Talk:Second law of thermodynamics/Archive 9

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Link to article defining Entropy

Today a link to the article Entropy was added to the opening paragraph, and then deleted a few hours later because (according to the edit summary) "that article is terrible and should not be linked". Given that most textbooks and teachers describe the Second Law in terms of entropy, I think that this article should provide guidance to readers who either may not know the word or else may not understand it too well. The page view statistics (accessible from the Revision history page) indicate that about 2000 readers per day consult this article, so it seems to reasonable to assume that some will know less about entropy than others.

I would also point out that Wikipedia actually has quite a few articles on entropy, as listed on the dab page Entropy (disambiguation). If the one named simply Entropy is judged to be "terrible", then perhaps the editors of this article should select the best or the most useful article from the dab page, and link the opening paragraph to the chosen article instead of just to Entropy. I do think that this article should provide guidance as to where to find the best information on entropy available on Wikipedia. If we do not, then the likely outcome is that some readers will just swear and type Entropy into the search box, and arrive (with 5 seconds extra effort) at the exact article described as "terrible". Dirac66 (talk) 19:49, 22 March 2016 (UTC)

• I agree, the entropy article is a mess, but this article should link to it anyway. Links should not be dependent on the quality of the linked article, only on its relevance. If the linked article is bad, we should fix it. PAR (talk) 21:33, 22 March 2016 (UTC)

• Editor Dirac66 as usual gives sound commentary. I agree that there is a problem here. My de-link was not the ideal solution. A better one is needed. At this moment I don't know what.

I suppose I should try to justify my claim that the said link was terrible. It was to an article that starts:

In thermodynamics, entropy (usual symbol S) is a measure of the number of specific realizations or microstates that may realize a thermodynamic system in a defined state specified by macroscopic variables. Most understand entropy as a measure of molecular disorder within a macroscopic system. The second law of thermodynamics states that an isolated system's entropy never decreases. Such a system spontaneously evolves towards thermodynamic equilibrium, the state with maximum entropy.

Looking at the sentences one at a time to say why I think that article is unsuitable as a link for this one's first sentence:

In thermodynamics, entropy (usual symbol S) is a measure of the number of specific realizations or microstates that may realize a thermodynamic system in a defined state specified by macroscopic variables.

That is couched in microscopic statistical mechanical terms, not suitable for the present article, which proposes that the macroscopic view is primary.

Most understand entropy as a measure of molecular disorder within a macroscopic system.

That expresses a viewpoint that may be plausible but is deprecated by the present article.

The second law of thermodynamics states that an isolated system's entropy never decreases.

A slick short cut deprecated by the viewpoint of the present article.

Such a system spontaneously evolves towards thermodynamic equilibrium, ...

This article says a change from thermodynamic equilibrium is usually caused externally by someone tampering with the walls.

...the state with maximum entropy.

The principle of maximum entropy is a doctrine that is perhaps admirable, but belongs to the theory of statistical inference, not thermodynamics. It is a faulty link for where it is in the other article.

Whew !! What a mouthful !!

I have avoided trying to significantly improve the article Entropy because I have felt it too hard a task for me.

With that, I will now pause, and look around and think a little, and see comments from others. Chjoaygame (talk) 22:10, 22 March 2016 (UTC)

I now see Editor PAR saying we should try to fix the said article. Perhaps he is right, but it wouldn't be too easy. It would take a concerted effort.Chjoaygame (talk) 22:15, 22 March 2016 (UTC)

I have now posted an obvious remedy. Comments from others?Chjoaygame (talk) 22:23, 22 March 2016 (UTC)

Yes, I think Entropy (classical thermodynamics) is a better place to direct the beginner, because it is almost entirely from the macroscopic viewpoint (except for the opening paragraph). Dirac66 (talk) 22:32, 22 March 2016 (UTC)

In response I have made some edits.Chjoaygame (talk) 23:16, 22 March 2016 (UTC)

Lead needs translation

The introduction section of this page needs to be translated back into English. The kind of English that most people will understand. [Inserted by 2601:153:801:8a76:7028:4d08:a27b:2240]

I have moved the just above unsigned comment made there, to the customary place here at the bottom of the page, and I have given it a section title that I think would reflect the intention of the non-signing poster.Chjoaygame (talk) 04:21, 2 April 2016 (UTC)

There is a tension between various desirable qualities in the lead. The just above comment favours "The kind of English that most people will understand." A desirable quality indeed, but one amongst others.Chjoaygame (talk) 04:31, 2 April 2016 (UTC)

Yes, ideally each article should be understandable AND accurate AND offer complete coverage of a subject (in combination with linked articles). This is not always easy to achieve.

However it might help if 2601:153:801:8a76:7028:4d08:a27b:2240 can specify which points s/he does not understand. Then others can work on clarifying them. Dirac66 (talk) 01:17, 3 April 2016 (UTC)

undid good faith edit; why

I undid this good faith edit. I have posted part of it in the first paragraph of the lead.

