Talk:Entropy/Archive 2

message: In reference to this:
"\delta Q of energy transferred by heating is denoted by \delta Q rather than dQ, because Q is not a state function while the entropy is."
That seems really unclear to me. What is the significance of Q not being a state function. Also, it seems like Q *is* a state function, after all, it doesn't matter how the heat got to the system, as long as it is there, right? the δ notation still confuses me, as I've taken plenty of math and have never seen a δ be used in algebra or calculus. Fresheneesz 10:55, 4 April 2006 (UTC)
replies: text: Heat isn't a state function since it's not a function of the thermodynamic state. I can figure out the change in energy between thermodynamic state A and state B, because energy is a state function, but I cannot know how the energy changed (What proportion was heat and what proportion was work?) unless I know the transformation taken between the two states. Heat and work are path functions.   However, I agree that the whole inexact differential stuff is  confusing, even for the initiated. Surely, its easier to understand \Delta E = Q + W than  dE = \delta Q + \delta W Nonsuch 19:18, 4 April 2006 (UTC)
replies: text: The way I think of it is that an exact differential is an infinitesimal change, while and inexact differential is an infinitesimal amount (remember that a differential is just the limit of a difference). Commander Nemet 04:56, 7 June 2006 (UTC)

text: That is only the Boltzmann definition. What is the extended one? LeBofSportif 07:23, 24 May 2006 (UTC)
replies: text: What I mean was the definition of entropy when the system is in thermal contact with a reservoir, \sigma =-\sum_{s}^{}{P_{s}\ln P_{s}}, that is, not an isolated system. --rhevin 08:13, 24 May 2006 (UTC)
thread_title: Thermodynamic definition

message: Does reverting "Entropy" increase its entropy?  Oneismany 05:29, 4 May 2006 (UTC)
thread_title:  Reverting "Entropy"? 

message: Ice melting - a classic example of entropy increasing. Is it really? Can't one contrive reversible melting simply by putting ice in water at 0 deg C?
Surely gas expanding into a vacuum is a much better example? LeBofSportif 19:48, 12 May 2006 (UTC)
replies: text: If the ice is melting (As presumable it is, because the surroundings in the picture are at room temperature) then entropy is increasing. But, yes, perhaps a better example could be found. Nonsuch 18:45, 24 May 2006 (UTC)

text: It's very difficult to show gas expanding into a vacuum in a way that most people will relate to.  However, many people have experience with pop cans.  May I propose  as a candidate?Alex Dodge 19:57, 17 June 2006 (UTC)
replies: text: Almost every chemistry textbook use ice (crystalline form), water (liquid form), and vapor (gas state) H2O molecule pictures and diagrams to show and contrast systems with high entropy and low entropy.  The second common pictorial example is to show dots (of gas molecules) expanding in a system subjected to a volume increase.  The ice picture example is the most informative.--Sadi Carnot 23:16, 19 June 2006 (UTC)
thread_title:  The Ice Example Picture 

message: "randomness and disorder" has once again been added to the definition. I must stress that we cannot leave "disorder" and "randomness" undefined in this context, simply because the informal use of such words does not in any way shape or form describe anything about entropy. Although I deeply dispise the attachment of the three words "disorder", "randomness" and "entropy", I will simply add a formal definition for randomess and disorder into the intro. Fresheneesz 07:16, 31 May 2006 (UTC)
thread_title:  Randomness and disorder 

message: This page says that the the book The Time machine is based on entropy, but theres no mention of that on the page for that book. Fresheneesz 09:02, 1 June 2006 (UTC)
thread_title:  entropy and the Time Machine 

message: According to the IEEE, the use of Negentropy and similar terms is now strongly deprecated.
Such words compound the conceptual difficulty people have with the meanings of entropy, with what is in effectively conceptually a double negative -- starting with entropy, ie the information you don't have, going to negentropy is then the information you don't not have.
Almost always this is not a good way to go, and such terms just get you into larger and larger knots.  Schroedinger used negentropy in quite a specific way, for the order that could be built up inside a living system, possible because of the entropy increase being dumped outside the cell.  But Brillouin's use was a mess, very confusing. 
These coinages have never taken off, and deserve to wither.   Negentropy perhaps rates a mention in "see also".  The rest really just deserve the ash heap of history -- *most* definitely they do not deserve high-profile special highlighting up at the top of what is meant to be a very simple very mainstream overview article.
-- Jheald 05:09, 20 June 2006 (UTC)
replies: text: These terms I don't really care about; they should, however, go in an end paragraph for the sake of orgnization.  If you will note the history section, someone else put the first one in, so I just clarified a bit with the others.  Also, I started a new header for the information entropy links and stuff to go.--Sadi Carnot 05:14, 20 June 2006 (UTC)
replies: text: No.  The terms should just die.  They're just useless cruft.  Bury them in the article on negentropy if you feel the overwhelming urge that they have to be linked to from somewhere. -- Jheald 05:40, 20 June 2006 (UTC)
thread_title:  Negentropy, Ectropy, Syntropy, Extropy 

