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Needs Revision. Contains a fundamental blunder.

The following sentence is wrong: " Heat ... is synonymous with heat flow and heat transfer." Heat is not synonymous with heat transfer. That statement is risible. I also commented on the talk page of the Heat Capacity article. "Freeman Dyson in writes: Heat is disordered energy." ← this is from my 1966 Physics textbook (Halliday & Resnick Pts I & II pg 640). Heat transfer is a process, heat is a type of energy. If someone wants to make an argument that the process is the thing, then they should do so explicitly, but NOT in the introduction. The logical problem I see in making this claim, is that multiple different processes in an isolated system can lead to identical heat energy transferred (but not identical final state, obviously). The process is not the (abstract) thing.173.189.78.236 (talk) 01:46, 18 May 2013 (UTC)

Heat is not a type of energy, it is a type of energy transfer. Heat(ing) is responsible for a change in the internal energy, it is a process by which the internal energy is increased. Similarly, work is not a type of energy but rather a type of energy transfer, a process by which the internal energy is increased. For a given internal energy, there is no way to divide it up into heat energy and non-heat energy, or work and non-work energy. The logical problem you pose is unclear. Can you give a concrete example? PAR (talk) 02:09, 18 May 2013 (UTC)

On the physics here, I agree with Editor PAR against Editor 173.189.78.236. In thermodynamics in its strict sense of language, "Heat is not a type of energy, it is a type of energy transfer"; the above comment of Editor 173.189.78.236 does not recognize this. The comment of Editor 173.189.78.236, that "The process is not the (abstract) thing", is logically muddled; it seems to make the mistaken assumption that 'heat' in thermodynamics is an enduring physical object; it is not, it is only a label for a kind of process. The quote from Freeman Dyson is couched in loose rhetorical language, and should not be read as strictly logical.

Nevertheless, in relation to the use of language, Editor 173.189.78.236 makes a reasonable point about in the sentence that he quotes from the Misplaced Pages article. The sentence that he quotes is worded so as to be open to being misread, because it does not make it clear enough that it refers narrowly to a very specific language usage, that of thermodynamics in its strict sense.Chjoaygame (talk) 22:48, 18 May 2013 (UTC)

The observation by editor 173.189.78.236 that Heat is not synonymous with heat transfer is entirely correct, heat is measured in joules (J), heat transfer in joules per second (J/s). Only the truly ignorant could possibly see these as somehow "equivalent". I propose that the statement (and its consequences in the article) be deleted.

Similarly I am replacing my contribution, removed here by User Cburnett. My contribution drew attention to the fact that it is only the energy that is equivalent in thermodynamic systems; bundling kinetic and potential energy in the same category, which is what the " = " does, is a mathemamatical simplification of physics much too far, clearly leading tho the kind of confusion noted by editor 173.189.78.236. --Damorbel (talk) 06:20, 27 May 2013 (UTC)

Further to the statement:-

Heat is not a type of energy, it is a type of energy transfer by editor PAR.

If heat is "not a type of energy", then just what is it?

Saying that it is "not a type of energy" cuts out most of physical existance (E = mc) which is either a remarkable scientific breakthrough or plain absurd.

Such statements have no place whatsoever in Misplaced Pages. --Damorbel (talk) 07:07, 27 May 2013 (UTC)

I have reversed an edit made by PAR in connection with this discussion. PAR explained his removal of my edit with the comment "heat is not a quantity, it is a process." This is a good example of the fundamental errors in the article - heat transfer is indeed a process, a very important engineering process but, as with many engineering terms, it is a handy short form for "transfer of heat energy". It would seem that this (lack of) distinction infects the whole article. --Damorbel (talk) 06:37, 28 May 2013 (UTC)

PAR is correct. Heat, like commercial electricity, can be discussed in either units of energy or power. But also like commercial electricity, heat is assumed to always flow. Unlike static electricity there is no static heat, and in any case, since there is certainly no static commercial electricity, it would be silly to imagine that the electric power company sells you a flow of commercial static electricity. Just because you get charged for electrical energy in joules (kw*hr) does not imply that the electrical energy ever arrived as anything else other than an energy FLOW. Heat is the the same. It is a type of energy that we always see in flow, and never rest. However, just as with commercial electricity, heat can be integrated and discussed in energy units. SBHarris 17:09, 28 May 2013 (UTC)

Sbharris, I would like to understand you more clearly. When you write:-

Heat, like commercial electricity, can be discussed in either units of energy or power.

Do you mean by this that the article should not distinguish between energy (joules) and power (watts, kWh, etc.)?

This is the distinction I am making and I do think any disagreement should be resolved quickly. --Damorbel (talk) 17:34, 28 May 2013 (UTC)

This article cannot make a big point of distinguishing kw from kw hrs. Commercial electrity is discussed in both terms and so is heat. But we cannot push the analogy too far because while charge is conserved, heat is not. Thus , the total heat absorbed by an object need not be its heat content. The very idea of heat content, due to nonconservation, is a bad idea. As well speak of an object's work content as its heat content. "Thermal energy content" sounds better but is no more legitimate. "Thermal energy flow" is as silly as static electricy flow. There is no static thermal energy. And we already have a name for thermal energy flow: it's called "heat." SBHarris 18:05, 28 May 2013 (UTC)

Another analogy - if you have a pond of water being fed by two streams, the "heat" stream and the "work" stream, the amount of water in the pond is not and cannot be divided up into "heat stream water" and "work stream water". Water is water. There is water added by the "heat stream" and there is water added by the "work stream", but once it's in the pond, it's just water. The amount of water in the pond is analogous to the internal energy. There is no heat energy, there is no work energy, there is only internal energy, and it is changed by the heat process or by the work process. PAR (talk) 07:45, 29 May 2013 (UTC)

Sorry, mass flow ("stream of water") is an invalid argument for either heat or work, neither of which are conserved as is energy.

The problem with the article is that it doesn't distinguish between heat energy (joules) and heat transfer (watts = joules/sec.), until it does it remains rubbish. --Damorbel (talk) 08:46, 29 May 2013 (UTC)

Joules / sec would be rate of energy transfer. That's not what we're talking about here. We're talking about the integral of that over time to give a total amount of energy transferred. Which would be measured in Joules. Or kilowatt-hours, just like your electricity meter does.

Of course, just because so many joules of electricity have come into your home, that doesn't mean that you can now say that your house now contains that many more joules of electrical energy. Because that wouldn't be meaningful. Similarly, in thermodynamics, heat is a measure of an amount of energy that has been transferred -- but not (at least, not in current usage) any identifiable aspect of the current state of the system itself. Jheald (talk) 09:59, 29 May 2013 (UTC)

Latest change to the article

Jheald has reversed my edit with the comment "WP has to reflect the position of the scientific community."

Since the article currently has:-

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.

- which is not compatible with the fact that the energy content of matter is directly proportional to its absolute temperature, i.e. its heat; whereas Heat transfer is proportional to temperature difference, not to absolute temperature. These are quite different matters and a Wiki article should make this quite clear. --Damorbel (talk) 05:38, 29 May 2013 (UTC)

As I wrote in my edit summary: WP has to reflect the position of the scientific community, not the personal theses of Damorbel.

I don't see any point in getting into prolonged further discussion with you about this. People have tried in the past, and it makes as much impression as talking to a brick wall. As Arbcom have reminded us in the past, talk pages are for improving articles, not for trying to straighten out your anyone's misunderstandings about physics.

So I'm not going to get into a discussion with you about this, and in future I shall just revert any more of this WP:OR from you on sight. Jheald (talk) 10:06, 29 May 2013 (UTC)

I don't see any point... Jheald, this is not relevant. The matter in hand is the distinction between heat (energy) and heat transfer, the distinction to be made is between joules and joules per second; currently the article doesn't do this and it should. If you do not agree then I invite you to explain why. --Damorbel (talk) 17:04, 29 May 2013 (UTC)

It is not really true that "the energy content of matter is directly proportional to its absolute temperature". Consider that not everything is an ideal gas (actually nothing is exactly an ideal gas), that the heat capacity of most substances varies with temperature, and that things can have (non-thermal) energy when they are at a temperature of absolute zero. Cardamon (talk) 17:11, 29 May 2013 (UTC)

By directly proportional I do not mean linearly proportional.

things can have (non-thermal) energy when they are at a temperature of absolute zero

True enough. But at 0K the heat is still zero joules. --Damorbel (talk) 18:03, 29 May 2013 (UTC)

Most books that I've seen say that "y is directly proportional to x" means that y = kx, with k being a constant. And most recent textbooks (I just checked three) seem to describe heat as energy transferred from one body to another. (Although I suspect that in the past heat was sometimes used in the sense of "thermal energy".) So I agree with Jheald's reversion. Cardamon (talk) 08:29, 30 May 2013 (UTC)

If I understand you correctly you are saying that Heat as energy (i.e. joules) is to be described as Heat transfer (i.e. joules per second or watts)

The point I am making is that joules and joules per second (watts) are not, cannot be, the same thing.

