Talk:Heat

Revised lead

I just note my change here because there is a really nasty debate above me.

Old first paragraph:

In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not contain heat. Nevertheless, the term is also often used to refer to the thermal energy contained in a system as a component of its internal energy and that is reflected in the temperature of the system. For both uses of the term, heat is a form of energy.

New first paragraph:

In thermodynamics, heat is the thermal energy transferred between systems due to a temperature difference. In colloquial use, heat sometimes refers to thermal energy itself.

I am not an expert in thermodynamics, so any comment on my rewrite is appreciated. Pinging User:Bilorv, User:Dominic Mayers, User:Kbrose, and User:Cessaune per above. CactiStaccingCrane (talk) 16:09, 1 June 2023 (UTC)

It was not a good idea to create an article only for the notion of heat transfer in thermodynamic. Of course, in that context, the term "heat" refers to transfer of energy. This shocks people because the term "heat" is often used differently, even in scientific contexts. The solution is to be less dogmatic. There is no need to make a big deal about the different allowed usages of the terms nor to emphasis a particular usage of the term. It is sufficient to naturally use the term to refer to energy transfer. People will understand perfectly with all the rigour needed and there will be no confrontation with other natural usages of the term. This requires a complete change of attitude where we worry less about defining a term, but convey the concepts instead. For example, we can say, when we give give a formula that $Q$ is the heat transferred, but the focus is on the concept, on the law, not on a general definition of the term "heat" in thermodynamic. Dominic Mayers (talk) 18:43, 1 June 2023 (UTC)

I think it's a good thing as well. CactiStaccingCrane (talk) 01:59, 2 June 2023 (UTC)

So, hopefully someone will find the time to remove all the unnecessary emphasis on definitions and just naturally explain the concept of heat transfer in thermodynamics. It's not easy, because one needs to take a different attitude that focalizes less on definition and more on what are the laws, the concepts, that the readers need to learn. A definition by itself is not interesting, especially if it shocks the readers. Dominic Mayers (talk) 02:59, 2 June 2023 (UTC)

When it comes to these concepts, definitions *are* the crux of correct descriptions in the respective disciplines. For example, even the term heat transfer is not a common term of physicists or in thermodynamics as a pure science, it is mostly a term of thermal engineering. In the scientific context it is just heat, because it already implies transfer. While some notable teaching physicists have used the term heat energy, it also is not commonly accepted language, because experts know that heat is always energy and nothing else. Perhaps some have used it in context of contrasting with other types of energy. Even the novice and casual use of heat is rarely accompanied with energy. So the idea that the laws of thermodynamics can be explained with casual language in a precise manner, is an illusion, and the notion that people will understand perfectly is nothing by subjective POV blubber, and not borne of the experience of teaching thermodynamics. When we cite Q as heat, it needs to be very clear what that means. kbrose (talk) 18:16, 2 June 2023 (UTC)

Just above is an example of someone who claims to be an expert in writing encyclopedic articles only because he teaches the subject and says that what others say is only subjective POV blubber, and not born of the experience of teaching. He forgets that the audience here are not his students. I maintain my common sense point. There is nothing non rigorous in explaining the meaning of a quantity $Q$, called heat, in the context of the laws that are introduced. Also, I am not saying that it's a bad idea to always use the term heat in a way that is consistent with the use of the term in these laws. But, we can do all these things, without making a big deal about terminology in the lead. We can mention at some point in the article that we use the term heat only with a given meaning, if we think it can help. It's not clear to me that it will help that much, but that is not what I discuss here. I say that it's weird to make a big deal about this in the lead. It makes the subject seem superficial. Dominic Mayers (talk) 02:55, 22 June 2023 (UTC)

I would recommend changing "heat is the thermal energy transferred between systems..." to "heat is the transfer of thermal energy between systems...".

This would emphasize that heat is a process (the transfer of energy) rather than implying that heat is a type of energy that resides within a system. Curiousdashpot (talk) 15:49, 28 February 2024 (UTC)

Heat as entropy

There is a paragraph in the article that states: "Today's narrow definition of heat in physics contrasts with its use in common language, in some engineering disciplines, and in the historical scientific development of thermodynamics in the caloric theory. The terminology of heat in these instances may be replaced accurately with entropy." This is backed up by a citation to a textbook by Hans U. Fuchs. However, this textbook is associated with the Karlsruhe Physics Course (de:Karlsruher Physikkurs), a somewhat controversial pedagogical program that renames some thermodynamical terms, and emphasizes the flow of entropy. I think this claim that common notion of heat can often be replaced by entropy should be backed up by mainstream sources. In case that is not possible, it should be removed. Jähmefyysikko (talk) 06:27, 21 June 2023 (UTC)

It may perhaps be possible to find 'mainstream sources' that seem to back up the claim that "The terminology of heat in these instances may be replaced accurately with entropy." In thermodynamics, almost anything can be found in 'mainstream sources', there are so many of them with such variety. I think that merely finding a 'mainstream source' for it, or several, is not sufficient reason to put it unqualified in the article as a reliably sourced proposition. On such a venerable topic as heat in thermodynamics, Wikipedia editors need to use experience and judgement in picking the mainstream, based on a wide reading of reliable sources. I think it unwise to try to represent every shade of opinion. I favour going for the best mainstream thinking.

