Talk:Second law of thermodynamics/Archive 6

reason for removal of new material
I have removed a newly inserted paragraph from the lead. The deleted material expresses an opinion that is often encountered but is, sorry to say, mistaken. The following is a statement of the true position.


 * A very tall adiabatically isolating vessel with rigid walls initially containing a thermally heterogeneous distribution of material, left for a long time under the influence of a steady gravitational field, along its tall dimension, due to an outside body such as the earth, will settle to a state of spatially uniform temperature though not of uniform pressure or density, and is then in internal thermal equilibrium and even perhaps in thermodynamic equilibrium.

This matter has been very carefully considered by the giants of thermodynamics, and again by a semi-giant Sydney Chapman, and again by more recent experts. The temperature in the state of thermodynamic equilibrium is spatially uniform in spite of gravity. The removed material was not supported by any reference and was thus exposed to immediate removal. If it had references, they would have been carefully scrutinized, and, I think, would most likely have been detected as unreliable. This matter is not open for grabs. Sad to say, the removed material reflects the opinion of, amongst others, an inventor of a perpetual motion machine. When proposed other than by someone well intentioned but not well educated in thermodynamics, it is quite often merely pseudo-science. It will not be treated leniently here.

Even if the removed material had not been mistaken, it would have been inappropriate in the place where it was inserted, because of relevance and detail. The removed material was inserted by an editor who did not sign in with a named account. It made a major direct reference to matters of climate. While climate science uses thermodynamics, it is not appropriate to put in material like that about climate science in the lead of the article on the second law, which is primarily purely a general physical matter.Chjoaygame (talk) 01:55, 6 September 2013 (UTC)

Verification failure in talk page
Two of the above references were checked and failed verification as support for claim made in the above statements. Gravitational fields are not involved in discussions about the second law of thermodynamics. They may or may not be involved in the combined first and second law. This is why such material failing verification ought not to be included within the article itself, neither in the lead nor in the body. My hope is that this editor will consider the ease with which other editors can check that "the giants of thermodynamics" never wrote such things, and that this editor will refrain from continuing to add either uncited or falsely cited content to the article. A general reader will also be served if this editor removes such uncited statements and/or verifiably falsely-cited statements that he or she has added in the past. Flying Jazz (talk) 06:47, 27 April 2015 (UTC)


 * In the flood of attacks by the above editor, I did not notice this one, perhaps partly because it has a title similar to another, below on this page. Now that I have noticed it, I see that it seems to be mistaken. In the other place, below on this page, where the above editor made more or less the same attack, he wrote that he had checked a Planck reference and a Maxwell reference. No Planck reference is in the above list. So it seems that of the above list, he actually checked only the Maxwell reference, and, writing in haste, did not actually check this immediately above list as such. Below I have dealt with the Maxwell reference, showing that the attack on it was mistaken. I will deal further with this flurry of attacks below at that place.Chjoaygame (talk) 07:12, 30 April 2015 (UTC)

reasons for removal of repeat of faulty edit
I have to say I am sorry I did an incomplete removal of the faulty edit of 6 Sep 2013 by an unnamed editor.

A near repeat of that faulty edit has been posted by editor Douglas Cotton.

I have now completed the removal of the original faulty edit as well as undoing the new posting by editor Douglas Cotton.

The reasons are several. One is that the original faulty edit and its new version are unsourced. Another is that the edit is in the lead but is not a part of a summary of the article content. Another is that the edit strays into climate theory, far beyond what is appropriate for the lead of this article. The strongest reason is that the edit is thoroughly wrong in physics. The evidence with sources that the edit is wrong is given in the first part of this talk page section. I have added another reference to a reliable source (ter Haar and Wergeland 1966) to the above reference list.

I may add that Loschmidt was responsible for a proposal that would lead to the faulty edit, but that Loschmidt was mistaken, and was corrected in his day. It is also the case that some experiments have been performed purporting to test the matter empirically, which have been interpreted to support Loschmidt. But the experiments are not of a good enough quality to reliably test the matter. For Wikipedia, at best they constitute unverified primary research and reports of them do not constitute reliable Wikipedia sourcing. They are therefore not admissible in the article. I mentioned in my previous remarks about this that faulty editing of the kind posted by editor Douglas Cotton will not be treated leniently here.Chjoaygame (talk) 08:53, 16 February 2014 (UTC)

section headed "Gravitational systems"
I would like to delete the sub-section of this article that is headed Gravitational systems.

In defence of the sub-section it might be proposed that it contains interesting and important material, or that it is well written. It may be so, but I say that is not an adequate reason to make this article the one that presents it.

