Talk:Thermodynamic equilibrium

message: It would seem the article needs to make a clearer distinction between the concepts of a "uniform" medium versus a system in steady state, the latter allowing spatial but not temporal dis-uniformity.  I can take a stab at some of this in the thermal context. Rnestle 18:31, 22 February 2007 (UTC)
replies: text: There's another state - equilibrium, which may not be uniform but will be steady state. This article should confine itself to the equilibrium state, with mention of other possibilities which should be developed in their own article. PAR 20:25, 22 February 2007 (UTC)
replies: text: As far as other articles, shouldn't we have an article called Thermal equilibrium? presently that link just takes one to the present article. Rnestle 21:40, 22 February 2007 (UTC)
thread_title: Steady state versus uniform conditions

message: What the heck is thermal dispersion? I am removing it from the article as it means nothing to me. --Drozdyuk (talk) 14:44, 14 July 2010 (UTC)
replies: text: Agreed, the reference was too ambiguous for any one to find it.  I believe the term that the previous author was looking for was "thermal diffusion", but perhaps by the term "dispersion" he was trying to to be inclusive of advective effects.  However, there is still a serious problem with this section in that the river example contradicts the previous statement "in an equilibrium state, there are no unbalanced potentials (or driving forces) with the system." The river, while not time variant, has temperature gradients (i.e. potentials) driving heat flows via Fourier's Law and is encountering thermodynamic irreversablity.  I think this section is confusing "equilibrium" with "steady".  Even so, the river analogy has complications in that the flow is only valid in the Eulerian frame of reference and that real rivers are turbulent and hence stationary (invariant statistics with respect to time) rather than steady (invariant spacial distribution of state variables).  Not sure what your background is Drozdyuk, so I apologize if I lost you with any of the aforementioned terminology.  In any case, I wish to look at some text books for reference next week for a solid reference on the meaning of the term "thermal equilibrium".  I think the truth is that it is often causally used in situations that really don't stand up to rigorous scrutiny because they depend on the frame of reference and a good article needs to discuss the distinction in a manner that people can understand.  —Preceding unsigned comment added by Bdentremont (talk • contribs) 04:29, 15 July 2010 (UTC)
thread_title:  Thermal dispersion? 

message: TThe current article (08/10/10) states: 
"Thermal equilibrium is achieved when two systems in thermal contact with each other cease to exchange energy by heat"
I believe is more proper to state that 
"Thermal equilibrium is achieved when there is no longer a net change of heat exchange between two systems in thermal contact with each other"
in the same sense as when a chemical reaction reaches equilibrium. My point is that heat exchange never "ceases," but that the rate of heat exchange between AB and BA are the same. I don't think my version expresses this idea fully, Can someone paraphrase properly? 
:I think an even better definition would be "when the net energy exchange rate by heat between two system is zero". But I'd like to dig what textbooks say, before. --Cyclopiatalk 00:44, 11 August 2010 (UTC)
thread_title:  Definition of Thermal equilibrium 

message: I feel that the phrase "global stationarity" is too technical for this article. I "think" I understand what it means, but I am very sure that the average reader won't. Q Science (talk) 16:36, 14 November 2010 (UTC)
thread_title:  Global stationarity 

message: :Possibly. I'd definitely find it useful in visualizing the planets more accurately. I'll request more input by notifying WikiProject Astronomy, see if this can get any extra opinions. --Starstriker7(Talk) 19:11, 26 November 2011 (UTC)
replies: text: No, many exo-planets are Super-Jupiter or Neptune sized, comparing those to Jupiter or Neptune would be better. Large Super-Jupiters should be compared to the smallest theoretical brown dwarf and Jupiter, smaller ones ( <5MJ ) can drop the brown dwarf comparison. 70.24.248.23 (talk) 23:11, 26 November 2011 (UTC)
replies: text: That's why I mentioned, with relevent values swapped in. I know for example Jupiter has a suface temperature, core temperature, and equilibrium temperature. I don't see the problem with swapping the gas giant values in. I think the main point would be the comparison of equilibrium temperatures, which is mainly influenced by distance. The irradiance of each planet would be good also but no one does a comparison of those, the equilibrium temperature is the closest thing.  24.79.40.48 (talk) 15:35, 28 November 2011 (UTC)
replies: text: Remember that thermodynamic equilibrium is a laboratory and theoretical thing, not found in general in nature, useful for basic theoretical studies, but not directly in practical applications. Thermodynamic equilibrium is a special kind of equilibrium, in which there is zero transport of everything. The kinds of equilibrium that pertain to planets involve massive transport of energy and matter, and are thus quite far from thermodynamic equilibrium.Chjoaygame (talk) 21:48, 28 November 2011 (UTC)
replies: text: ♦ What I will remember is your suggestion that a great many Astrophysicists, using Equlibrium Temperature, are out to lunch. 24.79.40.48 (talk) 03:25, 15 December 2011 (UTC)