You may indeed have a textbook that says this; my point is that such a statement cannot be correct. I am interested in your view. --Damorbel (talk) 17:59, 30 May 2013 (UTC)

Further to the matter of proportionality. In thermal matters the heat energy is that energy contained in the degrees of freedom of the system particles and this is linearly related to temperature by the Boltzmann constant. The reason why heat capacity of many materials is not constant is that, in many cases, the all possible degrees of freedom are not accessible because large potential energy barriers exist that arise from various interatomic forces; these potential energy barriers first need to be overcome before they can be accessed by the system energy. A simple example - ice has to be melted before H₂O can boil! --Damorbel (talk) 18:15, 30 May 2013 (UTC)

Yes, I agree that heat can be measured in Joules. No, I am not saying that heat is a rate of transfer of energy. I am saying that heat is an amount of energy (and an amount that can be measured in Joules) which is transferred from one object to another.

Here are some definitions from textbooks:

1) " Thermodynamics", by Herbert Callen, copyright 1960, first edition, no ISBN number. This gives a preliminary definition of heat on page 7 and a quantitative definition starting on page 17. The preliminary definition is: " ...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. A transfer to the hidden atomic modes is called heat."

The quantitative definition is: "The fact that the energy difference of any two states is measureable provides us directly with a quantitative definition of heat. To wit, the heat flux to a system in any process (at constant mole numbers) is simply the difference in internal energy between the final and initial states, diminished by the work done in the process."

2) From "Statistical physics", by copyright 1967, ISBN 07-004862-2, by Frederick Reif, page 35: "It is, however, quite possible that two macroscopic systems can interact under circumstances where no macroscopic work is done. This kind of interaction, which we call thermal interaction, occurs because energy can be transferred from one system to the other system on an atomic scale. The energy thus transferred is called heat. "

3) From "Statistical Mechanics", by Kerson Huang, copyright 1963, ISBN0 471 41760 2, pages 4, "(i) Heat is what is absorbed by a homogeneous system if its temperature increases while no work is done. …"

Note that all of these sources treat heat as an amount of energy ‘’transferred’’ from one system to another. Introductory physics books (and I could quote some if necessary) also treat heat as an amount of energy transferred from one system to another.

I suggest that the article follow this terminology. Cardamon (talk) 19:31, 30 May 2013 (UTC)

Cardamon, the (current) opening statement of the article is:-

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

..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.

This is incorrect in all respects, e.g. heat is the property of a body that gives rise to chemical change.

Also you write:-

heat is an amount of energy (and an amount that can be measured in Joules) which is transferred from one object to another without saying how this happens.

Please say:-

1/ Do you need a heat transfer causing temperature difference, to have "hotness"?

2/ Does a system at T > 0K in thermal equilibrium, thus without any heat transfer, contain any "heat"? --Damorbel (talk) 05:47, 31 May 2013 (UTC)

"Thus"

Editor DavRosen's addition to the caption of the picture of the surface of the sun needs comment and I think revision, at least while the official dogma is being enforced. His newly edited sentence reads: "Nuclear fusion in the Sun converts nuclear potential energy into other forms and keeps the Sun's temperature high. Some of this energy is ultimately emitted as black-body radiation, whose net transfer to Earth is due to its lower temperature and is thus a heating process."

The official dogma (in which of course I totally and unquestioningly believe) is that net transfer of energy by means other than mechanical, between closed systems, is transfer as heat. It is fantastically proud of itself that it does not mention temperature. Silly old Clausius, silly old Kelvin, silly old Maxwell, silly old Planck. These ignorant fools thought that something qualified as a heat transfer just because it was purely driven by a temperature difference. These ignorant fools did not know that they must not talk or think about temperature until it had been defined in terms of entropy through the second law of thermodynamics. That it had already been so defined by Kelvin, in terms of Carnot's principle, a version of the second law, in 1848 before the recognition of the first law, is of course no excuse, because the first law having the number one must be considered prior to the second law which has the number 2, and because there are never excuses for departure from official dogma. Of course today we are much cleverer than they were, and we know that the official dogma is the only way to think correctly; and we are humble and do not often congratulate ourselves on how clever we are.

But, dare I say it, it seems that DavRosen might be backsliding, and saying that the transfer of energy from the sun to the earth, each for this purpose being considered as a closed system (matter not transferred between them), by radiation, a means other than mechanical, is heat because it goes down a temperature gradient. He seems to imply this 'because' by use of the words "due to its lower temperature" and "thus". What diabolical wickedness. I am so shocked by this that I will need to rest and wait for his response. I suppose my shock would be dispelled if he just removed the word "thus".

Also, Editor DavRosen's edit seems to imply that the radiation from the sun is heat because it is black-body, also seeming to imply that it is black-body. True it is more or less near (though not exactly) black-body, but thermal radiation does not need to be black-body to qualify as a mechanism of heat transfer. I think this could be remedied by changing the word "black-body" to 'thermal'.Chjoaygame (talk) 06:56, 16 July 2013 (UTC)

Okay, good discussion and points, and I do think I'm going to learn something here.

But do you agree, even if not all heating processes are due to a temperature difference, that if a given energy transfer process is due to a temperature difference and decreases the temperature of the "sender" and increases the temperature of the "receiver" then it is is a form of heat transfer process? Focusing on black-body radiation itself, its net energy transfer from the Sun to Earth occurs because the Sun is hotter, correct? That is to say, if the Earth were hotter then it would transfer more bbr to the Sun than vice-versa.

I know that you in particular understand that all energy has mass and vice-versa, and matter isn't a well-defined concept, so any definition that relies on "no transfer of matter" is not meaningful in general -- should it perhaps be "no net transfer of momentum" instead?

In any case, do you agree that not all emission of energy (and not even all emission of radiant energy) from the Sun that reaches the Earth is thermal? Even if the Sun and Earth were both somehow kept cooled to abs. zero, some particle interactions within the Sun would still occur spontaneously (familiar radioactive decay is just one example) because they do not need to draw on or cool a thermal energy reservoir, and some of their products (some massive and some massless) would escape and reach Earth and transfer some energy to it; these would likely far exceed such transfers in the opposite direction simply because there is so much more of nearly every type of particle in the Sun than in the Earth. These particles carry some momentum, all of it away from the Sun and toward the earth (not in arbitrary directions as in the thermal case) and would do some work on the Earth by displacing it in the direction of this momentum transfer, in the direction of the force they exert on Earth. Although some of that energy would be dissipated in practice, it would be possible in principle to set up a device that would reflect some of them back towards the Sun with equal and opposite momentum and no dissipative loss, for example an electric field gradient acting on an electron coming from the sun until it reverses direction and heads back. Thus these particles *could* do mechanical work on the Earth, i.e. they needn't necessarily raise the temperature of the Earth, so they don't represent heat transfer. This is why I thought the 2nd original sentence, "Consequently, heat is transported to Earth as electromagnetic radiation.", was misleading.

Do you agree that, even for nuclear fusion at the Sun's temperature, not all the converted nuclear potential energy becomes available as internal thermal energy -- i.e. some can escape just as in the previous examples without any further thermal interaction within the Sun and thus without changing its temperature? This is why I objected to the original sentence "Nuclear fusion in the Sun converts nuclear potential energy into available internal energy and keeps the temperature of the Sun very high."

I'm sure there are other ways to rewrite the caption that would address these issues, but, come to think of it, why are we using such a complicated example? Why don't we switch to a more straightforward example, of which there are plenty?