Against the sub-section's appearing in this article, I think there are weighty reasons. The sub-section is mostly about essentially non-equilibrium scenarios, with a good dose of general relativistic considerations. The second law, however, is a law of classical thermodynamics, about processes that have initial and final states in thermodynamic equilibrium. Gravity on a small scale is within the scope of classical thermodynamics, but it is hardly so for large-scale systems that show great changes in the gravitational field during the "process", which is often not even from one state of thermodynamic equilibrium to another. It may be exciting to talk about large-scale systems, but it is not the province of standard texts on classical thermodynamics.

If it is desired to tell in Wikipedia about questions that are raised in the sub-section, then I think it should be told in a separate article.Chjoaygame (talk) 15:40, 23 May 2015 (UTC)
 * I tend to agree that this sub-section is off-topic and should be in a separate article. Perhaps a new article on Relativistic thermodynamics which could also include the present article on Relativistic heat conduction. Yes, I know that article is about special relativity, but the article could perhaps include Thermodynamics in special relativity, Thermodynamics and general relativity, and also Applications in astrophysics. Dirac66 (talk) 01:11, 25 May 2015 (UTC)


 * Thank you for this comment. I am not clued up enough to try to say how the material should be presented in some other article. I think simple deletion from this one would be ok. If someone is expert and energetic enough to put it up again in a more suitable article, that would be good.Chjoaygame (talk) 06:49, 26 May 2015 (UTC)

Appearance of the word "field" and the phrase "force-field"
In the current version of the article word "field" appears 15 times in the lead, always in the context of a force field, and it appears twice in the body, never in the context of a force field. This is consistent with other science articles at Wikipedia where some well-meaning person with a lot of time on his or her hands takes ownership of an article and plops a lot of nonsense into the lead due to their own ignorance about how the topic is taught and used in the world outside of Wikipedia. Of course, force fields have little or nothing to do with the second law. Because Wikipedia's science content elsewhere is heading downhill so rapidly due to neglect from the knowledgeable and well-meaning nonsense from the ignorant, I recommend that the same level of force-field nonsense be added to the body of this article in order to hasten the process of making Wikipedia's science as blatantly silly as possible. Flying Jazz (talk) 16:31, 24 April 2015 (UTC)


 * One always feels flattered to have one's work praised, especially when it is done with such eloquence as just above. The requested detail on thermodynamic equilibrium in the presence of an external force-field is to be found here. I will post a link. It is true that not too many texts talk about the topic of present concern. But it is of interest to some readers.Chjoaygame (talk) 21:46, 24 April 2015 (UTC)


 * The comment that starts this section is not quite explicit as to what its author would like done. I have made a fair guess at that, and tried to accommodate.Chjoaygame (talk) 12:17, 25 April 2015 (UTC)


 * Perhaps I should have been more explicit then. Force fields have little or nothing to do with the second law. A good second law article would not mention them. That is why texts don't include it, and that may be why you included no references in the entire section you created. I hope you consider removing this silly content from this article in order to improve the encyclopedia. You would be accommodating the general reader if you did that. However, building a general encyclopedia may be about including things "of interest to some readers" in your mind instead of including things of interest to the general reader. You may hold the view that silly off-topic things are important, and, if you hold that pro-silly-nonsense opinion (because that's what some readers want), then I admire your persistence at advancing that opinion while simultaneously hoping that you stop holding that opinion and repair the damage done to this article. Science at Wikipedia is like a mound of rubble that used to be a half-finished building, and your accomplishment in this article is like a man standing on that mound smashing a single brick. In a way, I do admire that. But I'd prefer to have the brick back. Maybe that will help convince someone later to try to rebuild a bit of the building. Flying Jazz (talk) 03:08, 27 April 2015 (UTC)


 * Thank you for these comments. I have supplied references.Chjoaygame (talk) 04:41, 27 April 2015 (UTC)

Verification failure at
It is not enough to "supply references." The references must say what an editor claims they say. This means that Planck, Maxwell, Gibbs, etc. must have all provided support for the sentence "The various temperatures within the adiabatically separate component sub-systems become respectively spatially uniform." It does not mean that those famous people mention equilibrium or the second law in a context different from "adiabatically separate component sub-systems." I have checked that Planck on page 40 at did not mention equilibrium in that context. I have checked that, while Maxwell mentions equilibrium over a dozen time in the treatise available at  he says nothing remotely similar to your claim about what he said. This is why all your references were removed. After checking two, I reached the conclusion that the others were also failures. Do not "supply references" that fail verification. Supply one, single, good reference that passes verification. Otherwise, you are a demonstrable liar about famous people, and you will most likely not gain support at Wikipedia by lying about famous scientists. Instead, people will call you names and you won't like it. Flying Jazz (talk) 06:03, 27 April 2015 (UTC)


