for example, the use of a stirrer, non-mechanical – for example, the use of a heating element, or a combination of the two. Let $W_{\text{na}}$ denote the mechanical work done on the system in a process which is not necessarily adiabatic; the suffices ${\text{na}}$ indicating that the process is not necessarily adiabatic. Then

$W_{\text{a}}-W_{\text{na}}=Q$                         (3.2)

and for all such processes

$Q+W_{\text{na}}=U_{2}-U_{1}$               (3.3)

               Here $Q$ is zero for adiabatic processes only. In a non-adiabatic process, $Q$ may be thought of as making up the deficit of mechanical work by heat. Hence, the amount of heat is defined in terms of mechanical work only. The convention adopted is that positive values of $Q$ will mean heat supplied to the system. Also, it should be noted that, although it has not been stated explicitly, attention has been confined to closed systems; that is, systems which do not transmit mass to, or receive mass from, the surroundings.

Dunning-Davies is not precise about exactly how to specify adiabatic and non-adiabatic work.

On page 26, Dunning-Davies wrote:

These forms of the law are those used at the birth of thermodynamics as a subject in its own right. As mentioned already, the laws were deduced from experiment and observation, and many of the ideas were borrowed from engineering. The notions and experiences of the engineer were used to obtain the laws of heat transformation and it is a tremendous achievement that a theory with many highly abstract concepts should be established by this approach. However, the approach to be adopted here is more mathematical in nature than some earlier arguments and is a modification of the method introduced at the beginning of this century by the mathematician Constantin Carathéodory. Carathéodory became interested in the problem of the formulation of thermodynamics at the instigation of his colleague, the physicist Max Born, and his highly mathematical original paper appeared in 1909. Because of the mathematical complexities of his approach, his work passed largely unnoticed, until the postwar work of such as Buchdahl, Landsberg, Turner and Zemansky made it far more accessible to scientists in general.

Evidently, Dunning-Davies knows the highly mathematical work of Carathéodory but seems unimpressed by the prior more thermodynamic work of Bryant.

Dunning-Davies so loves the caloric theory of heat that he sets up the above roundabout way of defining heat through mechanical processes only, apparently not impressed by Thompson's, Mayer's, and Joule's methods of allowing straightforward mechanical definition of quantity of heat by measuring its production in friction. Why do things the easy and obvious way when you can do them a hard way?Chjoaygame (talk) 10:06, 1 July 2023 (UTC)

Giles

Giles, R., 1964, Mathematical Foundations of Thermodynamics,Pergamon Press, Oxford.

On page 1, Giles wrote:

A familiar way of introducing the concept of absolute temperature in elementary expositions of thermodynamics is through the consideration of a Carnot cycle, in which a reversible heat engine operates between two heat reservoirs at different temperatures. This approach reveals clearly the essential nature of absolute temperature and has immediate physical appeal. The derivation of the concept of entropy, on the other hand, depends on considerations of a mathematically much more sophisticated nature, so that the physical significance of this concept remains initially relatively obscure.

On page 2, introducing another way of defining entropy, Giles wrote:

With this approach to entropy it is not necessary to define absolute temperature by means of a Carnot cycle; instead it can be obtained from entropy by a process of differentiation, just as entropy is usually obtained from temperature by integration. We thus obtain a way of introducing entropy which is physically very satisfying, since it emphasises the essential property of entropy: that its increase measures the irreversibility of a process. However, this approach is not entirely satisfactory from a logical point of view, since it still depends on the qualitative concept of temperature (through the use of a heat reservoir) and also on the possibility of making quantitative comparisons of energy changes (in the measurement of $E$).

Still on page 2, about a better way of defining entropy, Giles wrote:

The virtue of this approach to entropy is not only that it is independent of the concepts of temperature and energy, but that it is actually independent of any quantitative concepts at all. For it presents the measurement of entropy as resulting from a sequence of experiments of a qualitative nature, the result of each experiment being simply yes or no.

After some consideration of frictionless mechanical processes, and then explicitly defining entropy, looking at a thermodynamic system A connected to a mechanical device M in the surroundings, on page 109, Giles wrote:

If M is, for instance, a spinning flywheel this might be done by allowing M to rub on A until some energy, in the form of frictional heat, had passed from M to A; or an auxiliary electrical heater might be used as described in § 1.5.