DavRosen (talk) 16:32, 16 July 2013 (UTC)

I only want to ask you to remove the word "thus", and to replace the term "black-body" with the word 'thermal'. No more than that.

My reasons are: (1) For the sake of logical consistency and simplicity in an introduction, it is better to work directly from the official definition that is routinely insisted upon here, than to use an indirect line of reasoning, relying on deductions, such as you propose. The official definition is that heat is energy transferred from one closed system to another by means other than as macroscopic work; it is its pride and joy that it doesn't mention temperature. If you don't like it, you could try to overthrow the massive, even fierce, consensus of orthodoxy that has established it here. You may have noticed that a new section, more or less to the effect that perhaps the temperature-difference definition is not as ridiculous as the official dogma insists, has just been deleted, though not because it was faulty. If you care about this, you might like to restore that deleted section. (2) Both solar and terrestrial radiation are nearly but not exactly black-body, but are thermal.

As for your extensive discussion, only a few words. In talking about particles you are leaving the macroscopic world where heat lives, and entering the microscopic world where heat is not a natural citizen, because the natural citizens there are microscopic; internal energy is still a citizen there, but not heat as defined in the macroscopic theory; microscopic stories ruthlessly use the word heat, but they don't mean it as it is meant in the macroscopic theory. So far as I know, all heat transfer is due to temperature difference, but that is not the official definition. It is a deduction from it and from some other ideas. To try to bring in here the sophisticated idea, that there is no clear definition of matter, is a mighty distraction from the main line of thinking here, which assumes the distinction between matter and energy as given. If you don't admit that matter and energy are different here, because you insist that matter is not well defined, for consistency you also have to give up the idea of heat as far far far less well defined, and there is no point in having an article on heat at all. Systematic thinking works with well defined, limited-scope theories, and does not try to fit everything into a one-size-fits-all theory. Systematic thinking about heat is macroscopic and considers matter and energy to be distinct.Chjoaygame (talk) 19:30, 16 July 2013 (UTC)

Implication word ("thus") removed. Actually I ended up rewording a lot of it, and it still needs work.

Okay, I got a little carried away with absolute truth (as-we-know-it), and I've benefited from reading your words. I'm pretty sure someone else will come along who will want to remove even more of what I've said :-)

DavRosen (talk) 21:08, 16 July 2013 (UTC)

Good work in removing the worrying word.

As you say, the picture shows something that is "complicated", not quite "straightforward". The sun-earth-outer-space compound system is a non-equilibrium one. In a crude sort of way one may think of the earth as lying 'between' the sun and outer space. The earth is heated by the sun and cooled by outer space. Radiant heat is passing in net from sun to earth and then from earth to outer space. The sun is hotter than the earth, and the earth is hotter than outer space. Also the sun is being cooled by outer space; indeed this is most of the cooling of the sun. As a very rough approximation, the thermal energy of the sun is supplied by nuclear reactions within it, and this more or less balances the heat lost by the cooling mechanisms, and the earth is in more or less a steady state of internal energy, being supplied by the sun and depleted by outer space. This is a dynamical situation, more complicated or advanced than a simple transfer of energy, between a closed system and its surroundings by mechanisms other than adiabatic work, that advances the system from an initial state of internal thermodynamic equilibrium to a final one. I am not sure that it is quite the thing to try to expound in detail in a caption of a bright coloured picture in the lead of an article about heat. In particular, the idea of available internal energy, being supplied by nuclear reactions, is a bit complicated for an introductory caption of a picture in the lead of an article about heat. I don't worry too much about this picture. It is coloured and dramatic. I don't have strong views about its appropriateness. If you feel "pretty sure someone else will come along who will want to remove even more of what I've said", you could anticipate them and put in something that you think will not make someone want to do such a thing. On the other hand, there are some very worrying problems with this article, that deserve careful and circumspect attention.Chjoaygame (talk) 14:26, 17 July 2013 (UTC)

Good points. If you draw a system boundary as the convex hull of the earth & the sun (enclosing them and the space through which they can directly exchange radiation), then within this system there's a net heat transfer from the hot sun to relatively-cool earth; of course heat also flows in and out of the system as well. Although the net energy transfer in-out of the earth system itself may be near zero, the Sun provides something just as important: it counterbalances some of the increase in entropy of the earth, i.e. increases the ability to do work on earth. I guess you could say it provides a higher-temperature heat reservoir so that some work can ultimately be extracted from the heat transfer to earth (not sure i'm saying this correctly but of course it relates to a heat engine). For example a photocell on earth can convert some of the sunlight to electric energy that can do work, or, more importantly, plants do something similar through chemical energy, etc. DavRosen (talk) 18:08, 17 July 2013 (UTC)

Latest reversal

This reversal here explains:-

No, heat transfers potential energy also. When ice melts, kinetic energy and ten do not change. But heat flows.

I do not think there is a consensus anywhere for heat flowing, this should have died in the 19th century. It is completely destroyed by the conservation of energy. I suggest that explanations relying on "heat flowing" be confined to historical articles about caloric. Caloric flowed, but heat doesn't. Let's get rid of this non-scientific idea! (I consider this discussion sufficient to eliminate the (linked) edit unless, of course, a good defense of caloric appears! --Damorbel (talk) 15:46, 17 July 2013 (UTC)

• I don't care if you want to say "heat flows" or "heat transfers energy." Whatever. So long as you don't say "heat transfers kinetic energy." Heat transfers many kinds of energy. When ice melts at the same temperature as the water it melts in, kinetic energy is not being transferred. Rather, mean kinetic energy is the same in the ice as in the water, as they are the same temperature. If energy flows from one to the other, it is not kinetic energy, or at least no purely kinetic. The difference between ice and water at the same temperature, is that ice has more potential energy, having overcome the energy of binding of water molecules into the crystal. That energy is transferred into the crystal as heat when the ice melts. But that heat energy cannot be said to be really kinetic or potential energy. It's a mixture of of both and this depends on scale. All that can really be said about this energy is that it is composed of both kinds of energy microscopically. A molecule's kinetic energy can be absorbed into another molecule's potential energy, and vice versa. I reverted the phrase because you had inserted the word "kinetic" and that is wrong. It is not just a kinetic process. 22:29, 17 July 2013 (UTC)(Unsigned edit by SBHarris.)

• Editor SBHarris has made the right call here.Chjoaygame (talk) 22:52, 17 July 2013 (UTC)

SBHarris you write

I don't care if you want to say "heat flows" or "heat transfers energy."

If heat flows it is conserved. But, for example, in the carnot cycle heat neither 'flows' nor is conserved, the output heat, at a lower temperature, is always less than the input heat. The work done by a (perfect) Carnot machine is equal to the difference between the input heat and the output heat, since the work done by the carnot machine has an mechanical energy equivalent to the heat difference, energy is conserved.

Similarly with 'ice melting'. When ice melts there is no change of the kinetic energy in the ice because there is no change of temperature. The energy of the H₂O must increase to melt the ice but that is to break the crystal bonds of the ice. This energy of fusion can come from any source, chemical energy, mechanical work, there is no requirement for it to come from the kinetic energy of other particles i.e. heat. --Damorbel (talk) 06:17, 18 July 2013 (UTC)

Editor Harris, you write:-

The difference between ice and water at the same temperature, is that ice has more potential energy, having overcome the energy of binding of water molecules into the crystal.

I suggest that it is water that has more potential energy than ice, this is the so-called latent heat given up as it freezes.

And again you write:-

That energy is transferred into the crystal as heat when the ice melts.

How can it "transfer... into the crystal"? Surely the crystal ceases to exist when it melts? It the fusion energy (latent heat of fusion) transferred to the the water molecules that puts them in the liquid state.