 * Thank you for this comment. The references are to uniform temperature in adiabatically separate sub-systems. The Planck radiation reference says that regions in radiative exchange equilibrium have equal temperatures; this entails uniform temperature within a sub-system in thermodynamic equilibrium. I can now see that you want to take a position against the material I posted, and so I will not go further here. Your concern is about immediacy of context. I have looked at the reference you gave. I think it is consistent with what I posted and you have deleted. From your bolding, I infer that you have strong feelings here. Like you, I do not engage in edit wars, so I will not resist you in this.Chjoaygame (talk) 07:26, 27 April 2015 (UTC)


 * Though I do not intend to edit war, I think it reasonable that I comment more on your edit, with its edit summary "Entire section deals with work terms in combined first/second law. Not second law material."


 * You deleted text that was worded with the specific intent to exclude the case that I think your edit summary refers to. The work referred to in your citation is about transfer of matter into or out of the system of interest. You deleted a section that was worded with the specific intent of excluding that case. I am not sure whether you took that into account. Perhaps my wording did not succeed in making the exclusion clear. If it did not succeed, that would be a failure of execution not of intent.


 * In more detail, the table on the page to which you refer lists a differential quantity $ψdm = ΣghM_{i}dn_{i}$. The term $dn_{i}$ identifies the quantity as a transfer of matter into or out of the system of interest, deliberately excluded by the way I worded the deleted section. Work done by the external-field imposing factor was excluded also by forbidding motion of the centre of gravity of the system of interest with respect to the external-field imposer. The internal energy of the system of interest is distinct from its global potential energy and its global kinetic energy. So your concern that I was mixing first and second laws seems to need reconsideration. I don't think I was doing so. I concede that during the process of making the section, at first I did not succeed in excluding work by the field-imposer, but I did restrict it to work that altered the kinetic energy of the system as a whole. On thinking about that I saw that all forms of work needed exclusion for the narrow statement that I intended, because it is hard to assign an entropy related to the kinetic energy of the system as a whole. My aim was not to make the statement completely general and capable of dealing with every case. It was to make a narrow statement that allowed an externally imposed field to persist during the process, thus making it clear that such a field would not, through the law, create a temperature gradient at final equilibrium due to the field.Chjoaygame (talk) 08:34, 27 April 2015 (UTC)
 * The reader of a general purpose encyclopedia is best served by clear, focused, well-referenced, and verifiably correct material. Editor aims or what an editor is thinking about outside the context of serving that general reader are misguided. There are an infinite number of "narrow statements" that do or do not violate thermodynamic laws. If some of those statements are to be included in a second-law article then consideration for a general reader dictates that only the simplest and only the most second-law-focused out of that infinite number of possibilities will be chosen by an editor. That same consideration for the general reader also applies to talk page discussion which is why I won't be attempting to parse the remainder of what you've written above about "kinetic energy of the system as a whole" and "field-imposers" and such things. Flying Jazz (talk) 13:25, 27 April 2015 (UTC)

Recommendation for new Gravothermal effect article
The verification of references is important to serve the general reader of a particular article. The verification of references in order to address editors who show up in the talk page space is less important. In the talk page there is some issue about a "gravithermal effect" or "gravothermal effect." Here's what's written in the introduction to Alberty's IUPAC paper at :
 * In addition  to  the  terms  from  the  combined  first  and  second  laws  for  a  system involving PV work, the fundamental equation for the internal energy may involve terms for chemical work, gravitational work, work of electric transport, elongation work, surface work, work of electric and magnetic polarization, and other kinds of work.

Alberty's paper explicitly spells out IUPAC-supported nomenclature and terminology. It also conforms with my own impression of the second-law curriculum of a general science and engineering education. In general thermodynamics, gravity and other "external force fields" are added on to the first-law part of the combined first and second laws as additional work terms, and what's permitted or forbidden can be determined after that's done. To me, this means that there is no sound reason to include any section dealing with gravity (or electricity or elasticity etc.) in a general-purpose encyclopedia article about the second law. When editors argue with each other, irrelevant matters start to seem important, and the reader often pays the price by having an article with a huge amount of off-topic or tangential things in it. That doesn't mean either that the possibility or impossibility of a gravothermal effect is irrelevant in a broader sense. It might be important in fields where I lack expertise, like astrophysics. Maybe tidal work is also relevant to astrophysics as another work-term addition to a combined first-and-second law. I don't know. But I do think, based on Alberty's most-common nomenclature, that gravitational systems and/or "external force field" stuff don't belong in their own sections in a Second Law article. It might be a good idea for you and the people you've been arguing with to begin a new Gravothermal effect article explaining what it is and why it's real or not real and how it is or isn't involved with astrophysics or other fields. Gibbs was brilliant, but I don't think he considered what astrophysicists today consider because they have the advantage of building upon his brilliant foundation. But I honestly don't know. On that new Gravothermal effect article talk page, you and the various IP addresses and editors with whom you've been arguing can present focused article-specific arguments that may serve the reader of that new article. Flying Jazz (talk) 20:34, 4 May 2015 (UTC)


