Talk:Laws of thermodynamics/Archive 2

Possible First Law error??
Under first law I find the expression:

Increase in internal energy of a system = heat supplied to the system - work done on the system.

Shouldn't the minus be a plus, or if it is minus, shouldn't the word on be changed to by?

tjh — Preceding unsigned comment added by 129.210.19.211 (talk) 23:25, 4 January 2012 (UTC)

Article lead and the statement of the laws
I think the way the laws are stated in the article is very peculiar, not to mention unsourced. I plan to re-write them more or less from scratch following a source.  Waleswatcher  ( talk ) 04:47, 1 February 2012 (UTC)

Kittel and Kroemer have a nice, concise statement of all four laws. Unless someone objects, I'm going to change the article lead to conform to theirs.  Waleswatcher  ( talk ) 04:55, 1 February 2012 (UTC)


 * This has been thrashed around for a while. How about putting Kittel and Kroemer's statements on the talk page and see what comments occur? PAR (talk) 07:14, 1 February 2012 (UTC)

OK. Here are the laws of thermo according to Kittel and Kroemer. While I'm not tied to this particular source, it's a reliable source (and a standard text book in advanced courses on the topic).

Zeroth law. If two systems are in thermal equilibrium with a third system, they must be in thermal equilibrium with each other.

First law. Heat is a form of energy.

Second law: If a closed system is in a configuration that is not the equilibrium configuration, the most probable consequence will be that the entropy of the system will increase monotonically in successive instants of time. (I think this one can be trimmed slightly for clarity, something like "The entropy of any closed system not in equilibrium (the state of maximum entropy) almost always increases.)

Third law. The entropy of a system approaches a constant value as the temperature approaches zero.  Waleswatcher  ( talk ) 12:58, 1 February 2012 (UTC)


 * Kittel and Kroemer is not a text of thermodynamics. It is a text, as it announces in its title, of Thermal Physics. The difference between thermal physics and thermodynamics is that thermal physics takes account of the atomic constitution of matter, while thermodynamics does not. It is not a criterion of virtue that the statements must be telegraphic; they must be clear and accurate.


 * Dear Waleswatcher, have you checked any of the seven reliable sources cited for that lead? I think not. In fact, they do support what is written. The lead is a summary, and is not expected to be sourced sentence by sentence. If I may be so bold, this lead is more supported by reliable sources than many (perhaps even most?).Chjoaygame (talk) 15:39, 1 February 2012 (UTC)


 * Here is a very wicked point of view that needs to be expunged. It goes: "This intuitive assumption became known as the zeroth law of thermodynamics:
 * temperature is continuous at an ideal interface between two bodies, typically the interface between a thermometer and a body whose temperature is measured."
 * from page 88 of Müller, I. (2003), Chapter 5, "Entropy in Nonequilibrium", pages 79–105, in eds. Greven,A., Keller, G., Warneke, G., Entropy, Princeton University Press, Princeton NJ, ISBN 0–691–11338–6. It is important to make sure that this kind of wicked thought does not appear in the Wikipedia.Chjoaygame (talk) 16:00, 1 February 2012 (UTC)


 * Your question is quite bizarre, since K&K is one of the "seven reliable sources cited in the lead" (it's #2, to be precise). K&K is a text on thermodynamics that also discusses its underpinnings, namely statistical mechanics.  In any case, it is an indisputably reliable source on the laws of thermodynamics (although you seem to disagree with yourself on that).


 * I have not checked all six of the other sources, although I did look at several. In any case it's quite obvious that the current wording doesn't come directly from any of them.  It's a synthesis, and I think it's a poorly written one.  It is anything but clear.  The only real criticism I could see with K&K's formulation is a heavy reliance on entropy, which the reader might not be familiar with.  But it's very hard to discuss the laws of thermodynamics without that, and I don't think it's a good idea to twist oneself in rhetorical knots to avoid it.   As for your "wicked thought", I haven't the faintest idea what you're on about.   Waleswatcher  ( talk ) 20:35, 1 February 2012 (UTC)


 * I am glad that you have such masterly familiarity with the subject that you just call it "thermo" without the tedium of adding whether you mean thermal physics or thermodynamics, such tedious nonsense being proper only for the non-omniscient.


 * The lead is to be a summary of the article, not something cited word for word by single sources. The concept of synthesis needs to be considered in that light. You are naive in thinking that any one source can be "an indisputably reliable source of the laws of thermodynamics". I look forward to the exhibition of your literary skill that will correct the present poorly written text.Chjoaygame (talk) 21:07, 1 February 2012 (UTC)


 * Chjoaygame, it seems to me that Waleswatcher's recent change to the lead changed very little of the content. If he took out some important concept, you can tell us what it is. For example, the continuity of temperature was never in the lead in the first place. You think it should be? To me, it seems a sort of pedantic detail that can be in the main section on the zeroth law but omitted from the lead.
 * Chjoaygame, a historian of science might be interested in how thermodynamics was understood in the 19th century before the advent of statistical mechanics. But I don't see why any competent scientist or engineer alive today would want to close their ears to the actual explanation of why the laws of thermodynamics are true. They are not arbitrary axioms imposed by God, they are logical consequences of statistical mechanics. Certainly, the fact that K&K understand and discuss statistical mechanics does not disqualify them from understanding or discussing the laws of thermodynamics! I doubt you will find any thermodynamics textbook written in the past 100 years that does not mention statistical mechanics.
 * That said, there are certainly differences from textbook to textbook in which nuances are included or excluded from different laws. For example, "Does the third law say that it is impossible to cool a system to absolute zero?" Some textbooks say no, others say yes. Certainly, Waleswatcher, you should be cautious before deleting any aspects of the laws (in the main sections as opposed to the lead) because of that, at least without discussion. K&K is just one book, and may be omitting some nuance that should really be there. :-) --Steve (talk) 14:56, 2 February 2012 (UTC)


 * Sbyrnes, don't worry, I am not intending to edit here. My comments were made, I think, when the changes were being considered but before they were actually made.Chjoaygame (talk) 19:38, 2 February 2012 (UTC)


 * Waleswatcher is at it again: hiding the physics under smooth talk.Chjoaygame (talk) 15:37, 5 February 2012 (UTC)

airbrushing the fact away
Sbyrnes wants to airbrush away the fact that nearly all textbook statements of the first law refer to closed systems. His reason is that he doubts that even expert readers can understand the difference in this context. I do not see that as a reason for airbrushing the fact away.Chjoaygame (talk) 18:10, 27 October 2012 (UTC)Chjoaygame (talk) 19:01, 27 October 2012 (UTC)


 * First, can you say how "closed system" is defined? We should be sure we're talking about the same thing.


 * Second, you changed "The flow of heat is a form of energy transfer" to "The flow of heat is a form of energy transfer for a closed system". That suggests that you believe that the flow of heat is not a form of energy transfer for a non-closed system. Can you give an example of a non-closed system in which heat is flowing but energy is not being transferred? Ditto with work: You changed "Performing work is a form of energy transfer" to "Performing work is a form of energy transfer for a closed system." Can you give an example of a non-closed system in which work is being performed but energy is not being transferred?


 * Likewise, you edited to state specifically that a rock has to have a definite temperature (i.e. internal therrmodynamic equilibrium) in order for internal energy to be definable. Can you give an example where a rock without a definite temperature does not have a well-defined internal energy?


 * If it turns out that I was mistaken, I'm sorry in advance. :) --Steve (talk) 12:53, 29 October 2012 (UTC)


 * Thank you for these constructive and valuable comments.


 * A closed system in the current language is one that can gain or lose energy by thermal conduction or radiation but not by transfer of matter into or out of it. As you seem to be rightly pointing out, some texts (e.g. K&K, Callen) by a 'closed system' mean what the current language calls an 'isolated system'.


 * Yes, I would have done better to write 'the flow of heat is a form of energy flow between closed systems'. The wording "for a closed system" was not quite good grammar. You are right to infer a suggestion that the flow of heat is not a form of energy transfer for an open system. You ask for an example of an open system in which heat is flowing but energy is not being transferred. A fair question on the face of it.


 * But the precise question that is relevant asks can I produce an example of an open system in which heat is flowing, punto.


 * This I think is an important question, and one to which the answer has surprised me mightily. It is answered contradictorily or undefinitely in textbooks. The problem they face or ignore is that the current definition of heat flow requires it to be a logical complement to transfer of energy as work, and that work is primarily defined for thermodynamics for adiabatic processes. By definition, adiabatic work is impossible for an open system. Not many texts put the spotlight on this. Exceptions that shine the light on the spot include: Münster, A. (1970), Classical Thermodynamics, translated by E.S. Halberstadt, Wiley–Interscience, London, ISBN 0-471-62430-6, p. 46; and Haase, R. (1963/1969), Thermodynamics of Irreversible Processes, English translation, Addison-Wesley Publishing, Reading MA, p. 15; Haase, R. (1971), Survey of Fundamental Laws, chapter 1 of Thermodynamics, pages 1–97 of volume 1, ed. W. Jost, of Physical Chemistry. An Advanced Treatise, ed. H. Eyring, D. Henderson, W. Jost, Academic Press, New York, lcn 73–117081, p.20. Many other respectable texts (e.g. de Groot & Mazur 1962, pp. 17–19, 25–27) of thermodynamics and most texts of statistical mechanics solve the problem by using the word 'heat' interchangeably to mean 'internal energy', when they want to talk about transfer of internal energy between open systems, but it seems agreed here that heat transfer and internal energy are quite distinct concepts. I think one can speak of transfer of internal energy and of entropy between systems when one is thinking of concomitant transfer of matter and the internal energy that goes with it. But to try to uniquely separate the transferred internal energy into heat and work parts is not feasible for the usual reasons that we distinguish heat from internal energy. Thus the present definition of heat transfer simply does not generalize from transfer between closed systems, for which our definition is made, to transfer between open systems, for which our definition does not work. Arbitrary and reserved separations are possible of course, but they are just word games, not substantial physics. Strictly in our current definition, the answer to the above question about heat is no. Your second question, about work, can be considered likewise.


 * For open systems, such as considered for example by Gibbs, the closed-system concepts of heat and work transfer are superseded by the more general concepts of entropy and internal energy transfer. The second law of thermodynamics says much more than the simple fact that spontaneous heat transfer between bodies is from the higher to the lower temperature ones: it also says something about chemical reactions and diffusion, which can call for treatment in terms of open systems.


 * You say that I edited to state specifically that a rock has to have a definite temperature (i.e. internal thermodynamic equilibrium) in order for an internal energy to be definable. My edit made having a definite temperature a sufficient condition, not a necessary one, but observed that it was vague to leave it entirely unspecified as to what justified the definition of internal energy. The necessary and sufficient condition for a temperature is thermal equilibrium, not thermodynamic equilibrium. Thermal equilibrium is a matter of equilibrium of transfer of energy between the system of interest and the thermometric body, but the system of interest does not have to be in internal thermodynamic equilibrium. Local thermodynamic equilibrium is often an excellent approximation for the existence of a temperature.


 * You ask for an example of a rock without a definite temperature not having a well-defined internal energy. On the face of it this seems like a fair question. Thermodynamics is set up, for example by the Carathéodory system that dominates current thinking, for systems that obey the zeroth law of thermodynamics, that is to say, the definition of their states requires thermal equilibrium. Thermodynamics does not consider the states of systems that do not obey the zeroth law. So your question asks to deal with situations not considered by thermodynamics, and in that sense is asking more than the context requires. What thermodynamics deals with is cases in which a definite temperature can be assigned to a state. You are asking an extra-thermodynamic question. A molten rock with non-uniform temperature and turbulent flow inside it will present a problem when one tries to say where the smallest eddies of bulk flow grade into the largest fluctuations of molecular thermal motion; how to assign the energies to kinetic and internal components then? A rapidly evaporating rock will need careful treatment.


 * Einstein said that he thought that thermodynamics would not be overthrown within the limits of its applicability, not that it had unlimited applicability. It is reasonable for us to try to indicate those limits.Chjoaygame (talk) 21:15, 29 October 2012 (UTC)

direct statement of transitivity
The new version of the zeroth law is a bit unusual; it as a direct statement of transitivity, without actually using that term, which is an oft used term in algebra. Most texts express it as one of Euclideanity, without actually using that term. The term 'Euclidean' is rather eccentric. It seems to have no advantage other than curiosity value. Its use can be avoided by applying symmetry to the usual statement, to derive transitivity. These are truly trivial matters, even nugatory from the viewpoint of a physicist. A literature source for the direct statement of transitivity is nevertheless desirable. The editor who put up the new version should provide a citation and should fix the logical problems that have been introduced into the article by his edit. If he does not do so, his edit should be undone.Chjoaygame (talk) 04:20, 16 January 2013 (UTC)

I see it's already been undone!Chjoaygame (talk) 04:25, 16 January 2013 (UTC)


 * The most precise statement of the zeroth law is that thermal equilibrium constitutes an equivalence relation between thermodynamic systems. Unless you know beforehand what that means, its kind of opaque.