You have written nothing that supports deleting my edit; please explain why the deletion should stand. --Damorbel (talk) 07:15, 18 July 2013 (UTC)

Tidy up

I have tidied up the lead to make it explicitly express the current orthodoxy on transfer of energy as heat. I have cited more authoritative references.Chjoaygame (talk) 22:14, 17 July 2013 (UTC)

Maybe I'm taking this too literally

"Heat in physics is defined as energy transferred between closed systems by mechanisms other than work."

but this sounds like you're claiming that heat transfer between two given systems is impossible unless both systems are each completely closed to matter transfer. Why can't there simultaneously be both heat and matter transfer between two given systems? Or do you mean that, in order for heat transfer to exist, it has to be possible to define two closed systems across whose mutual boundary the heat is being transferred? Still seems confusing to me. DavRosen (talk) 04:22, 18 July 2013 (UTC)

The definition is standardly stated in cited reliable sources for closed systems, as you may verify by reading them and other standard texts on thermodynamics. I am reporting reliable sources, not offering my own view. The situation for open systems is not simple, as you may verify by reading standard texts on thermodynamics. The present article's lead is simply silent on the case of open systems, making no claim about them. Some more on this in the article on the First law of thermodynamics#First law of thermodynamics for open systems.Chjoaygame (talk) 04:38, 18 July 2013 (UTC)

Conservation of heat

Here This edit makes an already poor article worse, How is it possible to claim that:

Even though heat is not a conserved quantity, the term 'heat flow' is often used.

That means that the law of conservation of energy is being explicitly ignored. Gentlemen please!

The article contains massive deficiencies e.g. why no mention the fact that heat energy is zero at 0K?

The article has other very serious deficiencies, throughout the whole article it constantly confuses heat with heat transfer (calling the latter "heat flow"!), at the very least it should specify the difference. --Damorbel (talk) 07:48, 18 July 2013 (UTC)

It is simply a fact that may be checked by reading current reliable sources, that the term 'heat flow' is often used in reliable sources. It is not up to Misplaced Pages editors, gentlemanly though they may claim to be, to impose their own private views over what is found in reliable sources.Chjoaygame (talk) 09:07, 18 July 2013 (UTC)

Um, Chjoaygame, (I suppose it is your contribution above) the conservation of energy and the non consevation of heat is not a private view. If you wish to promote the caloric theory, please do it in that article. Even the wiki article on the conservation of energy explains the origins how and why heat is not a conserved quantity, this is so important it should be prominent in the Wiki article on heat.

An article on a scientific matter needs to be clear, the fact that many authors do not understand that 'heat flow' is a dead concept is every reason why the error should be identified, it is absolutely equivalent to the old flat earth concept, mention it but please don't ever cite it as a valid scientific idea. --Damorbel (talk) 09:34, 18 July 2013 (UTC)

Dear Damorbel, you ask for it to be noted in the article at the relevant point that heat is not conserved quantity. If you read the article you will find that it had already been so noted when you complained about it. No rational reader would read into that an attempt to deny the law of conservation of energy. The term 'heat flow' is often used by reliable sources; that is a peculiarity of customary language, but still a fact of usage, as may be easily verified by reading reliable sources. No rational reader would read into that an attempt to deny the law of conservation of energy. To make you happy, I have added explicitly that this is a peculiarity of customary language.Chjoaygame (talk) 10:02, 18 July 2013 (UTC)

Lead

Damorbel has made two significant edits, one an undoing, the other an overwriting of the lead.

The undo is claimed by Damorbel to be justified by "unavailability" of one of the cited reliable sources, but which one is not stated by Damorbel. All the cited sources are standard texts available in libraries. Damorbel's claim of "inaccessibility" is not accurate, and in any case would be an inadequate reason to delete the whole new section.

The overwrite is an attempt by Damorbel to impose his private views against the accepted orthodoxy of current reliable sources, yet another of his repeated attempts of this kind. Moreover Damorbel's overwrite contains errors of physics which have been pointed out to Damorbel elsewhere, including just above by SBHarris, and it would be redundant for me to repeat those criticisms of his private views again here. Damorbel needs to take heed of those criticisms, not ignore them as his overwrite attempts to do. Damorbel's attempt to re-write the lead is not acceptable.Chjoaygame (talk) 09:06, 18 July 2013 (UTC)

Please give reasons why the previous version of the article reported the consevation of energy and the non-coservation of heat correctly and why this was not a serious defect needing correction. --Damorbel (talk) 09:42, 18 July 2013 (UTC)

Your request for reasons is unfulfillable because it is based on a mistaken premise. Contrary to the mistaken premise of your request, the article did make the appropriate note that heat is not a conserved quantity; and no reasonable reader would have taken it to deny the law of conservation of energy. Nevertheless, as noted above, however, just to make you happy, I have added to the article an explicit note that we are dealing with a peculiarity of customary language.Chjoaygame (talk) 10:07, 18 July 2013 (UTC)

Your request for reasons is unfulfillable because it is based on a mistaken premise And what "mistaken premise" please? You do not identify any "mistaken premise", How am I supposed to respond?

The mistaken premise is specified in the sentence following the one you quote from me. Your mistaken premise was that the article failed to note that heat is not a conserved quantity. The article did note just that: "Even though heat is not a conserved quantity, the term 'heat flow' is often used." You ask "How am I supposed to respond?" You always have the option of reading the edits you complain about before complaining about them, and then you wouldn't be called upon to respond.Chjoaygame (talk) 13:40, 18 July 2013 (UTC)

'heat flow' is a concept belonging to the caloric theory of heat which is obsolescent because it did not take into account the conservation of energy, the term has no place in an article on Heat. --Damorbel (talk) 14:19, 18 July 2013 (UTC)

As I have pointed out before, the article makes no distinction between heat as a form of energy (joules) and heat transfer which is joules per second (watts). This is not "a peculiarity of customary language", it equally deficient with failing to distinguish between distance (metres) and speed (metres per second) and I see nothing in the article or the talk that deals with this fundamental objection to how the article is written, the article is grossly in error. --Damorbel (talk) 11:28, 18 July 2013 (UTC)

You are here raising another complaint, moving the goal posts while the ball is in midflight. Your just previous complaint was that it was invalid to speak of flow of a non-conserved quantity; the valid response to that, a response that you wish to deny, is that in the current literature in fact it is a peculiarity of customary language to speak of 'flow of heat', and the article reports that. You think that peculiarity wrong, and perhaps you may be right, but the Misplaced Pages does not try to dictate how language ought rightly to be used in the literature, no, the Misplaced Pages just reports how it is actually used there.

But now, as to your moved goal posts: You now complain, yet again, as you have endlessly done here before, that you think that heat should be read as a form of energy measured in Joule, and that heat transfer should be measured as a time rate measured in Watt. The answer to this has been repeatedly explained to you in these pages, and it would be redundant of me to try again to tell it to you yet again. You say that there is nothing in the article that deals with what you call "this fundamental problem". The "problem" is only in the language-processing recesses of your mind, and even if it were not redundant for me to try to do so, my skills at exposition are far from adequate to dislodge it from there.Chjoaygame (talk) 13:40, 18 July 2013 (UTC)

Joules and watts? No, not moving the goal posts, just another of the many defects in this article. Heat is measured in joules, heat transfer in watts, like distance and speed, very different concepts.--Damorbel (talk) 14:19, 18 July 2013 (UTC)

It doesn't matter of heat is conserved if you're talking about heat transfer across a 2-D surface. Heat energy in that case is "conserved" in the sense of not disappearing in fluxes across surfaces. Any flow into such a surface is the same as the flow out of the surface, with no caloric implied. In the same way, electricity is not conserved either, yet 3.6 MJ (1 kw-hr) of it going from the outside wiring into my house, is 3.6 MJ that winds up coming INTO my house. There is no loss or gain of energy there-- the energy that comes in from outside is the energy that winds up inside. Heat is the same. We can speak of electricity in MJ or in KW (as an energy or a power) and these are merely ways of talking about electricity as (either) a differential or an integral WRT time. In either case it's electricity and it's understand that electricity is always energy-in-motion, and that even when we speak of electricity as an energy, it was (and always will be) delivered at an energy-rate (a power), since electricity (as delivered from the electric company) never sits still. Nor does heat (perhaps there are ways that electricity can be though to sit still, but there aren't for heat). Thus, heat IS heat-transfer, just as electricity IS electricity-transfer. An amount of heat represents an integral of heat transfer over time, but not an amount of heat sitting somewhere, static. Okay?