text: That chart is nonsense. For instance, the Earth's "Global equilibrium temperature" is close to 5°C, not -18°C (which includes the albedo of clouds, ice, and the like). If the albedo is included for Venus (in order to make a fair comparison), the surface temperature should be 184.2K (-89°C), not 34°C. The greenhouse stuff is also nonsense, as is the claim that Venus is almost tidally locked (? - not really). Note: that chart was created by user:GabrielVelasquez the day before he was permanently blocked. I suggest that everything written by that person needs a real close look. Q Science (talk) 04:35, 29 November 2011 (UTC)
replies: text: Apart from the above criticism of the content of the chart, I would add that the chart would not be appropriate for this article on thermodynamic equilibrium even if it were not nonsense.Chjoaygame (talk) 22:43, 29 November 2011 (UTC)

text: I agree with Chjoaygame: this chart is completely inappropriate to this article, and even this talk page is not the place to discuss the usefulness of producing a standard chart. For a proper discussion, move it to someplace where editors with a suitable knowledge of the area will be involved. Quondumtalkcontr 08:11, 15 December 2011 (UTC)
replies: text: It seems that my above remarks are not making sense to some editors. Please let me try again. Equilibrium is a widely used word, with many meanings. Thermodynamic equilibrium is a term of art in thermodynamics, a specifically defined kind of equilibrium, indeed a kind that practically never occurs exactly as defined; it can be approximated in laboratory experiments. Thermodynamic equilibrium explicitly forbids flow of any kind, while the energy budgets of planets are all about significantly large flows of energy, the very denial of thermodynamic equilibrium. The question here is not as to the content of the table but as to the content of an article on thermodynamic equilibrium. I have not studied the table in question here, but it does not need study to say that the present Wikipedia article on thermodynamic equilibrium is not its natural home. Without prejudice as to the value of the table for elsewhere in the Wikipedia, the table has no place here.Chjoaygame (talk) 18:38, 15 December 2011 (UTC)
replies: text: Note, it would be courteous to state the actual question when starting an RFC. I infer it's whether to include the above chart? No, it refers to a different kind of equilibrium. Nobody Ent (Gerardw) 22:03, 16 December 2011 (UTC)

text: ♦ How convenient for your argument that they don't work here, but they work fine where the chart was copied from: Original Chart 24.79.40.48 (talk) 07:11, 19 December 2011 (UTC)
replies: text: Then please fix them here. After all, you are the one who added the chart here. Q Science (talk) 07:47, 20 December 2011 (UTC)

text: ♦ Again, Maybe this thing that scientist keep refering to needs its own article! instead of being redirected back here. 24.79.40.48 (talk) 07:14, 19 December 2011 (UTC)
replies: text: Perhaps you've not noticed that Thermodynamic equilibrium and Thermal equilibrium are distinct articles, and more importantly, distinct concepts. The relevant links in the Equilibrium temperature article appear to be correct as they are; the links to this article are only to point out that the two should not be confused. — Quondumtc 07:57, 19 December 2011 (UTC)

text: A very deceptive and rude statement given that the second article was just created out of the first as a result of this discussion here.24.79.40.48 (talk) 07:27, 10 January 2012 (UTC)

text: Nonsense, that you would compare a rock in your back yard to an extra solar planet and make the later as worthless says a lot about your reasoning, Any planet near the Habitable zone of the parent star is going to refer the concept of Equilibrium temperature in its article, bet on it! There are three or four such article that have this chart in them already. 24.79.40.48 (talk) 22:23, 8 January 2012 (UTC)
replies: text: Dear Editor 24.79.40.48, the question for the present purpose is not (1) whether or not the table is valuable or correct or interesting or important for climate science. The question for the present purpose is (2) whether it is relevant to the subject of the present article on Thermodynamic equilibrium; this question (2) is not affected by the question (1). Editors need to understand the articles to which they contribute. The article on Thermodynamic equilibrium is about a theoretical area of physics that is mostly concerned with small homogeneous systems and with strictly cyclic processes. By the criteria of the present article, planetary processes are far from thermodynamic equilibrium and discussion of them is therefore far from the concern of the present article. I have therefore tried to change the target of the re-direct from Equilibrium temperature to Climate model#Zero-dimensional models in order to satisfy your desire for a re-direct, as you will see below. But another editor insists that this is not acceptable, and I do not have time or inclination to struggle over it. However that re-direct problem is dealt with, it remains the case that a table about planetary equilibrium temperature is not suitable for an article on Thermodynamic equilibrium, no matter how excellent and valid and valuable might be that table might be from the point of view of studies of climate and planetary temperature. You may wish to verify this for yourself by studying the article on Thermodynamic equilibrium.Chjoaygame (talk) 04:10, 9 January 2012 (UTC)
thread_title: break