 * Lets use $$\rightarrow$$ to mean "is in thermal equilibrium with".


 * The Euclidean statement $$(A\rightarrow B,A\rightarrow C \Rightarrow B\rightarrow C)$$ is much more intuitively understandable, but is not, by itself, sufficient to establish the equivalence relationship. Only the property of reflexivity $$(A\rightarrow A)$$ is lacking.


 * The transitive statement $$(A\rightarrow B,B\rightarrow C \Rightarrow A\rightarrow C)$$ is also not, by itself, sufficient to establish an equivalence relationship. Here, the two properties of reflexivity $$(A\rightarrow A)$$ and symmetry $$(A\rightarrow B\Rightarrow B\rightarrow A)$$ are lacking. This makes it less precise than the already imprecise Euclidean statement.


 * I don't know what you mean by "the usual statement". If the usual statement is "If two systems are in TE with a third, they are in TE with each other", then you have another Euclidean statement. It doesn't require symmetry to yield the zeroth law, it again requires only reflexivity. In fact, symmetry is rather implied in the statement "in TE with each other", but Euclidean and symmetry do not yield equivalence. While this statement might be attractive because it doesn't deal with all those A's and B's and C's, on the downside, it is not a clear statement, due to that vagueness about symmetry.


 * This is the value of the Euclidean statement - it is clear and it requires a minimum of extra assumptions to establish the equivalence relationship that is the zeroth law. ONLY the equivalence statement allows you to assign a unique temperature to systems in mutual equilibrium. Any of the less precise statements deny you that ability. To say that the difference between a Euclidean or transitive statement of the zeroth law and an equivalence statement of the zeroth law is "nugatory" is to state that the zeroth law itself is "nugatory". You may say that the extra assumptions are intuitively and trivially obvious, but computers have no intuition, no sense of triviality, and if you are a computational physicist and ignore such distinctions, you will have garbage in and you will get garbage out. PAR (talk) 06:25, 16 January 2013 (UTC)


 * I wasn't advocating changing the statement to a direct one of transitivity (for which, by the way, I know of no source). I was proposing reasonable requirements, including a requirement for a reliable source, for someone who wished to try to do it, such as editor 84.28.160.155. I do not accept your view that "To say that the difference between a Euclidean or transitive statement of the zeroth law and an equivalence statement of the zeroth law is ″nugatory″ is to state that the zeroth law itself is ″nugatory″."Chjoaygame (talk) 16:10, 16 January 2013 (UTC)


 * The zeroth law of thermodynamics page gives Kondepudi as a reference for the transitive statement. Regarding the difference between the Euclidean and equivalence statement, you cannot assign a unique temperature to systems which are in thermal equilibrium with each other with the Euclidean statement, you can, however, with the equivalence statement. The whole point of the zeroth law is to state that such a unique temperature can in fact be defined. With the Euclidean statement, that point is lost. With the equivalence statement, that point is made. PAR (talk) 06:48, 17 January 2013 (UTC)


 * Ah, yes, I had forgotten about Kondepudi's statement with its unusual form! My comment about 'nugatory' was about the difference between the format that can be described as Euclidean and the one that can be described as transitive; I did not suggest that the equivalence that can be deduced was also in the same boat as the primary Euclidean and transitive statements. I don't know why you write so as to seem to attribute such a suggestion to me. I do not recall encountering the term 'Euclidean relation' with this meaning except here, and of course in the Wikipedia article Euclidean relation.


 * I haven't found the exact origin of the term 'zeroth law'. Arnold Sommerfeld seems to give the best clue I know. He writes of its origination by Fowler: "When giving an account of the book on thermodynamics of the great Indian astrophysicist M. N. Saha and his collaborator's, B. N. Srivartava, Allahabad 1931 and 1935." I haven't chased this up further; I don't know exactly what it means. The usually cited source is textbook material by Fowler and Guggenheim. As a detail, Sommerfeld's statement is different from that found in the text of Fowler and Guggenheim, more or less the usual one, without the A, B, C notation that Planck 1897/1903 used. An early version is of course that of Maxwell 1871, though with a different label.


 * For myself, I am not happy with the usual statements, partly for the same reason as you seem to be when you point out that the equivalence is what one wants here. For different presentations, one may also consider, amongst other things, the statement of the "Law of Equilibrium" by Bailyn 1994. It is quite long but may be summarized briefly as postulating the existence of states of thermodynamic equilibrium, as a basic presupposition of thermodynamics. Partly likewise, Callen 1960/1985 lists his "POSTULATE I" as asserting, in summary, the existence of equilibrium states parametrized by the internal energy. Callen attempts a systematic axiomatic presentation, that I think Tisza would describe as that of his MTE (macroscopic theory of equilibrium), and that I would describe as nearly that of Gibbs.Chjoaygame (talk) 19:31, 17 January 2013 (UTC)


 * Get rid of the mathematical statements about Euclidean, transitive statements altogether. They add nothing to the clarity of the article. 78.149.11.233 (talk) 15:39, 18 January 2013 (UTC)


 * Chjoaygame - thanks for comments on my edits. Sorry to say I feel it's still a bit clumsy in style and can be improved with no loss of meaning, accuracy, or introduction of ambiguity (re. your clunky reality comments :-) ). However will bow out now. 2.96.94.132 (talk) 19:06, 20 January 2013 (UTC)


 * I have two problems with the present zeroth law entry. The usual one - as stated, it is, rigorously speaking, incomplete. The statement is a Euclidean statement which does not allow systems in equilibrium to be uniquely tagged, by temperature or anything else. I have no problem with leaving the details to the zeroth law article, but we can avoid false statements without being opaque.


 * The second is the statement that it is "perhaps not the best", because it does not declare an order relationship (i.e. hotter and colder) on systems which are not in equilibrium with each other. This would be redundant - the order relationship is established by the Second Law and it makes no sense to postulate something which can ultimately be derived without the postulate. PAR (talk) 05:09, 21 January 2013 (UTC)


 * On your first point, if the issue with the customary statement is simply that it doesn't state that a system in thermal equilibrium is in thermal equilibrium with itself (i.e. the reflexive condition as far as I understand your previous points) then why not add that as an additional condition in the paragraph under the law? After all it does seem more to do with the definition of thermal equilibrium than the law. I think symmetry is covered by this form. So with the extra sentence you have implied equivalence to keep the most rigorous reader happy without the need to obfuscate the article in technical details and mathematical definitions of types of relationship which don't sit well with the rest of the article. A reference to the excellent section in the entry for the zeroth law elsewhere (which incidentally has the same definition for the law as here) would then satisfy would it not?


 * On your second point - I agree that if the ordering is ultimately derivable through the other laws (the scalar nature of the temperature seems to me to be implied in the zeroth but please correct me if this is wrong) then I agree that it doesn't belong in the discussion about the zeroth law. 78.145.252.112 (talk) 11:13, 21 January 2013 (UTC)

It is not part of the job of Wikipedia editors to construct and dictate the one true formulation of thermodynamics or of any of its laws. The zeroth law is widely discussed in the literature of reliable sources, from diverse points of view, and it is Wikipedia proper practice to report them.Chjoaygame (talk) 12:22, 21 January 2013 (UTC)


 * Noone is suggesting otherwise. If as PAR suggests it is inaccurate (from a rigorous standpoint) to state that the law permits the definition of temperature without also having reflexivity, and I presume this is prevalent in the literature, then it is reasonable to add that point. My suggestion is that we don't revert to the highly technical mathematical section that was there previously because a) it's not in keeping with the rest of the article, b) it's unnecessary - a simple sentence will suffice. On PAR's second topic, he says (I think) that the issue of temperature ordering is redundant as it's derived from the second law. If that's the case (and if that is well known in the literature) then it seems reasonable that it isn't mentioned at all as it seems a non-point. Certainly the more detailed article on the zeroth law doesn't seem to have a problem with this. As for the points about there being a diverse discussion on this law, that seems to me a perfectly good topic to put here, but then why pick out temperature ordering as one specific example? Finally my main aim is clarity, readability and accuracy of the article - aims that are not at all mutually exclusive as previous comments may have suggested. None of this involves constructing and dictating the 'one true formulation'. 78.145.252.112 (talk) 17:58, 21 January 2013 (UTC)


 * I am not sure if I should be reopening this discussion, but as an 'old school' physicist/mathematician I am a bit perturbed by the apparent lack of rigour seen above. The zeroth law restates, as the main article points out, a well-established classical (=19th century) principle on heat exchange - that is, when A is in thermal equilibrium with B (=heat energy sent from A to B is balanced by heat energy sent from B to A) and B is in thermal equilibrium with C, then A is also in thermal equilibrium with C (=heat sent from A to C equals heat sent from C to A). This result leads immediately to the concept of temperature as a state variable that characterizes the thermal equilibrium, and is possessed by all 3 bodies. Now, in the world of mathematics, and more specifically in set theory, there is the concept of an equivalence relation - when the relation between any two members of a given set of objects satisfies certain special conditions. If we have A and B as members of a set, and we write A~B to mean that A and B are equivalent (or more precisely, that A and B satisfy the conditions for an equivalence relation) then the conditions that we need are

(1) A~A for all A in the set - this is the reflexive condition (2) If A~B then B~A for all A and B in the set - this is the symmetric condition (3) If A~B and B~C then A~C for all A, B and C in the set - this is the transitive condition This has absolutely nothing to do with thermodynamics, it's a just a definition which helps in the structuring of ordered sets. However, it should be clear (at least to the educated reader) that some parallels can be made here. The result is that we can think of temperature as an ordered state variable that allows us to define thermal equilibrium as an equivalence relation in the mathematical sense - you just have to replace A with Ta (temperature of body A) and B with Tb, C with Tc, and you will see that the above fits exactly with the zeroth law. By implication, when A and B are not in thermal equilibrium, there must be a net heat flow between them and we say that one is at a different temperature than the other - for example Ta > Tb. This allows us to introduce temperature ordering, and then to define temperature scales, such as Kelvin. I feel that the above physics is missing from the main article but may help in its understanding. OldSchoolPhysicist ([[User

talk:OldSchoolPhysicist|talk]]) 15:41, 10 June 2015 (UTC)


 * The zeroth law is an equivalence statement regarding thermal equilibrium, nothing more, nothing less. A relationship which is symmetric and reflexive and transitive is an equivalence relationship. If any of the three properties are missing, it is not.


 * If we codify the statement "A is in thermal equilibrium with B" as A->B, then the transitive relationship is that A->B and B->C implies A->C. Although this is a true statement, it is not a statement of the zeroth law, because symmetry (A->B implies B->A) and reflexivity (A->A is true) are missing.


 * An equivalence relationship divides a set into disjoint subsets. If two systems are in the same subset, they are in thermal equilibrium, if not, they are not.


 * An equivalence relationship (and therefore the zeroth law) implies no ordering of those subsets. The systems that are members of a particular subset may be given a unique tag or name, so that two systems with the same tag are in equilibrium, two systems with different tags are not. In practice, systems are tagged by their thermodynamic temperature. The fact that temperature is ordered (hot > cold) does not follow from the zeroth law, it is no business of the zeroth law.


 * The zeroth law was so named (rather than the fourth or fifth law, or whatever) because it does not rely on any higher numbered law in order to be clearly stated. The statement:


 * "The result is that we can think of temperature as an ordered state variable that allows us to define thermal equilibrium as an equivalence relation in the mathematical sense."


 * is not right. Temperature does not allow us to define thermal equilibrium as an equivalence relationship, but rather the equivalence relationship is a necessary but insufficient requirement for the definition of temperature, which occurs in the second law.


