Talk:Second law of thermodynamics/Archive 4

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Archive 1

Archive 2

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recent raft of edits

The recent raft of edits was researched and sourced and well-intentioned, but was too much an expression of the editor's private thinking and speculation, verging on drivel at times.Chjoaygame (talk) 01:27, 17 February 2013 (UTC)

Can you please elaborate on this? it is widely accepted among particle physicists that the second law is a consequence of the initial conditions of the universe. What the H-theorem proves is that given that a system in time t1 is far from equilibrium, there is a high probability that in another time t2 it is closer to equilibrium; but in fact t2 can be either larger or smaller than t1. Therefore in order to prove the second law the H-theorem must be accompanied with the assumption of low-entropy initial conditions. Dan Gluck (talk) 20:54, 20 February 2013 (UTC)

In all, what you have done is deleting well-resourced (and well-intended, as you admit) material with no explanation. This is not in accord with WP policy. Please explain - or, even better, discuss the issue - before you revert. Specifically, where did I express my personal (hence, unsourced) opinion, and where did I go pseudo-scientifically?Dan Gluck (talk) 21:50, 20 February 2013 (UTC)

It is wrong to say that the second law is "derived" from the big bang, or that it is "derived" from statistical mechanics. The second law is a concise statement empirical fact. It is derived from an enormous body of experimental data. This is what makes it a "law". Maxwell's equations of electrodynamics are, likewise, a "law", a statement of empirical fact. If any valid experimental data were to be generated that disagreed with the law, it would be a law no more. Statistical mechanics makes a series of assumptions, and explains the second law, but it does not logically supercede the second law. If statistical mechanics makes a statement in conflict with the second law, then statistical mechanics is wrong, not the second law. The second law is likewise not "derived" from the big bang. It is derived from experimental data. The question of what the second law implies regarding the origin of the universe is a subject that is outside of the second law and should be thoroughly discussed in an article on cosmology. Mention of this should be made in this article, with appropriate links to an article on cosmology, but to imply that the second law "derives" from the big bang is wrong, and it should not appear here and there in this article. PAR (talk) 22:48, 20 February 2013 (UTC)

I do not wish to spend time on this, so I will not go into detail. I think the above remarks by PAR are sound and reliable. Dan Gluck proposes above that "it is widely accepted amongst particle physicists that the second law is a consequence of the initial conditions of the universe". I don't know what particle physicists widely accept, but if they accepted that, they would be mistaken. I continue to think that the recent raft of edits drifts into speculation, opinion, and even worse, which I will not name unless it becomes necessary.

That material is sourced does not ensure that it is reliably sourced. In scientific matters of this level of subtlety and complexity, reliable sourcing often requires a concordance of several well-established sources assessed by a person, or even by a consensus of persons, who are more or less expert in the subject. With all respect, I am not happy that what sourcing there is of the recent raft of edits has been adequately assessed. I repeat that I think the above remarks by PAR are sound and reliable.Chjoaygame (talk) 01:22, 21 February 2013 (UTC)

Yeah, well I agree with PAR on the philosophical level - though this has nothing to do with my recent edits - except that I would replace the word "derived" in his writing with the word "proven". Thus, it is wrong to say "the second law is proven by such-and-such theoretical considerations", and it would be better to state "the second law is confirmed by experiments, and can be mathematically derived by such-and-such, which strengthen the validity of this theory". However, this is not an article about philosophy of science. Indeed, the word "proved" should probably be changed to "can be derived" - where "derive" here means mathematical derivation. Regarding what Chjoaygame wrote - I agree that one can often find sources for rubbish. However, this seldom happens with a source like Hawking, one of the leading figures in the modern understanding of thermodynamics. If you have any reservations, it may be interesting to hear them, but you cannot change a well-sourced (in fact, extremely well sourced) argument based on your personal preferences or opinions. It could be, of course, that Hawking, Beckenstein, Green and most other high-energy physicists are wrong, but you need more than such an assertion to make an edit here. In any case, you still have not made a single factual claim.Dan Gluck (talk) 14:55, 21 February 2013 (UTC)

This is a specialized topic on which I am far from expert. I think that the sentence in the current version of the lead, "The second law is thought to be the source of the direction of time", is not duly supported in the body of the article, and therefore has no place in the lead at present. I also think it is nonsense, but not being an expert I cannot support that in detail. I am aware that it has often been said in the literature, by experts indeed. But I am not impressed that Stephen Hawking or any specialist of his kind might be able to provide other than unprovable speculation as support for the sentence. Such a broad claim needs support from a wider base than such specialists, no matter how thunderous their reputations. I also think that talk in the lead of "low-entropy initial conditions in the beginning of the universe" is verging on pseudo-science. Again I am no expert, and cannot support my thoughts in detail. But I think that the initial conditions of the universe are a matter for cosmology, and have little place in the present article. I can understand that cosmologists might think their subject and its conclusions are more important and reliable, for this article, than I do. You may feel that I did not have enough support to justify my initial undoing of your edit, and perhaps you may be right about that. My defence is that your edit was radical, and that it seemed to me to be over-speculative and to call on ideas not immediately the subject of the present article, and that no one else had objected to it; but it needed some more thought before it could be allowed to stand and wait for a fortunate accident of someone with the necessary time and energy and expertise finding it and criticizing it properly. My reason is therefore 'better criticize now and be mistaken, than not criticize now and let nonsense stand'.Chjoaygame (talk) 19:03, 21 February 2013 (UTC)

That's OK, I understand your caution. In the future please try to read the sourced material, at least a bit of it, in order to avoid deleting good edits. Otherwise you might deter less experienced wikipedians, including those who are themselves experts in the field they are writing about.

As for the subject matter, the relation between the second law and the arrow of time is no more pseudo-science than the theory of relativity is. Sometimes physics just has deep things to say about reality. However your remark that the lead cannot include stuff that doesn't appear in the article is correct, and I have added a small section about the subject. It is just too important to be left out, since this one of the main reasons for the important place of the second law in physics.

Regarding your suspicion of cosmologists, that's well understood, but actually high energy physics is not cosmology. It deals with particle physics, quantum field theory and general relativity, and in general with the fundemental laws of physics. In this framework the first law of thermodynamics (conservation of energy) is derived from more basic principles (to go technically, the energy is the Noether current of translation in the time direction, and is therefore conserved); likewise, the second law is also dealt with within this framework. Therefore this community is exactly where the expertise regarding the origins of the second law lies. Dan Gluck (talk) 22:07, 21 February 2013 (UTC)

I am not suggesting one bit that the relation between the arrow of time and the second law is pseudo-science, but the big bang theory is not the main reason for the importance of the second law. I am not suspicious of cosmologists, they do hard science, but, due to the fact that they cannot observe their systems of interest in the way that thermodynamicists can observe theirs here on earth, and the range of phenomena of interest are much greater than here on earth, they have not been able to come up with a theory of the universe that is as solid as the laws of thermodynamics. The big bang is not an established fact. We could be living in an infinite universe, in which case fluctuation theory predicts that there is no upper limit on the size of a local fluctuation. Our observed universe could be a random local entropy drop in an infinite universe. All we know for sure is that entropy is low, and getting higher everywhere we look. The second law states this quantitatively. End of story.