Some writers distinguish the French terms chaleur and calorique. For example, Stephen Brush, discussing Carnot, writes in a footnote:

Since Carnot did later abandon the caloric theory, it has sometimes been suggested that Carnot's discussion in the Reflexions should be considered as a "correct" modern thermodynamic analysis, by reinterpreting his term "calorique" as "entropy." I think T. S. Kuhn has effectively disposed of this suggestion by showing that whatever pedagogical value it may now have, this reinterpretation has no basis whatsoever in Carnot's own exposition of his theory, and can only confuse our historical understanding of the subject. Am. J. Phys. 23, 91, 387 (1955).

That relates closely to the claim presently under discussion.

I think that Editor Jähmefyysikko is right to remark that Fuchs' textbook is associated with a controversial pedagogical program. I think that if Wikipedia wishes to cite such a program, it should be done with clear indications of its controversiality, as distinct from mainstream orthodoxy.

Orthodox thermodynamics, perhaps mainly following Gibbs, uses two cardinal characteristic representations, the 'energy representation' $U=U(S,V,\{N_{j}\})$ and the 'entropy representation' $S=S(U,V,\{N_{j}\}).$ I think that putting the viewpoint of Fuchs as if it were mainstream tends to confuse. Usually, in contrast to the Fuchs viewpoint, that of Clausius is followed, in which an infinitesimal quantity of heat transferred is often enough shown in some way such as ${\text{đ}}q=T\ {\text{d}}S.$ This distinguishes 'heat' from 'entropy'.Chjoaygame (talk) 08:55, 21 June 2023 (UTC)

The comment in question does not belong in the History section.Chjoaygame (talk) 01:29, 22 June 2023 (UTC)

Removed it. Jähmefyysikko (talk) 04:13, 22 June 2023 (UTC)

Semi-protected edit request on 20 May 2024

Delete or change ext broken link

http://www.ing.unibs.it/~beretta/www.EliasGyftopoulos.org/EPGyftopoulos-papers/p84-BerettaGyftopoulos-ASME-AES20-33-1990.pdf

to

https://gianpaolo-beretta.unibs.it/Beretta-papers-online/m49-BerettaGyftopoulos-JERT-137-021006-2015.pdf

Thanks Cavallinux (talk) 10:33, 20 May 2024 (UTC)

 Done -Lemonaka‎ 11:30, 20 May 2024 (UTC)

Thanks Cavallinux (talk) 12:20, 21 May 2024 (UTC)

WP:Make technical articles understandable

Wikipedia’s advice at WP:Make technical articles understandable is applicable to this article on heat. The article fails some of the basic elements of this advice. Immediately after the lead there is a very short section on Notation and units and then a large section titled Classical thermodynamics, containing advanced information on entropy and enthalpy, and a lot of math.

There appears to be no good reason why readers of Wikipedia who come to this article to learn a little about heat should be confronted with the concepts of entropy and enthalpy, and a lot of math, before they reach more basic concepts such as the history of the subject, and the concept of heat transfer, both of which are accomplished without resort to math.

Wikipedia’s advice says Put the least obscure parts of the article up front. That is certainly not happening with the sections on entropy and enthalpy which are not "the least obscure parts" of the subject of heat!

Relevant background is as follows. Prior to mid-2018 the information on Enthalpy and Entropy was located much lower in the article, around items 4 and 5 in the list of contents. On June 24, 2018 this information was lifted much higher in the article so that it now appears immediately after the very short section on Notation and units. No meaningful edit summary was supplied. See the diff1. Next, the sub-sections on enthalpy and entropy were reversed in position so that entropy appears first, and enthalpy appears second. No meaningful edit summary was supplied. See the diff2.

The relocation of the two sections in question is most likely to have been made on the basis of their titles rather than on the basis of their technical contents, which is advanced and full of math. Unfortunately the User who relocated these two sections is no longer active on Wikipedia.

I will remove the two sections in question from their present location and return them to the position they occupied prior to June 2018, further down the list of contents. Dolphin (t) 12:33, 26 May 2024 (UTC)

NYUAD researchers shed new light on how heat is transmitted

Hi!

I came across this article that discovered new information on how heat is transmitted!

unfortunately i am unable to edit this article, but would be great if someone would add the information: https://gulfnews.com/uae/environment/nyuad-researchers-shed-new-light-on-how-heat-is-transmitted-1.103297823

Thank you to all editors and have a wonderful day Indipedian1991 (talk) 08:25, 26 June 2024 (UTC)

Thank you, Indipedian1991, for your heads up.

The article that you link to is about convection. That article says that convection is a kind of transfer of heat. But for thermodynamics, convection is a kind of transport of internal energy, not a kind of transfer of energy as heat. Convection is a kind of transfer of matter, which carries internal energy along with it. For thermodynamics, heat is energy in transfer by mechanisms other than thermodynamic work and transfer of matter. Those mechanisms are conduction, radiation, and friction. They operate at the atomic or molecular level, while convection is a bulk process. Consequently, the article that you linked to is not suitable content for the Wikipedia article on heat, which is about heat considered from a thermodynamic point of view.Chjoaygame (talk) 11:36, 26 June 2024 (UTC)