 * Thank you for this comment. Though it might seem straightforward and simple enough, your comment raises some important but rather subtle questions. At this minute I have other activities scheduled. I will try to reply later.Chjoaygame (talk) 00:45, 5 May 2015 (UTC)
 * I have now carefully considered what you propose. At present I think it would be inappropriate.Chjoaygame (talk) 06:13, 5 May 2015 (UTC)
 * Of course you think a Gravothermal effect article would be inappropriate. That's because you seem to think the effect doesn't exists at all because the combined first and second law forbids it after the appropriate terms are inserted into the combined first and second law. My comment was for those other folks who think it does exist. They're the ones who should start the new article. You should follow them over there, argue with them over there, and try to come up with an article that serves the reader over there. After a while, someone might stop by here (maybe even me when I have more time) and serve the reader by repairing the damage that was done by the inappropriate insertion of elements of that argument about the combined-first-and-second-law-with-additions into this article about the second law. Flying Jazz (talk) 13:59, 5 May 2015 (UTC)


 * Near enough, the present concerns are non-relativistic, not even special relativity. Consideration of gravothermal effects belongsundefined to general relativity. I am reasonably confident the the "several" "folks" are just one.Chjoaygame (talk) 14:26, 5 May 2015 (UTC)Chjoaygame (talk) 23:29, 5 May 2015 (UTC)

Externally imposed fields
It may be useful to comment here on some aspects of externally imposed fields. The above mentioned 2001 Committee report written by Alberty refers to a 1994 paper by him. This paper for gravity refers on page 1470 mainly to two admirable texts, by Guggenheim and by Kirkwood & Oppenheim In considering external fields, neither of these texts refers directly to the founding work by Maxwell, Gibbs, or Boltzmann. In considering a tall column in a gravitational field, Guggenheim contents himself on page 5 with the phrase "the temperature, assumed uniform". Kirkwood & Oppenheim are content to use a single temperature without even mentioning that it is so by assumption.

There are some points that need attention, and are to some extent dealt with by Alberty, by Guggenheim, and by Kirkwood & Oppenheim.
 * 1) In a gravity field, it is often necessary to represent the column as consisting of infinitely many infinitesimally thin-layer systems stacked contiguously.
 * 2) Gravity fields differ from electric fields in that usually the column in a tube is not heavy enough to significantly alter the earth's gravitational field inside the tube, whereas electric polarization is often significant for relevant electric fields. Besides work of electric transport, the electric field can interact through polarization with chemical reaction in a way that the gravity field does not.
 * 3) The total energy of a body is the sum of its internal energy, and respectively its potential and kinetic energies as a whole by virtue of the position and velocity of its centre of force in the external field.
 * 4) If a body moves as a whole due to gravity, it may thereby simply suffer a change in its kinetic energy as a whole, with no change in its internal energy.
 * 5) It can happen, however, that a part of the system, such as for example a suspended weight, moves due to gravity to a lower place within the system, while another part of the system, such as for example some paddles, is thereby set in motion within the system and thereby gains kinetic energy, which is then by friction dissipated and converted to internal energy within the system. Then gravity has done isochoric work on the system and increased its internal energy, at the same time lowering its centre of gravity. Of its total energy, the internal moiety has increased precisely at the expense of the potential moiety.