It's silly to insist that heat be a kinetic thing when there are plenty of ways to transfer heat that aren't kinetic. Heat transferred as radiation isn't kinetic, and that's reason enough right here not to generalize. But also there are latent heat transfers from mechanisms like steam condensation, that transfer large amounts of heat in turbine systems, and that heat energy is stored as latent heat of vaporization, not kinetic energy of molecules. Clear? SBHarris 01:25, 19 July 2013 (UTC)

SbHarris, you write:-

It doesn't matter of heat is conserved if you're talking about heat transfer across a 2-D surface. Heat energy in that case is "conserved" in the sense of not disappearing in fluxes across surfaces. Any flow into such a surface is the same as the flow out of the surface, with no caloric implied.

Imagine the Heat (with whatever definition) is presented to the surface of a cube of ice, if the heat source is >0C then the ice will melt without, at first, any change in temperature. What is conserved, if anything, the heat or the energy? --Damorbel (talk) 09:47, 19 July 2013 (UTC)

Why, both. The heat that leaves the water is the heat that enters the ice. Joules and watts of one is joules and watts of the other. To make or destroy heat you need a 3-D control VOLUME. A surface will never do. Just like electricity, where the analogy is close. Hope that's helpful, SBHarris 10:57, 19 July 2013 (UTC)

But to melt the ice T_H as I mentioned, must be >T_ICE. Let us say the heat comes from 80gm water @ 10C after a time this will have melted 10gm ice and everything is now at 0C, and nothing is at 10C any more, so the energy stays the same but the heat has disappeared! --Damorbel (talk) 12:05, 19 July 2013 (UTC)

Yes, so what? Heat is not conserved and can disappear into a control volume. That is why it is unwise to even use the phrase "thermal energy" except as a synonym for heat-flow = heat. Thermal energy can cross a surface into a volume, but cannot THEN be said to reside in said volume. All conservation laws of heat end after it crosses the surface, and become only conservation laws of internal energy. However, heat flow through a control surface represents energy in motion, and is conserved the way any type of energy is conserved. In this case, a certain amount of heat flows into the ice to melt it. This is heat that flows through the imaginary surface at the boundary of the ice. It comes from the water, which is cooled by its loss. The heat that flows into the ice is the same number of joules of heat that comes from the water. That is a surface boundary problem.

After that, however, all bets are off. The energy that crosses this surface is heat while it is in the act of crossing, but it is not (necessarily) entirely heat before, and it is not (necessarily) 100% heat after it has crossed. Heat is "conserved" while it crosses the surface inasmuch as the heat energy that leaves one volume is the same as the energy that enters the other. But after that, only the energy is conserved, as some of the heat can (and probably does) change forms to some sort of other energy that is non-thermal. Its "thermal-ness" (its nature) is not conserved when talking about the volumes it come from and goes to. Only when talking about the surface is the heat that leaves the water the same as the heat that enters the ice. After it has crossed, it is internal energy, but no longer need be heat (it CAN be heat in conduction, but there is no guarantee). And after it is past the surface it need not be any longer thermal energy, which is why we deprecate the term except at the 2-D boundary, through which heat flows. SBHarris 01:29, 20 July 2013 (UTC)

Please, use this: °C for degrees. I detest to see rubbish like ^oC and randomly chosen round symbols instead of °. Incnis Mrsi (talk) 15:38, 19 July 2013 (UTC)

Damorbel, could you specify a WP:reliable source that backs your claim about this proportionality (mathematics)? Incnis Mrsi (talk) 14:48, 19 July 2013 (UTC)

J C Maxwell 'Theory of Heat' p64 :-

If we assume, what is nearly though not exactly true, that the quantity of heat required to heat the lead is the same for each degree of rise of temperature... --Damorbel (talk) 15:16, 19 July 2013 (UTC)

Nearly though not exactly true. So… ? Incnis Mrsi (talk) 15:38, 19 July 2013 (UTC)

Errors

I tire of correcting Damorbel's faulty edits. I trust someone else may find time to do it on his latest]. Part of the trouble is that responding to his errors only encourages him to make more of them.Chjoaygame (talk) 13:49, 18 July 2013 (UTC)

I would like to have all details of these errors, please.

Your remark :-

Part of the trouble is that responding to his errors only encourages him to make more of them.

Must be seen as a personal comment. Please refrain, your opinions about me are of no relevance in Misplaced Pages. --Damorbel (talk) 14:03, 18 July 2013 (UTC)

Damorbel, I will try not to make any personal comments here. If you don't stop re-inserting your views against the consensus here, we're going to have to ask admins to take action against you to prevent this. You keep re-inserting your incorrect statements about heat being kinetic energy, etc. It's good that you're interested in this subject but you should take thermodynamics course or read textbk if you want to find out how the scientific community defines these terms rather than how you are defining them. Or, please try reading the Heat article in another language as linked on the left side, using Google Translate to read it in English. Otherwise, there are other venues where you can write essays about why these terms should be (re)defined in the way you describe, but not in an encyclopedia, please. In case it helps you at all, let me point out that thermal energy is stored in part in the oscillations of molecules and atoms, and oscillations involve a continual transformation between kinetic energy (reaching a max when the particle is moving fastests) and potential energy (when the particle is at its most extreme displacement). Look up oscillations of springs for this concept. Thermal energy is a term used to describe a property of a system or body, while the term heat is defined as only a property of a specific process that transfers a given amount of energy in certain ways (which represents a change in energy of one system and opposite change in another). Also, Joules/second simply aren't units of energy (nor of heat), they're units of power (pls. look it up), which is energy per unit time. DavRosen (talk) 14:23, 18 July 2013 (UTC)

10:27, 18 July 2013‎ Damorbel (talk | contribs)‎ . . (55,110 bytes) (-201)‎ . . (Undid revision 564791172 by DavRosen (talk)DavRosen writes:- " Pls. take course or read textbk)" Personal attack!) updated since my last visit (undo | thank)

Damorbel, I meant it as a constructive suggestion for finding out the accepted definitions of some of these terms, but I can see how you could view it as a personal attack, and I apologize for that. That does not give you the right to continue your edit war: you have re-inserted your views on heat being kinetic energy, among others, many times, and they have been corrected by several different editors. The consensus here is clearly that your views are your own, and not encyclopedic descriptions of mainstream scientific usage. You can't keep putting your own views in -- you have to first obtain/change the consensus here on the Talk page. I, myself, am not going to undo your undo of my undo of your views because I don't want to be seen as edit-warring. I have only done that single edit (undo) of this article on this dispute. Maybe I'll just tag. DavRosen (talk) 14:47, 18 July 2013 (UTC)

Damorbel, maybe it would help if you consider a solid rather than a gas. How can the thermal energy of a solid object (such as a piece of wood) be entirely kinetic when its molecules don't travel around? It has thermal degrees of freedom such as oscillation/vibration of those molecules, but the force keeping the molecules from traveling far is related the potential energy . DavRosen (talk) 14:59, 18 July 2013 (UTC)

DavRosen, I don't believe Damorbel is claiming that the thermal energy of an object is entirely kinetic. He is saying (I think) that the transfer of energy we call "heat" involves only kinetic energy. For example, supercooled water at -2°C has more potential energy than does ice at -1°C, but less kinetic energy. So, put in thermal contact, heat would flow from the ice to the water. Spiel496 (talk) 16:26, 18 July 2013 (UTC)

There was an edit conflict a while ago And I will add my material after this. --Damorbel (talk) 20:36, 18 July 2013 (UTC)

DavRosen, you write:-

that thermal energy is stored in part in the oscillations of molecules and atoms, and oscillations involve a continual transformation between kinetic energy (reaching a max when the particle is moving fastests) and potential energy (when the particle is at its most extreme displacement).

You are correct. But these vibrations are called 'degrees of freedom' where the potential and kinetic energy alternate, on average they are the same and each has a peak equal to twice its average, so the peak (of either kinetic or potential energy) is equal to the total energy content.

The concept of thermal energy does not involve any particular measure of temperature; two system have different thermal energies, but the same temperature - result no heat transfer. But if they have different temperatures but the same themal energy then there will be energy transfer (from the hotter to the colder.)

Finally. You write:-

Joules/second simply aren't units of energy

That is what I meant when I insisted that heat transfer is measured in Watts (Joules per second) and heat (by itself) in Joules. --Damorbel (talk) 20:42, 18 July 2013 (UTC)

DavRosen, I wonder if you get what I am saying about the 'potential energy' in an oscillating system. I had the same problem with this my self, it is not well explained and probably not very well by me. I think Spiel496 was pointing this out in his note above. Whatever the case I would like to be sure it is understood.