message: The table in question has now been newly put into the article on Thermal equilibrium. I am not impressed that it should be there and I am here asking editors with relevant interests to look at its being there, and to make their comments on that question in the talk page there.Chjoaygame (talk) 08:03, 10 January 2012 (UTC)
thread_title: the table now put into the article on thermal equilibrium

message: The lead is a summary of the article. There is no mention of information in the body of the article and therefore no reason to mention it in the lead. Information is not a concept of classical thermodynamics, and the body of this article is probably not the place to introduce it. This comment does not deny that information is relevant to thermodynamics, but says that this was not the way to express such relevance.Chjoaygame (talk) 03:46, 2 March 2012 (UTC)
thread_title:  lead comment on information 

message: This article mentions entropy only in the overview, this important thermodynamic concept is neither explained nor referenced in the rest of the article. Since the maximisation of entropy is fundamental to the concept of thermal equilibrium I suggest that this deficiency be remedied as soon as possible. --Damorbel (talk) 09:09, 31 December 2012 (UTC)
thread_title:  Entropy 

message: Earth scientists believe so, from geochemists sampling water to petrologists sampling rocks. Equilibrium is a relationship. Its existence is sought by simplifying the variables in those relationships (necessary and sufficient) to three classes: extensities, densities, and intensities. (The last two are intensive variables.) These, with phases, can be observed or measured to our satisfaction. If the equations are satisfied to the accuracy of our current instruments, the system is is equilibrium--by definition. Predictions will be reliable to our instruments' accuracies.
If we perturb the system when studying it, The Gibbs-Duhem equations predict that the system will respond in a manner that ameliorates these perturbations by buffering. This amelioration is also continuous, during phase changes, while experiencing a continuous flux of extensities; but if the generation of responses by internal reactions is much faster than the fluxes, the equilibrium relations will exist at every measurable point.
Practically, if two adjacent assemblages of minerals (differing in bulk composition) have densities that predict the same intensities, induction suggests they were in equilibrium. The system will be in equilibrium with respect to space (local equilibrium) and to time (quasi-static equilibrium [a most unhappy term]). It is the intensities that need be continuous (T, p, mu), not densities (specific entropy, concentrations).
So yes, geologists think there is an equilibrium even when any or all walls are relaxed. Those descriptions quoted in the article gave at least sufficient conditions; but most tried to strive for necessary conditions as well. (The connection with efficiency, asked above, was somewhat lost when switching to a theory of states rather than phenomena; but the relations sought above are the systems' characteristic functions and their derivatives.)
Geologist (talk) 06:04, 4 January 2014 (UTC)
thread_title: Does Equilibrium Exist?

message: I undid what was probably a good faith edit, unfortunately unsigned with a user name.
The undone edit intended to say that an externally maintained force field can produce temperature inhomogeneity in a body that is in a state of thermodynamic equilibrium.
There is in reliable sources unanimity that such is not so.
Nevertheless, it keeps being proposed by occasional users that it is so.
I think perhaps one reason why such users repeat the mistake might be that they see temperature inhomogeneity in non-equilibrium steady states in a gravitational field, and they fail to recognize that the difference between thermodynamic equilibrium and a non-equilibrium steady state is profound and far reaching. It invalidates their proposal. To understand this further, users should study the reliable sources, of which nine are currently listed in the article in the second paragraph of the subsection Uniform temperature of the section Characteristics of a state of internal thermodynamic equilibrium of the article.Chjoaygame (talk) 15:06, 13 November 2014 (UTC)
thread_title:  undid good faith edit; why 

message: I undid this good-faith edit. Thinking of the universe as a thermodynamic system is trying to stretch thermodynamics far beyond its scope. There are references to this effect in the article on Heat death of the universe. That topic is only of historic interest. It was conceived before the discovery of the general theory of relativity and the concept of black holes. Clausius poetically wrote of the entropy of the universe and suchlike, but that was fancy, not science. It doesn't fit here.Chjoaygame (talk) 18:42, 5 February 2016 (UTC)
thread_title:  undid good faith edit; why