References Chjoaygame (talk) 18:01, 11 May 2015 (UTC)Chjoaygame (talk) 20:39, 17 May 2015 (UTC)Chjoaygame (talk) 02:42, 27 May 2015 (UTC)

Possible intent of Chjoaygame
I believe what this editor meant to say is covered by the combined first and second law in the context of gravitational work as discussed by Alberty in Table 1 on page 1357 at. Other entities that you call "force fields" are also mentioned in that table and discussed in their proper thermodynamic terms in that article. Because this material is more appropriately discussed in the context of the combined first and second law, it is inappropriate for an encyclopedia article on the second law. That is my rationale for removing the entire section of the article dealing with "externally imposed force fields." Flying Jazz (talk) 06:08, 27 April 2015 (UTC)


 * My intent was to make it clear that the second law cannot be used to justify the mistaken claim that a system in its own internal state of thermodynamic equilibrium, in the presence of a gravitational or other field, has a temperature gradient established by the field. There is no such temperature gradient established through the effect of the second law or otherwise. That is what my references supported.Chjoaygame (talk) 07:54, 27 April 2015 (UTC)
 * I haven't been following the history of this article for years, so perhaps another editor claimed in the article that such things could happen, and so your intent was to claim in the article that such things could not happen. An infinite number of ridiculous things can be said ,disputed, and corrected, but the article space is not the place for that to happen. In the article, only the simplest of claims about the thermodynamic certainty/possibility/impossibility of processes serve the general reader. Those simplest of claims were the ones discussed by the founders of thermodynamics, and they are most likely already included in the article multiple times. Flying Jazz (talk) 13:39, 27 April 2015 (UTC)

Possible future actions regarding references that failed verification
I do not wish to engage in an edit war. If you persist in adding failed references to this article, it will be tagged as such with the appropriate template and delivered to Category:All_articles_with_failed_verification. If you remove the template, I will attempt to replace it once, and if you remove the template a second time, I will complain to some adcom or arbmin clerk type person for the first time since I joined Wikipedia in 2005. There's a first time for everything. Lying about famous scientists to support silliness is the one thing that will push my buttons. Flying Jazz (talk) 06:14, 27 April 2015 (UTC)

The Second Law does not say
The Second Law does NOT say "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." If that were the case, then it could be used to "prove" that water could flow uphill to a lake provided it flows further downhill in another creek. — Preceding unsigned comment added by 121.218.41.105 (talk) 08:58, 11 October 2014 (UTC)


 * Isn't that what they call a siphon? 133.48.61.207 (talk) — Preceding undated comment added 06:28, 9 July 2015 (UTC)

-

You have no valid grounds for changing this version referring to every process ....

Processes in which the entropy of an isolated system would decrease do not occur, or, in every process taking place in an isolated system, the entropy of the system either increases or remains constant

That version of the 2nd law comes from the textbook An Introduction to Thermodynamics, the Kinetic Theory of Gases, and Statistical Mechanics (2nd edition), by Francis Weston Sears, Addison-Wesley, 1950, 1953, page 111 (Chapter 7, "the Second Law of Thermodynamics").

- — Preceding unsigned comment added by 121.218.41.105 (talk) 09:19, 11 October 2014 (UTC)


 * Thank you for these comments.


 * There are very many statements of the second law. None of them is unreservedly perfect. It may not be easy for us to reach agreement about how it should be stated in the lead of this article. You object to the new version. You cite here another version.


 * Perhaps I may suggest that you might look more widely than at the version you have cited here.


 * There are reasons for the new version in the lead.


 * It should be brief and readily readable.
 * It should make the point that it refers to thermodynamic processes, not to physical processes in general.
 * It should be positive, not merely a negation.
 * It should be based on the best sources.
 * It should refer explicitly to real thermodynamic processes as opposed to fictive ones.
 * Very likely it should be stated in terms of entropy.
 * It should not be phrased so as to suggest that it is more widely applicable than is proper.


 * The new version to which you object was constructed with those reasons in mind. Perhaps that is enough comment from me for the moment.Chjoaygame (talk) 10:58, 11 October 2014 (UTC)

The 2nd law applies only to isolated systems?
That “The 2nd law applies only to isolated systems” is a premise used to explain evolution. Objections to evolution ( Violation of the second law of thermodynamics) This interesting understanding of the law should be addressed.LEBOLTZMANN2 (talk) 20:14, 12 November 2014 (UTC)


 * I don't think this particular article needs to accommodate or address cranks. Rklawton (talk) 21:51, 12 November 2014 (UTC)

=
=================

The processes must be dependent: they are "participating" (sub-)systems within the isolated system being considered. The law cannot apply to a sum of the entropy of two or more independent processes like water flowing uphill just because it "knows" it will flow further down the other side. That only happens when the up and down processes are dependent in a siphon. Cut the hose at the top and they are independent, each then gaining entropy. The Second Law applies to all forms of energy, not just thermal (kinetic) energy. For example, it also applies to potential energy in a force field like gravity. In such a case we have thermodynamic equilibrium when (PE+KE)=constant in a vertical plane and there are thus no unbalanced energy potentials, this meaning we have maximum entropy with a density gradient and a temperature gradient, each resulting from the Second Law. The pressure gradient is a corollary. See http://climateblogcritique.homestead.com — Preceding unsigned comment added by 121.217.24.180 (talk) 10:45, 9 January 2015 (UTC)