 * I have no objection to using temperature to illustrate the zeroth law, but it's like playing whack-a-mole on this page trying to eliminate the idea that the zeroth law hands you full-blown thermodynamic temperature on a silver platter, or that various incomplete statements of the law constitute reasonable differences of opinion, or that an ordering on the subset tags is part of the zeroth law. If you introduce order on the subsets, or introduce temperature in order to state the zeroth law, the logic becomes circular, twisted, redundant, and just wrong. PAR (talk) 22:16, 11 June 2015 (UTC)

the present section on the zeroth law is unacceptable
The present section on the zeroth law is unacceptable. Yes, there are various statements of the zeroth law, but they all are aimed at stating that the set of all thermally equilibrated systems can be divided into disjoint subsets. Thats jargon, its esoteric, but its intuitively simple. If you take a piece of paper, cut it up into 10 pieces, you have 10 disjoint subsets. You can take a pencil and put a tag on each one. There is no concept of ordering implied, there is no concept of continuity. The tags can be anything, "a","b","cat","dog","ding","dong","1","yes","no" and "maybe" for example. Those 10 pieces of paper don't imply any kind of numbering system. Only that they are distinct from each other - i.e. disjoint. Any statement that states anything more or less than the establishment of these disjoint subsets is to that extent an inferior statement of the zeroth law. If two points lie on the same piece of paper as a third, then they both lie on the same piece of paper - that's equivalent to the statement "if two systems are in equilibrium with a third, they are in equilibrium with each other". It's about the best statement there is of the zeroth law, but it still doesn't imply equivalence.

The zeroth law is a statement in predicate logic. If idea of applying logic to the subject of thermodynamics seems a little too obsessive-compulsive to you, then don't even bother trying to understand the zeroth law. Or Euclid's elements either. Just memorize it so you can sound erudite without the labor involved in understanding what you are talking about. If you think that the application of logic might be useful in studying thermodynamics then, with regard to the zeroth law, try making truth tables. Construct a matrix M with entries Mij. If system i is in thermal equlibrium with system j, then Mij=1. If it's not, Mij=0. Now try seeing what the various statements of the zeroth low tell you about that matrix. If you think reflexivity is nonsense, put an "N" in the diagonals. If something is unclear or unknown, put in a "U". Only the equivalence requirement allows you to fill in the entire matrix with 1's and 0's. The Euclidean, transitive, and symmetric-Euclidean statements do not.

I will delete the second paragraph of the zeroth law entry. The idea that the various statments of the zeroth law constitute a range of conflicting opinions about what might be nice to know, rather than user-friendly attempts to describe the equivalence relationship known as the zeroth law is simply wrong. (This comment was posted unsigned by editor PAR at 15:45, 22 January 2013; this signature/attribution posted by editor Chjoaygame.)

missing statement
As far as I understand your points, all that is missing is a statement of reflexivity. I've added one - please edit for correctness if it doesn't say what I think you're saying. 2.96.88.16 (talk) 16:52, 22 January 2013 (UTC)


 * The edit here added an unsourced premise, for the sake of a desired conclusion. Wikipedia editing is not a matter of logical games played with previous edits. The Wikipedia does not decide what is right and post it, without needing literature support for reliable sources. Recent posts here have changed the meaning of the article while speciously seeming only to make the expression look smoother; one error in those posts was to confound the notion "form of statement of the law" with "the law". The form of statement of the law is something that we can check directly. The law is a generalization the precise statement of which is the subject of our discussion. To confound the form of statement of the law with the law itself is, in the present context, a case of petitio principii, a faulty logical step. I will not now play the game of simply overwriting the work of other editors, but I think the current edits are faulty. It is not appropriate for editors to "presume" something about the literature, as has recently been done here; editors should work from what is there in the literature.


 * I wonder who was the anonymous complainant. My remarks were not personal attacks. The response of the co-editor confirms this. My remarks were criticism of editorial activity. I did not see the complainant remove a straight personal attack on me.Chjoaygame (talk) 17:19, 22 January 2013 (UTC)


 * Ah, yes, now I see. The anonymous complainant was editor 78.149.0.246. And yes, now I see he did remove the straight personal attack on me as well.Chjoaygame (talk) 03:59, 23 January 2013 (UTC)

diversity
With respect, some important parts of the Wikipedia material on the "zeroth law of thermodynamics" are significantly unsourced. I do not mean merely that some summary statements, which might be derived from sourced statements within the articles, are unsourced. I mean that some important parts of the material in the articles are significantly unsourced. With respect, the literature does contain a diversity of views on this, and it is not the duty of Wikipedia editors to extract from that diversity one unique "correct" view, to proclaim it ahead, or even exclusively, of all the others. Editor PAR seems to be of the view that the zeroth law is intended to provide an equivalence relationship; that is his own view; it is perhaps reasonable, but it is not explicitly supported in the article by a stated reliable source.

According to the lead entry of this section of the talk page, "the statement ″if two systems are in equilibrium with a third, they are in equilibrium with each other″. It's about the best statement there is of the zeroth law, but it still doesn't imply equivalence." This seems like a direct assertion that the proposition, that the law is intended to be a statement of equivalence, is unsourced, entirely unsourced. Yet is it the view of the Editor PAR, so far as appears, that the law is correctly considered as intended to be an equivalence statement.

The paragraph deleted from the present article drew attention, in accurate summary, to the existence of the diversity of views, which is expressed with a good supply of reliable sourcing, in the main article on the "zeroth law". The deletion verges on censorship of the Wikipedia expression of the diversity of the literature, censorship designed to restrict the contents of the Wikipedia, for the sake of a reasonable, but still unsourced, personal point of view from a respected editor. Perhaps I misunderstand that editor and have thus mistakenly misrepresented him; if so, I trust he will correct me.Chjoaygame (talk) 16:57, 22 January 2013 (UTC)Chjoaygame (talk) 17:27, 22 January 2013 (UTC)


 * The source I saw was Phillip Morse "Thermal Physics". I do not have access to this source at this time. Could you quote the part in Morse that refers to the zeroth law? It is my contention that there is not so much of a diversity of views as there is a diversity of attempts to simply explain a single view - that the consequence of the law is to lay the foundations of a subsequent development of temperature by declaring thermal equilibrium to be an equivalence relationship. Any source which claims that a consequence of its statement of the second law is that it allows a temperature to be uniquely assigned to any system and is the same for all systems that are in equilibrium with it, is declaring that its statement is equivalent to an equivalence relationship. If you have any sources which contradict this, please quote them, if possible. I will look for sources as well. PAR (talk) 20:00, 22 January 2013 (UTC)


 * I think it fair that I observe here that editor PAR is not saying that I have misrepresented him, though I invited him to do so if I had mistakenly done so.


 * Is it really up to me to provide quotes from sources at the request of other editors? It seems so. Well, Morse 1969 (second edition) does not list the zeroth law in his index. Reading the section headed Temperature in Morse's Chapter 2 on pages 8–10, I did not find the words "zeroth law". I am not sure what editor PAR is asking me to report. On page 23 Morse defines an absolute temperature (still apparently an empirical one) as one that is referred to an absolute zero. Morse does not actually use the term 'empirical' to refer to his temperatures here, but it is evident that he is referring to empirical temperature. On pages 49–53, he has a section headed The Thermodynamic Temperature Scale. The section derives the thermodynamic temperature scale from the Carnot cycle. (I may mention that Carathéodory makes a point that he is not using the Carnot cycle in his development.) I could go on. I did not encounter the words "zeroth law", but I did not read the whole book for the purpose. A Google "search within the book" search returned no match.


 * Editor PAR proposes what he deems a "single view" and then asks for sources that contradict it. He seems to be intending to reverse the burden of proof. For Wikipedia the usual idea is that the editor should find a reliable source for his material. The burden is on him to find the source. Sources usually say what they intend, without necessarily explicitly denying all the possible contraries. It is common knowledge that it can be hard to prove a negative. But this is what Editor PAR is asking others to do for him.Chjoaygame (talk) 21:17, 22 January 2013 (UTC)


 * The paragraph I removed concerning diversity had only one reference, P.M. Morse (1969) and I am concerned that I removed a sourced statement. From what you are saying above, I think I don't need to be concerned.
 * Regarding proving a negative, I don't mean to reverse the burden of proof. I see many discussions of the zeroth law that follow up with vague statements like "the zeroth law lays the foundation for temperature" and then move on. Since they make no specific reference to just how it does this, such references neither confirm nor deny my contention. Others like Kondepudi, after making the transitive statement of the zeroth law, make the statement "Thus, equilibrium systems have a well-defined, spatially uniform temperature;". False. But notice he is implicitly saying that the zeroth law implies disjoint subsets by saying they have a well-defined temperature. He is driving towards the equivalence statement, and mistakenly says the transitive statement will get him there. Lebon states "The property of transitivity of thermal equilibrium allows one to classify the space of thermodynamic states in classes of equivalence, each of which constituted by states in mutual thermal equilibrium." Absolutely and provably false, but again, stating the results of the equivalence statement. I don't have Adkins with me right now, so if you can find his statement of the zeroth law, I would appreciate it if you could quote it. At any rate, according to my notes, he follows up (on page 20) with "Temperature as we have defined it need not bear any simple relation to our intuitive ideas of hotness. Strictly speaking, we have done no more than construct isotherms and attach symbols to them." Change the word "isotherm" to "disjoint subset" and he states almost verbatim the point I made above, a result only obtainable from the equivalence statement. I will have to go to the local technical library to look up other statements to prove or disprove my point, but if you have any that prove or disprove it, please post them. PAR (talk) 06:19, 23 January 2013 (UTC)


 * The removed paragraph was a brief summary of extensive material presented with very many reliable sources in the main article on the zeroth law of thermodynamics, and could have had those references attached to it, too many for practical convenience for a brief summary here. The reference to Morse here added some material not referenced in the main article.


 * I agree with your statement that references neither confirm nor deny your contention. As I understand it, that means that your contention is original research. I have not tried to remove or deny your statement of your contention. I have, however, tried to show by reference to reliable sources that there is is to be found in them a diversity of views on this matter.Chjoaygame (talk) 10:12, 23 January 2013 (UTC)


 * Looking back over it, I see that my search for the term "zeroth law" in the talk page here was faulty. I failed to look under "laws of thermodynamics" in the index. There it is, on page 32: "Some writers, to ensure completeness of their set of axioms, set down a zero law of thermodynamics; that two bodies, each in thermdoynamic equilibrium with a third system, are in equilibrium with each other." Morse writes of the "zero law" not of the 'zeroth law'; so my computer search also failed. So I now would say that the Morse reference in the deleted paragraph was not up to the mark. Morse develops the concept of temperature in steps. His first step is what my reference stated, that "the property seems to be one-dimensional". I would have done better to cite more powerful sources for the point. There are several available. One is in the following from the [[Zeroth law of thermodynamics#Histroy|main article on the zeroth law]:


 * "The statement of the zeroth law of thermodynamics by Serrin in 1977, though rather mathematically abstract, is more informative for empirical thermometry: "Zeroth Law - There exists a topological line $$M$$ which serves as a coordinate manifold of material behaviour. The points $$L$$ of the manifold $$M$$ are called 'hotness levels', and $$M$$ is called the 'universal hotness manifold'."[Serrin, J. (1978). The concepts of thermodynamics, in Contemporary Developments in Continuum Mechanics and Partial Differential Equations. Proceedings of the International Symposium on Continuum Mechanics and Partial Differential Equations, Rio de Janiero, August 1977, edited by G.M. de La Penha, L.A.J. Medeiros, North-Holland, Amsterdam, ISBN 0-444-85166-6, pages 411-451.]"


 * It might be objected that this is a primary source, and overloaded with rigorous mathematicality. A secondary source (cited in the Wikipedia article on Temperature) by Serrin states the same facts but does not use the label "zeroth law"; Serrin writes on page 6: "It is convenient to begin our treatment by introducing the concept of hotness, which will be here considered a primitive notion within the theory. It is represented by a thermal manifold $H$ consisting of a set of hotness levels ... " and so on.[Serrin, J. (1986). Chapter 1, 'An Outline of Thermodynamical Structure', pages 3-32, in New Perspectives in Thermodynamics, edited by J. Serrin, Springer, Berlin, ISBN 3-540-15931-2.]


 * Another reliable source, perhaps the locus classicus, is also in the Wikipedia article on the zeroth law:


 * "An early example is in the textbook of statistical thermodynamics of Fowler and Guggenheim (1939/1965).[Fowler, R., Guggenheim, E.A. (1939/1965). Statistical Thermodynamics. A version of Statistical Mechanics for Students of Physics and Chemistry, Cambridge University Press, Cambridge UK.] Their focus of interest in that book was homogeneous systems (page 1), which they termed 'assemblies'. They dealt with assemblies that were either completely homogeneous or that could be divided into homogeneous parts, called phases (page 58). For their macroscopic thermodynamic account of phenomena, they started by accepting, on empirical physical grounds, the presupposed notions of thermal insulation, thermal contact, and thermal equilibrium (page 56). They emphasized that these notions "can be defined without any reference to temperature" (page 56). Moreover, they gave at this stage of their development of their theory no hint of the notion of heat transfer. On page 56, they wrote:


 * ...we introduce the postulate: If two assemblies are each in thermal equilibrium with a third assembly, they are in thermal equilibrium with each other.