The fundamental point of the first law is the existence of an internal energy as a state function and the existence of heat(ing) as a method of energy transfer, besides the macroscopic work terms. The first law cannot be derived from conservation of the Noether current of translation in time, unless you introduce the assumptions of statistical mechanics. Assumptions which do not need to be made in order to state or verify the first law. The second law is even more certainly not "dealt with within this framework". Cosmologists must certainly understand the laws of thermodynamics, and, since they are dealing with a wide range of phenomena, are possibly more liable to detect violations of these laws. But when you talk about the "origins" of the second law, this is disturbing. I assume you mean a study of the reason for low entropy to begin with. The second law makes no statement about the origin of low entropy, it simply maps out how things develop given the assumption of low entropy. In that sense, cosmologists have no more claim to expertise about the second law than any other discipline that uses it. They do have claim to understanding the origin of low entropy but then, this is not the province of the second law. PAR (talk) 05:45, 22 February 2013 (UTC)

I just dropped a pencil and it fell to the floor. This had nothing to do with the second law of thermodynamics. The microscopic explanation of the second law is in terms of combinatorics, not of quantum field theory. I see Dan Gluck has the bit between his teeth and I do not have time to try further to hold him back.Chjoaygame (talk) 06:38, 22 February 2013 (UTC)

A real expert in this area is Walter T. Grandy. On page 151, he writes: "Pondering the mystery of time asymmetry is indeed a worthy pursuit, but we find it quite difficult to relate this apparent feature of the universe to our local observations of irreversibility. It is rather presumptuous to speak of the entropy of a universe about which we still understand so little, and we wonder how one might define thermodynamic entropy for a universe and its major constituents that have never been in equilibrium in their entire existence. Is the Big Bang a reproducible process? On a more prosaic level, we have no idea how to envision, let alone calculate, the entropy of a worm! For these reasons we decline to speculate here on the relation of entropy to the long-term fate of the universe and whether or not it will run down and burn out." (Entropy and the Time Evolution of Macroscopic Systems, (2008) Oxford University Press, Oxford, ISBN 978-0-19-954617-6.)Chjoaygame (talk) 06:54, 22 February 2013 (UTC)

Par and Chjoaygame - I suggest you read pages 35-36 of the following article by Joel Lebowitz, the editor-in-chief of the journal of statistical physics, which also cites Boltzmann - you can't get more expert than this: [1]. In fact I will add this as a reference to the second law article here. According to google scholar Lebowitz's article is cited 233 times, more than any of Grandy's books - though the latter have a much greater scope.

Par's and Grandy's arguments are quite similar. It is an argument about the epistemological status of the second law, compared to the big bang thoery: the second law has been verified to a much greater extent than the big bang theory. This is true, but it does not mean that the big bang cannot be the reason for the second law. The issue is similar to the following: the fact that apples fall from trees is verified to a much greater extent than Newton's law of gravity. We are much more sure that apples fall from trees, than we are about Newton's laws. But still, we say that the fall of an apple is a consequence of Newton's laws. Thus, a reason can have a lower epistemological status than its effect. And while this subject is interesting, it is obviously not relevant to the article about the second law, but rather to an article about epistemology or the philosophy of science.

Finally, Chjoaygame - surprising as it may sound, the fact that pencils can fall from your hand but not rise up from the floor spontaneously to your hand is, in fact, a consequence of the second law. When a pencil falls off from your hand and hits the floor, its kinetic energy is dissipated by forming sound waves (i.e. phonons) in the floor's matter. These propagate seemingly randomly and thus turn to heat (Note that they are only apparently random because they are in fact correlated, as they all originate from a single event - the hit of the pencil in the floor). The opposite event - where sound waves in the floor arrive from all directions and at the same moment hit a pencil lying on the floor and cause it to hop in the air right into your hand - is perfectly possible by all physical laws, except for the second law: such an event leads to a decrease in the entorpy and therefore violates the second law.

Microscopally speaking, unless we prepare the sound waves in advance, such an event has an extremely low probability. But the way we choose to calculate probabilities relies on different assumptions about the initial and the final conditions of the system, and eventually assume that we start with low entropy conditions. I can elaborate more on this if you like. Dan Gluck (talk) 12:21, 22 February 2013 (UTC)

Dan Gluck, I am flattered that you care enough to try to change my mind, but I can only repeat that I see you have the bit between your teeth and that I do not have time to try further to hold you back.Chjoaygame (talk) 15:05, 22 February 2013 (UTC)

While I haven't looked in detail at the disputed edits, I agree with the basic point that Dan Gluck is making here. This article actually does mention the issues regarding time symmetry and irriversibility at the macro level, so I don't see why this can't be explained better and from the point of view of modern physics. Given what we do know and what is thought to be well established (and that's obviously not everything), the initial conditions are of crucial importance for the second law. Time reversibility (or more precisely the fact that by the CPT theorem, the time reversed system behaves in the same way as the original system as far as information/entropy is concerned) simply cannot be ignored...

Another thing is that we need to put in the missing small print in the derivation by Everett based on MWI. As this stands it looks like no non-trivial assumptions are made, but it are precisely these hidden assumptions that make it work. Count Iblis (talk) 12:43, 22 February 2013 (UTC)

I agree completely, time reversal assymetry and irreversibility is fundamental to understanding entropy and the second law, and more emphasis should be placed on it. It is the only really intuitive link that everyone, non-physicists included, have to understanding entropy. The point I was trying to make to Dan Gluck is that the origin of the less-than-maximum entropy universe that we live in is not addressed by the second law. It basically says that, given less-than-maximum entropy, entropy will increase. That's all. The question of the direction of the "arrow of time" is very much part of an understanding of the second law, but "where does the arrow begin?" is not. That's a subject for cosmology, and the expertise and range of physical principles needed to approach this subject goes way beyond the second law, covering practically all of physics as we know it now. The second law alone does not imply the big bang theory. The only advantage that cosmologists have in understanding and interpreting the second law is that they apply the second law to a much wider range of phenomena. This does not make them more expert on the understanding and interpretation of the second law unless they find a violation, and, to my knowledge, they have not. PAR (talk) 17:15, 22 February 2013 (UTC)

PAR, I agree with you completely, except for one sentence: you write 'The question of the direction of the "arrow of time" is very much part of an understanding of the second law, but "where does the arrow begin?" is not.'

In my opinion, It is a part of the understanding of the second law because it's supposed to be the reason for it.

You write "the origin of the less-than-maximum entropy universe that we live in is not addressed by the second law" - that's true. But again, this origin is the reason for the second law (at least theoretically), so we should mention it.

