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I have suggested that thermal energy be merged into this article, as it covers the same subject - the first paragraph of this page states heat is 'sometimes called thermal energy', and as I understand it, they are effectively the same thing. Why does thermal energy need its own article, which is no more than a stub anyway? Terraxos 06:03, 18 June 2007 (UTC)
I have performed a complex edit on these articles, please see the discussion at Talk:Heat (disambiguation). The way, the truth, and the light 20:51, 18 June 2007 (UTC)
It is true that people sometimes mistakenly interchange the words
heat and
thermal energy. However, this would be a very bad reason to merge them. It would be comparable to merging
buffalo with
bison or even to merging
moon with
green cheese.
Cardamon
04:42, 20 June 2007 (UTC)
I'm not sure why merging would be bad. These topics are addressed in the same place in the above references. Heat is just thermal energy in motion? Both are measured in the same units, and are the same thing but in different contexts, no? — Omegatron 01:58, 22 June 2007 (UTC)
The very fact that we're having this discussion means to me that the three topics should be addressed in the same article. Not because they're the same thing, but because they're not the same thing. ;-) — Omegatron 00:22, 23 June 2007 (UTC)
And with that comment, Way-truth-light added templates saying It has been suggested that this article or section be merged with Thermal energy and It has been suggested that this article or section be merged with Internal energy. Yes, the former was suggested. It was rejected. The latter hasn't been suggested. If you're going to suggest it, Way-truth-light, suggest it on this discussion page, coherently. And then add the template, with an informative edit summary. -- Hoary 09:53, 30 June 2007 (UTC)
User:The way, the truth, and the light - I would like to suggest that, if you add a merge template, you probably shouldn't mark the edit minor, as you did here, here, and here. Edit summaries would be nice too. This suggestion especially holds for mergers that you have some reason to believe would be controversial. Cardamon 11:03, 30 June 2007 (UTC)
I just performed a complex edit that I think will solve the problematic proposed merger of Heat (now Heat (thermodynamics)) with Thermal energy. While the merger could still be done (I will restore the tags) I now think that it might be better to keep the articles seperate at Thermal energy and Heat (thermodynamics) as they are different concepts - the first is a kind of internal energy, the second the transfer of that energy. Because of this change, Heat should be a disambiguation. The way, the truth, and the light 20:37, 18 June 2007 (UTC)
I think that The way, the truth, and the light's proposal is poorly considered. Heat is the transfer of thermal energy. End of story. -- ScienceApologist 21:32, 19 June 2007 (UTC)
Historically, the word "heat" has been used as a noun as well, but such use- although common- is often technically incorrect. The reason is this: there is no way to identify a definite amount or kind of energy in a gas, say, as "heat."
"Heat" as a noun flourished during the days of caloric theory, but by 1865 at the latest, physicists knew that they should not speak of the "amount of heat" in a gas. ...Usage that is technically improper lingers nonetheless...
Energy that is being transferred by conduction or radiation may be called "heat." That is a technically correct use of the word and, indeed, a correct use as a noun. Once such energy has gotten into the physical system, however, it is just an indistinguishable contribuation to the internal energy. Only energy in transit may correctly be called "heat."
The current page now states that "Heat is the transfer of thermal energy." I agree with Jheald that this usage is incorrect. Heat, used as a noun, refers to the energy being transferred, not the process. I can't come up with a good wording this second, though, so thought someone else might take a stab at it? -- Starwed 20:24, 21 June 2007 (UTC)
The current version, although it makes the sentance flow more smoothly, is a bit misleading.
This implies that it's possible to identify which energy in an object is heat. (It's implicitly defining heat as energy which will flow in a certain circumstance, implying that it exists even outside that process.) The reason for the tense chosen by Jheald was to elminate this ambiguity; it's only proper to refer to energy as heat during the thermodynamic process. Yes, this makes it hard to word the sentance nicely, but I don't think that's an excuse to decrease the accuracy of the statement. -- Starwed 17:28, 22 June 2007 (UTC)
Might it be helpful to describe heat as an "effect"? this would distance its association with "heat transfer" and could defined further as "an observed effect associated with a temperature difference"
The need is to distinguish heat from thermal energy, heat is measured by temperature in K, °C or °F etc., thermal energy in Joules. Anyone have a problem with this? -- Damorbel ( talk) 21:33, 10 January 2009 (UTC)
Dragons flight, you say " heat ... is measured in joules" and " temperature is measured in K", can you explain just what is measured by temperature? My point of departure being thermal energy is also measured in Joules. -- Damorbel ( talk) 10:10, 12 January 2009 (UTC)
Slightly reformatted
Are there any other sources which indicate otherwise? -- ScienceApologist 21:30, 19 June 2007 (UTC)
Please stop edit warring. You need to agree on one of the following:
I'd recomment two, which is what I am implementing. Remember both of you, WP:3RR. Matt/TheFearow (Talk) (Contribs) (Bot) 22:09, 20 June 2007 (UTC)
It seems there's been a recent edit war on this article, so I'm wary of making any large-scale changes, but it seems in
this edit a couple of sections (History and Overview) were deleted without any good reason that I see. Did they move somewhere else, or should they be restored to the current article? --
Bob Mellish
21:26, 22 June 2007 (UTC)
I don't know who messed (or mixed up) the heat, thermal energy, heat transfer, pages (e.g. put the history of heat into the thermal energy page, etc.) but I will quickly clean up the mess. Each term has a distinct meaning, internal energy was essentially defined by Rudolf Clausius in the 1850s (although he built on some shoulders). -- Sadi Carnot 04:15, 28 June 2007 (UTC)
The first line currently has the definition:
IMO this is poor, principally due to ambiguity, because it could be interpreted to mean any energy transferred from one object to another object is heat. Rather, some energy transferred from one object to another object is heat, but some energy is transferred as work.