 * They then proposed that "it may be shown to follow that the condition for thermal equilibrium between several assemblies is the equality of a certain single-valued function of the thermodynamics states of the assemblies, which may be called the temperature t, any one of the assemblies being used as a "thermometer" reading the temperature t on a suitable scale. This postulate of the "Existence of temperature" could with advantage be known as the zeroth law of thermodynamics" (page 56)."


 * Their "single-valued function" is obviously a map into the thermal manifold, representing the one-dimensional property referred to by Morse.


 * Thinking about it, I see now that this last reference, the locus classicus, would have been far better than the Morse one that I actually gave in the paragraph that you deleted here. It was careless of me to give only the Morse reference.Chjoaygame (talk) 13:33, 23 January 2013 (UTC)


 * Guggenheim supports my contention - that the consequence of the zeroth law is a uniquely defined "temperature" which is the same for the "several assemblies" that are in mutual thermal equilibrium. These "several assemblies" form one of the disjoint subsets I am talking about. I put temperature in quotes, because it is not thermodynamic temperature they are talking about, its the "tagging" system I am talking about, with no concept of continuity or order. If the sets were not disjoint, the "temperature" would not be unique. By the way, I favor their axiomatic approach which accepts, on empirical physical grounds, the presupposed notions of thermal insulation, thermal contact, and thermal equilibrium (page 56). (This comment was posted unsigned by editor PAR at 15:56, 23 January 2013; this signature/attribution posted by editor Chjoaygame.)


 * The "Guggenheim" reference that you mention is presumably to Fowler & Guggenheim (1939/1965); with edition and page, that is in the main article on the Zeroth law, and is copied above. [In that article, there is also a reference to Guggenheim (1949/1967) alone.] No one has for an instant doubted that these things are true, but you have insisted that exact wording matters.


 * The wording you have insisted upon focuses on the words 'equivalence' and 'Euclidean'. But this is not only about what is true; also, Wikipedia editors have a duty to provide reliable sources. You have been very particular about the difference between a Euclidean and a transitive statement of the law (deprecating the form that uses the word 'transitive'), for your argument that it is really intended to show an equivalence relationship, and now you cite a source that mentions neither the word equivalence nor the word Euclidean. Nowhere in the directly relevant source literature that I can recall does the word 'Euclidean' appear. I am not sure about the word 'equivalence', but I have to say I don't recall it in the sources, off the top of my head. Some perfectly respectable texts talk about transitivity or exemplify it in this context. Indeed, as a matter of fact, some even seem to confound Euclideanity with transitivity; Landsberg is an example. But, true to your insistence on your exact wording, you have deprecated the transitive wording, without mentioning the sources. Considering your insistence on exact wording, I think it fair now to note that Morse 1969 continues his remarks on page 32: "Others prefer to leave ″self-evident″ facts unstated." Morse was the co-author with Feshbach of one of the more widely cited texts on theoretical physics (1946/1999), Methods of Theoretical Physics, two volumes, 1946 version Technology Press, Massachusetts Institute of Technology, Cambridge MA. Morse 1969 is saying, in effect, that for him the exact wording is not notable. In your just above note, you mention neither the word equivalence nor the word Euclidean. It seems you have changed your ground. Where there is a diversity of expression in the relevant reliable sources, you have put insistent emphasis on particular wording; such insistent emphasis on particular wording is hardly sourced.Chjoaygame (talk) 19:30, 23 January 2013 (UTC)Chjoaygame (talk) 19:37, 23 January 2013 (UTC)


 * Would you please just take a moment and try to understand the zeroth law? Try to understand the difference between an equivalence statement and a transitive statement. Do you understand that a transitive relationship does not imply an equivalence relationship, or do you think that this is something upon which reasonable people can justifiably have differing opinions? The core contribution of the zeroth law to thermodynamics is that equilibrated systems can be assigned a temperature, those with the same temperature are in mutual thermal equilibrium, those with different temperatures are not. Do you dispute this? If you do not, then, if you understand the equivalence relationship, you will see that it's basically the only one that allows you to logically draw this conclusion. The transitive statement does not. This is absolutely, indisputably, rigorously and logically provable, a point upon which reasonable people CANNOT hold differing opinions. The only way out for an author who posits the transitive relationship as a statement of the zeroth law is to just blow off the symmetric and reflexive aspects as intuitively obvious and beneath mention. To a much lesser extend, the same holds true for the Euclidean statement. Sorry, but just blowing that off is offensive to me. I fully understand that somebody coming to the zeroth law for the first time does not need to be faced with all the predicate logic aspects of the zeroth law, but neither does someone who has some familiarity with logic need to be faced with a blundering logical contradiction for the sake of comfortable, dumb, false simplicity. If you sit down and try to understand the logical implications of all of the various statements of the zeroth law, and the conclusions drawn from them, you will see that they are NOT a collection of various opinions about what the zeroth law IS, they are various attempts to convey the core meaning of the zeroth law that I mentioned above, some of which, at best, "blow off" more "intuitively obvious" aspects than others. It is not our job as editors to present a dozen quotes from a dozen sources, without explanation, simply shrugging our shoulders at the differences and saying that the zeroth law is an unresolvable puzzle, a collection of differing opinions. That is a disservice to the reader. We must come to a consensus of understanding of the subject, write it down, and back it up with solid, respectable references which support that understanding. To think otherwise is to carry the concept of OR too far. Maniacal adherence to OR results in an article in which not one single word is not part of a referenced quote from a respectable source. That is not what we want. PAR (talk) 07:09, 24 January 2013 (UTC)

multiple addresses with a common unnamed editor
Posts on this page or in this article from addresses 80.41.74.87, 78.145.252.112, 78.149.0.246, 78.149.11.233, 2.96.94.132, and 2.96.88.16 all seem, as far as I can work out, to come from just one unnamed editor. Perhaps I am mistaken. If so, I would like to be corrected, because I find it muddling. I would feel happier, if those posts do come from just a single editor, to have a single name to attach them to. I do not know of any disadvantage that arises from an editor's having a name, provided it is a suitably chosen name to protect privacy. It is customary for habitual editors to give themselves a name.

One component of this supposed unnamed editor has taken it upon himself to label and delete from this talk page what, in his judgment, was personal attack, along with other material that was not personal attack. Some of the material that he removed, which was also in my judgment personal attack, as far as I can work out, was his own work. I would dispute that the rest of the material that he removed was personal attack.

I am no Wikilawyer to know about the legalities here.Chjoaygame (talk) 20:21, 23 January 2013 (UTC)

theories
My dear PAR, thank you for your frank remarks. You make it clear that you are desperately exasperated by my obtuseness. I am sorry that it has seemed to you that I don't understand the zeroth law. You seem to think I don't understand the difference between a transitive relation and an equivalence relation. And so on. For the sake of clarity, I can say here that yes, I did pass my exam in algebra and yes, I do know the difference between a transitive relation and an equivalence relation. And so forth. I do not blame you for thinking I don't, because we are thinking from different viewpoints, and I don't come over to yours as the only possible one; this makes me seem obtuse to you. I am not denying the algebraic things that you emphasize. There is nothing wrong with your algebra that I have noticed. If I have ever seemed to give any hint that I thought there was something wrong with your algebra, please accept now that I definitely did not mean that.

But I am trying to draw attention to the place of these things in the axiomatics of thermodynamics. As I see it, Tisza's classification of theories of thermodynamics is helpful. He talks of the Clausius-Kelvin theory, of the Clausius-Kelvin-Carathéodory theory, and of the macroscopic theory of thermodynamics (MTE). But Tisza fails, I think, to make it sufficiently clear what is the difference between the CK & CKC theories on the one hand, and the MTE on the other. We have been so busy fending off attacks from those who do not believe that thermodynamics is a subject in its own right that we have not had time to make these things clear here. Likewise, they are so busy attacking us that we don't have time to try to improve the kinetic theory side of the presentations.

As I see it, the CK & CKC theories differ from the MTE simply in that the CK & CKC theories refer to systems closed to exchange of matter, while the MTE refers to systems for which the exchange of matter is present. Formally, the MTE simply postulates the energy and entropy representations, $U = U(S, V, N_{1}, N_{2}, ...)$ and $S = S(U, V, N_{1}, N_{2}, ...)$. No worries about what these things mean as physical propositions. The CK & CKC theories, on the other hand, are very concerned to relate directly to experiment. The zeroth law is about that. Exactly how the CK & CKC theories relate to experiment is the difference between them. But they are both attacks on the same problem, the closed system as an experimental object.

An axiomatic system has some primitive notions and some axioms stated in terms of those primitive notions. The CK theory and the CKC theory have different primitive notions. The Carathéodory part of the CKC theory thinks that the CK theory is held by ignoramuses and clowns such as myself, who are simply too dumb to understand the virtues of the Carathéodory approach. Planck as far as I can work out, was one of the clowns. Truesdell was another. The Carathéodory people think that they are superior in understanding because they use fewer primitive notions than do the CK people. I have not seen a really systematic demonstration that this is so. Yes, the Carathéodory people say it and say it, but really, there is no rule that says you must have the fewest possible number of primitive notions. It is desirable to have few primitive notions, but there is no rule that says you must have as few as possible. I suppose when you see me write this, you will think 'Oh, my god, how can I spend time dealing with a fool like this?' I can only say that I am not convinced that the Carathéodory system really does have fewer primitive notions. As I said just now, I have not seen a systematic comparison of the theories for this purpose. Landsberg sets out a very systematic presentation with many axioms and sub-axioms and so forth. Perhaps it is possible to make the comparison on that basis, but I don't recall seeing it done. I am not sure exactly how to count primitive notions. Some are heavier than others and should get more weight in a count.

From a physical point of view, I am not convinced that Fowler really thought that the Fowler & Guggenheim 1939 re-statement of the Maxwell 1871 statement of the law was logically exact and perfect and exhaustive. I seem, indeed, (please put on and do up your seat-belt and put on your hearing and eye protections before reading the next few sentences), to recall someone saying that Fowler was just joking when he labeled the law the zeroth, at a conference. It was not part of a systematic exercise in axiomatics. It was a remark at a meeting, or perhaps a comment in a book review, as far as I can recall. Fowler was being very polite to Saha and Srivastava about their 1935 text which says early on page 1 that "every physical quantity must be measurable in numerical terms". They presume that temperature is a physical property and then deduce the statement "If a body A is in temperature equilibrium with two bodies B and C, then B and C themselves will be in temperature equilibrium with each other." They then italicize as if to state their basic postulate; "Any of the physical properties of A which change with the application of heat may be observed and utilised for the measurement of temperature." According to Sommerfeld, this was the text that made Fowler invent the term "zeroth law". Perhaps Fowler was not joking. Perhaps this sequence of events that I have proposed here is a misreading of Sommerfeld and a misreport of what triggered my unverifiable recall (I am sorry I did not keep a note of when I read that story). Perhaps something else. Carathéodory's name does not appear in the list of some 6 or 7 hundred references given in that 1935 text. Carathéodory's story was well on the map by 1921, way before either of the texts by our two Indian authors. Their 1931 text does not have that kind of philosophical exposition of temperature on its page 1. It just goes ahead and measures temperature with a thermometer. In the index of authors of the 1931 text, Clausius gets 18 mentions, and Kelvin gets 7. Carathéodory gets one: it is in a footnote. It reads: "Carathéodory has given a deductive method of obtaining the second law. He shows from the theory of differential equations that the expression $dQ = dU + pdV$ has an integrating factor which he identifies with $T$. See Landé, Handbuch der Physik, Band IX, Chap. 4." (Italics here as in original, not changed by me.) I don't see how Fowler could have been referring to the 1931 text for the "zeroth law" story.

I conclude that the zeroth law was not handed down by God chiseled on a tablet of stone. It is a convenient summary of some basic notions or propositions. The most exactly convenient summary will depend on the axiomatic system for which it is intended. The exact wording may vary according to the exact needs of the axiomatic system.