You are right that it could have been that the origin is a fluctuation in entropy rather than a low entropy in the beginning in the universe, there's a famous paradox about it, but it's a paradox because it destroys virtually all possibility of reasoning about the past. You are welcome to write about that in this article. But as for now, as long as we don't go into this subtlety, the reference to cosmology is just fine - it both avoids this complication and is correct (since it seems that cosmologists do find evidence for very low entropy in the past, namely the isotropy of the CMB). If you have a better suggestion, please bring it up.

Now for a little discussion of that paradox. If we take initial conditions of the universe to be at low entropy, there is no problem. But if we take high-entropy initial conditions, then it is highly unlikely to get a low-entropy fluctuation later. Thus just taking low-entropy initial conditions (i.e. in the big bang) is probably a better approach.

Regarding experts, I didn't bring Hawking as an expert because he is a cosmologist (in fact, he is not - he is an expert in general relativity), but rather because his work together with Beckenstein's on the thermodynamics of black holes is one of the most important works (or maybe just one important work) in relation to the theoretical foundations of thermodynamics. Anyway, Lebowitz is an expert on statistical mechanics, and he also points to the origin of the secnd law as a cosmological question. Dan Gluck (talk) 10:08, 23 February 2013 (UTC)

Well, then, we agree more than I thought. I also think mention should be made of the cause of the low entropy universe, but I still don't see that as fundamental to understanding the second law any more than understanding an electron is fundamental to understanding Maxwell's equations. I also disagree about your statement that "if we take high-entropy initial conditions, then it is highly unlikely to get a low-entropy fluctuation later. Thus just taking low-entropy initial conditions (i.e. in the big bang) is probably a better approach." The probability of a fluctuation of a given size increases with the amount of time you wait and with the size of the system. As the size or the time approaches infinity, the probability approaches unity. If I have liter container of gas, I can calculate the average amount of time that must pass before every one of the gas molecules in that container are located on the left half of the container, and that time is not zero. It's staggeringly large, but if you have an infinite amount of time, then it will certainly happen. If I have a large volume, I can calculate the probability that, in the next second, a liter-sized volume element will have all its molecules packed into its left half. That's a very low entropy volume element. The larger my volume, the higher the probability is that I will find one in the next second, even though that probability is staggeringly small for terrestrial-size volumes. I can calculate the average size of my large volume that would be needed to find such a low-entropy volume element in the next second, and its a finite number. If I have an infinite volume, then such a low-entropy volume element will certainly appear somewhere in the next second of time. In fact, an infinite number of such low-entropy volume elements will occur. I can calculate the average size of a volume needed to find an observable-universe-sized fluctuation with the entropy on the order of our own observable universe in the next second and that size will not be infinite. If I have an infinite volume, then such a low-entropy universe will certainly appear somewhere in the next second of time. In fact, an infinite number of such low-entropy universes will occur.

I'm not a cosmologist, so there may be reasons that these considerations cannot possibly hold in our universe. But then, I have a fair understanding of the second law, and I am quite sure that the second law will NOT be the reason that these considerations cannot hold. In other words, you have to bring in other considerations to prove that the above scenario cannot hold, which proves my point: You cannot use the second law (the direction of the arrow) alone to find the source of initial low entropy (the source of the arrow). You don't need to know the source of the arrow in order to understand its direction and a statement of its direction tells you little about its source. PAR (talk) 14:05, 23 February 2013 (UTC)

I see your point. This is in fact the Boltzmann brain idea/paradox. On the one hand, it is not so far from modern ideas about the multiverse combined with the anthropic principle; on the pther hand, these relate not to some point after the big bang but rather to how the big bang itself came about in a low-entropy state. The problems with assuming a later fluctuation scenario come both from the paradox that we get, and from the evidence for low entropy in the very early universe (mainly CMB isotropy, and possibly also the success of the nucleosynthesis calculations). But you are right that these are beyond the scope of this article.

I will try to make few changes to reflect this. Something like writing "the very early universe" instead of "the beginning of the universe" (though I'll put back the link to the big bang, since a link to "cosmology" is too vague; additionally, the big bang sometimes refer to the whole period until the formation of the CMB, for which there is already good evidence for low entropy); and will add a link to the Boltzmann brain article.Dan Gluck (talk) 23:03, 23 February 2013 (UTC)

I've made the changes, seems to me better now. Dan Gluck (talk) 23:13, 23 February 2013 (UTC)

repeated citation; query self-promotion

An edit has been posted which repeats reference. I have tidied this up.

Not an expert in this area, still I get the feeling that this section should have given significant explicit note to Einstein's fluctuation formula. Absence of this seems a serious weakness in the section.

This edit seems to draw attention to the possibility that its parent paragraph looks suspiciously like self-promotion. I am no Wikilawyer, and I do not know how to check on such a suspicion. Perhaps someone who knows more about it can comment?Chjoaygame (talk) 23:47, 20 March 2013 (UTC)

reason for deletion of new section

I have noted that the new section, now deleted by me, was covered by a note asking for its retention if the only objection to it was that it was currently not well written.

I have deleted it because of objection to its intellectual content and because of its inadequate sourcing.

I could expand very much on these reasons, but probably my expansions would provoke a superfluous response, unless my expansions were exceptionally well written.

Therefore I will be very brief. Thermodynamics is very well understood for homogeneous bodies, constituted of materials that reach their own internal thermodynamic equilibrium quickly on time scales short in comparison with the time scales of processes contemplated for them, in which there is no internal flow; that is classical equilibrium thermodynamics. For other systems, as those provisos weaken, thermodynamics is less well understood. For systems very far from thermodynamic equilibrium, thermodynamics is practically a pipe-dream rather than a well understood science. According to Grandy, W.T., Jr (2008), Entropy and the Time Evolution of Macroscopic Systems, Oxford University Press, Oxford UK, ISBN978-0-19-954617-6, on page 151: "... we have no idea how to envisage, let alone calculate, the entropy of a worm!" There is a literature on non-equilibrium thermodynamics, which purports to explain the emergence of order, and is worth reading, and which might perhaps be regarded as providing reliable sourcing for some of the statements in the new section, but is not cited in it; the new and now deleted section was inadequately sourced. It looks as if it was not even adequately thought out from this less speculative viewpoint.

The present article has regrettably already overstepped the bounds of well understood physics, but the new and now deleted section, if left standing, would have been an open invitation to extend the article into more unfounded and pseudo-scientific speculation and worse. The article at present mostly pretends to be scientific. If a speculative article is desired along the lines of the new and now deleted section, perhaps a new article without scientific pretensions would be considered.Chjoaygame (talk) 22:44, 23 April 2013 (UTC)

An encyclopedia documents facts, not truth. Narssarssuaq (talk) 12:21, 27 April 2013 (UTC)

a more general doubt about readability

There seems to be a tendency to what I want to call "nerd talk" on subjects like this. After reading the entire article (not the formulas!) I finally decided to look on the Simple English Wikipedia and found exactly what I needed. (As if to confirm the tendency, that article has a note on it that it should be simplified.) And I'm sure that only a very rare reader would be wanting this article here to be as technical as it is. In other words: I think the Simple English article would do very well as the main article on the second law of thermodynamics here on the English Wikipedia, with a link to a sister article called something like "Second law of thermodynamics (scientific)" containing the current article's text.