The previous version said " thermal energy which is transferred..." I appreciate this isn't ideal either, but it is necessary to identify what makes the contrast between heat and work, which the word "thermal" at least pointed to. Jheald 10:17, 28 June 2007 (UTC)
Cardamon, point #1 is fine if you want to change that. As to point #2, the Oxford definition still holds: heat is energy transferred from the cold body to the hot body via energy in the form of work input ( heat pump). As to point #3, please stop trying to mix terms together: Thermal energy now has is own article with three references; it is a very obscure term; internal energy, however, is a state function, the simplist of which is the first law of thermodynamics, the mathematical statement of which is given by:
where is the infinitesimal increase in the internal energy of the system, is the infinitesimal amount of heat added to the system, and is the infinitesimal amount of work done by the system on the surroundings. In other words, internal energy is a function U = f(Q,W, chemical potential,external forces, etc.). I hope this helps? -- Sadi Carnot 01:55, 29 June 2007 (UTC)
Sadi Carnot is completely right: heat is a process, not a kind of energy. you want internal energy or enthalpy for that. The heat pump is a good example of why it is important to keep to the standard definitions rather than folk definitions. Heat pumps to not cause heat transfer against the temperature gradient, but raise the internal energy of a fluid by doing work on it. This is all basic, first year undergraduate thermodynamics. MAG1 10:10, 29 June 2007 (UTC)
Incidentally, the quote from Callen's book is "An energy transfer to the hidden atomic modes is called heat. ...", which directly contradicts point 3, above. MAG1 10:16, 29 June 2007 (UTC)
Sadi Carnot can speak for himself, but confusing heat and internal energy does not help the reader, but misleads him. As Sadi said internal energy is a state function whose value for a system can be changed by the processes of heat and work (hence Callen's comment that heat is a transfer of energy): internal energy and heat are two different things, one is the energy possessed by a system, the other is the energy transferred over its boundary. As to the heat pumps, ok strike out fluid, put in system, the thermodynamic process is the same where internal energy is being changed through work. Work is a different process from heat. As I said earlier, this is all basic stuff. What should happen with mergers is for thermal energy to be deleted and a suitable note put in the internal energy page. MAG1 11:23, 30 June 2007 (UTC)
Up at the top of the section, the point is made that the word heat should be applied only to energy while it is being transferred. The article still states that heat is energy which is transferred. Is there any objection to clarifying the opening sentance in this manner? Repeating what I wrote at Talk:Heat (disambiguation):
Historically, the word "heat" has been used as a noun as well, but such use- although common- is often technically incorrect. The reason is this: there is no way to identify a definite amount or kind of energy in a gas, say, as "heat."
"Heat" as a noun flourished during the days of caloric theory, but by 1865 at the latest, physicists knew that they should not speak of the "amount of heat" in a gas. ...Usage that is technically improper lingers nonetheless...
Energy that is being transferred by conduction or radiation may be called "heat." That is a technically correct use of the word and, indeed, a correct use as a noun. Once such energy has gotten into the physical system, however, it is just an indistinguishable contribuation to the internal energy. Only energy in transit may correctly be called "heat."
-- Starwed 13:00, 3 September 2007 (UTC)
I have been away for a few weeks, but I see that this whole mess caused ScienceApologist to quit. Hopefully he will come back? In any event, let's all try to stick to standard textbook articles and definitions and to stay away from drastic page moves, mergers, section re-pastes, or original research, etc., just because one or two Wiki newbies doesn’t understand a term or whatever. Thanks: -- Sadi Carnot 00:07, 29 June 2007 (UTC)
There seems to be some kind of confusion on this page (for one or two editors (basically User: the Way)) who still think that these terms (or possibly others) should be merged? From my point of view, it is obvious that any merging of these terms is clearly ridiculous. To clarify that other countries agree with me, I have comparatively posted the related countries’ articles below:
The main editor causing the issues here seems to be User:The Way. His last edit, where he changed (a textbook referenced section) "so an object cannot possess heat" to "so objects do possess "heat", clearly disqualifies him from any kind of understanding of the related subjects (also note his edit warring and recent blocks). User:Cardamon seems to be in agreement with me; User:Omegatron seems to want to merge all three of them?; and User:MAG1 wants to delete thermal energy. If any other users still have some kind of merge issues, please state your case below, in specific terms, so we can discuss the matter (gain consensus) in an organized fashion. Thanks: -- Sadi Carnot 03:38, 2 July 2007 (UTC)
This talk page is turning into the Wikipedia Original Research Center on Thermal Energy. As far as I know, I am the only one who has taken the time to add references to the thermal energy page (and all 13 of the references on the heat page, except the Egyptian gods reference). Thus far, I’ve checked 5 scientific encyclopedias, 6 scientific dictionaries, 4 thermal physics textbooks, and 4 physics textbooks and 6 chemical thermodynamic textbooks and over a dozen thermodynamics textbooks. In over 90% of the indexes, the term is not found; in the dictionaries and encyclopedias (save Britannica) the term is not found. In two physics books, it is used as a synonym for the mechanical energy of a system that is converted into internal energy via friction. Cengel and Boles’ 2002 Thermodynamics – an Engineering Approach is the only textbook to give an explicit definition (pg. 17-18). In short, they define thermal energy, via bold text (definitions), as a portion of internal energy, as such:
Internal energy – the sum of all microscopic forms of energy of a system. It is related to the molecular structure and the degree of molecular activity and may be viewed as the sum of kinetic and potential energies of the molecules; it is comprised of the following types of energies: [2]
Type | Composition of Internal Energy (U) |
---|---|
Sensible energy | the portion of the internal energy of a system associated with kinetic energies (molecular translation, rotation, and vibration; electron translation and spin; and nuclear spin) of the molecules. |