This is not to say that exact algebraic reasoning does not matter, but is is to say that it is not the only thing that matters: the physical context also matters. And for me, there is no unique and universal physical context.Chjoaygame (talk) 08:55, 24 January 2013 (UTC)


 * Ok, its just that that paragraph seemed to be saying that the zeroth law was somehow a vague concept due to the various presentations that are given, and I thought you were defending it. As far as the axiomatics are concerned, I think you are right, a generally accepted axiomatic development of thermodynamics does not exist. I do not have a clear axiomatic understanding of thermodynamics. There are some systems in which the zeroth law is derived, and not worthy of the status of axiom or law and I wouldn't mind throwing it out if it is superfluous. I am not trying to say that the zeroth law has a valid place in axiomatic thermodynamics. The only point I am trying to make is that, if you accept mutual thermal equilibrium as a more primitive concept, the core point of the zeroth law is clear and unambiguous, clearer and less ambiguous than any of the other laws. PAR (talk) 14:18, 24 January 2013 (UTC)

Re: Today's revision.
I have removed some vandalism as well as some blatantly incorrect views of the 2nd Law. (As the temperatures of any system approach uniformity the system entropy must increase, staying the same is not an option!) --Damorbel (talk) 07:27, 6 February 2013 (UTC)


 * The Second Law is not about temperature approaching uniformity. It is about entropy approaching a maximum by the fastest possible route. In a force field temperatures do not tend to level out: instead unbalanced energy potentials tend to dissipate because that is what happens as entropy increases. So, if PE is the potential energy in relation to a force field and KE the kinetic energy (that being proportional to the temperature) then, in the absence of phase change or reactions, the dissipation process tends to make the sum (PE+KE) approach uniformity, and so a temperature gradient evolves and is the state of thermodynamic equilibrium. Probably the best example in our Solar System is the nominal troposphere of the planet Uranus where no solar radiation reaches the lower regions and no internally generated energy plays a role either, but the temperature gradient is there and close to the expected value, making the base of that troposphere hotter than Earth's surface. — Preceding unsigned comment added by 202.172.115.20 (talk) 02:29, 11 July 2017 (UTC)

Today's edit – 2nd law
Apart from explaining the 2nd law, I removed the link to the article on Thermodynamic equilibrium, replacing it with 'uniform temperature', because the article on Thermodynamic equilibrium allows many conditions with a non-uniform temperature, giving the impression that perpetual motion of the second kind is in fact possible. --Damorbel (talk) 07:44, 8 February 2013 (UTC)
 * Perpetual motion of the second kind will not happen from a state of thermodynamic equilibrium which, by definition, is maximum entropy. Entropy does not increase when it is already at a maximum, and so nothing happens on a macro scale, least of all any perpetual motion.  In a force field there will be a non-zero temperature gradient which will be thermodynamic equilibrium and it is stable because the sum of (PE+KE) is homogeneous, leaving no unbalanced energy potentials and thus no means for entropy to increase.  It is not correct to refer to thermodynamic equilibrium as "thermal equilibrium" as that tends to imply homogeneous kinetic energy (ie temperature) only.  — Preceding unsigned comment added by 202.172.115.20 (talk) 02:35, 11 July 2017 (UTC)

Undid edit about gravity
I undid a well-intentioned but unsourced and mistaken edit. The edit had been posted by an editor who has for some time been trying relentlessly to force the content of the edit in several internet forums. He should be aware that inadequately sourced and mistaken edits of this kind are not tolerated here.Chjoaygame (talk) 01:23, 16 February 2013 (UTC)
 * The brilliant physicist Josef Loschmidt explained why gravity forms a temperature gradient in 1876. I suggest you think about the comments above regarding the fact that the Second Law is about maximum entropy production and not about temperatures approaching uniformity. I'll thank you not to publish here your own interpretations of the Second Law which are very misleading. — Preceding unsigned comment added by 202.172.115.20 (talk) 02:39, 11 July 2017 (UTC)

First law modification
I've noticed that a lot of fat people claim that they count calories / don't overeat / eat below their basal metabolic rate / etc. and yet still gain weight. To me this flies in the face of the first law of thermodynamics. In today's politically correct, socially enlightened age, it seems that we should modify the first law of thermodynamics to make explicit reference to an exception in the case of people with "gland disorders". I will wait for feedback before making this modification. — Preceding unsigned comment added by 70.114.153.250 (talk) 09:35, 19 July 2013 (UTC)


 * Sorry; this is not an issue regarding the physical laws of the universe that govern its elementary thermodynamic principles. Rather, it is a completely health-related issue. The "exception" you refer to is merely a product of human metabolism, and such a claim that the perfectly natural manner of usage of material by the body (which, of course, is not the same for everyone) is due to an unfamiliar and somehow completely separate set of physics is downright nonsensical. These differences in metabolic rates and thus varying amounts of stored fat from one person (or other animal, for that manner) to the next result from explainable physical processes, and they do not in any sense defy the laws of thermodynamics. It seems instead that you have misunderstood these laws, confusing the unexpected storage of fat (?) with the impossible creation of new energy—an unreasonable and misled comparison. The addition of your unjustifiable claim—whether you request it here or not—will never take place; Wikipedia will simply not allow it. And if this is a joke of yours, Wikipedia is not the place to house it either.&emsp;&mdash;  | J  ~  Pæst  | &#8202; 08:14, 21 July 2013 (UTC)


 * It seems you completely failed to understand my point. Obviously I understand the laws of thermodynamics. Which is why I consider the statement that weight gain outside the predictions made by calories in/out MUST violate the laws of thermodynamics.
 * The only alternative is that said claims are invalid and made by people who are failing to accurately count their calories. Was this that difficult for you to understand? Either the physical law is in error, or these people are to be disrespected. Which is it? Your failure to understand my original point points to the likelihood that your contribution to this discussion is useless and I would ask for someone who understands thermodynamics (such as myself) to weigh in here. — Preceding unsigned comment added by 70.114.153.250 (talk) 08:39, 21 July 2013 (UTC)


 * Whose prediction is that? The "prediction" is plainly wrong beyond a doubt. It absurd that the article should take into account some random misconception about health—just so that the people you claim attribute it to "wrong thermodynamics" can see that it is indeed a separate issue. This is not personal. I understand thermodynamics completely.&emsp;&mdash;  | J  ~  Pæst  | &#8202; 09:27, 21 July 2013 (UTC)

Reverted, rather funny.
My attempt to add the 'physicists joke' version of the laws, under the section heading 'simple explanation', was immediately reverted just now, which I find rather funny. I'm guess the reverting editor assumed it was simple vandalism, and missed the point entirely (while also reverting a good-faith edit without an edit summary, etc....all those 'ignoring WP policy' things we just love). My point of adding it, with an explanation that it was the technically correct 'joke' version used by physics professors, was pretty simple, and the 'knee-jerk revert', apparently based on the fact that I'm not logged in, rather funny.

The current version of this article is technically correct. It also gives multiple explanations of the laws in a manner that would make absolutely no sense to the large majority of the people who would be looking up the laws on Wikipedia. The article does NOT need to be written from the perspective of 'various technical implications of the laws to physicists and engineers', at least as a whole. It DOES need to include an explanation of the laws to the random non-technical person who attempts to refer to Wikipedia. As it currently stands, a non-technical person who reads this entire article will leave with no clue of what the laws of thermodynamics are, or what they mean.

Most people who look this up on Wikipedia will be doing so because of some reference to the laws, or a particular law, in some random context. Nothing in the current version of this article will make the actual meaning of the laws even vaguely clear. Specifically, it is NOT stated, or even implied in a vaguely accessible manner, anything that would allow a layperson to understand....


 * First Law : The work done on or by a thermodynamic system is equivalent to the change in internal energy of the system.
 * Second Law : When work is done on or by a thermodynamic system, a certain amount of that energy is lost to inefficiency, related to the difference between the energy level of the input and the output. This loss is described as "entropy".
 * Third Law : It is impossible to eliminate this loss, even if an attempt is made to increase the efficiency by reducing the difference in energy levels between the input and the output.

While an involved, convoluted, and technical article, obviously watched over closely by self-appointed experts, might be a beautiful thing to them, it is fairly useless to people who are looking it up because they don't know what the laws mean. This article DESPERATELY needs a summary that explains the laws in completely non-technical terms, or it is effectively useless. 198.45.215.17 (talk) 22:44, 1 September 2013 (UTC)


 * Hi, 198.45.215.17. It probably didn't help that your edit summary only stated 'Adding a'. Also you should provide a citation (and maybe a link to the person came up with the quote) to help establish notability. C. P. Snow wrote:


 * Zeroth: You must play the game;
 * First: You can't win;
 * Second: You can't break even;
 * Third: You can't quit the game.


 * undefined


 * I personally think that it would be fine to add a statement along these lines. Fwiw, as a non-expert, I agree. Many of our science articles could be a little more friendly to the layperson. -- Hillbillyholiday talk 01:52, 2 September 2013 (UTC)
 * And yes, you shouldn't have been reverted like that either. -- Hillbillyholiday talk 02:03, 2 September 2013 (UTC)


 * Hillbillyholiday, I think you ought to go the trouble of tracking down to its source the statement attributed to C.P. Snow. And cite it.Chjoaygame (talk) 13:21, 2 September 2013 (UTC)


 * I see you think that the secondary source demonstrates notability. I am not happy that it is a reliable source that you have cited. I would like to see the original checked as verification of the reliability of your source.Chjoaygame (talk) 13:36, 2 September 2013 (UTC)


 * There are plenty of other sources out there with this quote. Feel free to change the reference, but it only needs the one.
 * As for the original source, I've already searched in vain for it.. It could be that he said it during his Reith lecture "The Two Cultures". Just a guess, it really doesn't matter. -- Hillbillyholiday talk 13:52, 2 September 2013 (UTC)


 * The lecture 'The Two Cultures' was not a Reith Lecture. It was a Rede Lecture. Your quote is not there. More than before I think you ought to check the reliability of your source by finding the original. That it might be cited many times on the internet is not evidence of reliability. This is not a job for you to palm off onto someone else. You apparently want the quote to stand.Chjoaygame (talk) 14:12, 2 September 2013 (UTC)


 * Looking at the linked page in Tom Mahon's book, I see that he is an unreliable source on thermodynamics. He writes of the third law "The third law says that as a system approaches absolute zero, all processes cease and the entropy of the system approaches a maximum." This is wrong. As a system approaches absolute zero, its entropy approaches the minimum value for it; for a perfect crystal that minimum value is just zero.


 * If there are plenty of sources out there for your quote, and you have searched in vain for the original source, there is a problem. That you have searched means that you have some feeling that the original source should be found. That plenty of sources have not led you to it is positive evidence that creates doubt as to their reliability.


 * The quote itself does not give any useful understanding of the laws. It is only intelligible to someone who already knows them. The original poster of this thing was concerned, so he says, that the article does not give useful understanding to someone who isn't familiar with the material. Whether that is true or not, it remains true that the quote doesn't give understanding. The quote is an "in" joke. I don't know the general Wikipedia attitude towards "in" jokes in articles. I don't recall seeing one apart from this one, which of course has been posted here many times before, and duly unposted. The quote is in fact misleading as it stands.Chjoaygame (talk) 16:10, 2 September 2013 (UTC)


 * Yet you fell it's fine to insert unreferenced stuff, like in this edit
 * Here's another source for that Snow quote: . From what I can gather it does seem to originate from the Two Cultures book, but again it doesn't really matter. Fair enough if you disagree in the information's inclusion, or if you feel the need to qualify the remarks somehow, but I would like to hear what other editors say before removing it. -- Hillbillyholiday talk 16:33, 2 September 2013 (UTC)


 * A scan search of a pdf file of the book The Two Cultures does not find your quoted joke, or anything like it. The new source that you cite just above does not mention the joke; it mentions only the comment about Shakespeare.Chjoaygame (talk) 21:50, 2 September 2013 (UTC)
 * Yes, it does. However, I notice that (like most of the sources ) that pdf doesn't state the Zeroth law. This source says it was added posthumously.
 * Also it seems someone has tried to find the origin of the quote without success. See: "This is an elaboration of the jocular laws attributed to C.P. Snow. I haven’t been able to find a more precise citation." -- Hillbillyholiday talk 23:15, 2 September 2013 (UTC)


 * Ok, yes, it does on the last page. I didn't notice that there are five pages in it. My mistake.


 * The origin of the joke is questionable. I have seen things like it many times, and I don't know if Snow is the original source. I doubt it.


 * I repeat what I wrote above:


 * "The quote itself does not give any useful understanding of the laws. It is only intelligible to someone who already knows them. The original poster of this thing was concerned, so he says, that the article does not give useful understanding to someone who isn't familiar with the material. Whether that is true or not, it remains true that the quote doesn't give understanding. The quote is an "in" joke. I don't know the general Wikipedia attitude towards "in" jokes in articles. I don't recall seeing one apart from this one, which of course has been posted here many times before, and duly unposted. The quote is in fact misleading as it stands."


