Talk:Second law of thermodynamics/Archive 5

request to clarify definition of heat
To any editors listening... A recent discussion at SkepticalScience (Sk), which has a very long comments section for a post about the Second Law and its relationship to the Greenhouse effect, has highlighted for me a problem with the current version of Clausius's statement. Many people don't understand that the heat flow being described is net heat. That heat can flow in both directions and the 2nd law simply requires that the flow from hot to cold be the greater so that the net is from hot to cold.

Some people latch onto the simpler form in the current statement to assert that Clausius didn't mean net because he didn't say it explicitly in that statement. This is then used in some wild arguments that the GH Effect violates the 2nd Law.

The conversation at SkS actually looked at various statements by Clausius, including others that more explicitly mentions the allowed bi-directional nature of the heat flux.

It would be worth while to expand the section on Clausius's statement to incorporate his more nuanced view from other statements and clarify his meaning.

The SkS discussion can be found here: http://www.skepticalscience.com/Second-law-of-thermodynamics-greenhouse-theory-basic.htm. Go to page 29 of the comments, comment 1446 by Dikran Marsupial citing Clausius and Tyndal's translation

Thanks Glenn Tamblyn (talk) 01:55, 26 August 2014 (UTC) Glenn Tamblyn


 * I moved the immediately above comment by Editor Glenn Tamblyn from further above to here as the usual place for new comments.Chjoaygame (talk) 10:33, 27 August 2014 (UTC)


 * I put in an explicit reminder as requested.Chjoaygame (talk) 10:52, 27 August 2014 (UTC)

Thanks Chjoaygame. Newbie here so I will leave it to others to discuss. 124.181.32.174 (talk) 11:56, 28 August 2014 (UTC)

New commentary from Clausius
Editor Glenn Tamblyn has supplied some new commentary quotes from Clausius. They are not statements of the second law. Indeed they directly contradict the second law, which says that natural processes are accompanied by increase of entropy. The Clausius comments are not about natural processes, but are instead about idealized or fictive mathematical quasi-processes, which can be prescribed to be reversible. The purpose of that is to define entropy, not to state the second law. The point of the second law is that natural processes are irreversible. The presence of the new commentary quotes from Clausius is therefore, in my opinion, misleading to a reader not already well familiar with the subject. I do not think it a good idea to add at this point in the article the detail that fictive quasi-processes can be made reversible. I think the new commentary should be removed.Chjoaygame (talk) 06:47, 16 September 2014 (UTC)

Edit re violations on short time scales
I am concerned that the recent edits by 122.177.32.77 (here and at Entropy) may have been dismissed too quickly. Yes, any claims of violating the second law are shocking. But in this case the added seven-line section was supported by references to articles in five leading physics journals, and two of the article titles (in Physical Review Letters and Physical Review E) even include the words violations and violating. So I don't think the material should be totally excluded from the Wikipedia article on the subject. I have not read the cited articles, so I admit the possibility that the edits in question were not accurate, but in that case the Wikipedia article should explain why and not just ignore the articles, given the importance of the sources.

Also, I do not understand the claim in the edit summary for the deletion to the effect that The second law does not refer to short time scales. Our article lead says that The second law of thermodynamics states that the entropy of an isolated system never decreases, Taken literally, never means not even for a picosecond (or less). If current research shows that it actually means never for more than 0.1 s [timescale mentioned in the deleted edit at Entropy, then I think the Wikipedia article should explain that. Dirac66 (talk) 00:18, 5 October 2014 (UTC)


 * Good to see this careful commentary.


 * Wikipedia lead statements of the laws are controlled by forces unknown to Newton. I made the edit on the assumption of a properly valid statement of the law, nearly as per Planck, which latter sadly was not acceptable to the forces. It is a sad fact that there is no unique, rigorous, and straightforward definition of entropy for a system not in its own state of internal thermodynamic equilibrium. Plenty of people wish there could be such a definition but the facts are painfully otherwise. To deal with non-equilibrium situations rigorously, one needs two- or more-time entropies. Not considered in this article. Various half measures are of course proposed by various experts, but they are still half measures. This article at present is not set up to consider such half measures.


 * Even Planck's most careful statement is not perfectly watertight and cast iron. If one wants to state the second law in terms of entropy, a proper statement is a tightened version of Planck's; something like the following: There may be initially given two or more thermodynamic systems, each in its own state of internal thermodynamic equilibrium. Then there may be a thermodynamic operation that initiates a thermodynamic process of transfer between the systems. The new arrangement of systems proceeds to a final state with all systems in their own states of internal thermodynamic equilibrium. Then the sum of the entropies of final states is greater than the sum of the entropies of the initial ones.


 * I can imagine what horror might be expressed if one tried to put this up. But it expresses, perhaps clumsily, a proper and valid statement of the law.


 * It would be lovely if one could say more. But I think it would be self-deception to do so. (1) The hardest point is that some like to imagine that some magical mathematical procedure will create a straightforward one-time entropy that will rigorously tell the direction of a process that doesn't start or finish with states of internal thermodynamic equilibrium. (2) Some like to forget that a process that starts from equilibrium needs something to start it, and it needs a mythically infinite time for it to finish itself. It is perhaps pleasant or convenient to try to hide or gloss over these two facts, but it is not good thermodynamics.


 * True, one never actually knows if one is dealing with a system that has waited long enough (inifinitely long) to reach its own internal thermodynamic equilibrium. But thermodynamics has its limits and that is one of them. It just postulates that one does know.


 * Small systems that show detectable fluctuations, and rapid processes that show up fluctuations, are specialist subjects, and I think they need explicitly specialist and properly thorough expression. I think they should not be tagged onto basic classical thermodynamics as afterthoughts.


 * I am suspicious that the edits in question were promotion, but that is only a subsidiary reason for undoing them. The decisive reason is as I have proposed just above.


 * That the lead is unsatisfactory is not, I think, I reason to allow other faults to come into the article.Chjoaygame (talk) 15:20, 5 October 2014 (UTC)
 * Thanks for your reply. I had not realized that the intro is still unsatisfactory. Perhaps you can try again to correct it and add sources. I note that the intro is now unsourced except for two references at the end of the third paragraph. This may be ok for some articles, but not for a subject as difficult and controversial as the second law of thermodynamics.


 * For now I am concerned with the recently deleted edit by 122.177.32.77. I think the experiments mentioned are important and do belong in the article, but perhaps they can be described without actually saying in Wikipedia’s voice that they are violations of the second law. So I propose restoring the text with some modifications.
 * Change section title to Statistical interpretations of the second law of thermodynamics and fluctuations
 * Change second sentence of section to Entropy fluctuations over short time scales in the case of trajectory of colloidal particles in water held in an optical trap have been experimentally demonstrated, and described by the authors as violations of the second law.
 * Add comment after the above sentence: this assumes that entropy can be defined when a system is not at equilibrium.