Latent energy | the internal energy associated with the phase of a system. |
Chemical energy | the internal energy associated with the atomic bonds in a molecule. |
Nuclear energy | the tremendous amount of energy associated with the strong bonds within the nucleus of the atom itself. |
Energy interactions | those types of energies not stored in the system (e.g. heat transfer, mass transfer, and work), but which are recognized at the system boundary as they cross it, which represent gains or losses by a system during a process. |
Thermal energy | the sum of sensible and latent forms of internal energy. |
This is the most rigorous and explicit definition of thermal energy I have been able to find in contrast to those (on this talk page) who use it in a loose sense to argue whatever point they are trying to win. In sum, heat Q, work W, and internal energy U are the main (and measurable) topics of discussion in science; thermal energy is not. -- Sadi Carnot 03:49, 3 July 2007 (UTC)
Jheald re-added this see-also/other-uses below the disambig link:
I have reverted this for several reasons. Firstly, thermal energy is not a “looser idea” of heat. Second, I defined thermal energy in the disambig, thus make the above redundant. Third, I defined thermal energy in the lead paragraph to heat as well as added the said internal energy table that defines and contrasts heat in relation to thermal energy. Fourth, the phrase “heat has a precise meaning, which is the subject of this article” (obvisously). Fifth, it makes the article cluttered (one disambig is enough) and puts too much emphasis on the term heat, which as I have explained above is not a common term in published textbooks. Lastly, I know (from the entropy article) that Jheald has a tendency to add lengthy explanatory sentences (captions) below the disambig; but compared to other science articles this is not the Wiki-way. -- Sadi Carnot 22:33, 5 July 2007 (UTC)
How about we try it the way I have it now, with a clarifying paragraph in the overview. I think this will be more clear to new readers than a mis-defined (and conjested) hat note. Plus, I moved most of the history section to a new page: history of heat. -- Sadi Carnot 00:06, 6 July 2007 (UTC)
Interesting discussion on heat only existing during transfer, which i think highlights a general point;
I think all words actually 'belong' to a human language, only being borrowed by physics, and as such are actually dynamic things, words can play happily with variable, illogical and even contradictory definitions. If you want to communicate without ambiguity and context sensitivity, then you have to use maths, that is what its for. To try and align an existing word with a newly defined concept, even if it is clearly better, is going to cause confusion in any educational context, and needs to be clearly explained as a different usage, over time new well defined, stable and generally useful definitions will tend to shine through, but you have to explain this with the current usage.
Think about the fact that the word 'Heat' existed before the equation that supposedly defines it?
Think about the problems this introduces with translation, where a word used for a thing will generally have different origins in a different language and so direct equality is only an approximation, you will then have to try and force words that are close in meaning in every language.
The term 'word Nazi', for me, in this context, carries a useful concept, and so the translation issue might be termed 'word imperialism', which carries equally insulting overtones.
But back on the definition of Heat, how about this; Feynman seemed to be happy that Heat exists as a static quantity, or did he just understand his audience?
Now although ice has a "rigid" crystalline form, its temperature can change-ice has heat. If we wish, we can change the amount of heat. What is the heat in the case of ice? The atoms are not standing still. They are jiggling and vibrating.
Feynman lectures on physics, chapter 1, lecture 1
for me the alternatives should just be pointed out and the usage being applied defined in each article, some less technical articles using Heat as internal energy, which then refers to a more advanced article, thermodynamics, that uses and clearly indicates it use as not commonly used. Asplace 19:51, 28 September 2007 (UTC)
here is a simpler restating of the issue;
heating IS the addition of heat.
heating is making something hotter. ( this is the crunch statement, which is no longer true with the thermo-dynamic definition of heat)
making something hotter is to raise its temperature
if the above are correct, then;
addition of heat MUST cause a rise in temperature. (rememeber this is not physics, its simply what the words mean in their common usage.)
and since the reverse is true, then;
temperature change IS heat change
example: say a gas in a closed system is condensing, it has not reached an equilibrium (without considering systems not at equilibrium you ignores basically all change), energy is liberated as the intermolecular forces draw the particles closer together, pressure drops but no external work is done, as long as the volume remains the same, and there is no reason it can't, so the energy released can only end up in the form for thermal energy, so the system gets hotter without any external energy flow. people would talk about this as the new heat having been supplied from some internal mechanisms. just like burning fuel and other chemical reactions.
and the point of the example is that its a case where temperature change is not the result of external energy flow and so also means external energy flow does not always result in a temperature change and so external energy flow is NOT heat (using the common definition), unless you try and persuade people that heating is not the same thing as making something hotter, which is not going to be easy, without a lot of confusion and BS. Asplace 22:13, 7 October 2007 (UTC)
please stop commenting, i tried but i can really not make a meaningful interpretation of all this, i can see parts of it that are simply wrong, parts that might be inconsistent if they meant anything, but mostly its just irrelevant to the point. Please do yourself a favour and check what you are saying, although from my experience this sort of stuff is consistently poorly understood. Asplace 17:56, 8 October 2007 (UTC)
OK, but reassigning the term 'heat' to a new definition, in such a way that;
"heating" and "getting hotter" are now disconnected, is going to be the source of huge confusion. Asplace
try another example:
earth irradiated by the sun, light has to be work in the first law, earth in a vacuum, so earth is not 'heated' by the sun!!