 * The immediately foregoing unsigned IP comment is conflict of interest promotion by an easily recognised recidivist and is an improper comment here.Chjoaygame (talk) 13:44, 9 January 2015 (UTC)

No it's not a "conflict of interest" as the author had no significant pecuniary interest in presenting such valid physics which cannot be refuted because it is a direct corollary of the Second Law of Thermodynamics. — Preceding unsigned comment added by 121.216.226.179 (talk) 23:48, 15 February 2015 (UTC)


 * I have restored the above autosignature, that had been removed by the user who posted the unsigned comment. That user is an easy recognizable version of Editor User:Douglas Cotton, who is now posting from dynamically signed IP addresses.Chjoaygame (talk) 06:17, 16 February 2015 (UTC)

Style of article
The entire article is written in a style that only a scientist or a science major can fully grasp. It assumes that the ordinary layman can understand all this, which is not the case. It should be rewritten in a style that is intelligible to people who are not scientists. AlbertSM (talk) 16:54, 13 February 2014 (UTC)

In particular, note the interpretation of dq.... as an "infinitesimal" is at odds with the universal teaching of calculus that dq is a real number. To most non specialists this is nonsense - it conveys no useful information. Pondhockey (talk) 04:10, 22 July 2015 (UTC)

clever ideas
I am unhappy with this edit. It relies on a clever or loose, but evidently misleadin,g statement of the second law: "... the Second law of thermodynamics, which says that large dynamical systems evolve irreversibly towards the state with higher entropy, ..." A safer statement is about thermodynamic systems, not about "large dynamical systems". We are here looking at the routine consequences of the use of clever or loose statements of the law.Chjoaygame (talk) 12:04, 15 September 2015 (UTC)

Many people have many clever ideas, and beating the second law is a tempting field for them. The problem that faces us here is quick and clever "statements of the second law". Too quick and too clever.

The second law of thermodynamics is a law of thermodynamics. Thermodynamics is a macroscopic subject. Its most basic assumption, yes most basic assumption, is the existence of a special and idealised kind of physical system. This assumption is sometimes (not widely) called the minus oneth law. It states that systems exist which are in their own respective states of internal thermodynamic equilibrium. This means that they are in respectively macroscopic states that are stationary, that is to say, repeatedly macroscopically specified, over a very long time. A single instantaneous microscopic specification, such as is contemplated for the Poincaré recurrence theorem, is nowhere near enough to tell whether a system is in its own macroscopic state of internal thermodynamic equilibrium.

Poincaré's recurrence theorem is, at first glance, about a physical system that is defined as starting in some instantaneously microscopically specified state. Its macroscopic state, on that basis, is not specified. In particular, it has nowhere near passed the test of being in its own state of internal thermodynamic equilibrium. This means that Poincaré's recurrence theorem, at first glance, is not about a system that obeys the minus oneth law.

The second law is about several systems, each satisfying the minus oneth law, separated from one another by walls of specific permeabilities, for example adiabatic walls. It follows that the Poincaré recurrence theorem, at first glance, does not refer to systems that are contemplated by the second law.

But the Poincaré recurrence theorem, at second glance, may be regarded as being about the whole history of a system. The history lasts a very long time. Indeed, if the system is regarded as macroscopic, as contemplated by thermodynamics, the Poincaré recurrence theorem may be regarded as a proof that every relevant system, if its history is followed for a long enough time, will obey the minus oneth law, by being in an obvious sense stationary, and thereby become eligible as a thermodynamic system in its own state of internal thermodynamic equilibrium. In this perspective, the Poincaré recurrence theorem, far from challenging the second law, is a way of demonstrating the reasonableness of that presupposition of the second law which is sometimes known as the minus oneth law.

The second law is about several systems, each initially obeying the minus oneth law, separated from each other by walls of specific permeabilities. Then the second law envisages an event that is explicitly prohibited for a Poincaré recurrence theorem system. That event is called a thermodynamic operation. It changes the permeabilities of the walls. The newly walled systems are then allowed to interact and evolve under their own steam for an indefinitely long time, indeed until they all reach a new set of thermodynamic equilibria, with the changed wall permeabilities. The Poincaré recurrence theorem is about a system that has permanently unchanging walls. It is not about the processes that are described by the second law.