 * I think the citation of Snow as the source of the joke is close to or outside the bounds of verification. The joke is misleading and does not offer understanding to someone who does not already know the laws, to a purported "random non-technical person".Chjoaygame (talk) 00:48, 3 September 2013 (UTC)
 * Fair enough. I'm not saying it's essential, but plenty of sources attribute it to Snow. The IP who added the quote presumably wants it kept — you don't. I'd like to hear what others have to say.
 * The section you added as a counter to the quote strikes me as odd: "The practically endless energy supply". Isn't that the same as saying "The finite energy supply"? -- Hillbillyholiday talk 01:26, 3 September 2013 (UTC)

removal of caveat
Rather than restore the caveat I would prefer to delete the joke. It does not have a sourcing that meets proper reliable sourcing standards and does not add usefully to the article. Other articles don't have this kind of facetious stuff put on them. The effect of the joke is to imply that thermodynamics is trivial, that any fool can understand it. I regard the removal of the caveat as violent, because it was not discussed first on the talk page, though the remover knew it would be likely opposed. If you want this joke to stand in Wikipedia I would suggest you write an article about 'Jokes about thermodynamics', and put it there.Chjoaygame (talk) 21:09, 30 October 2013 (UTC)

Lede is terrible and does not conform to wiki style
The lede of this article is awful. The statements of the laws are so long and convoluted as to be essentially unrecognizable even to me, someone very knowledgeable about the topic, and hence are probably completely incomprehensible to the average reader. In general, the lede - which is supposed to be a succinct summary of the content of the article - is too long and fails in its purpose. Unless there are objections, I will revert the lede to an earlier revision, perhaps https://en.wikipedia.org/w/index.php?title=Laws_of_thermodynamics&oldid=475230438.  Waleswatcher  ( talk ) 20:22, 28 November 2013 (UTC)


 * You feel that the lead of this article is terrible and awful. To justify this, you appeal to your personal status as very knowledgeable about this topic.


 * I find the lead to be ok. I think it reflects reliable sources.


 * I object to your reverting to an earlier version.Chjoaygame (talk) 21:25, 28 November 2013 (UTC)


 * I agree with Waleswatcher's opinion: the current lead is much less informative and readable than the old one. Introductions are supposed to be succinct and comprehensible at a glance, something that blowing up the text to almost 3x the length with needlessly complex language defeats entirely. They don't have to reflect every source, that's the article's body's job, just their gist. mathrick (talk) 09:28, 29 November 2013 (UTC)


 * +1 for revert, as long as you carry over the wikilinks for keywords such as thermal equilibrium where appropriate. mathrick (talk) 09:31, 29 November 2013 (UTC)


 * As I understand it, the policy on the lead is summarized as follows.


 * Manual of Style/Lead section


 * "The lead section (also known as the lead, introduction or intro) of a Wikipedia article is the section before the table of contents and the first heading. The lead serves as an introduction to the article and a summary of its most important aspects. (Wikipedia leads are not written in news style, and journalistic leads serve different purposes from encyclopedic leads. )


 * The lead should be able to stand alone as a concise overview. It should define the topic, establish context, explain why the topic is notable, and summarize the most important points—including any prominent controversies. The notability of the article's subject is usually established in the first few sentences. The emphasis given to material in the lead should roughly reflect its importance to the topic, according to reliable, published sources. Apart from trivial basic facts, significant information should not appear in the lead if it is not covered in the remainder of the article.


 * The lead is the first part of the article most people read, and many read only the lead. Consideration should be given to creating interest in reading more of the article, but the lead should not "tease" the reader by hinting at content that follows. Instead, the lead should be written in a clear, accessible style with a neutral point of view; it should ideally contain no more than four paragraphs and be carefully sourced as appropriate."


 * As I read it, Wikipedia policy for the lead is stated in a broad way. One element of it is that the lead serves as a summary of the most important aspects of the article. More broadly, the policy could be read as an open invitation to say what one feels is the right stuff.


 * Ideally perhaps a lead should consist of four paragraphs, but a lead about four laws may perhaps be better non-ideal.


 * What Editor mathrick says is "needlessly complex language" may also be viewed as splitting the ideas so that each idea has a sentence of its own, to make each idea more clearly accessible to the newcomer. The sentences are in themselves not in complex language. For example, there are in the literature very many different ways of stating what is labeled 'the first law of thermodynamics'. The underlying reason for this is that the law summarizes a complex of ideas. Very often a literature statement will make one of them explicit, leaving the rest unstated and perhaps even hardly implied. For example, some editors here like to think of the first law as no more than a repeat of the law of conservation of energy. Others are very keen to emphasize that it establishes only the concept of internal energy and no more. Some texts mention heat and work without mention of conservation of energy or of internal energy. The idea that the law is 'simple' seems comfortable to those experts who already know all about it. But for those who don't, it is not 'simple'. That's why editors here differ very strongly about it, because each has his own 'simplicity'. I guess that Editor Waleswatcher finds the statements essentially unrecognizable for the reason that he gives, that he is "very knowledgeable about the topic", meaning that he has his own ideally simple version, not entangled with by the variety of viewpoints that appears in the literature.Chjoaygame (talk) 00:55, 1 December 2013 (UTC)


 * According to Clifford Truesdell, James Clerk Maxwell wrote:
 * "In the popular treatise, whatever shreds of the science are allowed to appear, are exhibited in an exceedingly diffuse and attenuated form, apparently with the hope that the mental faculties of the reader, though they would reject any stronger food, may insensibly become saturated with scientific phraseology, provided it is diluted with a sufficient quantity of more familiar language. In this way, by simple reading, the student may become possessed of the phrases of the science without having been put to the trouble of thinking a single thought about it. The loss implied in such an acquisition can be estimated only by those who have been compelled to unlearn a science that they might at length begin to learn it.
 * "The technical treatises do less harm, for no one ever reads them except under compulsion. From the establishment of the general equations to the end of the book, every page is full of symbols with indices and suffixes, so that there is not a single paragraph of plain English on which the eye may rest."
 * I think Maxwell's words may guide us here.Chjoaygame (talk) 15:03, 1 December 2013 (UTC)
 * I'm not involved in this discussion, but I saw this on my watchlist and I find it appalling. Wikipedia is not a technical treatise, and if we create something "no one ever reads except under compulsion", we will have utterly failed at our mission. -- LWG talk 15:34, 1 December 2013 (UTC)


 * We have here a supply of moral outrage: "lede is terrible and does not conform", ... "awful", from one respected local editor. And from one who is not involved: "I find it appalling." Sad to say he doesn't say exactly what he finds appalling. He continues "... if ... we will have utterly failed in our mission." Sad to say he doesn't say what is our mission. This stimulated me to find out what is our mission. So I found the five pillars, of which I think two are especially relevant right here.


 * "The fundamental principles by which Wikipedia operates can be summarized in five "pillars":


 * BluePillar.svg Wikipedia is an encyclopedia: It combines many features of general and specialized encyclopedias, almanacs, and gazetteers. Wikipedia is not a soapbox, an advertising platform, a vanity press, an experiment in anarchy or democracy, an indiscriminate collection of information, or a web directory. It is not a dictionary, a newspaper, or a collection of source documents, although some of its fellow Wikimedia projects are.


 * "RedPillar.svg Wikipedia does not have firm rules: Wikipedia has policies and guidelines, but they are not carved in stone; their content and interpretation can evolve over time. Their principles and spirit matter more than their literal wording, and sometimes improving Wikipedia requires making an exception. Be bold, but not reckless, in updating articles and do not agonize about making mistakes. Every past version of a page is saved, so any mistakes can be easily corrected."


 * I do not find in either of the above quotes from policy a guideline that "Introductions are supposed to be succinct and comprehensible at a glance." Succinct, yes, but comprehensible at a glance, no. Comprehensible by an average interested reader yes, of course.


 * As I read it, an encyclopaedia is not an attempt to make its material accessible at a glance to someone who isn't interested in it, unwilling to think a single thought about it. An encyclopaedia is an attempt to make reliable material accessible to someone who is interested in it. This is my interpretation of the relevant aspects of the core of Maxwell's first paragraph above.Chjoaygame (talk) 09:44, 2 December 2013 (UTC)


 * As for his concern to avoid Maxwell's "technical treatise", which has "every page full of symbols", Editor LWG need not worry: the lead that is proposed to be removed contains no symbols.Chjoaygame (talk) 13:07, 2 December 2013 (UTC)
 * Chjoaygame, I apologize if I caused you to feel as if you were a target of moral outrage. I have no axe to grind and no crusade to further other than to make wikipedia as useful as possible for as many people as possible. For a clear explanation of the need for readability as well as accuracy in the lede of an article, I refer all involved to MOS:INTRO. I would distill the underlying principle to this: if it is unlikely that anyone who is able to understand the lede would not already know the information contained therin, then the lede is not accessible enough. Other than that, my advice to everyone involved is to take a deep breath and a step back and make sure their work will serve the needs of the readers. It is incredibly easy to escalate a simple difference of vision for an article into a perception of persecution or malicious intent on the part of other editors. -- LWG talk 21:58, 2 December 2013 (UTC)


 * Thank you, Editor LWG, for your concern for my feelings. I saw the moral outrage directed at a reading of the lead, not against myself. I reacted to your comment because it seemed to respond to the emotive header of this talk page section, not making it clear that you had actually read the present lead that is proposed to be removed. For example, that contains no symbols, yet your outrage seemed directed against a "technical treatise", indicated by Maxwell as "with every page full of symbols with indices and suffixes". You seemed to be responding emotionally to a man of straw that you had created by not reading the present lead.


 * It is good that you make your interest more explicit, in writing "no crusade to further other than to make wikipedia as useful as possible for as many people as possible." You flesh that with a link to detail in the article to which I also had linked. I take the liberty of here quoting the first subsection of your linked section.


 * " Provide an accessible overview
 * See also: news style and summary style.
 * "The lead section should briefly summarize the most important points covered in an article in such a way that it can stand on its own as a concise version of the article. The reason for a topic's noteworthiness should be established, or at least introduced, in the lead (but not by using "peacock terms" such as "acclaimed" or "award-winning"). It is even more important here than in the rest of the article that the text be accessible. Do not hint at startling facts without describing them. Consideration should be given to creating interest in the article. Editors should avoid lengthy paragraphs and over-specific descriptions, since greater detail is saved for the body of the article.


 * "In general, introduce useful abbreviations, but avoid difficult to understand terminology and symbols. Mathematical equations and formulas should be avoided when they conflict with the goal of making the lead section accessible to as broad an audience as possible. Where uncommon terms are essential, they should be placed in context, linked and briefly defined. The subject should be placed in a context familiar to a normal reader. For example, it is better to describe the location of a town with reference to an area or larger place than with coordinates. Readers should not be dropped into the middle of the subject from the first word; they should be eased into it."


 * We are here concerned with things that have been debated at length on this and closely related talk pages. We are concerned with interpretation of the above quotes and related policy advice.


 * The audience should be as broad as possible, yes, but possible within what constraints? It would be broader if it contained more or less irrelevant attractors. I am concerned that an important aspect of constraint should be reliability. Reliability includes taking into account a suitable range of sources and editorial viewpoints. For example, the proposed replacement lead states the first law as "Heat is a form of energy". There has recently been a hot debate on the talk page for the article on heat. A strong component of that debate would vigorously reject that proposed replacement statement for various reasons. Thermodynamics is a subject of importance. It seems simple because it has been worked on for over a century. There are various viewpoints for it. I posted the quote from Maxwell because it warned against such glibness of presentation that the reader does not actually encounter the basic ideas. What is "comprehensible at a glance" to an expert may not be so to a newcomer.Chjoaygame (talk) 23:10, 2 December 2013 (UTC)


 * The things you quote yourself point towards restoring the older version. The keywords in all those passages are "accessible", "brief", "concise", "familiar", not "no-one would read except under compulsion". All things being equal, longer is always less accessible, and obviously less brief, so that alone is reason to prefer the old revision, which is less than half as long.


 * It's also better formatted, highlighting the crucial definitions, and less concerned with mentioning everything ever, rather than the gist of things. Intros should not mention everything there is about the topic, that's why we have the full article body afterwards. The lead should provide the absolutely shortest, simplest explanation of the topic possible. Not shorter, but not longer either. If something can be skipped without creating a fundamentally incorrect understanding of the topic, it should be. Nobody cares how correct and broad your intro is if nobody reads it. mathrick (talk) 00:19, 3 December 2013 (UTC)


 * I note your comments, and the cover note you supply for them. According to some editors, who provide more or less reasonable arguments in the recent talk page discussion of heat, the here proposed replacement first law statement "Heat is a form of energy" is fundamentally incorrect. It comes from a text that more or less seeks to abolish thermodynamics as a subject in its own right, so as to replace it by a new and improved approach called 'thermal physics'. The here proposed replacement second law statement relies on the concept of entropy, which is a not-easy-to-understand technical term, and there are well-known statements of the second law that do not use it.