FYI 1. you can sample the temperature of an object without effecting it, by using a probe at the same temperature and noting the lack of energy exchange, you seem to be confusing this with quantum mechanics somehow.
2. In TD there is no distinction between the sources of non thermal internal energy, so no point in talking individually about chemical,nuclear?,phase change,crystallisation etc etc.
3. You seem to be stuck in thinking this is a conceptual problem, it isn't, its about assigning an existing word to a concept which has significant differences from existing usage, I've checked the Feynmann lectures and an old university thermodynamics text book ( F. mandl ) i had lying around and the usage of the term is definitely counter to that used in this article. I and these sources are not suffering from conceptual problems. Asplace 19:58, 10 October 2007 (UTC)
example
an object in a vacuum is irradiated by a laser, the energy in the light has to be work, not q, in the first law, so by this articles definition of 'heat' the object is not being 'heated', but clearly it gets hot!! this is not what the word 'heat' means, and i have previously given multiple very well regarded and verifiable sources that show this clearly, so as i understand it as a good wikipedian i have a responsibility to start correcting this article. Asplace 18:55, 11 October 2007 (UTC)
BTW, wiktionary has 'heat' as thermal energy, and so does the article called sensible energy? i guess if you looked, the 'thermal energy' definition of heat would be in hundreds of articles, many of which might be linking to this article, which then uses a different one, confusing or what? —Preceding unsigned comment added by Asplace ( talk • contribs) 19:10, 11 October 2007 (UTC)
i think you need some reference to heat being only applicable to the NET transfer of thermal energy, in that, when two objects are in TDE and equal amounts of thermal energy are flowing in either direction, then no 'heat' is considered to be flowing, since dS is zero, but that with the removal of one of the two energy flows, the other energy flow although not ostensibly changing would need to be relabeled from thermal energy to 'heat'. This would emphasis that this definition of heat can not generally be broken down into subsystems, as might be assumed if casually compared to energy or force, but is a property of a complete dynamic system. —Preceding unsigned comment added by 82.27.224.69 ( talk) 16:31, 13 October 2007 (UTC)
Names of units called after persons must start with lowercase: joule and watt (abbreviation is uppercase: J and W). -- Virginia fried chicken ( talk) 12:20, 25 November 2007 (UTC)
There is much confusion in this article, most of which arises because there is no satisfactory defintion of temperature. The two are intimately linked by the Boltzmann constant. Defining heat (Q) as "any transfer of energy" as does the opening statement is a contradiction, a transfer of heat would be a change δQ, a change of energy would be δE. According to this definition, what then is Q if it isn't the form of energy called heat?
The origin of modern "heat science" (thermodynamics) was the realisation that heat was not a substance ( caloric or phlogiston) but the kinetic energy of some sort of fundamental particles that were free to move, i.e to vibrate in a fixed location for a solid and move freely as for a gas, there being an intermediate liquid phase for many materials. The reality of this was establisbed by Einstein with his explaination of Brownian motion which gave conclusive mechanical evidence for Dalton's atomic theory. Subsequent work showed that composite, none spherical particle (now called molecules) had other degrees of freedom that contained energy, thus their total energy, at a given temperature, was greater than the fundamental particles. (Fundamental paricles are only approximated by monatomic gases.)
The conclusion is; heat is that energy contained in the motion of fundamental particles, particles whose mass is unspecified but can only have motion in three (translational) degrees of freedom. This definition of heat does not exclude particles with more than three degrees of freedom, but the definition (and the reality!) of temperature takes into account the translational degrees of freedom only. There is a good reason for this, translational movements are the only way fundamental particles can exchange miroscopic mechanical energy, which explains why temperature is such an important property in thermodynamics.
There is a problem of usage which causes many difficulties and much confusion, because the translational and other motions of molecules are intimately linked, the heat of a system of particles is given as the total energy of the particles, change the translational motions (i.e. change the temperature) and you assuredly change the vibrational energy. The clue here is the various specific heats, materials with different specific heats are pressed into the same definition of temperature when it comes to exchanging energy through collisions.
It interesting to note that this is a purely mechanical definition -- Damorbel ( talk) 13:52, 16 January 2009 (UTC)
When I first loaded this page, there was about three paragraphs of Arabic text in the beginning of the article. After refreshing, everything was normal. Was there some kind of vandalism that was quickly fixed or something? —Preceding unsigned comment added by 68.228.166.58 ( talk) 19:38, 1 November 2009 (UTC)
what is the differance between heat and tempature? —Preceding unsigned comment added by Lorifalcon ( talk • contribs) 02:15, 6 November 2009 (UTC)
Heat is a flow of energy. Temperature is a measure of energy content.-- Nick Y. ( talk) 15:34, 6 November 2009 (UTC)
And heat capacity then? What is your definition of heat capacity ( specific heat).-- Damorbel ( talk) 22:29, 6 November 2009 (UTC)
This new revision [1] really makes a laughing stock of the whole article, it reference the First law of thermodynamics which completely contradicts it! For example "The first law of thermodynamics states that the energy of a closed system is conserved". No it doesn't, the first law article "states that energy can be transformed (changed from one form to another), but cannot be created or destroyed." The "First law" article recognises that in the course of energy transformations these tranformations can result in equilibrium conditions, typically chemical transformations do not go to completion but result in an incomplete state but the total energy involved does not change.
More rubbish "In physics and thermodynamics, heat is the process of energy transfer from one body or system due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body" Oh really? What about chemical reactions, combustion etc.?