One may say that one does not accept the minus oneth law. That is very reasonable, because in reality the idealization of a system in its own state of internal thermodynamic equilibrium is never realized in Nature. Nothing in the entire universe has ever been, or will ever be, in ideal thermodynamic equilibrium. But while rejecting the minus oneth law, one can forget all about thermodynamics. Thermodynamics isn't even a starter without the minus oneth law as an assumption. The second law is ruled out as nonsense from the start. No need to challenge something that is already recognized as nonsense.

For the second law, one needs systems that have their respective classical entropies, near enough. They have to obey the minus oneth law near enough.

Many physicists fondly dream that a system that does not obey the minus oneth law might have an entropy in the sense of classical thermodynamics. If a system is not near enough a minus oneth law system, it needs something other than than classical thermodynamic entropy to describe its behavior. More carefully speaking, it doesn't have an entropy in the sense of classical thermodynamics. Prediction of its future calls for information that explicitly denies the conditions for classical entropy. It calls for a sequence of many-time entropies that tell about its future. This is not classical second law territory.

Clever games with the Poincaré recurrence mainly demonstrate that their players are not interested in the second law, and indeed are not interested in thermodynamics. They don't come near challenging it, no matter how clever their players.Chjoaygame (talk) 17:14, 14 September 2015 (UTC)

Perhaps some further remarks about the minus oneth law may be apposite.

According to Martin Bailyn:


 * THE LAW OF EQUILIBRIUM: A macroscopic, bounded, nongravitating system that is otherwise isolated or in a uniform environment attempts to reach an asymptotic state called equilibrium characterized by constant and piece-wise uniform values of its intensive state variables, unless it is already in equilibrium, in which case it will remain indefinitely in this state unless acted on by systems with different state variables, or systems in relative motion.

This might perhaps be confused with the second law of thermodynamics, but such is not Bailyn's view of it. He treats it as a presupposition for the definition of state variables, though not labeling it the "minus oneth law". His treatment of the second law follows much later in his survey. Logically in Bailyn's presentation, it has the effect of what Marsland, Brown, and Valente call the minus oneth law.

Planck's presentation in his Treatise has the same logical form. He does not introduce the idea with the word 'equilibrium'. He simply says:


 * §6 In the following we shall deal chiefly with homogeneous, isotropic bodies of any form, possessing throughout their substance the same temperature and density, and subject to a uniform pressure acting everywhere perpendicular to the surface.

This statement comes after his statement of what was stated earlier by Maxwell, and later, perhaps jokingly, by Ralph H. Fowler, called the "zeroth law of thermodynamics". But logically it again has the effect of what Marsland, Brown, and Valente call the minus oneth law.

Herbert Callen also begins with an equivalent of the minus oneth law:


 * Postulate 1. There exist particular states (called equilibrium states) of simple systems that, macroscopically, are characterized completely by the internal energy $t = const.$, the volume $t$, and the mole numbers $T(x, y, z)$ of the chemical components.

Guggenheim writes:


 * §1.02   Thermodynamic state. Phases


 * The simplest example of a system to which thermodynamics can be applied is a single homogeneous substance.

I think these reliable sources are concordant with the view of Marsland, Brown, and Valente.Chjoaygame (talk) 03:28, 15 September 2015 (UTC)

with respect
With much respect, I have to try to choose between the expression of the law by Max Planck and that by Editor Waleswatcher. While I regard Waleswatcher's version as quick and clever, I find Planck's safer and less likely to mislead. Planck's statement makes it clearer that one is looking at a process that starts and ends with states of thermodynamic equilibrium. Sad to say, Waleswatcher's is routinely read as if the process started from a non-equilibrium state, with the usual consequent muddles. For some years, with a recent interruption, Waleswatcher has been urging his quick and clever statement. I think it inferior to Planck's.Chjoaygame (talk) 02:42, 15 September 2015 (UTC)


 * Planck's statement (or rather, a translation of something he wrote in German more than a century ago) is already in the body of the article where it belongs. The lede is supposed to summarize the article, and in this case, make a clear, concise, and intelligible statement of the second law in plain modern English that ordinary people (that is, the vast majority of readers of this article) can understand.  I certainly don't think that what I wrote is the best possible phrasing and I'm happy if you or others can improve it, but I do think it's superior to the previous. It is not necessary (or even desirable) for the lede to use the most technically precise or detailed language, that can come later.  As for beginning and ending in equilibrium, the second law holds true even when that is not the case, and is invariably applied to situations where that is not the case.  The article can and should explain the idealized thermodynamic limit, but not probably the lede.   Waleswatcher  ( talk ) 10:46, 15 September 2015 (UTC)


 * Good to have this comment from you.