Sorry if I was a bit sensitive about personal remarks but they are very much against Wiki policies. --Damorbel (talk) 20:50, 18 July 2013 (UTC)

If you understand that the oscillations can alternate between potential and kinetic energy, then why do you insist on using only the term kinetic energy, and removing the term potential energy in connection with heat and temperature everywhere you see it mentioned? You say "Heat in physics is defined as the kinetic energy the particles of body.", "When two closed systems come into thermal contact, they exchange the kinetic energy of their particles. The result is a spontaneous net transfer of kinetic energy, ", , "Heat in a body is stored as the kinetic energy of the particles, changes in heat energy in a body result in temperature change. ", Heat is the kinetic energy of particles, atoms, molecules etc. and their underlying microscopic degrees of freedom." Etc. DavRosen (talk) 21:13, 18 July 2013 (UTC)

You write:-

why do you insist on using only the term kinetic energy

In a resonating system (degree of freedom) the total energy, when oscillating between kinetic and potential, is constant; the peak energy can be either kinetic or potential - in each case the peak is equal to the total energy. Since it is only the kinetic part that communicates energy to adjacent particle (corresponding to a collision in gas theory). The use of the term kinetic energy for particles in solids is justified precisely because the peak (kinetic energy) is equal to (average) total energy. --Damorbel (talk) 06:58, 19 July 2013 (UTC)

I'm not so sure the transfer mechanism is always kinetic per se: the particles may be coupled at the boundary by their electrostatic force on one another as they get close, in which case the transfer is partially as electrostatic potential energy during part of the transfer. But, more importantly, the principles of the thermodynamics hold regardless of the specific microscopic mechanism by which thermal contact and transmission occur, so nothing is gained by specifying that it must always be kinetic. Even if in practice with ordinary matter in solid/liquid/gas phpases the transfer were of a specific microscopic nature, thermodynamics could just as well be applied to other, more exotic types of systems where this might not be the case, such as might perhaps arise under the extreme conditions of a black hole or with exotic particles (not just atoms); this is speculation but the laws of thermodynamics don't depend on such microscopic details.

We are probably on the same wavelength. You write " the particles may be coupled at the boundary by their electrostatic force on one another " But I prefer electromagnetic forces. Photons do the job for EM radiation and they transfer momentum in rather the same way as a collisions do in gases, the main difference is that emission of photons leaves behind a recoil reaction that conserves linear momentum, this was postulated by Einstein in a 1917 paper "On the Quantum Theory of Radiation", it is a 'good read'. --Damorbel (talk) 15:04, 19 July 2013 (UTC)

In any case, the sending system's average microscopic potential energy does decrease and the receiving system's avg PE does decrease by some amount, at least if some vibrational dofs exist. In the case of only vibrational DOFs, half the transferred energy shows up as a change in avg potential energy and half as a change in avg kinetic energy. This is because each particle reaches its peak at an independent time so overall half the thermal energy is kinetic and half is potential microscopically at any given time for a typical vibrational dof. But again the specific form of energy or types of DOF at the microscopic level don't affect the thermodynamic behavior of the system at a macroscopic level, which is why we simply call it thermal energy rather than focusing on exactly what form the energy takes in a particular system at a particular time at a microscopic level. Thermal energy, no matter what you want to call it and what forms it may take microscopically, goes to zero in lockstep with the abs. temp., all else being equal/unchanging. DavRosen (talk) 14:48, 19 July 2013 (UTC)

Also, when you examine a given system at a given time, without knowing what it's state was in the past, there is no way to tell, in general, exactly how much of its internal thermal energy it aquired through a heat transfer process (say, thermal contact with a hotter body), and how much it acquired through work being performed on it by application of a force. For example, a gas system at P,V,T could have originally been in any of a number of states, and thus gotten to the present state via different amounts of work and heat processes. You can't say it "has" a certain amount of heat and a certain amount of work, because it's impossible to tell which combination got it there. Similary, you could start at its present state and get it to nearly 0 degrees K entirely via thermal contact with something even closer to 0 K, or you could get part of the way there by letting it do work on something in its surroundings and then do the rest thermally. So how do you know "how much heat" it had in it, unless you always count both the heat and the work? The property of the system that goes to zero at 0 K is its thermal energy, not "its heat". By saying thermal energy, we're agnostic about how much work (vs heat) might have been involved in adding or removing the thermal energy. DavRosen (talk) 21:46, 18 July 2013 (UTC)

further tidy up

I have tidied up some introductory sections to remove faults which were inserted during and survived the recent flurry of edits.Chjoaygame (talk) 17:35, 19 July 2013 (UTC)

helpful intervention

We have been favoured by the helpful intervention of Editor Apteva. Some helpful comments by this editor are to be found here. I read, perhaps mistakenly, on the page User:Apteva that this editor is not an administrator but would like to be, and that he is a kind of patroller.

Particularly helpful are Editor Apteva's remarks that "the article is a mess, and needs people who have a basic understanding of heat contributing, but not by edit warring. It is a technical subject which requires the assistance of someone who is an expert." This is most helpful when juxtaposed with his further comment that "As far as the general public is concerned, anyone who has taken (and passed) even one thermodynamics course qualifies as an expert on heat and temperature," and his comment that "the editor in question has clearly studied thermodynamics, qualifying them as an expert in the subject." (I always like to see that the neutral pronoun "they" is used instead of the native English speakers' 'he', because political correctness is most important for me.) From the context, I read (perhaps mistakenly, but hard to verify because of the fancy bureaucratic language) that in this quote, by "the editor in question", Editor Apteva means Damorbel. If Editor Apteva really means all this, what he says appears to mean that the article requires the assistance of someone such as Damorbel. It is good to know that we are guided by such wisdom, by someone manifestly holier than us.

The administrative mind is a wonderful thing, for which we all may be most grateful. Yet I remain puzzled as to how Editor Apteva is qualified to force his opinions on us as he seems to have done.Chjoaygame (talk) 18:03, 19 July 2013 (UTC)

• Chjoaygame, that's not helpful. I think we and almost all the editors here are on the same page with regard to the disruptive edit-warring of Damorbel, over a long period of time, to replace some established definitions with his own throughout articles, but let's start with the assumption that anyone new who wants to help is well-intentioned. DavRosen (talk) 18:16, 19 July 2013 (UTC)

Perhaps we are all on the same page, but as a routine, Damorbel gets away with it scot free, and our being on the same page is inefficacious. There are lots of little messes left by him that I have not touched because I routinely do not respond to his depredations because if I do it is usually followed by a punitive raid from him. As for the very helpful Editor Apteva, as far as I can see he sees his role as to defend Damorbel's depredations, and somehow he seems to have some kind of power to delete efforts to do something effective to the contrary. I am puzzled about that apparent power. Can you enlighten me?Chjoaygame (talk) 19:08, 19 July 2013 (UTC)

I am definitely not defending anyone's actions. As I see it the article needs work, and edit warring is not the way to fix things. All of us have our own knowledge about subjects, but we need to support that with reliable sources. I am detecting different opinions of what the article should say, which could partly come from different definitions of the word heat. For example, the article begins by saying "in physics and chemistry, heat is". Well what is heat outside of physics and chemistry? Is this article only about heat as defined by physics and chemistry? And do those two even use the same definition for heat? I found the last section, "Usage of words" particularly confusing, even though it was certainly written to clarify the word heat. Apteva (talk) 21:44, 19 July 2013 (UTC)

Whether or not you intend it, your sanctimonious comments have an effect of defending someone's action. The depredations of the someone are a major obstacle to others trying to do useful work on the article. You should think more carefully about your actions in this. We tried to specify the article as about a single defined area, Heat (thermodynamics), because "Thermodynamics is a branch of natural science concerned with heat and its relation to energy and work". But it didn't work, largely because of some editors being dominant over others.Chjoaygame (talk) 05:20, 20 July 2013 (UTC)

• I am not commenting on who would be helpful in bringing the article up to WP:GA or WP:FA status, only commenting on what needs to be done. The lead is too long, has too many references in it, most of the article is unreferenced, and many of the references are difficult to verify. The lead is used to summarize the article, and normally only statements that would be surprising need to be referenced in the lead, with all statements in the lead supported by references in the body of the article. I see no surprising statements in the lead that require referencing in the lead. Encyclopedias need to meet the needs of all readers, and topics need to be introduced in relatively simple terms. If heat is used with more than one meaning, separate articles or separate sections of this article can be used to cover those separate meanings. It is always important to focus on content, and not on the specific contributors (WP:FOC). Comments to or about contributors belong on that contributor's talk page. What's up with the lower case section headings? Section headings are always sentence case, and begin with a capital letter. Is there some reason for deviating from that convention here? See the section about neutral section headings here: WP:TALKNEW Apteva (talk) 18:32, 19 July 2013 (UTC)

Good to have your further advice. Many thanks.Chjoaygame (talk) 18:56, 19 July 2013 (UTC)

good edit

DavRosen changed the wording from one that used the specialist term "closed" to an ordinary language usage about transfer of matter.