 * As for fluctuations being a specialist subject, I think they should be mentioned briefly to inform the reader that they exist, and avoid implying that entropy can never decrease under any circumstances. A short section (here 7 lines) is sufficient if it includes a link to a relevant main article (such as Fluctuation theorem ?) for the few readers who want more details.


 * And I don’t worry about promotion (conflict of interest) here because the sources are refereed papers in leading journals. It is more a concern when the sources are personal websites or advertisements. Dirac66 (talk) 01:25, 6 October 2014 (UTC)


 * "Thanks for your reply." Good to see your careful considerations.


 * "I had not realized that the intro is still unsatisfactory. Perhaps you can try again to correct it and add sources. I note that the intro is now unsourced except for two references at the end of the third paragraph. This may be ok for some articles, but not for a subject as difficult and controversial as the second law of thermodynamics." I think it can be ok to write without explicit sourcing in the lead (I distinguish the lead from a separate section that is labeled 'introduction', as here). I agree that the material in the lead should be well and properly sourced somewhere in the article, but I think it is often good enough if the sourcing is deeper within the article. The lead is a summary. I will perhaps comment more on the present lead in due course. I am not persuaded that the second law is difficult or controversial, except where "improved" versions of it are concerned. I think the "improvements" can easily create problems. Indeed I think they can be manufactured in order that they should create problems that then call for "solutions".


 * "For now I am concerned with the recently deleted edit by 122.177.32.77. I think the experiments mentioned are important and do belong in the article, but perhaps they can be described without actually saying in Wikipedia’s voice that they are violations of the second law." We are looking at a suite of edits, in this and the Entropy article. In the Entropy article, the edits are from user 122.177.32.77, the same as the author of the ones in this article. They are a fair few and I think I may fairly ask discussants here to look for themselves rather than that I try to list them all here. That user 122.177.32.77 is apparently focused on this one issue, and has been diligent and persistent in driving his cause. The edits mostly culminate in a section about "Entropy changes in a Thermodynamic Process Under Potential Gradients", by Sinha Dhiraj. They refer to the Hamiltonian of the system. This is not part of classical thermodynamics. If at all, it should be presented in its own right in a suitable place, not as an appendage to the classical discussion. It has a strong flavor of presentation of personal work, which I regard as very suspicious of conflict of interest, a thing to be carefully guarded against, and worried about very much, I think. The word soapbox comes to mind.


 * An example of my undoing actions is here. The undone lead-in has a strongly personal appearance: "In a recent work published in Physica A, a leading peer reviewed international journal of statistical physics, Dhiraj Sinha has presented a novel formulation of the second law of thermodynamics while incorporating the role of conservative vector fields in entropy changes." We seem to be looking at steps to work around my undoing actions. The experiments mentioned as lead-in are discussed in Wikipedia in other places, where they are more appropriate. I think they are put here just in order to provide cover for the Sinha personal work. I agree with Editor Materialscientist that we seem to be looking at "undue promotion of recent primary research". For me, it is not enough that material be sourced from "refereed papers in leading journals". In general, Wikipedia editors are assumed (rightly I think) to be not competent to judge the reliability of such material.


 * I could spend much time writing more about this, but I hope that the above is enough to persuade editors that my undoings are justified. I am not in favor of the kinds of change you suggest.Chjoaygame (talk) 03:17, 6 October 2014 (UTC)
 * All right, I appreciate your opinion. I have now noticed that the article already has an adequate section on Non-equilibrium states, which contains the important information including two references to Evans and Searles - one theoretical and one experimental paper. So I will agree that we do not need the other section which you have deleted. I will just make some minor changes to the existing section - such as adding the word fluctuation to the section title so that it shows up in the Table of contents, and rewriting the sentence with the word spacetime which is elsewhere usually associated with special relativity. Dirac66 (talk) 23:37, 6 October 2014 (UTC)


 * Thank you. Please would you consider waiting a few hours. I have an urgent appointment and will be back later. Looking at the section on 'Non-equilibrium states, I see some regrettable faults. I have done some thinking about this matter recently, but not written it up.Chjoaygame (talk) 00:13, 7 October 2014 (UTC)Chjoaygame (talk) 00:22, 7 October 2014 (UTC)
 * OK, I will wait. Dirac66 (talk) 01:44, 7 October 2014 (UTC)
 * Thank you.Chjoaygame (talk) 05:28, 7 October 2014 (UTC)
 * Thank you. Now I have had a shot at it.Chjoaygame (talk) 07:50, 7 October 2014 (UTC)

Two or several-times entropies?
To Chjoaygame: I think that your edits of the last 48 hours have improved both the lead and the section on non-equilibrium states. I have changed two sentences to make them clearer, hopefully while preserving your intended meaning. A third sentence which I find mystifying is the one about two- or several-times entropies, but I have just discovered that the source book by Attard is in our university library, so I will (eventually) check it out. Could you insert the relevant page number(s)? And is two- or several-times entropies the exact term used by Attard? Also, perhaps if this is a definition of a quantity related to entropy, it should be mentioned as a new section in the Entropy article instead of here, since the Second Law refers to ordinary entropy. Dirac66 (talk) 23:48, 8 October 2014 (UTC)
 * Or perhaps the article on entropy production? Dirac66 (talk) 00:13, 9 October 2014 (UTC)


 * Thank you. Yes, your further edits seem to me to be good.
 * The whole book is about the many-times entropies. I didn't think a particular page number would help. I don't recall if he uses those exact words, but they are pretty much what he says. My words are more or less ordinary language that springs to the mind of a reader of his book. I think they are suitable for the present purpose. Checking, I find on page 24 "two-time entropy". He also calls it "second entropy" and "transition entropy". He talks about "third entropy". Glancing through, I didn't find "many-times entropy" but I seem to recall it from past readings; perhaps I imagined it.


 * Attard is a very naughty boy. He talks all kinds of jumbled stuff about probability. He says he settles for the Popper propensity stuff. His notation is logically inconsistent and lazy. But his basic idea, of generalized entropies, is, I think, right, and worthy of mention; but hardly more than a mention. He says plenty that needs saying, but sad to say he is quick and efficient in how he says it. I don't feel I have a really good understanding of it. What matters here is that he is offering a genuine generalization of macroscopic entropy. You suggest "instead of here". Perhaps, but I think it might also be right to mention it here, to register the right direction for proper generalization. As I read it, the Attard idea is not about entropy production; that is, I think, a concept that belongs to local thermodynamic equilibrium theory.