The sub-section that I have deleted read as follows:

Biology vs. Physics

There are several ways to distinguish a living system from a "dead" system, e.g. an oyster from a rock. One of the most efficient one is by entropy. Nonetheless, this created a problem in the turning of the 19th-20th century. The problem is simple: according to Darwin, theory of evolution, the university goes from simple to complex, from disorganized to organized; however, according to thermodynamics, it goes in the opposite, from organized to disorganized, the entropy either increases or remain constant for reversible processes. Further, to complicate more the story, living systems can revert entropy, it decreases. Most of the problematic is ongoing research, e.g. non-equilibrium thermodynamics, others were (partially) solved by the theory field called complex systems; or in the context of biology, the general systems theory.

That post is loosely and inadequately thought out, and expressed in a conceptually faulty way. Fritjof Capra is not a reliable source. There are some grammatical errors in the text. A sub-section in some ways along the lines of that post might perhaps have a place in this article, but it would need to be much better thought out.Chjoaygame (talk) 14:44, 17 April 2016 (UTC)

I have added a new section in which I try to improve on the post that I undid.Chjoaygame (talk) 20:15, 17 April 2016 (UTC)

Perhaps the new section should mention explicitly that living organisms are open systems, so that the simple entropy maximization for closed systems does not apply. Dirac66 (talk) 22:22, 17 April 2016 (UTC)

A good point. Will try.Chjoaygame (talk) 04:49, 18 April 2016 (UTC)

deteriorative rewrite of lead that had previously been reached through this talk page

Here Editor Waleswatcher, without engaging on this talk page, has totally rewritten a lead that was substantially accepted on this talk page. His rewrite was a quickie that replaced a safe statement that had a fair explanation. His rewrite deteriorated the article.Chjoaygame (talk) 00:49, 30 April 2016 (UTC)

I don't agree, and I also think this helps address the "translate into English" comment by the IP above. Waleswatcher (talk) 12:13, 30 April 2016 (UTC)

Since there are fundamental disagreements which cannot be reconciled, I have opened an RfC to get wider input. Kingsindian ♝ ♚ 17:39, 30 April 2016 (UTC)

proposals for changes

Editor Dirac66 proposes some changes to the present version of the lead. I would like to respond.

• Proposal to add some word such as for example "real (or natural or spontaneous)". This proposal seems to me reasonable, but not compelling. "Real" evokes philosophical questions that may work against it. "Natural" has the support of Planck and some texts that follow him, but has been criticized on this talk page, and I have some sympathy with such criticism. "Spontaneous" has the problem of potential conflict with the key point, that thermodynamic processes are initiated by a thermodynamic operation, that is to say, by an agent tampering (Guggenheim 1949) with the walls. 'Actual' is a word that I have often thought about for this task, but have felt it perhaps an overload. Eventually I have been going with the idea that the law makes its statement about processes that do occur, as remarked by Editor Dirac66, so that plain 'occur' is enough.

My mistake, I did put in the word "actually". It's there.Chjoaygame (talk) 07:41, 1 May 2016 (UTC)

• Proposal to delete the sentence about making the walls more obstructive. Editor Dirac66 is right that it seems obvious that making the walls more obstructive will not trigger a new process. But I think it worth making explicit for the sake of indicating the cause of irreversibility. The asymmetry comes from the thermodynamic operations, not from the internal dynamics of the materials.Chjoaygame (talk) 00:57, 1 May 2016 (UTC)

undid good faith edit; why

I undid this good faith edit because it introduced superfluous ideas. From a hotter to a colder body, heat flow is one-way. The idea of net flow is unduly complicating, with no benefit.Chjoaygame (talk) 09:30, 1 May 2016 (UTC)

Between hotter and colder bodies, energy flows both ways, but more energy flows from the hotter to the colder than from the colder to the hotter, which means the net flow is from hotter to colder.

A chemist or physicist would understand that "heat flow" is always a net energy flow, so, technically, the word "net" is redundant. But Wikipedia is not read solely, or even mostly, by chemists and physicists, and a lot of people without specialized education in the sciences don't understand the fact that "heat flow" means net thermal energy transfer. Including the word "net" clarifies the meaning for such people, it does not complicate it.

I'm going to change "heat flow" / "net heat flow" to "heat flow (net thermal energy transfer)" to clarify it. Does that satisfy your concern, Chjoaygame? NCdave (talk) 11:21, 15 May 2016 (UTC)

Without getting too deeply into this point, I am nervous about glossing over it too simplistically. While the net-flow concept is unavoidable, I do not like skipping the point that in limited times and places there can be localised decreases in entropy ("open systems") and these, though they seem negligible from the gross physics point of view, are the basis of all life, and a great deal of engineering. I have not checked to see whether such concepts are covered in the article in this connection. JonRichfield (talk) 07:24, 17 May 2016 (UTC)