From the changes you have made I suspect that you do not have the necessary knowledge to edit this already deeply flawed article. If you really want to making changes you should first consult on the discussion page. -- Damorbel ( talk) 08:20, 13 November 2009 (UTC)
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![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 | Archive 4 | Archive 5 |
I have suggested that thermal energy be merged into this article, as it covers the same subject - the first paragraph of this page states heat is 'sometimes called thermal energy', and as I understand it, they are effectively the same thing. Why does thermal energy need its own article, which is no more than a stub anyway? Terraxos 06:03, 18 June 2007 (UTC)
I have performed a complex edit on these articles, please see the discussion at Talk:Heat (disambiguation). The way, the truth, and the light 20:51, 18 June 2007 (UTC)
It is true that people sometimes mistakenly interchange the words
heat and
thermal energy. However, this would be a very bad reason to merge them. It would be comparable to merging
buffalo with
bison or even to merging
moon with
green cheese.
Cardamon
04:42, 20 June 2007 (UTC)
I'm not sure why merging would be bad. These topics are addressed in the same place in the above references. Heat is just thermal energy in motion? Both are measured in the same units, and are the same thing but in different contexts, no? — Omegatron 01:58, 22 June 2007 (UTC)
The very fact that we're having this discussion means to me that the three topics should be addressed in the same article. Not because they're the same thing, but because they're not the same thing. ;-) — Omegatron 00:22, 23 June 2007 (UTC)
And with that comment, Way-truth-light added templates saying It has been suggested that this article or section be merged with Thermal energy and It has been suggested that this article or section be merged with Internal energy. Yes, the former was suggested. It was rejected. The latter hasn't been suggested. If you're going to suggest it, Way-truth-light, suggest it on this discussion page, coherently. And then add the template, with an informative edit summary. -- Hoary 09:53, 30 June 2007 (UTC)
User:The way, the truth, and the light - I would like to suggest that, if you add a merge template, you probably shouldn't mark the edit minor, as you did here, here, and here. Edit summaries would be nice too. This suggestion especially holds for mergers that you have some reason to believe would be controversial. Cardamon 11:03, 30 June 2007 (UTC)
I just performed a complex edit that I think will solve the problematic proposed merger of Heat (now Heat (thermodynamics)) with Thermal energy. While the merger could still be done (I will restore the tags) I now think that it might be better to keep the articles seperate at Thermal energy and Heat (thermodynamics) as they are different concepts - the first is a kind of internal energy, the second the transfer of that energy. Because of this change, Heat should be a disambiguation. The way, the truth, and the light 20:37, 18 June 2007 (UTC)
I think that The way, the truth, and the light's proposal is poorly considered. Heat is the transfer of thermal energy. End of story. -- ScienceApologist 21:32, 19 June 2007 (UTC)
Historically, the word "heat" has been used as a noun as well, but such use- although common- is often technically incorrect. The reason is this: there is no way to identify a definite amount or kind of energy in a gas, say, as "heat."
"Heat" as a noun flourished during the days of caloric theory, but by 1865 at the latest, physicists knew that they should not speak of the "amount of heat" in a gas. ...Usage that is technically improper lingers nonetheless...
Energy that is being transferred by conduction or radiation may be called "heat." That is a technically correct use of the word and, indeed, a correct use as a noun. Once such energy has gotten into the physical system, however, it is just an indistinguishable contribuation to the internal energy. Only energy in transit may correctly be called "heat."
The current page now states that "Heat is the transfer of thermal energy." I agree with Jheald that this usage is incorrect. Heat, used as a noun, refers to the energy being transferred, not the process. I can't come up with a good wording this second, though, so thought someone else might take a stab at it? -- Starwed 20:24, 21 June 2007 (UTC)
The current version, although it makes the sentance flow more smoothly, is a bit misleading.
This implies that it's possible to identify which energy in an object is heat. (It's implicitly defining heat as energy which will flow in a certain circumstance, implying that it exists even outside that process.) The reason for the tense chosen by Jheald was to elminate this ambiguity; it's only proper to refer to energy as heat during the thermodynamic process. Yes, this makes it hard to word the sentance nicely, but I don't think that's an excuse to decrease the accuracy of the statement. -- Starwed 17:28, 22 June 2007 (UTC)
Might it be helpful to describe heat as an "effect"? this would distance its association with "heat transfer" and could defined further as "an observed effect associated with a temperature difference"
The need is to distinguish heat from thermal energy, heat is measured by temperature in K, °C or °F etc., thermal energy in Joules. Anyone have a problem with this? -- Damorbel ( talk) 21:33, 10 January 2009 (UTC)
Dragons flight, you say " heat ... is measured in joules" and " temperature is measured in K", can you explain just what is measured by temperature? My point of departure being thermal energy is also measured in Joules. -- Damorbel ( talk) 10:10, 12 January 2009 (UTC)
Slightly reformatted
Are there any other sources which indicate otherwise? -- ScienceApologist 21:30, 19 June 2007 (UTC)
Please stop edit warring. You need to agree on one of the following:
I'd recomment two, which is what I am implementing. Remember both of you, WP:3RR. Matt/TheFearow (Talk) (Contribs) (Bot) 22:09, 20 June 2007 (UTC)
It seems there's been a recent edit war on this article, so I'm wary of making any large-scale changes, but it seems in
this edit a couple of sections (History and Overview) were deleted without any good reason that I see. Did they move somewhere else, or should they be restored to the current article? --
Bob Mellish
21:26, 22 June 2007 (UTC)
I don't know who messed (or mixed up) the heat, thermal energy, heat transfer, pages (e.g. put the history of heat into the thermal energy page, etc.) but I will quickly clean up the mess. Each term has a distinct meaning, internal energy was essentially defined by Rudolf Clausius in the 1850s (although he built on some shoulders). -- Sadi Carnot 04:15, 28 June 2007 (UTC)
The first line currently has the definition:
IMO this is poor, principally due to ambiguity, because it could be interpreted to mean any energy transferred from one object to another object is heat. Rather, some energy transferred from one object to another object is heat, but some energy is transferred as work.