 * If you really want to remove the mention of Attard's stuff I haven't a strong defence for keeping it. He should work more on it, I think. My only defence is that it is in a section that criticizes loose use of the word entropy, about non-equilibrium.Chjoaygame (talk) 04:44, 9 October 2014 (UTC)


 * I have seen how to edit on this device. Good!
 * I have followed your suggestion and removed the flaky statement. Thank you for that thought.Chjoaygame (talk) 17:33, 9 October 2014 (UTC)
 * That seems probably best at the level of this article. But I searched for second entropy and found that you had mentioned it in the more specialized article Non-equilibrium thermodynamics. I have included a link to that article in the Non-equilibrium section here, for those readers who are interested. Dirac66 (talk) 19:09, 9 October 2014 (UTC)

Overhaul
I am now working on an overhaul of the article. Anyone is welcome to see my draft and edit or give advice.--Netheril96 (talk) 03:44, 9 October 2010 (UTC)

Well, when you write "In each adiabatically separated compartment, the temperature becomes spatially homogeneous, even in the presence of the externally imposed unchanging external force field" you are mistaken because there is a redistribution of energy such that the mean sum of molecular gravitational potential energy and molecular kinetic energy is homogeneous, and thus there is a redistribution of temperature, becoming cooler at the top. This is because changes in gravitational potential energy in molecular flight between collisions cause changes in entropy. This is why and how there is a huge temperature difference in the cross section of a Ranque Hilsch vortex tube wherein a huge force field is generated artificially.

From your introduction one could conclude there are two distinct and very different types of entropy.. so different that you say "Don't mix thermodynamics and statistical mechanics up". This is misleading because it hides the fact that the heat expression for entropy is actually only a special case of the statistical expression! A significant point which should be included. (Vh mby (talk) 03:09, 27 April 2011 (UTC))

Actually the second law has been justified on macro terms having no relation to statistical thermodynamics. See, for example , and more specifically 

THERMODYNAMIC equilibrium is characterized by maximum entropy (within system constraints) and thus a lack of any unbalanced energy potentials. It can never be an isothermal state in a vertical plane in a gravitational field. (Such is never seen in the troposphere of any planet, for example.)  This is because mean gravitational potential energy (per molecule) must be taken into account and it would cause an unbalanced energy potential in a vertical plane if mean kinetic energy were homogeneous. The gain in potential energy must be offset by a loss in kinetic energy, and indeed this transition takes place in every movement of molecules between collisions. Hence, at thermodynamic equilibrium the Second Law implies (as a direct corollary) that there will be a density gradient and a temperature gradient. A pressure gradient follows as a corollary of these two gradients, because pressure is proportional to the product of temperature and density. If what I'm saying were not correct, then you cannot explain the necessary energy input at the base of the nominal troposphere of Uranus where it's hotter than Earth's surface, but there is no direct Solar energy nor any internal energy source of any convincingly detectable magnitude. What happens is that new solar energy absorbed near the top of the Uranus atmosphere disturbs the thermodynamic equilibrium (with its associated temperature gradient) and here is indeed then a heat transfer from cooler to warmer regions because such a transfer is necessary to achieve a new state of thermodynamic equilibrium with the same temperature gradient but a higher overall temperature level. The same happens on Venus and Earth. — Preceding unsigned comment added by 121.217.3.117 (talk) 08:18, 13 October 2014 (UTC)


 * I am leaving the above comment about unbalanced energy potentials in the location where it was misplaced by its writer, who did not sign with a user name. Perhaps the comment is from a banned user. It is not valid in physics. Perhaps it may help if I say that I moved the previous comment, which perhaps came from the same writer, to the bottom of this talk page, which is the customary place for new comments, not the top of the page as this one is placed.Chjoaygame (talk) 10:40, 13 October 2014 (UTC)Chjoaygame (talk) 10:46, 13 October 2014 (UTC)

Yes it is valid physics written by a qualified physicist with decades of experience in thermodynamics. Your assertive statement is without any foundation in the laws of physics. Gravitational potential energy is one of the forms of energy which must be taken into account in determining when thermodynamic equilibrium is attained. If you think not, then edit the Wikipedia article on thermodynamic equilibrium if you want to mislead people.

Clausius statement
The "hot to cold" statement is merely a corollary which has certain prerequisites. Because thermodynamic equilibrium involves all forms of energy, this Clausius statement is only applicable for non-radiative heat transfer if the gravitational potential energy remains constant.

— Preceding unsigned comment added by 121.218.41.105 (talk) 09:01, 11 October 2014 (UTC)

Th equations for thermodynamic potentials specifically exclude changes in gravitational potential energy. Yet one of these, namely the entropy equation is used to prove the Clausius statement. Hence the Clausius statement is merely a corollary of the Second Law which only applies in a horizontal plane. — Preceding unsigned comment added by 101.161.181.169 (talk) 10:36, 8 February 2015 (UTC)


 * Hi Mister 101.161.181.169! The current version of the Thermodynamic Potential article says gravitational potential energy is "typically disregarded," but just because something isn't mentioned, that doesn't mean it's "specifically excluded." Head to section 1.3 of Alberty's pretty paper at, take a look at Table 1, and there's a nice mgh there for the contribution of gravitational mechanical work to thermodynamic internal energy. Yay! When you wrote "a horizontal plane," you probably meant h, but g or m could change and everything else in Alberty's table could also change. Simple things are easier to understand, so why bother with anything in Alberty's table 1 when thinking about or writing about the second law? However, I think I understand where you're coming from. What I don't like in the Clausius statement in this article is that it is not correct. The article states that entropy increases or remains constant for isolated systems and that the entropy of the universe will reach a maximum. The reality is that entropy increases or remains constant for adiabatically closed systems and it reaches a maximum for isolated systems. The phrase "adiabatically closed" allows for work interactions like everything in Alberty's table, including your mgh. Yay! Gravity CAN get involved in a system, and its entropy will still increase or remain the same according to the second law. The term "isolated" excludes everything in Alberty's table 1. Boo. If gravity keeps getting involved adding work to a system then entropy might not ever reach a maximum. I pointed this out back in 2006 at Talk:Second_law_of_thermodynamics/Archive_2 but it's not surprising that it hasn't been corrected yet. Such is life. If you want to learn thermodynamics, take an engineering course at a good college. Certain details at Wikipedia about science in general and thermo in particular have never been rigorous and won't be changing any time soon. Flying Jazz (talk) 21:38, 8 February 2015 (UTC)

The Clausius statement is crystal clear and should be beyond any discusson, as it is a LAW of NatURe! I admit that translating such a beautifully clear statement phrased in Clausius's own language (for Clausius it is german) is easier and that complex  abstract concepts like the 2nd law will suffer in translation. This is no excuse to get it all wrong like Kelvin. Although his 'offical' statement is ok, all his propagation is outright WRONG. Kelvin caused governments to write outright illegal laws. Illegal by the terms of the universe! He caused a most despicable misconeption of laws of nature throughout all foremost english speaking countries! Kelvin's proagations and concepts are in their gist severely wrong; whereas The second Law stands as a law of nature in all its beatuy.