On page 115, Giles wrote:

Further, we have, by Theorem 9.2.3, for any infinitesimal quasi-static process

${\text{d}}E=T\ {\text{d}}S-P\ {\text{d}}V$                        12.1 (2)

and, in particular, for an infinitesimal quasi-static adiabatic process ${\text{d}}E=-P\ {\text{d}}V$. These results accord with the description of $T$ and $P$, as defined above, as absolute temperature and pressure.

          Equation 12.1 (2) expresses the energy transferred to the system in an infinitesimal quasi-static process as the sum of two terms, ${\text{d}}E=T\ {\text{d}}S$ and $-P\ {\text{d}}V$, which we may call, respectively, the heat supplied to the system and the work done on the system'. It should be noted that the terms "heat" and "work", thus defined, apply only to quasi-static processes; the present formulation of thermodynamics provides no such division of the energy transferred in a non-quasi-static process.

As Giles observes, his definition of heat here relies on the concept of a quasi-static process. Is this perhaps necessary for a definition of heat? For example, the definition of thermodynamic work, for a finite increment of volume at constant pressure requires that the process be slow enough to allow the pressure of the system to be defined throughout it; this definition also requires that the process be slow enough to allow the temperature to be defined throughout it. This definition demands the simultaneous definition of heat and thermodynamic work.

We may observe that this definition of heat does not consider such an abrupt process as hammering to produce heat. Hammering, drilling, fluid friction, and rubbing, convert energy from the surroundings directly into heat. The energy from the surroundings can be measured directly without regard to the intimate details of the process, and, provided it is all converted to heat, it can measure the quantity of heat directly. That is the merit of the works of Thompson, Mayer, and Joule. It might reasonably be objected that in such processes, some of the energy from the surroundings is converted into heat in the surroundings. For example, the hammer will become hot. It seems to follow that some kind of idealization is necessary for the precise definition of thermodynamic quantities.

Eventually, Giles defines heat through his prior definition of entropy. He relies on entropy as measuring the whole irreversibility of any thermodynamic process. He is presenting the idea of heat after he has settled on the second law of thermodynamics. This is reasonable and logically defensible, though it is not the commonest way to define heat. This mathematically oriented reasoning of Giles competes with the older physically oriented work of Clausius, that defined entropy in terms of infinitesimal increments of heat, and with the older physically oriented work of Bryan and mathematically oriented work of Carathéodory that defined heat as a residual from work. It is often felt that defining things in terms of adiabatic work is straightforward, and is evidently based on simple physics.Chjoaygame (talk) 09:41, 3 July 2023 (UTC)

temporarily out of alphabetical order

Schroeder

Schroeder, D.V., Introduction to Thermal Physics, 2000, Addison Wesley Longman, San Francisco. Schroeder is writing from the viewpoint that starts from microscopic physics, as against the thermodynamic viewpoint that starts with macroscopic physics. He leads with

      Heat is defined as any spontaneous flow of energy from one object to another, caused by a difference in temperature between the objects. We say that "heat" flows from a warm radiator into a cold room, from hot water into a cold ice cube, and from the hot sun to the cool earth. The mechanism may be different in each case, but in each of these processes the energy transferred is called "heat."

      Work, in thermodynamics, is defined as any other transfer of energy into or out of a system. You do work on a system whenever you push on a piston, stir a cup of coffee, or run current through a resistor. In each case, the system's energy will increase, and usually its temperature will too. But we don't say that the system is being "heated," because the flow of energy is not a spontaneous one caused by a difference in temperature. Usually, with work, we can identify some "agent" (possibly an inanimate object) that is "actively" putting energy into the system; it wouldn't happen "automatically."

      The definitions of heat and work are not easy to internalize, because both of these words have very different meanings in everyday language. It is strange to think that there is no "heat" entering your hands when you rub them together to warm them up, or entering a cup of tea that you are warming in the microwave. Nevertheless, both of these processes are classified as work, not heat.

      Notice that both heat and work refer to energy in transit. You can talk about the total energy inside a system, but it would be meaningless to ask how much heat, or how much work, is in a system. We can only discuss how much heat entered a system, or how much work was done on a system.