The previous version said " thermal energy which is transferred..." I appreciate this isn't ideal either, but it is necessary to identify what makes the contrast between heat and work, which the word "thermal" at least pointed to. Jheald 10:17, 28 June 2007 (UTC)
Cardamon, point #1 is fine if you want to change that. As to point #2, the Oxford definition still holds: heat is energy transferred from the cold body to the hot body via energy in the form of work input ( heat pump). As to point #3, please stop trying to mix terms together: Thermal energy now has is own article with three references; it is a very obscure term; internal energy, however, is a state function, the simplist of which is the first law of thermodynamics, the mathematical statement of which is given by:
where is the infinitesimal increase in the internal energy of the system, is the infinitesimal amount of heat added to the system, and is the infinitesimal amount of work done by the system on the surroundings. In other words, internal energy is a function U = f(Q,W, chemical potential,external forces, etc.). I hope this helps? -- Sadi Carnot 01:55, 29 June 2007 (UTC)
Sadi Carnot is completely right: heat is a process, not a kind of energy. you want internal energy or enthalpy for that. The heat pump is a good example of why it is important to keep to the standard definitions rather than folk definitions. Heat pumps to not cause heat transfer against the temperature gradient, but raise the internal energy of a fluid by doing work on it. This is all basic, first year undergraduate thermodynamics. MAG1 10:10, 29 June 2007 (UTC)
Incidentally, the quote from Callen's book is "An energy transfer to the hidden atomic modes is called heat. ...", which directly contradicts point 3, above. MAG1 10:16, 29 June 2007 (UTC)
Sadi Carnot can speak for himself, but confusing heat and internal energy does not help the reader, but misleads him. As Sadi said internal energy is a state function whose value for a system can be changed by the processes of heat and work (hence Callen's comment that heat is a transfer of energy): internal energy and heat are two different things, one is the energy possessed by a system, the other is the energy transferred over its boundary. As to the heat pumps, ok strike out fluid, put in system, the thermodynamic process is the same where internal energy is being changed through work. Work is a different process from heat. As I said earlier, this is all basic stuff. What should happen with mergers is for thermal energy to be deleted and a suitable note put in the internal energy page. MAG1 11:23, 30 June 2007 (UTC)
Up at the top of the section, the point is made that the word heat should be applied only to energy while it is being transferred. The article still states that heat is energy which is transferred. Is there any objection to clarifying the opening sentance in this manner? Repeating what I wrote at Talk:Heat (disambiguation):
Historically, the word "heat" has been used as a noun as well, but such use- although common- is often technically incorrect. The reason is this: there is no way to identify a definite amount or kind of energy in a gas, say, as "heat."
"Heat" as a noun flourished during the days of caloric theory, but by 1865 at the latest, physicists knew that they should not speak of the "amount of heat" in a gas. ...Usage that is technically improper lingers nonetheless...
Energy that is being transferred by conduction or radiation may be called "heat." That is a technically correct use of the word and, indeed, a correct use as a noun. Once such energy has gotten into the physical system, however, it is just an indistinguishable contribuation to the internal energy. Only energy in transit may correctly be called "heat."
-- Starwed 13:00, 3 September 2007 (UTC)
I have been away for a few weeks, but I see that this whole mess caused ScienceApologist to quit. Hopefully he will come back? In any event, let's all try to stick to standard textbook articles and definitions and to stay away from drastic page moves, mergers, section re-pastes, or original research, etc., just because one or two Wiki newbies doesn’t understand a term or whatever. Thanks: -- Sadi Carnot 00:07, 29 June 2007 (UTC)
There seems to be some kind of confusion on this page (for one or two editors (basically User: the Way)) who still think that these terms (or possibly others) should be merged? From my point of view, it is obvious that any merging of these terms is clearly ridiculous. To clarify that other countries agree with me, I have comparatively posted the related countries’ articles below:
The main editor causing the issues here seems to be User:The Way. His last edit, where he changed (a textbook referenced section) "so an object cannot possess heat" to "so objects do possess "heat", clearly disqualifies him from any kind of understanding of the related subjects (also note his edit warring and recent blocks). User:Cardamon seems to be in agreement with me; User:Omegatron seems to want to merge all three of them?; and User:MAG1 wants to delete thermal energy. If any other users still have some kind of merge issues, please state your case below, in specific terms, so we can discuss the matter (gain consensus) in an organized fashion. Thanks: -- Sadi Carnot 03:38, 2 July 2007 (UTC)
This talk page is turning into the Wikipedia Original Research Center on Thermal Energy. As far as I know, I am the only one who has taken the time to add references to the thermal energy page (and all 13 of the references on the heat page, except the Egyptian gods reference). Thus far, I’ve checked 5 scientific encyclopedias, 6 scientific dictionaries, 4 thermal physics textbooks, and 4 physics textbooks and 6 chemical thermodynamic textbooks and over a dozen thermodynamics textbooks. In over 90% of the indexes, the term is not found; in the dictionaries and encyclopedias (save Britannica) the term is not found. In two physics books, it is used as a synonym for the mechanical energy of a system that is converted into internal energy via friction. Cengel and Boles’ 2002 Thermodynamics – an Engineering Approach is the only textbook to give an explicit definition (pg. 17-18). In short, they define thermal energy, via bold text (definitions), as a portion of internal energy, as such:
Internal energy – the sum of all microscopic forms of energy of a system. It is related to the molecular structure and the degree of molecular activity and may be viewed as the sum of kinetic and potential energies of the molecules; it is comprised of the following types of energies: [2]
Type | Composition of Internal Energy (U) |
---|---|
Sensible energy | the portion of the internal energy of a system associated with kinetic energies (molecular translation, rotation, and vibration; electron translation and spin; and nuclear spin) of the molecules. |