 * If you are going to insist that the zeroth law completely defines temperature, you must at least reference the statement. And by reference, I mean a reference which lays out the development of temperature as a real number from the zeroth law, not simply a bare unsupported statement. If temperature is

not defined by the zeroth or first law, then it cannot be used in a statement of the second law.


 * Do not eliminate a clearly referenced statement by simply declaring the source outdated. The truth of a statement is not a function of how old it is. Please at least explain in what sense the statement has been rendered untrue. The first Clausius statement is older than the referenced statement. Is it too outdated?
 * The referenced statement was not a verbatim copy added without thought. It is a very clear restatement of what was said in the reference, rendered in the third person, with modifications and clarifications. The statement actually says something. Please read the statement and point out its flaws. PAR (talk) 12:47, 2 November 2010 (UTC)

PS - to be accurate, a referenced statement was deleted, not replaced, the summary is wrong in this sense. PAR (talk) 13:10, 2 November 2010 (UTC)


 * I still disagree with you that temperature is "undefined" before second law, but the ordering of temperature indeed is undefined, so the reformulation of Clausius statement excluding the concept of "hot and cold" is acceptable, in my opinion.--Netheril96 (talk) 14:13, 2 November 2010 (UTC)

Contradiction
The statement "even in the presence of the externally imposed unchanging external force field" is contradictory to the fourth paragraph wherein there is a correct explanation regarding external force fields and when they do or do not have an effect on temperature. A force field, such as the centrifugal force field in a Ranque-Hilsch vortex tube, causes there to be a temperature gradient, such as in the radial cross-section of that vortex tube, and in a planet's troposphere subjected to gravitational force. This results directly from the Second Law of Thermodynamics because, when the sum of molecular potential energy (relative to the force field) and kinetic energy is homogeneous there are no unbalanced energy potentials, and thus maximum entropy exists. The fourth paragraph includes the condition "subject to the condition that the compound system moves as a whole within that field" whereas that condition is not repeated in the next paragraph which thus incorrectly generalizes the statement regardless as to whether or not the "compound system moves as a whole within that field." For example, when wind descends vertically above the South Pole we have a case of "the whole system" moving and thus cold air from the upper troposphere is conveyed to the surface at similar temperatures without there being sufficient time for gravity to form the temperature gradient that it normally does in calm conditions in any planetary troposphere, regardless of whether or not there is a surface at the base thereof or any penetrating solar radiation reaching the lower troposphere.

— Preceding unsigned comment added by 121.216.226.179 (talk) 23:17, 15 February 2015 (UTC)


 * I have changed the syntax of the fourth paragraph of the lead to indicate more clearly that it covers the fifth paragraph.


 * The proposals in the above unsigned comment by IP editor 121.216.226.179 mostly refer to systems not in thermodynamic equilibrium. They are therefore not applicable to the second law for processes that start and finish with the compound system in thermodynamic equilibrium.Chjoaygame (talk) 06:40, 16 February 2015 (UTC)

undid well considered edit
I have undone a well considered edit. I am here offering what I regard as a justification for my undo.

I have some time ago carefully considered, as perhaps a suitable source for the present article, the book cited by the undone edit, <Čápek, V. and D.P. Sheehan, Challenges to the Second Law of Thermodynamics (Theory and Experiment); Vol. 146 in Fundamental Theories of Physics Series, (Springer, Dordrecht, Netherlands, 2005) ISBN: 1-4020-3015-0.> Perhaps I may add here a comment from the undone edit: "Most of these are theoretical and have little hope of being experimentally tested within the foreseeable future. Several have been resolved in favor of the second law; however, the majority still await experimental test or resolution."

My take on the proposed "challenges" is that they are not challenges to properly stated versions of the second law. They are challenges to various straw men, constructed to provide specious grounds for challenge. Many of them are about non-equilibrium scenarios, or about "entropy" for non-equilibrium systems. Such are not the province of strict statements of the second law, and so are not suitable to appear in the present article.

I do not wish to disparage the careful and diligent work of the editor whose edit I have undone. I am sorry that it may leave him feeling that his careful work has been rejected. It is that I think the properly stated second law is valid and reliable, and that the article should leave the reader in no doubt about that. I think it is possible to worry about the law, but that proper worries are more subtle than are captured in much literature.

It is not the aim of Wikipedia to present "mainstream" views. The aim is to find and report reliable sources.Chjoaygame (talk) 00:46, 1 March 2015 (UTC)
 * I am not expert enough to offer detailed comment on the merits of the deleted section written by Yusefghouth. However I am uncomfortable about completely removing what seem to be two well-written and balanced paragraphs with many references to leading refereed journals. Is there nothing at all of value in the deleted text?? If as I suspect it is partly correct, then the good parts should be of interest to readers of this article. Why not use the proposed text as a starting point, and try to correct any errors or misstatements?
 * For example you write above that Many of them are about non-equilibrium scenarios, or about "entropy" for non-equilibrium systems. Such are not the province of strict statements of the second law, and so are not suitable to appear in the present article. I would reply that there is no Wikipedia editorial policy which restricts the article to only equilibrium systems. Why not keep the section, and add a statement similar to your criticism, perhaps Many of them are about non-equilibrium scenarios, or about "entropy" for non-equilibrium systems. They are therefore usually considered as not the province of strict statements of the second law. This would have the merit of allowing each reader to decide whether s/he is interested in non-equilibrium systems.Dirac66 (talk) 02:53, 1 March 2015 (UTC)
 * I looked at the new edit before it was deleted and thought it should stay. I agree with Dirac66. It has now been restored. I suggest it is left while the matter is discussed further. It probably needs some changes but essentially it is worth stating. -- Bduke   (Discussion)  04:55, 1 March 2015 (UTC)

The edit that I undid, with a note "see talk page", has been restored by the editor who posted it, with an edit summary "please explain". I don't know if he read my above talk page justification, but he has not replied to it.

Editor Dirac66 asks is the edit entirely unsuitable for the article. He suggests using the edit as a starting point for new material. Editor Bduke concurs with that.

The arguments offered so far are that the edit is well referenced, and that it is open to question whether the law is about non-equilibrium scenarios.

I think that the edit is essentially misleading and ill-conceived, so that no amount of referencing could rescue it. I accept that it is supplied with relatively many references, but I counter that none of them deals with the real issues at stake, and that they therefore do not qualify as reliable sources for the purpose.