Actually, a more fundamental problem is lurking here: Scientific stuff can't be described in simple language without losing accuracy, so authors really knowing the subject are generally unable to write such simpler descriptions. One "solution" could be to include a "non-accuracy clause" in such articles somewhat like the caution clause in medical ones, although I confess I'm smiling at the idea. With such a clause in place, authors may feel easier about giving up some correctness and thus be better dispositioned to write a readable text.

If you know a good place to raise this (second) point, please let me know. Geke (talk) 11:36, 4 April 2013 (UTC)

I don't think there is a problem with this article being technical or being too nerdy, the problem as I see it is that it doesn't cater to the casual reader. It should really try to do both. In particular, the second law of thermodynamics has a special place in popular culture (the popular concept of disorder), yet there is no acknowledgement of this, or any explanation or discussion that could shed light on the popular concept. As such, the article isn't of much use to the casual reader. Hzh (talk) 23:56, 11 May 2013 (UTC)

Actually it is more than the "casual reader" that is left behind. The style of this article, notably including omission of dependent variables, makes this only readable to the already informed.

a "more recent statement"

The recently added "more recent statement" has perhaps some problems.

It is not altogether clear that it is not some kind of self-or-related-party promotion. There are in the literature probably hundreds of more recent statements of the law, and no reason is cited for selecting from amongst them the one actually chosen here. In contrast, the other statements cited in the article are celebrated ones with widely recognized historical importance. The "more recent statement" is placed with special emphasis or prominence, not in the list of historically recognized statements, but in the preamble to that list, as if the "more recent statement" was somehow better or preferable or otherwise more important.

The term "reversible weight process" is a slightly idiosyncratic usage of language. Yes, it makes sense, and is physically valid, but it is not a regular part of the ordinary usage and is not defined here.

The term "state" is used in a slightly idiosyncratic way by the "more recent state". A thermodynamic state is usually taken as being a state of internal thermodynamic equilibrium. The term "state" here intends that the system in general not be in a state of internal thermodynamic equilibrium. Moreover, it seems that the initial "state" of the system, as intended by the "more recent statement" needs a process of externally driven work to bring it to its eventual internal state of thermodynamic equilibrium. It seems odd that externally driven work is needed, when one might expect that the state of internal thermodynamic equilibrium will be reached eventually simply by internal evolution without externally driven work. These points are not explained in the article as it stands.

Combining these reasons, I am unhappy with the recently added "more recent statement".Chjoaygame (talk) 21:48, 1 June 2013 (UTC)

Work Gain

It has been shown that the second law of thermodynamics can be violated using entanglement, unless this paper is refuted or I am misunderstanding the paper and the news articles that referenced it. http://arxiv.org/pdf/1207.6872v1.pdf — Preceding unsigned comment added by 70.249.57.112 (talk) 21:49, 17 October 2012 (UTC)

The paper doesn't claim to violate the second law. It claims:

We have extended the second law of thermodynamics with feedback control to the case of ini- tially entangled states. We have shown that work can be extracted beyond classical correlation from entangle- ment. — Preceding unsigned comment added by MorphismOfDoom (talk • contribs) 19:23, 5 June 2013 (UTC)

pseudo-science

Editor Dan Gluck, your edit has a cover note that tries to make out that we are looking here at a point of view issue. No, this is about precise thinking in a scientific article. Clausius and Kelvin were being expansive and rhetorical. Their expansive ideas on this subject are not adequate science today, and Wikipedia should not suggest to the contrary. It is bad enough that the article Heat death of the universe tries to suggest to the contrary, but that pseudo-scientific contagion should not spread to here. To appear 'neutral' about this is to support pseudo-science.Chjoaygame (talk) 22:40, 30 July 2013 (UTC)

Dear Chjoaygame, first I want to thank you for keeping this article in a high level and clean of nonsense like that fringe material you just deleted few days ago (the "contra-something law", I don't really remember). Regarding the subject at hand, the naive heat-death scenario is simply an old scientific theory, which has been replaced, but this is surely not pseudo-science. Therefore, I see no point in giving it a whole section. However It is, in fact, not very far from the current view of matters, so I changed the section name to something like "future of the universe" and wrote the current understanding of things, based on a very highly-cited article (187 according to google). Additionaly, I saw another problem with the former version: it looked more like wikiquote than wikipedia. A scientific article should not give such long quotes, just state the facts (or opinions if facts are not available or have many interpretations) and cite. Dan Gluck (talk) 20:42, 1 August 2013 (UTC)

Thank you Dan Gluck. Yes, perhaps I put it a bit hard calling it pseudo. It's old, as you say. I wrote the full quotes because I wanted editors and readers to be sure I did not misrepresent, or be assumed to be misrepresenting, the sources (editors often don't check sources for things that they don't like and overwrite). In this case you have initially airbrushed away, and eventually deleted, all my sources, which I think are more reliable and authoritative on thermodynamics than the cosmological arXiv article you have regrettably cited; that arXiv article hardly considers the problems with defining entropy. I would still say that the current view of matters is complicated and very hard to simplify. I would not call it the current understanding of things, I would call it the current lack of understanding of things. How do dark matter and dark energy fit into nice simple articles about thermodynamics?

I do not at all like free-wheeling, may I even say lofty, expressions of editorial opinion such as you have written, especially based on a single source, no matter how widely cited it might be according to Google (the more widely cited, the more likely to be pseudo?); and that source admits a variety of more or less mutually incompatible thoughts about this.

I think Truesdell is right to have called the Clausius aphorism "sybillic", and that if it is mentioned at all in the article it should be nailed to Clausius and suffer some comment such as Truesdell's. For an article about the second law, I think technical the difficulty of defining entropy for the universe is more important than ideas about expansion of the universe. This article is not about cosmology, but you have come close to turning the section into such. Clausius' use of the word "universe" was hyperbolic and should not by Wikipedia be supported as if it were literally justified.

I won't argue with you about this because I can see that you are firmly intent on giving it an airing here. My preference would be to omit the section, or again call it the heat death story, making it clear that it is esoteric and of mainly historical interest for thermodynamics, no matter what cosmologists might think about it.Chjoaygame (talk) 02:19, 2 August 2013 (UTC)

edit on Maxwell's demon

I have removed the unsourced comment, as well as its newly proposed replacement. The comment was unsourced for too long. The newly proposed replacement is primary research, not adequately supported by reliable secondary sources. And evidently not to the point. Information erasure is not information acquisition.Chjoaygame (talk) 00:50, 31 December 2013 (UTC)

non-equilibrium

The article contains the following piece of wisdom:

"The entropy of a system that is not in equilibrium can be defined as:

S=-k_{\mathrm {B} }\sum _{j}P_{j}\ln \left(P_{j}\right)

see here. Here the

P_{j}

is the probabilities for the system to be found in the states labeled by the subscript j. In thermal equilibrium, the probabilities for states inside the energy interval

\delta E

are all equal to

1/\Omega

, and in that case the general definition coincides with the previous definition of S that applies to the case of thermal equilibrium."