 * Your comment inaccurately implies that I am supporting a "technical treatise" which has "every page full of symbols with indices and suffixes." No, I am not in favour of a treatise, either popular or technical, about which Maxwell wrote. I am in favour of an entry in an encyclopaedia; no symbols in what I am supporting. I am not supporting the glibness that Maxwell warns against. What you seem to want is an extreme ("absolutely") reading of the policies.


 * What is being proposed here is a wholesale revert, under a rousing banner. Such a thing is questionable, for example here. Perhaps some specific edits might be easier to deal with.Chjoaygame (talk) 08:11, 3 December 2013 (UTC)

Given that there seems to be something of a consensus I've gone ahead and reverted to the older version I referred to earlier. In my opinion it is far superior to what was there, although it can certainly be improved.  Waleswatcher  ( talk ) 18:43, 3 December 2013 (UTC)


 * Taken would be more accurate than given. Wikipedia is not a democracy. Not a trace of argument here. Just opinion for a wholesale revert. We are familiar with this style of editing.Chjoaygame (talk) 21:34, 3 December 2013 (UTC)
 * Please refrain from vague assertions like this, as, correct or incorrect, they are not conducive to useful discussion. -- LWG talk 22:16, 3 December 2013 (UTC)


 * Always good to have more moralizing from you.Chjoaygame (talk) 02:21, 4 December 2013 (UTC)
 * Alright boys, just unzip your pants and measure. — Preceding unsigned comment added by 74.5.204.40 (talk) 20:26, 4 December 2013 (UTC)

Discussion moved from LWG's talk page
joke

I now see that you are the one who removed the warning about the joke. At the time I thought your cover reason was not nearly adequate, but there was no reply on the talk page to my objection and I felt it would be a waste of time to argue. I don't see jokes about other physics subjects. The imputation "The following simple expression of the four laws" is of course nonsense. The joke is not a simple expression of the four laws. It is a hint at them for someone who already knows them. The joke is grossly misleading to a someone who doesn't already know the laws and their limitations. The warning was valid.Chjoaygame (talk) 21:58, 4 December 2013 (UTC)
 * I altered the wording to make it clearer that it is a whimsical metaphor, not a scientific description (though I think few people would have mistaken it for one). -- LWG talk 22:21, 4 December 2013 (UTC)


 * It's still misleading for someone who doesn't know the limitations of the laws. I think it was lazy editing not to track the source down better. A serious editor who wanted it to stand would have tracked it down better. I couldn't find Snow having written it and it doesn't strike me as the kind of thing he would write. So, though I don't know, I am unconvinced by the "has been attributed to".Chjoaygame (talk) 23:42, 4 December 2013 (UTC)

here follows that part that took place on the article talk page

 * As far as I'm aware, there is no proof that Snow is the author, however it is certainly a common saying attributed to him in many different sources (see for example this page, which seems to be expressing similar concerns to yours but nonetheless accepts the gambling metaphor as common and attributes it to Snow). Specifically in what way do you think that readers will be confused by this? It's clearly stated to be non-serious, and an in-depth discussion of the laws is right there directly above it. -- LWG talk 02:51, 5 December 2013 (UTC)


 * Readers who do not know the laws in advance of their reading them here are unlikely to recognize immediately that a person's activities are not relevantly covered directly by the four laws. The four laws are mostly stated for states of thermodynamic equilibrium, in many ways a zero-sum world. A person's activities are deeply in a non-equilibrium world. In the non-equilibrium world, life is a matter of winning all the time, in the thermodynamic sense, because the sun provides more or less endless energy. The joke suggests a zero-sum world; that is radically misleading to someone who doesn't understand the subject in advance of reading the article. Life is about using solar and other energy sources to grow and thrive; this is the very contrary to a zero-sum game, or worse, as suggested by the joke. Just saying that it is a joke does not give hint of this. This was pointed out in the warning that you deleted because you felt it "detracts from the tone of the article". The discussion of the laws in this article, which you call "in depth", does not come near hinting at the fundamental importance of non-equilibrium thermodynamics for life. Nor should it.


 * As for lazy editing. Must we now spend time investigating Wikipedia entries that are not properly sourced because the Wikipedia editors who post and defend them are too lazy to do it themselves?Chjoaygame (talk) 04:54, 6 December 2013 (UTC)


 * I'm not sure I understand. Thermodynamics is a part of physics, and people read this article to learn about physics, not to learn whether or not they should have an optimistic outlook on life. The humorous statement of the laws certainly appeals to a cynical outlook to make its joke: that is extremely common in humor. To worry that the presence of this little section of the article will make people falsely conclude that life is unwinnable seems silly and unnecessary I do not think that the danger of misinterpretation is very great, and in any case it is not our responsibility on wikipedia to correct our readers' philosophical misconceptions. -- LWG talk 05:46, 6 December 2013 (UTC)


 * Consistent with the rest of your answer, you didn't address the point about lazy editoring, while you have time to tell me I am silly. As I have already noted, it is always good to have your moral guidance.Chjoaygame (talk) 06:05, 6 December 2013 (UTC)


 * If my use of the word "silly" offends you, I will alter it. I did not respond to your concerns about "lazy editing" because they were too vague for me to comment usefully on them. I must once again respectfully remind you that potentially inflammatory claims about other editors must be made carefully and clearly.


 * As an example of what I mean, which I hope you will not take offense to: this is the fourth time you have used sarcastic and dismissive language towards me, which serves no purpose other than to engender ill will between us. I am not your enemy, and if you will be willing to offer me a little respect, it will be much easier for us to work together. -- LWG talk 14:23, 6 December 2013 (UTC)


 * No comment.Chjoaygame (talk) 16:02, 6 December 2013 (UTC)

edit on second law
I changed part of the first sentence in this section from " tendency of natural processes to lead towards spatial homogeneity of matter and energy..." to read "tendency of processes within closed systems to lead towards spatial homogeneity of matter and energy". I think we're to the point after (Bak et al 1988) and its progeny that we can go ahead and start assuming natural processes are embedded in open/dynamic systems. I don't know if this particular article is where you'd want to discuss the whole 'closed systems might only exist in labs' thing, but the edit at least conforms better to the wording of the 2nd law in the intro section. — Preceding unsigned comment added by 161.130.178.208 (talk) 19:31, 14 January 2014 (UTC)


 * All natural processes have some tendency towards spatial homogeneity. True, gravity can work the other way, but still the tendency towards homogeneity is operative at the same time.Chjoaygame (talk) 20:36, 14 January 2014 (UTC)

embarrassing 'almost'
The Second Law, as currently stated is somewhat embarrassing as a law due to the use of 'almost'. Keep in mind that laws are just laws - they don't necessarily describe reality. We usually give them the title of 'law' because they are consistently true under the right conditions. For example, Newtons second law does not describe reality. However, under the right conditions (non-relativistic) it is almost always right. But we say that Newtons second law is "F = ma" and the law is almost always (approximately) correct NOT that the law itself is "F = ma, almost always." Equivalently, I think the 2nd law should be stated as "entropy increases," with no qualifier. The article should state somewhere that the second law does not always hold, and under what conditions it does. Thermodynamics is the study of large ensembles of particles/states/etc, and in the limit (as N -> inf) the second law does always hold. Argentum2f (talk) 18:57, 7 March 2014 (UTC)


 * Thermodynamics studies some universal properties of macroscopic systems. Statistical mechanics studies ensembles of particles.Chjoaygame (talk) 02:44, 8 March 2014 (UTC)
 * Agreed, though irrelevent to point of my post (unless I'm missing something?). Shall I remove the 'almost' or is there a compelling reason to leave it that way? Argentum2f (talk) 23:59, 12 March 2014 (UTC)
 * Newton's law would be entirely correct if it was preceded by "in the limit as c/v->0 ....". Or, that could be omitted and an addendum added saying that Newton's law is only valid in that limit. I would think either way was good, as long as the qualifier was very up front, not lost in the noise somewhere. Likewise for the Second Law - the vague "almost" is not good, neither is removing it. Remove the "almost" and precede the statement with "in the limit of an infinite number of particles..." or an addendum saying the Second Law is only strictly valid in that limit. I sort of prefer the latter. PAR (talk) 03:22, 13 March 2014 (UTC)


 * Talk of particles belongs naturally in an article about statistical mechanics, but not primarily in an article about thermodynamics. Talk of a law about 'infinitely many' of them seems open to the same kind of "embarrassment" as talk about 'almost'. The statement about thermal equilibrium is hardly the best one, because the law really refers to thermodynamic equilibrium, which includes more than thermal equilibrium; for example it includes chemical equilibrium, not mentioned in the statement. The definition of the entropy of a system not in its own state of internal thermodynamic equilibrium is hardly settled. For example, Lieb, E.H., Yngvason, J. (2003) say "Despite the fact that most physicists believe in such a nonequilibrium entropy, it has so far proved impossible to define it in a clearly satisfactory way." (from 'The entropy of classical thermodynamics', Chapter 8 of Greven, A., Keller, G., Warnecke (editors) (2003). Entropy, Princeton University Press, Princeton NJ, ISBN 0-691-11338-6, page 190.) Lieb & Yngvason have more to say along similar lines. Walter Grandy is of the same view. A system starting in a state far from its own internal state of thermodynamic equilibrium could become isolated only by a radical thermodynamic operation, which would be a contrived artificial experimental manipulation, and in fact cannot be actually done. Therefore the fate of a strictly isolated system is a theoretical physicist's speculation, not an observed experimental fact. I think it a very delicate matter to talk of strict validity while such coarse problems exist. The statement of the law in this article is an editorial freehand creation, different from another editorial freehand creation which currently leads the article on the second law of thermodynamics. I don't think there is much compelling reason here. It seems a matter of freehand editorial creativity.Chjoaygame (talk) 10:43, 13 March 2014 (UTC)


 * Citing Zurek, Čápek & Sheehan write "It is now commonly held that the second law arises as a consequence of the interaction between a quantum system and its thermal environment." (Čápek, V., Sheehan, D.P. (2005). Challenges to the Second Law of Thermodynamics: Theory and Experiment, Springer, Dordrecht, ISBN 1-4020-3015-0, p. 25.) It would follow from this view that the second law should not be stated in terms of the adventures of an isolated system.Chjoaygame (talk) 00:10, 16 March 2014 (UTC)


 * Neither PAR nor I said anything about an infinite number of particles, just the limit as N approaches infinity (a mathematical construct that translates to an approximation when discussing reality) so no "embarrassment" there. But that's not really important. You seem to be more familiar with the technical aspects and the literature of the subject then I am, so I wont argue anything there. The issue here is that the first statement (the first sentence) of the second 'law' is not a law... it conveys (almost) no actual information. The only conclusion that can logically be made from the statement is that entropy can increase. Perhaps it could be rephrased as 'never decreases' or 'always increase or remains constant' or similar. If not, then perhaps it should be removed. What I'm talking about is not simply a difference in "editorial freehand creations." (By which I understand you mean different versions of stating the same thing). The statement in the article dedicated to the second law does not say the same thing - it specifically conveys the idea that entropy can't decrease, which is not at all implied by "almost always increases".Argentum2f (talk) 22:43, 20 March 2014 (UTC)


 * I am not defending the present statements, neither in this nor in the second law article, which are not my work. I am just pointing out that they were largely created freehand by an editor who does not feel the need to check or cite sources because he says he is knowledgeable.


 * I am just saying that fine tuning of these statements may be a difficult task, and even if easy would require circumspection. There are many who feel they have the one and only best statement of the law.


 * As for the main substance of your comment. You are right to point out some apparent vagueness in the second law. You may be right to say it should be felt as embarrassing. The law is said by some to be a probabilistic statement, with debate about what that might mean. The word 'almost' is evidently intended to convey the idea of probability. It is traditional and customary nevertheless to call it a law. Whether that tradition is right is of course open to question. At present the article does not question it. The full scope of the law may turn out to be difficult to settle.


 * On the logic of the law, it may not be so much the particle numbers as the relevance and sources of "noise" that are in question, which I think is Zurek's view. The law is primarily an expression of observed macroscopic fact, secondarily a deduction from microscopic theory. The scope of the observations is not easy to state briefly.