The key here is as I have written above, that the "challenges" are not true challenges to the law properly stated. They might be passed off as 'challenges' to faulty statements of the law, or as 'challenges' to various straw men. To earn a place in the article, proposed challenges should be much more critically and carefully thought out and constructed than are the remarks in the disputed edit. The disputed edit makes no attempt to deal with real issues and flaws in the proposed "challenges", and seems entirely unaware of what are those issues and real flaws. The disputed edit concedes that that there is incomplete experimental evidence for the "challenges", but that concession amounts to a petitio principii, assuming that the logical groundwork has been done that would make experimental checks relevant as genuine challenges worthy of the name. It is the lack of logical groundwork that is the reason why the edit is properly described as misleading and ill-conceived.

Editor Dirac66 proposes to offer the reader a personal choice about whether to consider non-equilibrium scenarios. I respectfully disagree. We are here concerned with one of the most respected laws of physics. There is no room for personal choice here. It would gravely mislead the reader to suggest that there is such room. If someone wishes to have more detail on this in the article, a suitable course of action would be to survey and analyse the literature on the theory of non-equilibrium scenarios and report on it. That is not remotely attempted by the disputed edit.

In a nutshell, the law is a law of classical thermodynamics. It is about processes that start and end with systems in their own respective states of internal thermodynamic equilibrium, in thermodynamic equilibrium with one another as allowed by the walls. The "challenges" do not address that law. To put them into the article would be to muddy that fact.

Many physicists would dearly love to think that the law is more general than the one just stated in the previous paragraph. Many physicists blithely assume that it is so. Then the proposed "challenges" might have some place in the article. But the law is not so. Those who wish to take it as being so need to establish their case, or to state some more general law, admitting non-equilibrium scenarios, and write an article about it. In effect, the edit represents wishful thinking, that the law be faulty, supported by flawed statements of it or wrong assumptions about what it means.

I am saying that disputed edit is hopelessly flawed and is not a suitable basis for a proposed section criticizing the law. I think Einstein is right about this. His considered opinion is not to be ignored. Classical thermodynamics, within its proper scope of applicability, will never be overthrown, however much some may wish to see it happen. To use the disputed edit as a basis for an addition to the article would be to invite an endless flow of drivel, with no compensating benefit.

The disputed edit should be entirely deleted. If someone wishes to challenge the second law in the article, they should do so with a fresh start, on a much better logical and structural base than the disputed edit.Chjoaygame (talk) 08:20, 1 March 2015 (UTC)


 * Editor Arthur Rubin has now deleted the edit in question a second time with the edit summary Well-referenced, but contradicted by even better references, so should not be here. Could we have the even better references please? Dirac66 (talk) 12:51, 1 March 2015 (UTC)
 * Actually, thinking it over, do we have reliable sources that the articles constitute "challenges" to the 2nd law? Even if the articles are peer-reviewed, this would require an independent reliable source.  — Arthur Rubin  (talk) 16:31, 1 March 2015 (UTC)

Editor Dirac66 is right to express concern about this matter. It is very important for the article. The bar is to be set high for this discussion. I do not expect that I can safely clear it, but I will offer something here. No source here is perfect, just as, present company excepted, nothing in the real world is perfect.

Callen, H.B. (1960/1985). Thermodynamics and an Introduction to Thermostatistics, (1st edition 1960) 2nd edition 1985, Wiley, New York, ISBN 0-471-86256-8, on p. 3 writes "The contrast between thermodynamics and its counterpart sciences raises fundamental questions which we shall address directly only in the final chapter. There we shall see that whereas thermodynamics is not based on a new and particular law of nature, it instead reflects a commonality or universal feature of all laws. In brief, thermodynamics is the study of the restrictions on the possible properties of matter that follow from the symmetry properties of the fundamental laws of physics."

This emphasizes that thermodynamics aims at generality. Consequently its scope is limited.

Callen also writes on page 5 "Perhaps the most striking feature of macroscopic matter is the incredible simplicity with which it can be characterized. We go to a pharmacy and request on liter of ethyl alcohol, and that meager specification is pragmatically sufficient. ... The pertinent few emerge as macroscopic coordinates, or “thermodynamic coordinates”."

And on page 6 "By definition, suggested by the nature of macroscopic observations, thermodynamics describes only static states of macroscopic systems."

And, shock of shocks, on page 15 he writes "In practice the criterion for equilibrium is circular. Operationally, a system is in an equilibrium state if its properties are consistenly described by thermodynamic theory!"

Also on page 15 "A description of a thermodynamic system requires the specification of the “walls” that separate it from the surroundings and that provide its boundary conditions."

Münster, A. (1970). Classical Thermodynamics, translated by E.S. Halberstadt, Wiley–Interscience, London writes on p. 52 "An isolated system is in thermodynamic equilibrium when, in the system, no changes of state are occurring at a measurable rate. ... The proviso 'at a measurable rate' implies that we can consider an equilibrium only with respect to specified processes and defined experimental conditions."

I will not continue along these lines because the question is so general and fundamental that my efforts can appear only as 'walls of text', the more the worse!Chjoaygame (talk) 17:25, 1 March 2015 (UTC)

outline
I am the author of the edit in question. I appreciate the civil and measured tone of these exchanges, something often lacking in discussions of this important law. I respectfully request that my edit be reinstated because the rationale for removing it is based on inaccurate information and an improper understanding of the second law. I would like to address what seem to be the principal concerns, specifically:

(A) The challenges are strawmen arguments.

(B) The challenges represent nonequilibrium systems to which the second law does not apply.

(C) It is unclear what the scope of the challenges are, whether they are classical or quantum, microscopic or macroscopic in nature; hence, whether the section should be retitled.

I will address these in order.Yusefghouth (talk) 21:49, 13 March 2015 (UTC)

(A) claim of straw men
The editor Chjoaygame's claim that these challenges are strawmen is a minority viewpoint, in fact, one that I've never seen before until I read his remarks. Furthermore, it seems at odds with a large body of evidence, namely, that these many challenges have been published by some of the best known scientific journals and presses in the world. The referees and editors of these 50-100 articles, monographs and conference proceedings apparently did not consider them strawmen, otherwise they would not have published them. Take one editor in particular, Gerard 't Hooft, Nobel laureate in physics and editor of Foundations of Physics. He oversaw the publication of the papers stemming from the 2006 AAAS symposium on second law challenges, published in Found. Phys. in 2007 (Reference 71 in the contested edit). He was also editor in 2014 when reference 85 was published, offering the first experimental evidence for second law breakdown in the laboratory. I don't understand why the reviews of so many editors and referees from so many good journals and scientific presses over the last 30 years have been brushed aside. Any additional light you can shed on this would be appreciated.Yusefghouth (talk) 21:49, 13 March 2015 (UTC)


 * There would be a huge payoff for anyone who could fault the second law. Such a person would outrank Clausius, Kelvin, Einstein. The Nobel Prize would be peanuts for such a person. So the incentive seems great.