message: It is a pleasure to read since it is pure physics taken to an easy reader's understanding. I was bad in physics and would have hoped my teachers would read that so they would actually teach this matter well. Thanks ;) Lincher 01:10, 22 June 2006 (UTC)
replies: text: I agree that most of the article is well-written, and easy to understand the way the material is presented, however it is not purely physics and that is important to note.  Things like informational Entropy and disorder are neither useful, nor used, ideas in physics.  What in this article is described as "disorder" is (meant to be equivalent to) what is known in physics as multiplicity or "degeneracy of states," rather and they are not the same thing.  Informational Entropy is something that is useless to most physicists, unless you are speaking of a field like quantum computing.  The challenge to improving this article though is that there are many more non-scientists with strong opinions about fields in which they are not authorities, whom are quite often unwilling to allow the expertise of an authority to contribute to an article such as this, than there are actual authorities on the subject. In short, some of the best edits get reverted.  For now, consider this article an average, basic review.  It's quality will improve with time - I plan on contributing to that effort as well. Astrobayes 20:35, 22 June 2006 (UTC)
thread_title: GA awarded

message: Paul, you made several semantic edits which change the context and tone of the article, but you added no citations for any of them.  Your edits, if properly cited, could provide a valuable educational addition to the article.  If not cited however, they seem an awful lot like POV. Astrobayes 20:24, 22 June 2006 (UTC)
thread_title: About [[User:Paul Venter]]'s Edits

message: At the bottom of the Overview section, it reads that the second law does not apply to the infinite Universe, yet further down the article in 'The Second Law' section, it reads that the entropy of the Universe does tend to increase. Maybe I'm missing something, but this may need clarifying in order to properly state whether or not the Second law applies to the universe or not.
:: Perhaps it was commenting on the fact that the second law states that entropy "tends to" increase - rather than always increases. Entropy doesn't always increase, it can decrease. However, the law states that in our humon observation, it usually increases. Fresheneesz 19:36, 29 June 2006 (UTC)
replies: text: This is correct, and is in fact the crux of the entire concept of Entropy. Astrobayes 21:52, 29 June 2006 (UTC)
thread_title:  The second law does not apply? 

message: This article and Entropysimple.com are up for deletion. They merely contain 4 external links to web pages about entropy. I have added them to this article. If the regulars here like them, they can stay. If not they will go. The two articles concerned are most likely to be deleted and rightly so. --Bduke 01:07, 27 June 2006 (UTC)
replies: text: Scientists are concerned with understanding the interactions between matter and energy in physical systems in the Universe, and quantifying these observations and understandings such that their conclusions are internally consistent, physically meaningful, testable, and reproducible.  Your statement regarding religious connotations therefore does not apply.  The reactions of scientists to clear up a broad misunderstanding by many people of a concept as important to the understanding of the physical world as is Entropy, is no different than the current efforts by scientists to clear up misconceptions that non-scientists have about stellar evolution, hot nucleosynthesis, evolution, particle physics, and so on.  Perjoratives such as you use here are really inappropriate.  We scientists are just doing our jobs to educate, and by that education to inspire and promote the love of knowledge.  I would gladly discuss any science topic you wish by email at shale_d2010@yahoo, or on my talk page. Cheers, Astrobayes 19:55, 27 June 2006 (UTC)
replies: text: Maybe. I'll look at them in more detail. I noted the comment from another chemist on the deletion page and I saw that the first one was by a retired academic. As a retired academic chemist who has taught physical chemistry, I may have an input. Give me a bit of time, and let us see what others think. --Bduke 02:08, 27 June 2006 (UTC)
thread_title: [[Entropy Sites]]