I have recently discovered by advanced methods of scientific research that $P (j) = the length of a piece of string$ .

If someone has a better estimate than this, perhaps they may have a case to retain this piece of wisdom. But, unless the estimate is mightily better, I am keen to delete this piece of wisdom.Chjoaygame (talk) 16:07, 19 January 2014 (UTC)

Done.Chjoaygame (talk) 09:10, 16 February 2014 (UTC)

why Planck's statement is preferable

I have undone a good faith edit. The edit that I undid replaced Planck's preferred statement of the second law with a statement by another writer.

Planck's statement is preferable for several good reasons.

One is that Planck is recognized by another reliable source as a most excellent and reliable authority, a fact known to many without need for that particular reliable reference. The proposed new statement is not backed up by a reliable source for its excellence.

Another is that Planck's statement is better than the one from the other writer. This is because Planck is well aware of, and has elsewhere explicitly stated, the difficulty or impossibility of defining entropy for a system not in thermodynamic equilibrium. The other writer's statement talks about changes in the entropy of an isolated system. This can have strict meaning only if the isolated system is a compound of several simple systems each with its own internal state of thermodynamic equilibrium, the compound being in some initial equilibrium state, and then a thermodynamic operation changes the connections between the subsystems and sets in progress some thermodynamic processes which lead to a new compound equilibrium state. The recounting of this complicated story is avoided by Planck's better formulated version. Planck's version takes the story into account. It avoids the possible suggestion, present in the other writer's version, that a simple isolated system might change its entropy, a suggestion rife with problems, as observed by Planck.Chjoaygame (talk) 10:30, 2 March 2014 (UTC)

reasons for undo

I have undone an inappropriate edit. There are several reasons why that edit was inappropriate and perhaps even improper.

The edit was an addition to the lead, of a detailed piece of reasoning that is not covered in the article. The lead is the place for summary of the article, not for presentation of new detailed reasoning. The edit concerned the precise definition of a thermodynamic process involving several thermodynamic systems. This varies from text to text, and the lead of the article on the second law is not the place to analyze this.

The analysis offered in the undone edit was not sourced, and was evidently an expression of editorial opinion or point of view verging on original research which is not allowed by Wikipedia policy.

Perhaps also a problem might be that the edit was anonymous and perhaps idiosyncratic, and the question arises whether it might have been a case of sock-puppetry, which is forbidden in Wikipedia.Chjoaygame (talk) 02:28, 4 March 2014 (UTC)

Prigogine & Stengers quote

I have restored the just-previously removed quote from Prigogine & Stengers. Prigogine is a Nobel Prize winner, for his work on non-equilibrium thermodynamics, with special reference to the second law, that, largely speaking, showed how the second law is compatible with the evolution of life. The second law is sometimes seen as a statement that nature tends to disorganization, while the evolution of life is sometimes seen as a development of organization in nature. The two are compatible and it is worth saying that in an article on the second law. The reason is that the second law refers primarily to systems that are in thermodynamic equilibrium while the evolution of life is essentially rooted in systems that are not in thermodynamic equilibrium. Prigogine and others have shown that there is no incompatibility in that. It is useful to remind readers of this in this article.Chjoaygame (talk) 07:09, 6 March 2014 (UTC)

I made the removal of the quote, and I still find it to be irrelevant on the article as it stands. If there had been a section with common misconceptions of the second law, i.e. that it "refutes evolution" the quote could be entirely appropriate. However, without that context, I would say that the quote seems out of place.Tuxino OKH (talk) 03:25, 7 March 2014 (UTC)

One or two of the other quotes are nonsensical or poorly stated. I suppose you could object to them too. Though I think you are being stringent, just to make you happy, I have deleted the one you find irrelevant. Along with it I have removed one that offers a defective statement of the law, and a moral view that the Prigogine quote was intended to counter.Chjoaygame (talk) 10:35, 7 March 2014 (UTC)

The reason I didn't object to any of the other quotes is that they dealt directly with thermodynamics, whereas the one I removed was only related to the subject in a rather roundabout way. And, yes I suppose I am somewhat stringent. I have no objection to your removal of the other quote. Tuxino OKH (talk) 20:46, 7 March 2014 (UTC)

"a quote from a primary source"

This edit explained itself in its cover note on the grounds that the version it removed was "a quote from a primary source".

Not so. The quote is from a 2003 authoritative review by J. Uffink, published by Princeton University press, of the literature including secondary sources. Primary sources on the second law of thermodynamics are for example Carnot, Clausius, Rankine, and perhaps Kelvin, early and middle nineteenth century authors. Planck's 1926 article was an authoritative review, particularly assessing the Carathéodory view. Planck's textbook has been through 11 editions because of its accepted authority. It is not a primary source. It is at least a secondary source, and Uffink's review, from which the quote was copied, is a reliable tertiary source, which explicitly recognized the authority of Planck on this matter.Chjoaygame (talk) 09:13, 10 March 2014 (UTC)

reasons for undo

I have undone another attempt to put into the article a repeated claim that is contrary to reliable sources. The attempt was unsourced and was placed out of context. The context was the possibility of black holes affecting the applicability of the second law, but the attempt was about planetary atmospheres, not black hole possibilities. The attempt comes from a mistaken belief which has been repeatedly expressed by edit attempts here, made by the same editor, who elsewhere is promoting a book he has written about the subject. The attempt is fringe science, and contradicts the consensus of Maxwell, Boltzmann, Gibbs, and Chapman, as well as of other modern authors.Chjoaygame (talk) 07:43, 18 March 2014 (UTC)

undid self-promotion that also happens to contradict reliable sources.

I have undone a set of edits which were self-promotion. The cited source was a publication by the editor who posted the edits which I undid. It is against the rules of Wikipedia for an editor promote his own research and publications, WP:PROMOTION. As it happens, the publication expresses a doctrine that is contradictory to reliable sources, so that even if it had been posted and cited by someone else, the edit that cited it would have needed to be undone. The doctrine promoted in the publication contradicts many reliable sources in many respects. It is not the kind of thing that is acceptable in Wikipedia; it may be described as fringe science masquerading as mainstream science. The editor who posted this material has several times recently tried to post material substantially like it, and the posts have been undone for the same reasons. The Wikipedia has a strict rule, WP:OR, against edits which are original research, including original synthesis, WP:SYN, of the research of others. A primary rule of Wikipedia is that material must have reliable sources, WP:RS. Many reliable sources are contradicted by the edits which I have undone.Chjoaygame (talk) 12:30, 29 March 2014 (UTC)

faulty edit undone

I have undone a sequence of faulty edits.

The edits were an attempt to post parts of several previous faulty edits along the same lines. The repeated creation of a need to undo these faulty edits raises the question of disruptive editing. The faulty edits are obviously in good faith in the sense that they represent the faulty editor's beliefs about what should rightly be in the article. But they are repeated without regard to reasons for their previous undoing given on the talk page. The reasons slready given on the talk page are sound and should not be ignored. It is perhaps useful that I repeat here that the faulty edits are in support of promotion of a recent publication of original research of the editor who posted them, and that he has been persistently trying to post this doctrine, which contradicts reliable sources.