Footnote: Many physics and engineering texts define W to be positive when work-energy leaves the system rather than enters. Then equation 1.24 instead reads ΔU = Q − W. This sign convention is convenient when dealing with heat engines, but I find it confusing in other situations. My sign convention is consistently followed by chemists, and seems to be catching on among physicists.

Schroeder does make the important point that "both heat and work refer to energy in transit.

But, like Çengel et al., Schroeder defines thermodynamic work by exclusion of heat.

This reverses the logic of Bryant and Carathéodory, who define heat by exclusion of work. Schroeder's definition of work, by exclusion of heat, is in contrast with the usual idea in physics, that work is defined mechanically, in terms of such things as the ability to lift a weight. Thermodynamics began with the idea that spontaneous work is done by the working body of a heat engine, not with Schroeder's idea that

Usually, with work, we can identify some "agent" (possibly an inanimate object) that is "actively" putting energy into the system; it wouldn't happen "automatically".

Schroeder doesn't seem to consider friction within the system such as occurs in Joule's paddle wheel experiment.

In the above quote from Schroeder, there is no mention of friction. His first mention of friction is in the following footnote:

Even for quasitatic compression, friction between the piston and the cylinder walls could upset the balance between the force exerted from outside and the backward force exerted on the piston by the gas. If W represents the work done on the gas by the piston, this isn't a problem. But if it represents the work you do when pushing on the piston, then I'll need to assume that friction is negligible in what follows.

Though Schroeder is not focusing on friction, that remark is compatible with the above remark of Bryant:

Another important exception occurs when sliding takes place between two rough bodies in contact. The algebraic sum of the works done is different from zero, because, although the action and reaction are equal and opposite the velocities of the parts of the bodies in contact are different. Moreover, the work lost in the process does not increase the mutual potential energy of the system and there is no intervening medium between the bodies. Unless the lost energy can be accounted for in other ways, (as when friction produces electrification), it follows from the Principle of Conservation of Energy that the algebraic sum of the quantities of heat gained by the two systems is equal to the quantity of work lost by friction.

And with the above remark of Bridgman:

We have the paradoxical result that the work received by the block from the pavement across the surface of separation is not equal to the work done on the pavement by the block.

This may be interpreted by saying that ordinary physical work done by a mechanism in the surroundings must sometimes be distinguished from thermodynamic work done on its surroundings by a thermodynamic system, as for example by a heat engine.

Perhaps it is, as Schroeder thinks, "strange to think that there is no "heat" entering your hands when you rub them together to warm them up." Perhaps rubbing one's hands together mainly has the effect of increasing the blood flow through the hands? It is not quite the same as rubbing two pieces of ice together.

Classical theoretical texts on thermodynamics define changes in the internal energy of a thermodynamic system strictly in terms of thermodynamic work done by a body enclosed in a container with adiabatic walls. In practice, perhaps most measurements of change in internal energy are done by calorimetry, as for example in Joule's paddlewheel experiment.

In thinking about thermodynamic work, one should bear in mind that thermodynamics is primarily about differences between thermodynamic states. This is why thermodynamic work is defined by differences between thermodynamic states. Thermodynamics is not simply about forces that an "agent" in the surroundings can exert to do work on the thermodynamic system. It is about forces that a thermodynamic system can exert to do work on its surroundings; such work can be received in the surroundings partly as work against friction, i.e., as heat.

It is perhaps worth remarking at this point that "chemical work", referring to such quantities as $\mu \ {\text{d}}N$, might safely be called 'chemical work-like change'. This is because "chemical work" is defined neither by mechanical forces that the surroundings exert on the system, nor by mechanical forces that the system exerts on the surroundings, but by changes in the state variables of the system.

Schroeder is a chemist who approaches thermodynamics as secondary to microscopic physics, apparently not a physicist who learnt thermodynamics as a macroscopic topic from Carnot, Joule, Mayer, Joule, Bryant, Carathéodory, and Planck. One may ask, which is better for Wikipedia, that it give priority to the thinking such as Fourier's, in terms of partial differential equations and the caloric theory, or that it reflect the knowledge of a cave man or pre-industrial coachman, that friction generates heat? I am inclined to bear in mind that Wikipedia is often enough quoted just from the first defining sentence of an article, as if that authoritatively settles a question.Chjoaygame (talk) 04:09, 29 June 2023 (UTC)