 * Right here the objection is to my rhetorical term 'straw man', not to the real substance of my reasons. That others do not use the rhetorical label 'straw man' is not an answer to my argument.


 * My argument is that the proposed "challenges" are not challenges to the second law. They are falsely advertised. They are challenges to mis-statements or misunderstandings of the second law. There is a huge incentive to mis-state he second law, and correspondingly one must be very strict in demanding a correct statement. Weighty claims need weighty support. A faulty statement of the second law is not weighty support for anything.


 * So here I need to state the second law: "The second law of thermodynamics states that in a natural thermodynamic process, there is an increase in the sum of the entropies of the participating systems."


 * We need to talk physics here. This statement is about entropies of thermodynamic systems. Strictly speaking, a thermodynamic system has an entropy only when it is in a state of its own internal thermodynamic equilibrium. Many physicists would dearly love it not to be so. But they indulge themselves with wishful thinking. This immovable obstacle is not faced by the proposed "challenges", nor by the proposer of the 'challenge' section of the article. The question is not about whether the internal workings of a process means a temporary departure from thermodynamic equilibrium, as mistakenly in good faith suggested by the 'challenge' proposer. The equilibrium requirement is for the initial and final states of the process. This is what the second law refers to. It does not refer to the internal workings of the process. No amount of good faith or wishful thinking can change that.


 * What matters here is this argument, not whether one likes to label it a charge that straw men are being created.


 * Perhaps it may save time if I mention here the so-called 'entropy production' formulas of the 'local thermodynamic equilibrium' approximation. They make for good approximations for suitable problems, and are speciously labelled as if they refer to some kind of non-equilibrium "entropy". But they are not calculators of entropy strictly read. And here we need strict reading.


 * At the standard of reasoning needed to challenge the second law, to talk of entropy for non-equilibrium states one must define it. That has not been done. There is no real challenge offered here.Chjoaygame (talk) 00:12, 14 March 2015 (UTC)

(B) non-equilibrium question
It is claimed that these challenges are nonequilibrium systems to which the second law does not pertain. Actually, the second law applies to all thermodynamic systems, whether they are at equilibrium or not. In fact, it pertains especially to nonequilibrium ones. Take the Planck formulation: "The entropy change for any spontaneous process is never negative." A "spontaneous change" refers to a "nonequilibrium process." Or the Clausius formulation: "Heat flows from hot to cold, not vice versa." Again, a nonequilibrium process. In fact, many -- if not most -- formulations of the second law explicitly or implicitly invoke nonequilibrium. To assert otherwise is simply mistaken. These many challenges to the second law, by definition, require reversals of the normal direction of entropy change; therefore, they require nonequilibrium behavior at some point. To forbid noneqilibrium systems from discussion of the second law is not only mistaken in the physics, but also begs the conclusion.Yusefghouth (talk) 21:49, 13 March 2015 (UTC)


 * These remarks have been dealt with in sub-section (A). I do not wish to be harsh, but I have to say here that these remarks thoroughly misunderstand the physics. Such misunderstanding is widespread, and is supported by much wishful thinking.Chjoaygame (talk) 00:16, 14 March 2015 (UTC)

(C) eclectic set
The modern challenges cited in the edit are an eclectic set. Some are entirely classical in nature (e.g., gas-surface dynamics, solid state, biologically-inspired), while other are quantum mechanical (e.g., Capek's models, superconductor systems). They range in size from microscopic (molecular machines) to planetary in scale; their temperatures range from absolute zero up to the melting points of the refractory metals and ceramics. It is not accurate to call them purely classical or quantum, microscopic or macroscopic so I chose the term "modern challenges." I would be happy to expand the edit to make this point, but I believe it is implicit in the text already.Yusefghouth (talk) 21:49, 13 March 2015 (UTC)


 * That the set of "challenges" is eclectic is evidence of the range of misunderstandings of the second law, not an argument that any of them is a real challenge. One valid one would be enough.Chjoaygame (talk) 00:22, 14 March 2015 (UTC)

Summary
In summary, I do not believe the criticisms of my edit are reasonable grounds for its removal. Furthermore, I believe the edit adds new life to the important and healthy discussions begun more than a century ago by Loschmidt, Maxwell, Zermelo and other pioneers of thermodynamics. I respectfully request that my edit be reinstated. Yusefghouth (talk) 21:49, 13 March 2015 (UTC)


 * I hope this time I have done a better job of responding to your edit, giving persuasive or convincing reasons why it is wrong for this article. It is not that the details of your edit are lacking respectively their own merits in suitable contexts. It is that they are not real challenges to the second law.


 * It is not the purpose of the article on the second law to add life to discussions, however important and healthy they are.Chjoaygame (talk) 00:30, 14 March 2015 (UTC)

Better section title: Not Challenges but Quantum limits

 * Editor Arthur Rubin has questioned the use of the word challenges in the section title. The word appears to be based on the book title by Čápek and Sheehan (2005) also mentioned above by editor Chjoaygame, as well as on the title of the symposium proceedings edited by Sheehan (2011) - both are listed as references in the deleted section. For this article, perhaps a more acceptable section title would be Quantum limits to the second law, based on the title of an earlier conference proceedings in the same reference list also edited by Sheehan: First International Conference on Quantum Limits to the Second Law (2002). This would imply restricting the section to questions concerning very small systems, and exclude macroscopic systems. Dirac66 (talk) 17:37, 1 March 2015 (UTC)


 * Perhaps it seems unduly harsh to reject the proposed new material. The new material purports to "challenge" one of the most deeply accepted laws of physics. It has set the bar high for itself. The key is not, however, in the word 'challenge'. It is deeper than that. As a law of classical thermodynamics, the second law is about macroscopic systems. Some kinds of kinetic theory and statistical mechanics are about very small systems. To cover this by a change of title would be to move the goalposts during the game.Chjoaygame (talk) 19:52, 1 March 2015 (UTC)

undid well intentioned edit
I undid a well intentioned edit.

The article could be extended infinitely if it were to try to deal with the kind of matter submitted in the edit. That would be a bad path to open up.