The faulty edits amount to the insertion of the following into the lead:

"In order to understand how the process described in this law leads to gradients in density etc in a gravitational system (where gravitational potential energy must also be taken into account) we refer to the fact that the state of thermodynamic equilibrium has no unbalanced energy potentials. Hence it has homogeneous entropy and may be said to be isentropic. If this were not the case, then entropy could still continue increasing, because the state of maximum entropy (within the system constraints) would not have been attained."

The present faulty edits are unacceptable for several reasons.

In general, they are a chatty explanation in the lead, but are not an appropriate summary of the context of the contents of the article. The explanation they give is not well enough expressed for lead explanation, even if one were appropriate here. Talk of "unbalanced energy potentials" is too vague for a lead explanation.

Morevover, they are faulty in physics. One reason for this statement is that it is not correct in context in physics to say that "the state of thermodynamic equilibrium has no unbalanced energy potentials". This claim in context includes gravitational potential energy. Beyond the vagueness of the phrase "unbalanced energy potentials" is that thermodynamics is not about energy potentials loosely taken, it is specifically about thermodynamic potentials. A gravitational potential is not a thermodynamic potential. Another reason is that the claim about homogeneous entropy is wrong in physics. The condition for thermodynamic equilibrium in a body is that its total entropy be maximum subject to the constraints, not that its entropy density be homogeneously distributed. Moreover, the use of the term "isentropic" is wrong. Isentropic refers to thermodynamic processes, not to a distribution of entropy density as is obviously intended in the faulty edit.

I am sorry to say that if this kind of attempt should be repeated, I would feel that I should seek some kind of administrative remedy.Chjoaygame (talk) 06:29, 30 March 2014 (UTC)

link to dissipation

The first clause of the first sentence of the lead reads "The second law of thermodynamics states that the entropy of an isolated system never decreases." The law refers to all modes of increase of entropy, not only dissipative modes. Planck pointed out that diffusion in an ideal gas mixture increases entropy but is not a form of dissipation of energy.<Planck, M. (1897/1903). Treatise on Thermodynamics, translated by A. Ogg, Longmans Green, London, p. 100.> The link misleadingly suggests that all increases of entropy are due to dissipation. This is not a reason to expand the first clause; it is a reason to remove the link.Chjoaygame (talk) 18:28, 30 March 2014 (UTC)

undid faulty edit

I have undone a faulty edit. The faulty edit was another repetition of the string of edits by the editor who posted it, edits which contradict the reliable sources which concur in saying that in a system isolated apart from being subject to an externally imposed force field, in the present of such a field, the state of internal thermodynamic equilibrium is characterized by spatial homogeneity of temperature. The reliable sources are listed at Thermodynamic equilibrium#Characterisitics of a state of internal thermodynamic equilibrium#Uniform temperature.

It seems to me that the repeated posting of faulty edits such as this one has become a matter of editorial conduct.Chjoaygame (talk) 11:16, 31 March 2014 (UTC)

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 sentence. This is good.Chjoaygame (talk) 08:12, 1 April 2014 (UTC)

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 )

The Second Law of Thermodynamics article has serious omissions.

NOR

"The WP article gives the overall mistaken impression that the Second Law is only about thermal equilibrium whereas in fact it is about thermodynamic equilibrium as is stated at the top, but never further discussed. Hence it is the Second Law which brings about the density gradient in the troposphere, for example, because thermodynamic equilibrium also includes mechanical equilibrium.

"Consequently I have added an additional paragraph (copied below) in an appropriate position in the text. This has nothing to do with my book, might I add, and I have never mentioned my book, although I did quote my March 2012 peer-reviewed paper as a reference, which was deleted. That paper had citations to other peer-reviewed material, such as Dr Hans Jelbring's paper on atmospheric mass.

"The paragraph I have added in order to overcome this serious shortcoming in the WP article reads (or did read) ...

""So, whilst the statement in the previous paragraph applies, as it says, to a non-gravitational system, a more detailed explanation is required for an isolated system in a gravitational field. Thus we need an understanding of the fact that the Second Law of Thermodynamics is an all-embracing law pertaining to thermodynamic equilibrium evolving as entropy increases. For example, it also explains the obvious density gradient in a planet's troposphere, and this is because entropy will increase if there are unbalanced energy potentials, such as extra gravitational potential energy in molecules at higher altitudes."

"Douglas Cotton, B.Sc.(physics), B.A.(economics), Dip.Bus.Admin

"March 30, 2014— Preceding unsigned comment added by Douglas Cotton (talk • contribs) 10:17, 30 March 2014 (UTC) "

The above quoted comment was posted on my talk page but since it is of general concern for the article, I have copied it here.Chjoaygame (talk) 13:52, 30 March 2014 (UTC)

As to "The WP article gives the overall mistaken impression that the Second Law is only about thermal equilibrium whereas in fact it is about thermodynamic equilibrium as is stated at the top, but never further discussed." I agree that the second law is about thermodynamic equilibrium not restricted to thermal equilibrium. The wording in terms of "thermal" equilibrium was posted by an editor whom I do not bother to correct because of his editing habits.

As to "Hence it is the Second Law which brings about the density gradient in the troposphere, for example, because thermodynamic equilibrium also includes mechanical equilibrium." This comment is so vague that it would hardly make sense for me to try to respond to it.

As to "Consequently I have added an additional paragraph (copied below) in an appropriate position in the text. This has nothing to do with my book, might I add, and I have never mentioned my book, although I did quote my March 2012 peer-reviewed paper as a reference, which was deleted. That paper had citations to other peer-reviewed material, such as Dr Hans Jelbring's paper on atmospheric mass." The additional paragraph is not justified by this comment. Though you have not explicitly mentioned your book here, you cited your own research paper. That counts here as original research and is not admissible here. It is also promotion of your paper. The material you posted is, according to your comments elsewhere, part of the book that you have been promoting explicitly elsewhere. Consequently, it is virtual or indirect promotion of your book. Moreover, the criterion here is not whether the material has been "peer-reviewed" whatever that might mean; the criterion here is that the cited source should be reliable. Sad to say, neither your paper nor those of Dr Hans Jelbring qualify as reliable sources here. They are both fringe science. Consequently your added paragraph is inadmissible as you posted it.Chjoaygame (talk) 14:12, 30 March 2014 (UTC)

My response

The density gradient results from hydrostatic equilibrium which, in a planet's troposphere, is the same as thermodynamic equilibrium because there can only be the one state of maximum entropy of course. This equilibrium results from the balancing of the pressure-gradient force and gravitational force. Does that help you understand how gravity forms a density gradient in accord with the process described in statements of the Second Law, wherein this state of thermodynamic equilibrium (with a density gradient) develops?