I think this was a very good move. The point is not whether matter transfer might happen. The point is whether it actually does happen. I regard this as a useful conceptual clarification, that opens the way to further clarity.Chjoaygame (talk) 05:26, 20 July 2013 (UTC)

Convection

Convection is a perfectly good description of the third type of heat transfer, and actually, "convective circulation" is less accurate. "Convective heat transfer" would just be saying the same thing twice. Apteva (talk) 08:21, 20 July 2013 (UTC)

Convection is a general term, and includes the transfer of matter and internal energy. The definition of heat transfer excludes transfer of matter as mechanism. To make convection into a form of heat transfer, convection needs to be stripped of its matter transfer. That is done by insisting that it be circulatory. Thus, strictly speaking, heat transfer by convection has to be specifically and exclusively by convective circulation, as explained in the article, with a reference a classic example in a classic reliable source. Convection in general carries internal energy but not heat. People who cover what they say with "actually" usually mean that they have insight superior to the delusive view of their target, who sees only the imaginary, not the actuality.Chjoaygame (talk) 10:09, 20 July 2013 (UTC)

There is no requirement that the convection be circulatory to transfer heat. It is better to just say there are three types of heat transfer, conduction, convection, and radiation. Calling two of them simple and one complex is not helpful either. Apteva (talk) 11:38, 20 July 2013 (UTC)

Careful attention to the definition accepted in the article will reveal that convection in general transfers internal energy, but not in general heat. This is because only circulatory convection excludes transfer of matter between the source and the destination of the transferred internal energy, and transfer as heat excludes transfer of matter as a mechanism.Chjoaygame (talk) 12:33, 20 July 2013 (UTC)

The mathematics of convection do not impose that the convection be circulatory. The medium that contacts the hot object does not need to return to the hot object, which is what the word circulatory means. Just say,

Heat is a means of transferring energy from a hotter object or region to a colder object or region, and can be done by conduction, convection, or by radiation. Heat is measured in Joules, or in calories. In physics and chemistry heat is only the transfer of energy. Older and more common definitions of heat, such as in engineering, define heat as the energy that an object or region has due to the object or region's temperature, with the total heat being roughly proportional to the mass and temperature, in addition to the transfer of energy. A calorie is defined as the heat required to increase the temperature of one gram of water by one degree Celsius. A Joule is defined using physical parameters, the work done in applying a force of one newton through a distance of one meter. One calorie is roughly or even exactly 4.184 joules (food uses the kilocalorie, calling 1,000 calories one calorie).

Apteva (talk) 19:12, 20 July 2013 (UTC)

You apparently try to apply standards of a thermodynamics textbooks to a Misplaced Pages article, which is discouraged. Convection is a type of motion. It may caused by whatever reason. Is includes what is called convection in thermodynamics, but is broader. It usually results in a heat transfer, but a convection is a mechanism and the heat transfer is its result. It is convective circulation a pleonasm; convective heat transfer is, contrary, perfectly meaningful: there are three types of heat transfer, and the heat is not the only thing that can be transferred. Incnis Mrsi (talk) 10:25, 20 July 2013 (UTC)

• It depends on the way you choose to specify the thermodynamic description of the system. So, you have a physical system, an exact description of which would require you to specify an astronically large amount of information. The thermodynamic description of a system is a coarse grained description of the system, what is included here is everything that is visible after the coarse graining is performed. Energy transfer that becomes invisible due to the coarse graining is by definition heat. You are free to decide how you perform the coarse graining, but this then affects the separation of energy transfer into heat and work. Also, the same physical system can be out of thermal equilibrium in one description, barring one from describing it thermodynamically at that coarse graining level, while in a more fine grained description one can see that it consists of subsystems that are in internal thermodynamic equilibrium which are not in thermal equilibrium with each other. If the latter is approximately true when the coarse graining is fine enough, one considers the system to be in local thermodynamic equilibrium. Count Iblis (talk) 10:59, 20 July 2013 (UTC)

• As Editor Incnis Mrsi rightly says, convection is a broad or general word, not specifically belonging to thermodynamics, and not restricted to transfer of energy. It just means that something is carried by bulk flow. It is not restricted to circulatory pictures, though of course, it is usually part of a circulation.

Perhaps it is discouraged by Misplaced Pages policy to apply the standards of a thermodynamics textbook to a Misplaced Pages article. Editor Incnis Mrsi is the Wikilawyer here, and would know. But the policy doesn't seem to cover this article at present. Perhaps it should, and perhaps it can be imposed on it starting now. But till that happens, the article has been more or less thermodynamical in style.

When convection includes actual transfer of matter between the source and destination of the transported internal energy, it is excluded by the strict definition of heat transfer: it is just transfer of internal energy, properly speaking; 'heat transfer' is not a thermodynamically acceptable expression for it.

Editor Incnis Mrsi says that 'convective circulation' is a pleonasm, meaning that usually convection is eventually part of a circulation, because of conservation of matter. In that sense he is right. But, in another sense, the one obviously intended here, and detailed in the article, what is eventually part of a circulation is not necessarily circulatory when taken by itself. An open thermodynamic system can be defined to include only a part of a circulation, and to exclude the rest of it. As Editor Count Iblis rightly says, "It depends on the way you choose to specify the thermodynamic description of the system."Chjoaygame (talk) 11:30, 20 July 2013 (UTC)

• It does seem at least a bit confusing to state in 1st sentence that heat is an energy transfer other than by transfer of matter (or work), and then in 2nd sentence list convection, which clearly involves transfer of matter in some way. Let's clarify the definition in our own minds and them we can decide how to write it.

To that end, a question: Suppose I have 2 systems: each is is a bottle of water at 2 diff. temps., & the process I perform is: exchange 1/4 of the water of each with one another (& allow time for temp equilibrium within each), so that after the process they each still have the same amt of water but their temperatures have changed. Can this be considered a heating process, and if not, what is it? The net result is the same as if I had transferred the heat by conduction, but I didn't.

DavRosen (talk) 19:14, 20 July 2013 (UTC)

Conduction. You placed one quarter cold water into a body of warm water, which by conduction transferred the heat from the warm water to the cooler water. The convection that resulted was not a part of the heat transfer, and just meant that the cold water was dispersed within the warm water. The lead section needs to introduce the subject in words that are clear and easy to understand, particularly the lead sentence, which is used to define the subject. Apteva (talk) 20:40, 20 July 2013 (UTC)

• Hmm, your answer doesn't seem very clear or easy to understand, but it could just be me. Are you sure the energy transfer between my two systems was simply heat conduction through the boundary of the two systems? Heat conduction would not involve transfer/exchange of matter across the boundary, but rather energy being conducted between *adjacent* matter on the two sides of the boundary where the matter itself does not move across the boundary, correct? I moved the energy across the boundary entirely by moving actual water which had an amount of energy stored within it -- where exactly did all that "conduction" happen? DavRosen (talk) 21:06, 20 July 2013 (UTC)

Conduction. You placed one quarter cold water into a body of warm water, which by conduction transferred the heat from the warm water to the cooler water. The convection that resulted was not a part of the heat transfer, and just meant that the cold water was dispersed within the warm water. Like Maxwell's box, let us instead assume that the two containers have chambers that can be separated with insulating and non-insulating membranes that are removed, so that the water is not moved in any way when the exchange is made, but is suddenly in contact with water of a different temperature, and will transfer heat by conduction from the warmer to the colder water. The lead section needs to introduce the subject in words that are clear and easy to understand, particularly the lead sentence, which is used to define the subject. Apteva (talk) 20:40, 20 July 2013 (UTC)

• In thermodynamics, the system(s) can be defined how ever one chooses for purposes of the analysis of interest, with a defined boundary between them. I defined the two bottles as the two systems of interest in order to talk about what energy is transferred across the boundary between them. In your answer you changed that definition and talked about transfer that occurred within one of the bottles, which is interesting but it wasn't what I wanted to know. Are you saying my definition of the two systems is inherently invalid, or that my question is meaningless or unanswerable without redefining the system boundary as you did?