The article is about the second law of thermodynamics, not about entropy production.Chjoaygame (talk) 22:38, 24 March 2015 (UTC)

request for comment from local editors
I would like to ask for comment from local editors about the recent edits of Editor Douglas Cotton to this and closely related pages. I am concerned mainly about conduct, but content cannot be ignored, and perhaps the two cannot be easily separated. I am asking here for comment from local editors before, and hopefully preventive of, an RfC from outside editors.Chjoaygame (talk) 14:47, 30 March 2014 (UTC)

request cancelled–problem seems solved
Editor Douglas Cotton seems to have begun to use the talk page instead of just posting his innovations immediately as edits. This seems to me to remove the potential problem of editorial conduct mentioned in the just previous comment. This is good.Chjoaygame (talk) 08:15, 1 April 2014 (UTC)

Editor Douglas Cotton, it should be noted, gained a university scholarship and degree in physics in the 1960's and has written two comprehensive peer-reviewed papers and a book about the Second Law, and developed an hypothesis pertaining to all planetary core and surface temperatures that is soundly based on the Second Law of Thermodynamics and the Kinetic Theory of Gases as used by Einstein and many others. (For details and links to the papers see http://climate-change-theory.com ) 121.217.80.138 (talk) 02:28, 3 April 2015 (UTC)

Application to pressure, density and temperature gradients in force fields
The Second Law can be used to explain and quantify density, pressure and temperature gradients in force fields, such as are empirically observed in experiments with centrifugal force, and of course observed in all planetary tropospheres and even in borehole measurements in the outer 10km of Earth's outer crust. These temperature gradients represent the state of thermodynamic equilibrium with maximum entropy, which is of course what the Second Law says will evolve. In short, energy potentials have dissipated when the mean sum of molecular kinetic energy and gravitational potential energy is homogeneous at all altitudes. The density gradient stabilizes when there are equal numbers of molecules passing up and down across any horizontal plane, and also, the mean kinetic energy of those molecules is equal for those coming from above and those from below. Since pressure is proportional to the product of density and temperature, these two conditions ensure pressure is the same from above and below each horizontal plane, and so there is stability which is characteristic of maximum entropy. But the conditions make it clear that molecules in flight between collisions as they cross any horizontal plane must have had less kinetic energy at a higher level and more kinetic energy at a lower level. This leads to us understanding that the temperature gradient is the state of thermodynamic equilibrium. It also allows us to understand that, if new thermal energy is absorbed in a troposphere which is in thermodynamic equilibrium with a temperature gradient, then that new energy will spread out in all accessible directions over the sloping thermal plane, with some heat diffusion and natural convection downwards towards warmer regions and the surface. This obviates the need to "explain" heat transfers into the surface by radiation from a colder atmosphere, which would of course violate the Second Law. Such heat transfers can only happen by heat diffusion and natural convective heat transfer (involving kinetic energy transfer in molecular collisions) because of the action of gravity upon individual molecules whilst in flight between collisions. 121.217.80.138 (talk) 02:29, 3 April 2015 (UTC)

Clausius statement is a corollary only in horizontal plane
From the above discussion we see that the Clausius "hot to cold" statement is really only a corollary of the Second Law which is only applicable in a horizontal plane. That should not surprise anyone, because the equation used for entropy in the proof of that statement has no term for gravitational potential energy. 121.217.80.138 (talk) 02:29, 3 April 2015 (UTC)

independent processes, not participating systems
The text ought to read "in every independent natural process in an isolated system" and not refer to the "sum" in "participating systems." Such participating systems (in reality they are processes) would have to be dependent, and so, in effect, they comprise a single independent process. For example, consider what happens in the two sides of a siphon which could be considered two dependent processes or one independent process. The Second Law explains why water can flow up one side of a siphon provided that it flows down further on the other side. If you cut the hose at the top you then have two independent processes. 121.217.80.138 (talk) 02:34, 3 April 2015 (UTC)

Entropy maximized by fastest route
As discussed at http://entropylaw.com new understandings (since 1988) include the fact that entropy will be maximized by the fastest available route. They draw an analogy with a warm log cabin in the snow, wherein it will cool through whatever windows or doors are open and allow the fastest overall rate of cooling. 121.217.80.138 (talk) 02:34, 3 April 2015 (UTC)

TEMPERATURE GRADIENT CAUSED BY GRAVITATION
The following paper supports the deduction above that the entropy maximization described in the Second Law of Thermodynamics leads to there being a temperature gradient in a force field such as gravity. Chuanpingliao International Journal of Modern Physics B (Impact Factor: 0.46). 01/2012; 23(22). DOI: 10.1142/S0217979209052893 ABSTRACT Thermodynamic deduction and experimental results both demonstrate that gravitation causes temperature gradient in an adiabatic system, i.e., gravithermal effect: The higher altitude the lower temperature. (See:http://www.researchgate.net/publication/263879139_TEMPERATURE_GRADIENT_CAUSED_BY_GRAVITATION ) 121.217.80.138 (talk) 02:27, 3 April 2015 (UTC)


 * I have spent some time checking the paper cited just above here, and references in that paper. The citation data offered just above here contains errors, and I had to spend time circumventing those.


 * From this checking I can report that the paper cited just above here is nowhere near to being a reliable source, and cannot be cited as a source in a Wikipedia article. It contains elementary errors of physical reasoning.Chjoaygame (talk) 06:23, 3 April 2015 (UTC)


 * Could we please have an explanation of these elementary errors of physical reasoning, and if possible a source to support the claim that they are errors? I am not familiar enough with this debate to decide whose physics is correct, but I do think that we should be more careful to respect Wikipedia policy. At the moment we have a source article which has been published in a refereed journal but which has been declared nonreliable by a pseudonymous (as are we all) Wikipedia editor without either arguments or another source. It is true that the article is a primary source whereas secondary sources (such as review articles) are preferred, but that does not seem a sufficient reason to overrule it without proper explanation. Dirac66 (talk) 02:44, 4 April 2015 (UTC)


 * I think it fair to draw attention to the circumstances here. Responding at all to the above capitalized post might attract a charge of feeding the trolls, and perhaps I was wrong to respond at all. There is a solid consensus of reliable sources on the question. In the current round of related posts, we are looking at a fringe view that is being repeatedly pushed by an editor who posts in various places under various names, partly to evade bans, and who has tried to promote his self-published book on the question. His view contradicts the solid consensus of reliable sources. The reliable sources have been posted before on this or related pages and are given in the article where this matter really belongs, at Thermodynamic equilibrium.Chjoaygame (talk) 17:32, 4 April 2015 (UTC)


 * That the matter is brought up here is another way of evading the weight of those sources where they belong. Here they are again: "The temperature within a system in thermodynamic equilibrium is uniform in space as well as in time. This is so in all cases, including those of non-uniform external force fields.        "


 * The article that is cited in the capitalized post makes a basic error of physics, which repeats that of the poster. It arbitrarily and gratuitously adds a term for gravitational potential energy to the list of component terms for the internal energy. As not too often clarified in texts, but made explicit by Crawford's 1963 text, the total energy of a body is often expressible as the sum of three terms, the internal energy, the kinetic energy of the motion of the body as a whole, and the potential energy of the body as a whole in the externally imposed force field, for example gravity. Putting the externally imposed potential energy into the internal energy is a basic mistake.