The paper by Dr Hans Jelbring (based on his research for his PhD in climatology) was published in Energy and Environment. My interest is not about which journals are assumed "fringe" or otherwise: it is about what hypothesis is supported by both the laws of physics and empirical evidence. My personal judgment (which is not clouded by any pecuniary interest) is based on thousands of hours of research in climatology and relevant physics, and that judgment is that the gravito-thermal hypothesis of Dr Jelbring, myself and some others is capable of explaining all planetary temperatures above and below any surface, and is supported by a wide range of different empirical evidence, including the increasing temperature in the Venus surface, the measured cooling effect of water vapor, the temperature gradient in the Ranque-Hilsch vortex tube, the thermal gradient (very close to the -g/Cp value) in the Uranus troposphere, and other data even in Earth's outer crust. In contrast, the radiative greenhouse conjecture has no such evidence, or any validity based on the laws of physics.

Douglas Cotton (talk) 13:40, 1 April 2014 (UTC)

The Second Law is not just about temperatures or "hot to cold"

NOR

The Second Law of Thermodynamics refers to processes within isolated systems, not bodies, and it should specify that the concept of the total net change in entropy should only relate to either a single process or a sequence of dependent processes. If there are two or more independent processes, then each must result in no decrease in entropy. The two sides of a siphon represent dependent processes, but if you cut the hose at the top you have independent processes, and so the water no longer moves upwards on the shorter (input) side. There are many cases of one-way radiation (such as the Sun warming a black disc under the surface of water) and, in fact, any radiation should be treated as a one-way independent process.

The concept that temperature, pressure etc become spatially homogeneous only applies in the absence of an external force field or, if a gravitational force field is present, then only in a horizontal plane within that force field. In all other situations the force field gives rise to a situation in which molecules have non-homogeneous potential energy due to that force field. That potential energy must be taken into account in entropy computations.

The Second Law discusses thermodynamic equilibrium, which can exhibit gradients in density, for example, in a gravitational field. In fact, thermodynamic equilibrium is the same as hydrostatic equilibrium in this case (when all net energy transfers cease) because there can be only one state of maximum entropy.

As said above, we must consider not just molecular kinetic energy (that determines temperature) but also gravitational potential energy. When we do this, we understand from Kinetic Theory how a density gradient develops, and so too does a temperature gradient. If, for example, you had a long horizontal cylinder of gas with homogeneous density and temperature, and you then turned it to a vertical position, there would be more net downward movement of molecules than upward movement. So a density gradient develops, but also a temperature gradient because more molecules are gaining kinetic energy as they move to lower regions, whilst fewer are losing kinetic energy as they move upwards. Temperature depends only upon the mean kinetic energy of molecules, not the density. Pressure follows because it is proportional to the product of temperature and density. High pressure does not cause high temperature: rather it is the result of high temperature coupled with high density. Pressure does not maintain high temperatures either.

There is solid empirical evidence of a strong force field redistributing molecular kinetic energy (thus causing different temperatures) in a Ranque-Hilsch Vortex tube where forces of the order of over a million g are developed in a tube with radius about 6mm.

Douglas Cotton (talk) 03:23, 1 April 2014 (UTC)

It is good to see that Editor Douglas Cotton is now using the talk page to express his views on what the articles should say. I will continue this comment shortly.Chjoaygame (talk) 08:06, 1 April 2014 (UTC)

The above comment by Editor Douglas Cotton begins "The Second Law of Thermodynamics refers to processes within isolated systems". Indeed that is how the law is advertised in the first sentence of the lead. The lead first sentence is "The second law of thermodynamics states that the entropy of an isolated system never decreases, because isolated systems always evolve toward thermodynamic equilibrium— a state depending on the maximum entropy."

We have here a good example of why that form of statement, while slick and apparently clever, is dangerous and not used by most reliable sources. For example, Čápek, V., Sheehan, D.P. (2005). Challenges to the Second Law of Thermodynamics: Theory and Experiment, Springer, Dordrecht, ISBN 1-4020-3015-0, pp. 3–13, examine 21 formulations of the law. They start by quoting Truesdell "Every physicist knows exactly what the first and second laws mean, but it is my experience that no two physicists agree on them." They consider first 12 statements that do not mention processes in isolated systems, and do not mention thermodynamic equilibrium. Their 13th statement is not cited to any particular source, but is offered as from "many researchers". It reads "Equilibrium The macroscopic properties of an isolated system eventually assume static values." They use the word 'equilibrium' as a header for that statement but it is not part of the statement. They comment "Note that here, as with many equivalent versions, the term equilibrium is purposefully avoided. They give as their fourteenth statement one by Gyftopolous and Beretta. It does not talk explicitly of processes, or of an isolated system. Commenting on these two statements, Čápek & Sheehan say "There are no truly isolated systems in nature; ..." and give reasons why. The next on their list that mentions an isolated system is by Gibbs, but it does not refer to processes in an isolated system. It talks about virtual variations in entropy. They soon quote the mathematical giant V.I. Arnold: "Every mathematician knows that it is impossible to understand an elementary course in thermodynamics."

The problem as I see it is illustrated by Editor Douglas Cotton's comment. Entropy as defined in classical thermodynamics refers to systems already in their own states of internal thermodynamic equilibrium. If a system has an entropy, and is then isolated by a thermodynamic operation, no non-trivial process ensues, and trivially the entropy does not change. For a process to occur in an isolated system, and be described by entropy, the system must be compound and consist of several subsystems, initially already in their own separate states of internal thermodynamic equilibrium. The process must then be initiated by a thermodynamic operation, to move from the initial state of separate equilibria, to a joint equilibrium. This all takes words to make clear. Editor Douglas Cotton comes near to dealing with it by talking of a single process versus two or more independent processes.

The point I am making here is twofold. One is that there are no truly isolated systems in nature, and that to talk of processes in isolated systems involves complications of statement that are not obvious on the surface. That is why the most classical statements of the law are not of the form advocated by Editor Douglas Cotton, or of the form stated in the lead of the article, a form that I have not tried recently to alter because of the difficulty of doing so, but which I think is poor. Editor Douglas Cotton is right to say that if a system undergoes a time sequence of independent processes, each process in the sequence must obey the second law. But he gives an example, not of a time sequence, but of a spatial separation of temporally simultaneous but physically dependent processes. This is a complicated story.

Editor Douglas Cotton moves on: "There are many cases of one-way radiation (such as the Sun warming a black disc under the surface of water) and, in fact, any radiation should be treated as a one-way independent process." The problem here is that he is using thinking of process in two different ways in the same sentence. In the first way he thinks of warming as a process. This is the thermodynamic sense of process, which involves transfer of energy as heat. Then he refers to one-way radiation as a process; this is a use of the word that is contrary to the thermodynamic usage. Apart from magnetic media, the Helmholtz reciprocity principle governs thermodynamic transfers of energy as heat. Thermodynamics does not admit a notion of radiation as a one-way independent thermodynamic process. Editor Douglas Cotton does not accept that thermodynamic principle, and it is his privilege to do so, but while he does so he is talking fringe science, not thermodynamics. The Wikipedia article on the second law does not admit fringe science.