 * One might say that 'almost' is used in higher mathematics and is not embarrassing there. 'In the limit as N tends to infinity' for an approximation might well be translated into ordinary language by 'almost'.Chjoaygame (talk) 02:10, 21 March 2014 (UTC)


 * In 1875, Kelvin wrote
 * "By merely looking on crowds of molecules, and reckoning their energy in the gross, we could not discover that in the very special case we have just considered the progress was towards a succession of states, in which the distribution of energy deviates more and more from uniformity up to a certain time. The number of molecules being finite, it is clear that small finite deviations from absolute precision in the reversal we have supposed would not obviate the resulting disequalization of the distribution of energy. But the greater the number of molecules, the shorter will be the time during which the disequalizing will continue; and it is only when we regard the number of molecules as practically infinite that we can regard spontaneous disequalization as practically impossible. And, in point of fact, if any finite number of perfectly elastic molecules, however great, be given in motion in the interior of a perfectly rigid vessel, and be left for a sufficiently long time undisturbed except by mutual impact and collisions against the sides of the containing vessel, it must happen over and over again that (for example) something more than nine tenths of the whole energy shall be in one-half of the vessel, and less than one tenth of the whole energy in the other half. But if the number of molecules be very great, this will happen enormously less frequently than that something more than six tenths shall be in one-half, and something less than four tenths in the other. Taking as unit of time the average interval of free motion between consecutive collisions, it is easily seen that the probability of there being something more than any stated percentage of excess above the half of the energy in one-half of the vessel during the unit of time from a stated instant, is smaller the greater the dimensions of the vessel and the greater the stated percentage. It is a strange but nevertheless a true conception of the old well-known law of the conduction of heat, to say that it is very improbable that in the course of 1000 years one-half of the bar of iron shall of itself become warmer by a degree than the other half; and that the probability of this happening before 1,000,000 years pass is 1000 times as great as that it will happen in the course of 1000 years, and that it certainly will happen in the course of some very long time. But let it be remembered that we have supposed the bar to be covered with an impermeable varnish. Do away with this impossible ideal, and believe the number of molecules in the universe to be infinite; then we may say one-half of the bar will never become warmer than the other, except by the agency of external sources of heat or cold. This one instance suffices to explain the philosophy of the foundation on which the theory of the dissipation of energy rests."Chjoaygame (talk) 06:38, 24 March 2014 (UTC)

I removed the almost. --192.75.48.150 (talk) 19:10, 3 July 2014 (UTC)
 * This matches the intro of the second law article.
 * That article gives various alternate formulations, and it's never stated with an "almost" ... or should I say, it is almost never stated with an almost ;)
 * FWIW, I, random anonymous editor with an opinion, concur with the first post in this thread. The law states that entropy never decreases; if you want to split hairs over infinitessimal probabilities, then, the right way is that law has an infinitessimal probability of being violated, not that the law admits such excursions.

Removing reference to Perpetual Motion Machines from basic definitions of the laws
There is no reason to include such text as "Equivalently, machines that violate the first law (perpetual motion machines) are impossible" to a definition of the first law.

A variant on this could be put on the definition of ANY law. E.g. "Any two bodies in the universe attract each other with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. Equivalently, machines that violate the law of gravitation (anti-gravity engines) are impossible." Or try "Anything that can go wrong will go wrong. Equivalently, machines that violate Murphy's Law (reliable machines) are impossible."

If it is necessary to address the impossibility of perpetual machines in this article (and I'm not sure that it is necessary) then perhaps someone can compose a brief section within the body of the article. Though this seems more relevant to an article on perpetual motion, and is not essential to understanding the thermodynamic laws.


 * I don't agree with this. In contrast to the examples you give, the impossibility of perpetual motion is not just a consequence of the laws of thermodynamics, it's a statement equivalent to the law.  In general there are many equivalent statements of the various laws, and I think what we want to try to do for this article is give the statements that are the most clear and meaningful to a general reader.  In addition, reliable sources mention the impossibility of perpetual motion machines in their statements of the laws (for instance, Kittel and Kroemer p.49).  Reverted on this basis (but happy to discuss it further).   Waleswatcher  ( talk ) 21:03, 3 June 2014 (UTC)


 * Today was the first time I've read this article and I agree that the references to perpetual motion machines in the lead are confusing. Perpetual motion isn't key (or even very important) to understanding the laws of thermodynamics. Pburka (talk) 12:04, 11 July 2014 (UTC)
 * Indeed, I agree too that there is no need to refer to perpetual motion. Perpetual motion would be just as much a violation of the First Law. The statement is in no way equivalent to the Second Law which is all about the irreversibility of natural processes which (if there are unbalanced energy potentials) will take place, this reducing those unbalanced energy potentials and thus increasing entropy. The energy potentials can relate to kinetic energy (temperature) or potential energy, or even to energy relating to phase change and chemical reactions, substances dissolving in fluids etc. The Second Law is about all these things. It can be used, for example, to show why a stable non-zero density gradient exists in a planet's troposphere: that state is maximum entropy or, by definition, thermodynamic equilibrium. Equations for entropy need to include terms for these other forms of energy where they are likely to change. Hence, the Clausius "hot to cold" statement is merely a corollary of the Second Law that only applies in a horizontal plane without phase change or reactions. — Preceding unsigned comment added by 202.172.115.20 (talk) 03:03, 11 July 2017 (UTC)


 * I agree that references to perpetual motion machines should be removed from these statements of the Laws of Thermodynamics. They are difficult enough to define anyway and the perpetual motion references just add extra unneeded complexity.49.224.149.180 (talk) 02:01, 25 January 2019 (UTC)

undid "improvement"
I undid a good-faith "improvement". It had removed appropriate material, and added redundant material. The sentence already contains a link to the law of conservation of energy, which does not need to be spelt out there. The impossibilities of perpetual motion machines are usefully stated there.Chjoaygame (talk) 19:01, 19 December 2014 (UTC)
 * No, it is not relevant here, especially the reference to thermal energy here: "Equivalently, perpetual motion machines of the second kind (machines that spontaneously convert thermal energy into mechanical work) are impossible." The Second Law is not about "thermal energy" which is kinetic energy of particles. It is about entropy and the law has far wider implications and applications. For example, because of the Second Law, water from a dam flows down pipes and that Second Law process can indeed produce mechanical work in generating turbines at the foot of the mountain. It is very inappropriate for the article to place limitations on the Second Law in this way. The Clausius statement is merely a corollary that only applies if kinetic energy is the only energy that can change or be redistributed. — Preceding unsigned comment added by 202.172.115.20 (talk) 03:13, 11 July 2017 (UTC)

Laws or principles?
Are this scientific statements laws or just principles? In other languages this laws are called principles, for instance French (principes de la thermodynamique). I think it is important to clarify the distinction between laws and principles.

Also where the ideal gas law stands in connection to the set of 'laws' of thermodynamics?--5.15.59.0 (talk) 10:14, 20 January 2016 (UTC)


 * Mostly in English I think they are laws of thermodynamics. They are are mostly more or less directly verifiable by empirical evidence, and circumscribed in meaning. Mostly in English I think principles are more abstract and uncircumscribed, and not directly verifiable. The ideal gas law is not a law of thermodynamics. It is an idealized equation of state.Chjoaygame (talk) 14:14, 20 January 2016 (UTC)
 * If the ideal gas law is not a law of thermodynamics, then whose law is it? It is definitely a law. (Concepts need to have the same name in any language to avoid confusions, that's why the concept of controlled vocabulary has been developed). These supposed laws can be compared to the laws of motion which also have ambiguous status. Only one of them is a true physical law, Newton's law of motion. The confusion between law and principle is quite frequent and seems to originate from the translation from Latin of Newton's Principia where there are called leges motu (axiomata sive leges motu). Laws of logic or laws of thought are another example of confusion between laws and principles.--5.15.50.146 (talk) 14:45, 26 January 2016 (UTC)
 * The ideal gas law is a law for ideal gases. In thermodynamics, it has the status of an equation of state. Wikipedia does not propose to say what is right. It proposes to say what reliable sources say.Chjoaygame (talk) 18:40, 26 January 2016 (UTC)
 * There are two questions here. If the question is just which term to use in the articles, then I agree that English Wikipedia should follow the great majority of English-language sources and refer to the laws of thermodynamics. We could perhaps also note briefly that other languages refer to principles, indicating that there is some international disagreement on their status as laws.
 * But the more important question is what is the experimental evidence for these laws (if they are laws). Of the four English Wikipedia articles on the four laws, only the first law article covers this question, with a section on Evidence for the first law of thermodynamics for closed systems. I think that the other three articles also need sections on Evidence for the zeroth/second/third law ... Dirac66 (talk) 20:10, 22 January 2016 (UTC)
 * Of course there are two aspects, the second having a greater importance. For instance the third law is actually a theorem, Nernst's theorem, so the status of law is shaky. --5.15.50.146 (talk) 14:49, 26 January 2016 (UTC)
 * Conservation of energy is also a principle, for instance.--5.15.50.146 (talk) 14:57, 26 January 2016 (UTC)

RFE: History / 'etymology'
I think it would be helpful to have a brief overarching history section, indicating: —DIV (120.17.150.38 (talk) 08:08, 28 May 2016 (UTC))
 * when each 'law' was first suggested (and by whom);
 * when each 'law' was first recognised as a "law";
 * hence (perhaps), why they are numbered in the (somewhat peculiar) way that they are [ e.g. why not just 1, 2, 3, 4? ].

The Second Law is about entropy maximization, not heat transfer
Entropy is a measure of progress towards the state of thermodynamic equilibrium. It is NOT a measure of disorder, whatever that means anyway. That state of maximum entropy occurs when all unbalanced energy potentials have dissipated. Those energy potentials need not only involve molecular kinetic energy, that is, temperature. They include gravitational potential energy of molecules as well. The Clausius statement is now understood by us physicists to be merely a corollary of the Second Law which only applies when only kinetic energy affects entropy - hence only in a horizontal plane in a gravitational field. When the world starts to understand entropy correctly, it will be realized that there can be an increase in entropy associated with DOWNWARD heat transfer in a planet's troposphere, and this also happens in other force fields, notably in a vortex tube along any radius as there is heat from the cooling central regions to the outer warming regions. There is no other valid explanation for planetary core and surface temperatures. It happens when a prior state of thermodynamic equilibrium (which DOES have a non-zero temperature gradient vertically in a planet's troposphere) is disturbed with the absorption of new thermal energy at the higher altitudes - as happens mostly in the morning. That's how the surface warms each morning even under thick cloud cover. The colder clouds do NOT raise the surface temperature with their radiation. The surface temperature cannot be explained with solar radiation or any other radiation. — Preceding unsigned comment added by 202.172.115.20 (talk) 01:21, 18 July 2016 (UTC)

Why there MUST be a non-zero temperature gradient in a force field
The state of maximum entropy (which the Second Law says will be approached) is called "thermodynamic equilibrium" by physicists. In that state entropy is homogeneous and there are thus no unbalanced energy potentials. In other words, nothing can happen spontaneously as no net energy tends to move across any internal plane. But molecular gravitational potential energy is just as relevant as molecular kinetic energy, the mean of which is related to temperature. If you consider a horizontal plane in the troposphere, at thermodynamic equilibrium the pressure from above the plane equals that from below the plane. But, by the Ideal Gas Law, pressure is proportional to the product of temperature and density. At thermodynamic equilibrium there is also no net transfer of mass across any internal plane. It follows that there must be equal numbers of molecules passing upwards across that horizontal plane as there are crossing downwards. Hence, since the pressure is equal, the mean kinetic energy of the molecules passing upwards equals the mean kinetic energy of those passing downwards. Now, gravity increases the percentage chance that a molecule will move downwards after a collision, that probability thus becoming a little above 0.5. Hence there must have been a lower density of molecules above the plane than below it, and so we have a stable density gradient which results from the Second Law process of entropy maximization. Likewise, because gravity accelerates the motion of molecules between collisions, there must have been a lower mean molecular kinetic energy above the plane and a higher one below the plane. Hence the Second Law process of entropy maximization is what causes the stable temperature gradient in any planet's troposphere. Inter-molecular radiation between radiating molecules works against the gravitationally induced temperature gradient, reducing it by up to about a third of its theoretical magnitude, as we know happens in more moist regions. But the fundamental IPCC assumption that the surface temperature would have been the same as that found at the radiating altitude in the absence of radiating molecules is wrong. — Preceding unsigned comment added by 202.172.115.20 (talk) 01:43, 18 July 2016 (UTC)