(Btw, separate question about the systems as you chose to define them: you described the energy transfer between the old and new water within one bottle as conduction followed by water dispersal, but wasn't that dispersal itself part of the heat transfer mechanism? If there had been a thin, thermally conductive membrane between the new and old water, it would have taken much longer to reach equilibrium because it would stop convection across the boundary (although there would still be convection separately on each side). How do you explain how quickly it equilibrated unless you consider convection across the boundary (which, by the way, will tend to be cyclical convection in this case until equilibrium is reached, unlike my setup, where there was no cyclical transfer during the finite process that I defined.)?)

DavRosen (talk) 21:20, 20 July 2013 (UTC)

Since none of this has anything to do with article, there is no point in discussing this. To put something like this into the article would require finding this example somewhere and providing whatever explanation was presented in that source. Apteva (talk) 22:20, 20 July 2013 (UTC)

Apteva, you are the one who started this discussion in order to remove the term "convective circulation", stating the view, "Convection is a perfectly good description of the third type of heat transfer, and actually, "convective circulation" is less accurate. "Convective heat transfer" would just be saying the same thing twice.. I'm just trying to figure out exactly what definition of heat your statement is consistent with, so we can be sure we are conveying such a definition. We can't simply say something that has an apparent logical contradiction, so we we need to find a way to address or acknowledge this inconsistency if we are going to have it in the lede. Currently we state in 1st sentence that heat is an energy transfer other than by transfer of matter (or work), and then in the 2nd sentence you propose listing convection, without any qualification such as "circulation", but are you saying that convection doesn't involve transfer or matter, or that the first sentence is not stated correctly? Or that somehow it's a a different sense or type of transfer of matter, in which case we need be sure we are explaining this distinction somewhere. Chjoaygame's qualification, "convective circulation" attempted to address this this inconsistency because circulation would imply at least that there is no net transfer of matter over whole cycles. You proposed simply removing this qualification, without proposing an alternative means of resolving the inconsistency. I think you may be on to something: there may be a better way to resolve the inconsistency without simply saying "circulation". My question and followups above, about which you say "none of this has anything to do with article", were merely an attempt to identify such a means of resolving this apparent inconsistency in a way that's better and that would allow us to follow your suggestion in removing the term "circulation". DavRosen (talk) 00:06, 21 July 2013 (UTC)

I would resolve the inconsistency by clarifying the "transfer of matter" to mean into or out of the system. And I see nothing wrong with calling the third heating method "convection". If there's some confusion surrounding that word, then let's define it carefully within the article, but it seems clear enough to me. Is there anything lacking in this wording?:

In physics and chemistry, heat is energy transferred between a system and its surroundings other than by work or by the transfer of matter into or out of the system. The transfer of energy can occur by conduction, radiation, and convection.

I would also prefer replacing "its surroundings" with a second system, but that's another topic. Spiel496 (talk) 01:02, 21 July 2013 (UTC)

Heat vs. heat flow/transfer

I think edits such as , while obviously incorrect, point to the necessity to explain some terminology, as it's used mostly in engineering rather than physics. First, that edit is (wrongly) trying to rename "temperature" to "heat". (I think any high-school textbook can properly explain the difference between those, so I won't delve on that here.) Secondly, that edit is trying to rename "heat" to "heat flow". The distinction between "heat" and "heat flow" (or "heat transfer", but in the sense of the physical process rather than the engineering discipline) is actually somewhat esoteric. Per : "In contrast to thermodynamics, which mainly deals with homogenous systems, the so-called phases, heat transfer is a continuum theory which deals with fields extended in space and also dependent on time. This has consequences for the concept of heat, which in thermodynamics is defined as energy which crosses the system boundary. This contradiction with thermodynamic terminology can the be resolved by considering that in a continuum theory the mass and volume elements of the body are taken to be small systems, between which energy can be transferred as heat. Therefore, when one speaks of a heat flow within a solid body or fluid, or of the heat flux vector field in conjunction with the temperature field, the thermodynamic theory is not violated." Someone not using his real name (talk) 22:17, 20 July 2013 (UTC)

Minor typo from the quoted book: "can the resolved" should be "can be resolved". Please tell me the book was not written by one of our editors. Step one write WP article. Step two write book based on that article. Step three quote the book as a source for the article. So if heat is heat transfer, what is heat? (Please Do Not Answer) Apteva (talk) 22:40, 20 July 2013 (UTC)

Thanks for spotting the typo. As for the rest of your post, I think it's alas entirely nonconstructive. Someone not using his real name (talk) 22:47, 20 July 2013 (UTC)

By the way, there is an article doi:10.1119/1.1341254 which argues that "heat transfer" is an oxymoron "because heat cannot be stored". This is mostly a linguistic rather than conceptual problem though. More here: "John Jewett (26) observes that in fact heat can be a noun, but is the name of a process rather than the name of what is transferred. The main point is that using heat as a noun to designate “the heat in a body” is incorrect, and one way to avoid error is to use heat either as an adjective (e.g., “heat process”) or verb (e.g., “heat water”)." citing J. W. Jewett, “Energy and the confused student III: Language,” Phys. Teach. 46, 149–153 (March 2008) . It goes a bit further to say "It is no more appropriate to speak of heat in a body than work in a body. Both statements are not sensible. As pointed out by Mark Zemansky, (24) “Heat and work are methods of energy transfer, and when all flow is over, the words heat and work have no longer any usefulness or meaning . . . and once the transfers are over, we can speak only of the internal energy of the system. It is impossible to subdivide the internal energy into two parts, one due to a heat transfer and the other to work.” cited to M. Zemansky, “The use and misuse of the word ‘heat’ in physics teaching,” Phys. Teach. 8, 295 (Sept. 1970). It concludes with "it is well to heed the words of Walter T. Grandy (28) “In the 21st century it is still common to speak of heat as if it were a ‘substance’ that flows and can be thought of as a fluid; scientifically we still use the phrase ‘heat capacity’ that connotes an amount of something, although we know better. We take note of these foibles only to emphasize that human perception remains a bit ‘fuzzy’ in discussing the concept of heat, difficult to pin down at times. Technically, however we have no trouble agreeing that heat is not a substance, but a process of energy exchange between macroscopic systems and their environments.” citing W. T. Grandy, Entropy and the Time Evolution of Macroscopic Systems (Oxford University Press, Oxford, 2008), p. 2. Some of this is probably useful to mention in the wiki article. Someone not using his real name (talk) 23:59, 20 July 2013 (UTC)

Jewett has another paragraph worth citing, pointing to the differences between common language use and the notion in physics: "Consider some phrases used in common language: “heat transfer,” “flow of heat,” and “the heat radiated outward.” These phrases refer to a transfer of energy but represent incorrect uses of the word heat. The phrases can be tested by substituting the words “energy transfer” for “heat.” Each phrase sounds awkward or redundant when this is done. For example, “heat transfer” becomes “energy transfer transfer.” Other common phrases include “the heat of the day” and “too much heat in the air.” In these uses, heat is being used to represent temperature. Another common statement is “heat rises.” In this case, heat is used to mean warm air!" 86.121.18.17 (talk) 00:10, 21 July 2013 (UTC)

The technical term heat does have some linguistic problems. One way to reduce the problem is to use terms like " energy transfer as heat" or " energy transfer by a heating process". Another is to talk about " energy transferred thermally" or " energy transferred by a thermal process". The problem with using the word "thermal" that way is keeping it from coming right before the word "energy", because then you're into a different meaning: "thermal energy transfer" could mean a transfer of thermal energy, which isn't necessarily by a heating process. DavRosen (talk) 01:41, 21 July 2013 (UTC)

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