 * I would like to say something about the view that "As for beginning and ending in equilibrium, the second law holds true even when that is not the case, and is invariably applied to situations where that is not the case."


 * I think that view is mistaken. This difference of view is probably important for how the law should be stated. As Planck states the law, the entropy of the compound system needs to be defined for both the initial and final states. Classical entropy, the quantity of concern for the second law as Planck states it, is defined only for systems that obey what is sometimes (see the immediately above section) called the minus oneth law, that is for systems with each subsystem in its own state of internal thermodynamic equilibrium.


 * The law envisages an initial compound system consisting of subsystems separated by walls of specific permeability, all in thermodynamic equilibrium. The law then envisages a thermodynamic operation that changes the permeabilities. Temporary disequilibrium follows, with temporary loss of definition of entropy. Eventually a final equilibrium is established, conforming afresh to the minus oneth law, subject to the new permeabilities, with recovery of definition of entropy. The law then compares the initial and final entropies.


 * For a system that is not in its own state of internal thermodynamic equilibrium, the classical entropy is undefined. The definition of the state of a system not in equilibrium requires specification of rates and various possible memory quantities. Then one needs many-time entropies, not classically contemplated, and not part of the ordinary domain of the second law. This is why the second law contemplates initial as well as final equilibria.


 * One might wish that a single one-time entropy would exist to tell about the state of a non-equilibrium system. But it would be a fond hope rather than a safe thought. An example that might help would be in ergodicity. The one-system finite-duration-of-time average is the same as the ensemble-of-systems instantaneous average. Generally, this doesn't hold for non-equilibrium.


 * Perhaps that is enough for now. I look forward to your further comments.Chjoaygame (talk) 11:51, 15 September 2015 (UTC)


 * Could someone quote the (proposed) statements in the lead, so that someone who hasn't been following this article closely can edit. — Arthur Rubin  (talk) 15:01, 15 September 2015 (UTC)


 * The edit in question changes a translation from Planck to another version.


 * The translated Planck version reads:


 * The second law of thermodynamics states that every natural thermodynamic process proceeds in the sense in which the sum of the entropies of all bodies taking part in the process is increased. In the limiting case, for reversible processes this sum remains unchanged.


 * The other version reads:


 * The second law of thermodynamics states that the total entropy of an isolated system or systems never decreases, because isolated systems always evolve toward thermodynamic equilibrium, the state with maximum entropy.


 * It seems that at present, it is an open question as to exactly what the text should be.Chjoaygame (talk) 15:16, 15 September 2015 (UTC)

section should be deleted
I have moved the following comment to here from a place above in this page:


 * In a nutshell, the section of the present second law of thermodynamics article headed Controversies is not about thermodynamics. It is about statistical mechanics.Chjoaygame (talk) 21:33, 14 September 2015 (UTC)

I think the section of this article, headed Controversies, should be deleted, because it is faintly ridiculous.

The 'controversies' it refers to were invented historically as attacks on statistical mechanics, rightly presupposing the validity of the second law. They were not invented as controversies that purport to impugn the second law. Their presence in this article misleadingly suggests that they do so. It misrepresents them to so suggest by placing them in this article. They belong in their own articles and perhaps in articles on statistical mechanics, not here.Chjoaygame (talk) 21:58, 20 September 2015 (UTC)


 * In my view, statistical mechanics is more fundamental (and hence more important) than thermodynamics, and the statistical mechanics underlying entropy and the second law should have a very prominent place in this article. As such, while I agree with you that the these were "attacks" on stat mech, I don't think the controversies section should be deleted.  Instead, the relation between thermo and stats should be explained clearly near the beginning of the article, and then the section could be recast as controversies related to that connection.   Waleswatcher  ( talk ) 04:12, 21 September 2015 (UTC)


 * Thank you for this response.Chjoaygame (talk) 07:42, 21 September 2015 (UTC)
 * On a grand overview of physics, perhaps statistical mechanics may be more fundamental and more important than thermodynamics. Perhaps quantum field theory may be more fundamental and important than thermodynamics, or even than statistical mechanics. Be that as it may, this is an article about the second law of thermodynamics, and not about a grand overview of physics. The second law, within its scope of applicability, is not controversial. Purported statements of it that allow it to seem controversial are thereby faulty. Statistical mechanical controversy does not constitute a challenge to the second law. Controversy about the second law may be seen in questions of how best to state it. These are not questions of statistical mechanics.Chjoaygame (talk) 02:40, 11 October 2015 (UTC)