 * Another basic mistake is the confusing of kinetic theory reasoning with thermodynamic reasoning. The kinetic energy of a molecule is reduced by conversion into potential energy as it rises, but only the initially faster molecules rise very high. The statistics just balance so that the temperature remains uniform.


 * Another basic mistake is to confuse non-equilibrium situations with equilibrium situations. There is no general law about temperature uniformity for non-equilibrium situations. They are not directly addressed by the second law, but are mistakenly cited as evidence for a mistakenly imagined "gravito-thermal effect". Forces that sustain non-equilibrium situations often create non-uniformity of temperature, but this is not evidence about equilibrium.


 *  Citations 


 *  Cited bibliography 


 * Bailyn, M. (1994). A Survey of Thermodynamics, American Institute of Physics Press, New York, ISBN 0-88318-797-3.
 * Boltzmann, L. (1896/1964). Lectures on Gas Theory, translated by S.G. Brush, University of California Press, Berkeley.
 * Chapman, S., Cowling, T.G. (1939/1970). The Mathematical Theory of Non-uniform gases. An Account of the Kinetic Theory of Viscosity, Thermal Conduction and Diffusion in Gases, third edition 1970, Cambridge University Press, London.
 * Crawford, F.H. (1963). Heat, Thermodynamics, and Statistical Physics, Rupert Hart-Davis, London, Harcourt, Brace & World, Inc.
 * Gibbs, J.W. (1876/1878). On the equilibrium of heterogeneous substances, Trans. Conn. Acad., 3: 108-248, 343-524, reprinted in The Collected Works of J. Willard Gibbs, Ph.D, LL. D., edited by W.R. Longley, R.G. Van Name, Longmans, Green & Co., New York, 1928, volume 1, pp. 55–353.
 * Maxwell, J.C. (1867). On the dynamical theory of gases, Phil. Trans. Roy. Soc. London, 157: 49–88.
 * ter Haar, D., Wergeland, H. (1966). Elements of Thermodynamics, Addison-Wesley Publishing, Reading MA.


 * It is claimed in the cited paper, and in other papers, that experimental evidence advanced therein disposes of the theoretical consensus. There has been published (sorry, I don't have the source at my finger tips, nor time and inclination to hunt it down; if you think it should be found, you have found a way to do a public service) a criticism that effectively disposes of the previously claimed experimental "evidence".


 * One or two of the papers quoted by the cited paper accept the uniform temperature rule. Others don't consider the question.


 * Editors who were not happy with this reply of mine would be free to read the cited article and assess it for themselves.Chjoaygame (talk) 13:06, 4 April 2015 (UTC)Chjoaygame (talk) 13:46, 4 April 2015 (UTC)
 * OK, thank you very much for this detailed reply. I now agree that we have sufficient reason to justify not using the cited paper. I will confess that I suspected it was wrong, since it suggests the possibility of a perpetual motion machine to somehow convert thermal into gravitational potential energy, but of course suspecting is very different from being able to justify properly.
 * I think we should also mention briefly in this article that equilibrium implies uniform temperature, with a link to the detailed and sourced presentation at Thermodynamic equilibrium. The fact is a useful consequence of the second law since it implies that vertical temperature gradients must be maintained by continual energy inputs, as in the deep ocean or the atmosphere. Dirac66 (talk) 14:37, 4 April 2015 (UTC)
 * Thank you for this support. I have added a link to the comments about this in the lead of the article.Chjoaygame (talk) 17:36, 4 April 2015 (UTC)

Confusion regarding "system" and "process"
About three or four years ago Wikipedia explained the Second Law like this: “An isolated system, if not already in its state of thermodynamic equilibrium, spontaneously evolves towards it. Thermodynamic equilibrium has the greatest entropy amongst the states accessible to the system.” That was good. The current statement “The second law of thermodynamics states that in a natural thermodynamic process, there is an increase in the sum of the entropies of the participating systems" implies that there are "systems" within the single process referred to. In fact, the law is about a process that happens within a single isolated system. If there is more than one process, then such processes must be dependent, not independent. So, in effect, a sequence of dependent processes is just a single process anyway.  What you need to understand is that the Second Law is describing what happens in nature when there are unbalanced energy potentials. Such unbalanced energy potentials autonomously tend towards the state of balance, and this happens by the fastest possible route. That state of thermodynamic equilibrium has maximum entropy and no remaining unbalanced energy potentials. That is the Second Law of Thermodynamics, which is not just about heat and temperatures, because entropy can involve all forms of energy. Douglas Cotton 58.164.63.3 (talk) 11:41, 25 April 2015 (UTC)
 * I agree with most (but not all) of your first few sentences, and agreement in talk pages has been rare for me lately. But, unfortunately, your last few sentences head out toward left field. There is a quibble about a second law definition for isolated systems (entropy reaches a maximum at equilibrium) versus closed adiabatic systems (work interactions are possible, so entropy increases but it might not reach a maximum). You can read my old talk page babble about that quibble at Talk:Second_law_of_thermodynamics/Archive_2. But, as often happens, I didn't cobble a consensus from the rabble by dabbling in babbling quibbles. Mentioning that distinction for closed adiabatic systems probably wasn't appropriate for the lead anyway. The people arguing with me had my respect back then (They weren't really a rabble.), and they made some good points. Consensus was reached, and the result was an article where adiabatic closed systems weren't mentioned once. But, as usual, German Wikipedia ended up agreeing with me because they do science better over there. If you head over to, you'll see "In einem geschlossenen adiabaten System kann die Entropie nicht abnehmen, sie nimmt in der Regel zu." I also agree that multiple processes are best regarded as a single process. As long as all subprocesses fall within system boundaries, the second law applies to the entire process. And I also agree that discussing a compound anything (system or process) in the lead would be a mistake. However, the concept of unbalanced energy potentials is just as silly as all that silly force field stuff. Alas, the silliness cannot be avoided in science at English Wikipedia in the long term. It just becomes a matter of stamina about which silly editor sticks around to get the silliest material in, and removing their silliness just makes the silly people mad. The times of respectful consensus were short. After google translate improves, the science articles at German or Swedish Wikipedia may become useful for English speakers. Until then, why not try to convince Chjoaygame about unbalanced energy potentials? And he can try to convince you about force fields. I'll watch. Flying Jazz (talk) 04:14, 27 April 2015 (UTC)