Latent energy | the internal energy associated with the phase of a system. |
Chemical energy | the internal energy associated with the atomic bonds in a molecule. |
Nuclear energy | the tremendous amount of energy associated with the strong bonds within the nucleus of the atom itself. |
Energy interactions | those types of energies not stored in the system (e.g. heat transfer, mass transfer, and work), but which are recognized at the system boundary as they cross it, which represent gains or losses by a system during a process. |
Thermal energy | the sum of sensible and latent forms of internal energy. |
This is the most rigorous and explicit definition of thermal energy I have been able to find in contrast to those (on this talk page) who use it in a loose sense to argue whatever point they are trying to win. In sum, heat Q, work W, and internal energy U are the main (and measurable) topics of discussion in science; thermal energy is not. -- Sadi Carnot 03:49, 3 July 2007 (UTC)
Jheald re-added this see-also/other-uses below the disambig link:
I have reverted this for several reasons. Firstly, thermal energy is not a “looser idea” of heat. Second, I defined thermal energy in the disambig, thus make the above redundant. Third, I defined thermal energy in the lead paragraph to heat as well as added the said internal energy table that defines and contrasts heat in relation to thermal energy. Fourth, the phrase “heat has a precise meaning, which is the subject of this article” (obvisously). Fifth, it makes the article cluttered (one disambig is enough) and puts too much emphasis on the term heat, which as I have explained above is not a common term in published textbooks. Lastly, I know (from the entropy article) that Jheald has a tendency to add lengthy explanatory sentences (captions) below the disambig; but compared to other science articles this is not the Wiki-way. -- Sadi Carnot 22:33, 5 July 2007 (UTC)
How about we try it the way I have it now, with a clarifying paragraph in the overview. I think this will be more clear to new readers than a mis-defined (and conjested) hat note. Plus, I moved most of the history section to a new page: history of heat. -- Sadi Carnot 00:06, 6 July 2007 (UTC)
Interesting discussion on heat only existing during transfer, which i think highlights a general point;
I think all words actually 'belong' to a human language, only being borrowed by physics, and as such are actually dynamic things, words can play happily with variable, illogical and even contradictory definitions. If you want to communicate without ambiguity and context sensitivity, then you have to use maths, that is what its for. To try and align an existing word with a newly defined concept, even if it is clearly better, is going to cause confusion in any educational context, and needs to be clearly explained as a different usage, over time new well defined, stable and generally useful definitions will tend to shine through, but you have to explain this with the current usage.
Think about the fact that the word 'Heat' existed before the equation that supposedly defines it?
Think about the problems this introduces with translation, where a word used for a thing will generally have different origins in a different language and so direct equality is only an approximation, you will then have to try and force words that are close in meaning in every language.
The term 'word Nazi', for me, in this context, carries a useful concept, and so the translation issue might be termed 'word imperialism', which carries equally insulting overtones.
But back on the definition of Heat, how about this; Feynman seemed to be happy that Heat exists as a static quantity, or did he just understand his audience?
Now although ice has a "rigid" crystalline form, its temperature can change-ice has heat. If we wish, we can change the amount of heat. What is the heat in the case of ice? The atoms are not standing still. They are jiggling and vibrating.
Feynman lectures on physics, chapter 1, lecture 1
for me the alternatives should just be pointed out and the usage being applied defined in each article, some less technical articles using Heat as internal energy, which then refers to a more advanced article, thermodynamics, that uses and clearly indicates it use as not commonly used. Asplace 19:51, 28 September 2007 (UTC)
here is a simpler restating of the issue;
heating IS the addition of heat.
heating is making something hotter. ( this is the crunch statement, which is no longer true with the thermo-dynamic definition of heat)
making something hotter is to raise its temperature
if the above are correct, then;
addition of heat MUST cause a rise in temperature. (rememeber this is not physics, its simply what the words mean in their common usage.)
and since the reverse is true, then;
temperature change IS heat change
example: say a gas in a closed system is condensing, it has not reached an equilibrium (without considering systems not at equilibrium you ignores basically all change), energy is liberated as the intermolecular forces draw the particles closer together, pressure drops but no external work is done, as long as the volume remains the same, and there is no reason it can't, so the energy released can only end up in the form for thermal energy, so the system gets hotter without any external energy flow. people would talk about this as the new heat having been supplied from some internal mechanisms. just like burning fuel and other chemical reactions.
and the point of the example is that its a case where temperature change is not the result of external energy flow and so also means external energy flow does not always result in a temperature change and so external energy flow is NOT heat (using the common definition), unless you try and persuade people that heating is not the same thing as making something hotter, which is not going to be easy, without a lot of confusion and BS. Asplace 22:13, 7 October 2007 (UTC)
please stop commenting, i tried but i can really not make a meaningful interpretation of all this, i can see parts of it that are simply wrong, parts that might be inconsistent if they meant anything, but mostly its just irrelevant to the point. Please do yourself a favour and check what you are saying, although from my experience this sort of stuff is consistently poorly understood. Asplace 17:56, 8 October 2007 (UTC)
OK, but reassigning the term 'heat' to a new definition, in such a way that;
"heating" and "getting hotter" are now disconnected, is going to be the source of huge confusion. Asplace
try another example:
earth irradiated by the sun, light has to be work in the first law, earth in a vacuum, so earth is not 'heated' by the sun!!