message: Since the debate on Entropy and Disorder isn't really going anywhere, I thought I would try a different tack, and make abject appeals to authority. (Not my favorite approach.) Frank's appeal to authority is that recent physical chemistry textbooks use the term "disorder" far less than they used to. I find this unconvincing since introductory physical chemistry textbooks really suck at explaining the deeper principles. (I curse Atkins to this day.) In response, let me quote Callen, arguable one of the finest books on thermodynamics yet written:
: "Thus we recognizer that the physical interpretation of the entropy is that the entropy is the quantitative measure of the disorder in the relevant distribution of the system over its permissible microstates"
Or how about Feynman's Lectures in Physics, another very good book :
: "We measure 'disorder' by the number of wasy that the insides can be arranged, so that from the outside it looks the same. The logarithm of that number of ways is the entropy. The number of ways in the separated case is less, so the entropy is less, or the 'disorder' is less."
Or "Thermal Physics" by Finn, another good, modern thermodynamics textbooks.
: "It is usual to identify [entropy] as a measure of 'disorder' in the system. This implies that we expect the disorder of an isolated system to increase."
Whatever. Nonsuch 00:51, 6 July 2006 (UTC)
replies: text:  I don't think we should be looking at useage of the term in physics or chem books. One reason being that those books don't usually explicitely condone or condemn the term or concept - they just use it. Thus its basically original research to use that argument. However, anyone that understands entropy will tell you that terms like "disorder" and "mixedupedness" are failing at teaching our children the important concept of entropy that has its base in heat and statistics - *not* "order", whatever that is. Fresheneesz 04:21, 7 July 2006 (UTC)
thread_title:  Appeals to Authority 

message: First, I owe an apology to Nonsuch and to Jheald for speaking harshly to them when I felt that they had not taken the trouble to consider what they or I said.  That's not my prerogative nor an objective judgment of their diligence. (I greatly appreciate their courtesy in not responding in kind.)  
I get overly excited by any discussion involving entropy. The correct presentation of a basic understanding of thermodynamic entropy to undergraduates in chemistry has been my primary focus for about 8 years. My good luck in discerning what is now accepted by most chemistry text authors has been as amazing to me as it is unknown to those not in chemistry instruction.
Second, I have written too lengthy pieces in this Talk page. That was certainly not from a desire to write [I have papers to do before I pass on!!], but to explain clearly a modern view of thermodynamic entropy in chemistry as measuring the spreading out of energy from being more localized to becoming more dispersed, spatially and temporally. [The latter 'temporally', ties the idea to Leff's interpretation of a system's constantly changing per instant from one accessible microstate to another as an 'entropy dance' over time.] One of 'the modern view's' many advantages, I believe, is that even concrete-thinking students can readily 'get' the idea of active molecules spreading out in space -- both in 'thermal' or 'configurational' entropy, while that 'half of the whole picture' seamlessly fits into the next level of understanding: quantization of energy levels, microstates, etc.
The profound newest view -- that entropy is a two-factor function (please click on the CalPoly seminar ) -- explicitly clarifies the difference between thermodynamic entropy and information 'entropy' in my opinion. (It is has passed the first barrier of article peer-review with only one dissenter now being countered.)
With Jheald, I agree that it is time for a focus on the actual Entropy page. Because I believe that naive readers will be the most frequent visitors, but NOT the only visitors of course, the initial introduction should be for them -- but NOT in any chatty style. (Sorry; the suggestion made in the Talk above was fast-typed chatty, but no way should it be such in the Entropy page.) I'll work on a 'possible' late today, of course subject to review.FrankLambert 18:12, 7 July 2006 (UTC)
thread_title: Apology

message: The problem with this whole discussion is that (some of) the respondents are not fully reading what other people write.  To Nonsuch, I did not cite any of Frank's work as a peer-reviewed source.  Look above - far above - in this page and you'll find a link I left in a discussion (which everyone ignored because they were all too busy making their individual points to consider others) that highlights an example of physical systems whose Entropy increases as disorder decreases, and it was written by the chemist Brian B. Laird, not Frank Lambert, and was published in the peer-reviewed Journal of Chemical Education. How did you miss this? You were a bit busy making your point I guess to read what I wrote.  I understand though, after reading all of your comments I can see you feel strongly about your conception of Entropy and you feel what you say has important authority above the rest of us.  But please, read what others write before you say something that illuminates that you are neither reading nor seriously considering what everyone else is saying here.  That you missed this link to the citation above shows this clearly.  However, there are many of us who are specialists in this field and this article unevenly presents informational statistical disorder over Entropy (by which I mean energy transfer at a specified temperature) - and those Wikians who have expertise on this subject should not have their expertise denigrated because a few individuals have adopted this article and refuse to let the edits of others remain.  There are those of us who have gone to school for years studying these subjects so please consider that there may be individuals in this world who, in addition to you, also have important contributions to add to an encyclopedic article such as this.  I am curious, what is your educational background that gives you such authority on this subject?  Knowing your educational background would really be illuminating for this discussion and would perhaps offer us all a perspective from which we could approach discussions with you (e.g. someone with a mathematics degree approaches topics differently than someone with a degree in computer science or history).  I would love to be here every day but I work nearly 50 hours a week at a DoE research facility and I don't have time to get online repeat what I've said before and to spend my time arguing about something which is common scientific knowledge. I think it is time for a peer-review of this article itself.  And we're wasting time in these discussions rather than making bold edits on the article.  Cheers, Astrobayes 20:41, 7 July 2006 (UTC)
thread_title:  Sources, Education, and Peer-Review