Editor Douglas Cotton moves on to say, in summary, that a gravity field causes a gradient of temperature in an otherwise isolated system. This is a strongly and genuinely held belief of Editor Douglas Cotton, to judge from his many statements of it, here and elsewhere. But it in direct contradiction to reliable sources. I do not wish to repeat and repeat and repeat the recitation of those reliable sources, and so I leave it to the reader to find the link to them in the just preceding section of the present talk page, headed 'undid faulty edit'. This belief of Editor Douglas Cotton is also fringe science, not thermodynamics. Again, the Wikipedia article on the second law does not admit fringe science.

I will not go further at present. I think I have made my view clear, that Editor Douglas Cotton has a good faith belief in some fringe science, but that does not come into the Wikipedia article on the second law.Chjoaygame (talk) 09:51, 1 April 2014 (UTC)

My response:

Yes there are variations in the way the Second Law of Thermodynamics is expressed, but the general theme in virtually all modern statements is that entropy increases towards a maximum value. That maximum value must be an equilibrium state, because, once reached, entropy can neither increase or decrease, and hence there will be no unbalanced energy potentials. Because molecules interchange kinetic energy and gravitational potential energy, both forms of energy must be included in considerations regarding unbalanced energy potentials. This leads to there having to be homogeneous entropy, which thus has a temperature gradient (as well as a density gradient) because (PE+KE)=constant and only KE determines temperature. Pressure becomes a corollary, being proportional to the product of density and temperature.

The thermal gradient is easily observed and measured when a large artificial gravitational force is generated, such as in a Ranque-Hilsch vortex tube, so I consider that the gravito-thermal gradient is proven both theoretically and empirically. There are some errors in Springer & Dordrecht, and one is in their attempted rebuttal of this effect (postulated by Josef Loschmidt) wherein they do not understand that their thought experiment was merely creating a new combined system wherein solids, liquids and gases all develop thermal gradients and, even though there are different gradients, a new state of thermodynamic equilibrium will evolve with no perpetual cyclic energy flow.

So, I suggest that it is intuitively obvious that the whole concept of increasing entropy to the maximum attainable amount is what the Second Law is all about, and is what will happen spontaneously.

Esoteric discussion regarding isolated systems is not particularly important when considering the extrapolation of the proof of the gravito-thermal effect in an ideal gas to the whole troposphere. The final state (given the name thermodynamic equilibrium) has to be such that entropy can no longer increase, and since it cannot decrease, it remains constant. It should also be obvious that entropy can only remain constant if there are no unbalanced energy potentials - a condition mentioned in Thermodynamic equilibrium - because then no net energy will flow any more across any internal or external boundary.

So, no, entropy certainly does not, as you say, refer to "systems already in their own states of internal thermodynamic equilibrium." As you can read in WP, entropy may be considered a measure of progress towards thermodynamic equilibrium. As one who has helped many physics undergraduates for nearly 50 years, I detect that you display a serious misunderstanding of entropy when you make a statement like you did above. And my example of a siphon does entail a time sequence for any particular ensemble of water molecules: they only go up (against gravity) because at a later time they must go down with a greater drop than the original rise. There is no interdependence in the various processes when, for example, the Sun raises the temperature of a black disc beneath water, which water then evaporates, and then energy is released some days later when rain or hail forms in the clouds.

The issue of two-way radiation, but only one-way transfer of thermal energy is covered in great detail in my paper "Radiated Energy and the Second Law of Thermodynamics" published on several websites two years ago in March 2012. It is not a particularly relevant matter, however, when discussing, for example, why the nominal Uranus troposphere displays a gravitationally induced thermal gradient, even though at its base there is no significant solar radiation, or internal energy generated, or any surface. So I will not discuss radiation matters any more, and the article omits to do so anyway, which is something of a shortcoming.

It is the existence of the now-proven gravito-thermal gradient (virtually a corollary of the Second Law of Thermodynamics) which opens up a whole new paradigm wherein the pre-determined temperature profile in a planet's troposphere sets the "supporting temperature" where the profile intersects the surface, and this is what slows both radiative and non-radiative cooling processes in the early pre-dawn hours. Only when you understand that the sloping temperature plot represents a state of thermodynamic equilibrium - only then can you correctly understand how this then enables thermal energy to pass (by non-radiative processes) from newly warmed upper troposphere regions (on Venus, for example) down into the surface, but only while restoring thermodynamic equilibrium with its sloping thermal plane.

Douglas Cotton (talk) 13:12, 1 April 2014 (UTC)

Douglas was your paper peer-reviewed? If so please link to the review paper abstract, thanks. Prokaryotes (talk) 15:42, 1 April 2014 (UTC)

The criterion here is not whether or not the paper was peer-reviewed, whatever that might mean. It is whether or not the paper is a reliable source by Wikipedia criteria, or whether or not the intended post is original research by Wikipedia criteria. The reasons given above establish that the intended posts belong to fringe science and therefore not to the Wikipedia article. The argumentation presented by Editor Douglas Cotton just above confirms those reasons. If Editor Douglas Cotton wants his doctrines to be expressed in Wikipedia articles, there is a proper course of action for him for that end. He should see that his doctrine is published in valid form outside Wikipedia, and wait till it is acknowledged by Wikipedia reliable sources outside Wikipedia, and following that, Wikipedia editors will detect its presence in Wikipedia reliable sources, and judge its suitability or unsuitability for posting in Wikipedia articles. Editor Douglas Cotton himself is not a suitable editor to put his doctrine up in Wikipedia articles because for him to do so would be some combination of impermissible original research and undue promotion of own work.Chjoaygame (talk) 17:16, 1 April 2014 (UTC)

formulations

Prigogine in 1978 wrote: "I should emphasize that 150 years after its formulation the second law of thermodynamics still appears to be more a program than a well-defined theory in the usual sense, as nothing precise (except the sign) is said about the $S$ production."<Time, structure, and fluctuations, Science 201: 777–785.>Chjoaygame (talk) 22:27, 15 April 2014 (UTC)

decay or evolution

The opening paragraph reads "always evolve toward thermodynamic equilibrium". thermodynamic systems do not "evolve" they decay towards equilibrium. (ref Peter Atkins - Creation Revisited). So I propose replace "evolve", which gives entirely the wrong sense to the general reader, with "decay". Vh mby (talk) 12:50, 18 May 2014 (UTC) It seems no one has any problem with this.. (done) Mike 23:29, 25 May 2014 (UTC)

I moved the immediately above comment to the usual place for new comments, here, at the end of the article, in a new section.

As it happens, I don't agree that "evolve" gives entirely the wrong sense to the general reader. I see evolve as a fairly neutral word, while decay has a suggestion of deterioration. Peter Atkins is only one of many writers, and on such matters as this, he is not authoritative. Since I am not happy with the lead statement of the law anyway, I am not now going to try to tweak it.Chjoaygame (talk) 05:22, 26 May 2014 (UTC)