FYI 1. you can sample the temperature of an object without effecting it, by using a probe at the same temperature and noting the lack of energy exchange, you seem to be confusing this with quantum mechanics somehow.
2. In TD there is no distinction between the sources of non thermal internal energy, so no point in talking individually about chemical,nuclear?,phase change,crystallisation etc etc.
3. You seem to be stuck in thinking this is a conceptual problem, it isn't, its about assigning an existing word to a concept which has significant differences from existing usage, I've checked the Feynmann lectures and an old university thermodynamics text book ( F. mandl ) i had lying around and the usage of the term is definitely counter to that used in this article. I and these sources are not suffering from conceptual problems. Asplace 19:58, 10 October 2007 (UTC)
example
an object in a vacuum is irradiated by a laser, the energy in the light has to be work, not q, in the first law, so by this articles definition of 'heat' the object is not being 'heated', but clearly it gets hot!! this is not what the word 'heat' means, and i have previously given multiple very well regarded and verifiable sources that show this clearly, so as i understand it as a good wikipedian i have a responsibility to start correcting this article. Asplace 18:55, 11 October 2007 (UTC)
BTW, wiktionary has 'heat' as thermal energy, and so does the article called sensible energy? i guess if you looked, the 'thermal energy' definition of heat would be in hundreds of articles, many of which might be linking to this article, which then uses a different one, confusing or what? —Preceding unsigned comment added by Asplace ( talk • contribs) 19:10, 11 October 2007 (UTC)
i think you need some reference to heat being only applicable to the NET transfer of thermal energy, in that, when two objects are in TDE and equal amounts of thermal energy are flowing in either direction, then no 'heat' is considered to be flowing, since dS is zero, but that with the removal of one of the two energy flows, the other energy flow although not ostensibly changing would need to be relabeled from thermal energy to 'heat'. This would emphasis that this definition of heat can not generally be broken down into subsystems, as might be assumed if casually compared to energy or force, but is a property of a complete dynamic system. —Preceding unsigned comment added by 82.27.224.69 ( talk) 16:31, 13 October 2007 (UTC)
Names of units called after persons must start with lowercase: joule and watt (abbreviation is uppercase: J and W). -- Virginia fried chicken ( talk) 12:20, 25 November 2007 (UTC)
There is much confusion in this article, most of which arises because there is no satisfactory defintion of temperature. The two are intimately linked by the Boltzmann constant. Defining heat (Q) as "any transfer of energy" as does the opening statement is a contradiction, a transfer of heat would be a change δQ, a change of energy would be δE. According to this definition, what then is Q if it isn't the form of energy called heat?
The origin of modern "heat science" (thermodynamics) was the realisation that heat was not a substance ( caloric or phlogiston) but the kinetic energy of some sort of fundamental particles that were free to move, i.e to vibrate in a fixed location for a solid and move freely as for a gas, there being an intermediate liquid phase for many materials. The reality of this was establisbed by Einstein with his explaination of Brownian motion which gave conclusive mechanical evidence for Dalton's atomic theory. Subsequent work showed that composite, none spherical particle (now called molecules) had other degrees of freedom that contained energy, thus their total energy, at a given temperature, was greater than the fundamental particles. (Fundamental paricles are only approximated by monatomic gases.)
The conclusion is; heat is that energy contained in the motion of fundamental particles, particles whose mass is unspecified but can only have motion in three (translational) degrees of freedom. This definition of heat does not exclude particles with more than three degrees of freedom, but the definition (and the reality!) of temperature takes into account the translational degrees of freedom only. There is a good reason for this, translational movements are the only way fundamental particles can exchange miroscopic mechanical energy, which explains why temperature is such an important property in thermodynamics.
There is a problem of usage which causes many difficulties and much confusion, because the translational and other motions of molecules are intimately linked, the heat of a system of particles is given as the total energy of the particles, change the translational motions (i.e. change the temperature) and you assuredly change the vibrational energy. The clue here is the various specific heats, materials with different specific heats are pressed into the same definition of temperature when it comes to exchanging energy through collisions.
It interesting to note that this is a purely mechanical definition -- Damorbel ( talk) 13:52, 16 January 2009 (UTC)
When I first loaded this page, there was about three paragraphs of Arabic text in the beginning of the article. After refreshing, everything was normal. Was there some kind of vandalism that was quickly fixed or something? —Preceding unsigned comment added by 68.228.166.58 ( talk) 19:38, 1 November 2009 (UTC)
what is the differance between heat and tempature? —Preceding unsigned comment added by Lorifalcon ( talk • contribs) 02:15, 6 November 2009 (UTC)
Heat is a flow of energy. Temperature is a measure of energy content.-- Nick Y. ( talk) 15:34, 6 November 2009 (UTC)
And heat capacity then? What is your definition of heat capacity ( specific heat).-- Damorbel ( talk) 22:29, 6 November 2009 (UTC)
This new revision [1] really makes a laughing stock of the whole article, it reference the First law of thermodynamics which completely contradicts it! For example "The first law of thermodynamics states that the energy of a closed system is conserved". No it doesn't, the first law article "states that energy can be transformed (changed from one form to another), but cannot be created or destroyed." The "First law" article recognises that in the course of energy transformations these tranformations can result in equilibrium conditions, typically chemical transformations do not go to completion but result in an incomplete state but the total energy involved does not change.
More rubbish "In physics and thermodynamics, heat is the process of energy transfer from one body or system due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body" Oh really? What about chemical reactions, combustion etc.?
From the changes you have made I suspect that you do not have the necessary knowledge to edit this already deeply flawed article. If you really want to making changes you should first consult on the discussion page. -- Damorbel ( talk) 08:20, 13 November 2009 (UTC)
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