Talk:Entropy (order and disorder)

message: I've revised this section a bit to clarify the process. However, the bit about the second law seems a bit dodgy as magnetic energy clearly goes through the insulated chamber – perhaps you could reconsider that bit? .. dave souza, talk 11:16, 17 November 2006 (UTC)
replies: text: I think the discussion is incorrect here.  If the magnetic field is reduced adiabatically, the amount of order in the spin has to remain the same (Delta S = 0).   The temperature does indeed decrease because the entropy is roughly a function of B mu / T, and in order to keep entropy fixed with decreasing B, then T must also drop.  —Preceding unsigned comment added by 135.245.8.36 (talk) 19:57, 27 April 2008 (UTC)
replies: text: Have a look at the cited NASA page on the effect – it's to do with the energy involved in aligning the magnetic field, rather than any appearance of "order" or "disorder". .. dave souza, talk 20:07, 27 April 2008 (UTC)
thread_title: Adiabatic demagnetization

message: This section is giving too much prominence to the hobbyhorse of a few chemistry teachers.  This Frank L. Lambert, in particular, is just someone with a bee in his bonnet.  The entire section should just be removed. 98.109.238.95 (talk) 19:32, 24 June 2013 (UTC)
replies: text: Dear anon, you appear to disagree with a number of very good textbooks. Perhaps you prefer a disordered approach, but this method is useful for many people. . dave souza, talk 20:48, 24 June 2013 (UTC)

text: Taking the more recent and concrete example you cite, Thermodynamics Demystified doesn't use the terms "order" or "disorder" to explain entropy, so it seems to have taken on board the difficulties introduced by these terms. When were the others published? . . dave souza, talk 05:45, 25 June 2013 (UTC)
replies: text: The "Difficulties" section is at a low level. It is not scientific argumentation or even good pedagogy; it's a series of unfocused metaphors to the point of ranting. 84.227.244.192 (talk) 01:18, 16 September 2014 (UTC)
thread_title:  The "difficulties" section, or, the dispersal section. 

message: This entire Wikipedia page seems to be devoted to a controversy rather than scientific exposition. Perhaps it should be retitled to reflect that? 
Or -- since it is pretty muddy -- just thrown away? 
In the introductory paragraphs:
1) ...entropy is commonly associated with the amount of order, disorder, or chaos... 
Not what it is, but what people think about it.
2) This stems from Rudolf Clausius' 1862 assertion... 
For the next paragraph, we fly through through a historical development rather than giving a definition. 
3) In the 2002 encyclopedia Encarta, for example, entropy is defined as a thermodynamic property which serves as a measure of how close a system is to equilibrium, as well as a measure of the disorder in the system. 
This is not a definition either.
4) In the context of entropy, "perfect internal disorder" is synonymous with "equilibrium", but since that definition is so far different from the usual definition implied in normal speech, the use of the term in science has caused a great deal of confusion and misunderstanding. 
What definition? Do you mean the "synonymy" of perfect internal disorder with equilibrium? That is not a definition in a scientific sense; I cannot even tell which term is intended here to be the definiendum.
5) Locally, the entropy can be lowered by external action. This applies to machines, such as a refrigerator, where the entropy in the cold chamber is being reduced, and to living organisms. This local decrease in entropy is, however, only possible at the expense of an entropy increase in the surroundings. 
This instructive commentary seems entirely out of place in the introduction. You have not even told the reader that entropy increases, and in any case, what does this have to do with entropy as disorder? Something, I'm sure, but it hasn't been said here.
The whole article continues in this way. Spongy.
The article may have one positive function: to serve as a dump site for these kinds of controversies while other articles get freed of them. 84.227.245.245 (talk) 10:51, 15 September 2014 (UTC)
replies: text: As an example of a thermodynamics article that exhibits all the historical talk and verbal wordage that I criticized in this article, yet manages to be crisp and informative, see diathermal wall.  84.227.255.16 (talk) 08:08, 16 September 2014 (UTC)
thread_title:  Disorder 

message: Part of the confusion regarding entropy and disorder is that we frequently only consider structural or spatial ordering (phase space) when analyzing the entropy of a system. A good example of where this can lead to mistakes is the entropy of helium-3 in its liquid and solid phases. If one only considers the spatial degrees of freedom of a quantity of helium-3, one would be led to believe that the liquid phase was more disordered (greater entropy) than the solid phase, since the size of the spatial phase space of the liquid phase is greater than that of the solid phase.
But that is not always the case. Solid helium-3 can have greater entropy than liquid helium-3 due to the greater spin disorder (greater size of the spin phase space) of solid helium-3 than liquid helium-3. In other words, when you consider both the degree of disorder of the spins and the degree of disorder of the positions, the solid phase has more overall disorder than the liquid phase, even though the former has less positional/spatial disorder than the latter.
For a good discussion of this phenomenon see https://physics.stackexchange.com/questions/410550/why-is-the-latent-heat-of-fusion-of-helium-3-a-negative-quantity . For the source of the quote (made in a discussion of the same phenomenon), see https://books.google.com/books/about/First_Order_Phase_Transitions_of_Magneti.html?id=rgZADwAAQBAJ . Here is context of the quote:
Entropy has contributions from all phase space, and disorder is not solely about structural disorder. All liquids are more [structurally NLG] disordered than their corresponding solid phases in terms of [the the greater volume of their positional/spatial phase space determined by NLG] their positions in real space, and this governs the common observation that solids melt on heating. Nevertheless, liquid helium-3 is a quantum Fermi liquid and is highly ordered in momentum [phase NLG] space [which is independent of positional/spatial phase space NLG]. The entropy of the liquid [due to momentum phase space NLG] varies approximately linearly with T as [(T/Tf*)ln2], where Tf* is the effective Fermi temperature. On the other hand, the spins in solid helium-3 are not aligned until it is cooled to about 1 mK, and its [momentum space NLG] entropy is approximately constant at Rln2 [where R is the gas constant == Boltzmann's constant per mole NLG] above about 10 mK.
...
The statement "increasing the temperature causes a transition to the phase with higher entropy" has no known exception.
...
Entropy depends on the total disorder and not just on structural disorder.
I think this example would help illuminate the critical point that there are different kinds of disorder/degrees of freedom/phase spaces, and all of them must be analyzed when measuring entropy. -- Nick (talk) 17:44, 4 September 2019 (UTC)
thread_title:  "Entropy depends  on the total disorder and not just on structural disorder."