Talk:Entropic force

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I could throw a picture of rubber bands or something on here, but I bet we have something better available. -Craig Pemberton 08:44, 16 November 2009 (UTC)[reply]

I think the example of the particules diffusing in the volume is not a good example of an entropic force since in this case there is indeed a microscopic force acting. It is the force related to the multiple collisions experienced by each particule. When integrated at the macroscopic level, it translates into partial pressure which tends to equilibrate in the volume. An other example taken from the physical review letter paper on the subject would be more precise. AlexisGiauque (talk) 16:51, 14 March 2014 (UTC)-Alexis[reply]

I have removed it before I noticed your comment. Independently of your argument, picture should be related to examples. This article name is not a synonym to 'entropy' and content should reflect this difference. That this animation was here for so long shows how careless previous editors were and general misunderstanding of the concept. --Asterixf2 (talk) 17:36, 10 March 2016 (UTC)[reply]

De-emphasized speculative theories

I de-emphasized the new and speculative physics theories, interesting though they may be, to primarily focus on the chemistry examples which are ubiquitous and very important. See WP:UNDUE. I also deleted some explanations (like the galaxy collision and copper) that I thought were incorrect or misleading. We can put them back if there's a citation to a reliable source. (I would be surprised if there was.) The section still has citations to unpublished papers, and discussion of non-notable theories, so in my opinion it could be reduced even further. But I'll just leave it be for now. :-) --Steve (talk) 03:23, 3 June 2011 (UTC)[reply]

"On Wikipedia, notability is a test used by editors to decide whether a given topic warrants its own article." Therefore, this rule does not apply to the contents. In the contents of an article sum of knowledge should be represented, especially see Wikipedia:Neutral_point_of_view/FAQ#Pseudoscience with wp:due weight, wp:npov and wp:notcensored. --Asterixf2 (talk) 20:07, 10 March 2016 (UTC)[reply]

Controversial theories and bias

Controversial theories generally should be mentioned when external sources are available, including Wikipedia:Neutral_point_of_view/FAQ#Pseudoscience with wp:due weight, with wp:npov and wp:notcensored. "Speculative" is an inadequate description without external source claiming so, hence "Controversial" should be used instead. Before my edits this article was misrepresented and subtly ridiculed - not wp:npov. --Asterixf2 (talk) 18:41, 10 March 2016 (UTC)[reply]

MET

This concept should be mentioned Special:PermanentLink/708941331#Evolutionary_origin. I agree that it is a fringe theory. If you think my previous edit has given undue weight to the theory I may rewrite it, but I am convinced that it should be mentioned on grounds of wp:npov. I'd argue it is not pseudo-science but only fringe theory. It won't be given undue weight if it is mentioned in a section named "speculative". Even if it is pseudo-science in your opinion, that I don't share, it should be mentioned, see: Wikipedia:Neutral_point_of_view/FAQ#Pseudoscience and questionable science therein. Please also see use primary/self-published sources. If you don't agree please suggest alternative page for this concept to be mentioned as it is perhaps not notable enough to have its own article. --Asterixf2 (talk) 10:20, 8 March 2016 (UTC)[reply]

Please sign all your talk page messages with four tildes (~~~~). Thanks.

Without reliable wp:secondary sources the lot could be just as well plain nonsense. That's why we have this policy. Without such sources, any mention, however short, would i.m.o. be undue. - DVdm (talk) 11:16, 8 March 2016 (UTC)[reply]

I fully agree that it may be plain nonsense, but we are not to judge here. Some time ago people burned Giordano Bruno at stake for saying earth is not a center of universe. However, the source I have found cites no articles that are pseudo-science. The opposite is true, it is heavily backed up by scientific papers from arXiv and most of them were published in peer-reviewed journals. I simply find evolutionary perspective in physics severely underrepresented on wp wp:npov.

You said that it should not be mentioned, because it could be nonsense. Anticipating such response, I have explicitly provided link to wikipedia guidelines saying that even if it was pure pseudoscience (=nonsense) it should be mentioned with due weight Wikipedia:Neutral_point_of_view/FAQ#Pseudoscience. Also, I'd like to point out that most of niche pseudoscientific theories have their own pages. Because such page seems to be overkill I suggest mentioning it here, without full description of the theory in 'speculative' category of low category page. This is the least weight.

Last but not least, cited by you guidelines, clearly state that secondary sources are needed for interpretations, but are not necessary for straightforward descriptive statements about primary sources. --Asterixf2 (talk) 18:42, 8 March 2016 (UTC)[reply]

If a fringe theory is known only from primary sources, it is no allowed in wikipedia. We don't want kooks to flood wikipedia with nonsense. We discuss only those fringe theories which are widely discussed in reliable sources. Without secondary sources wikipedians cannot judge whether it is just plain idiotic kookery or a reasonable fringe theory. Staszek Lem (talk) 19:38, 8 March 2016 (UTC)[reply]

My central point is, as guidelines say Wikipedia:Neutral_point_of_view/FAQ#Pseudoscience, even if it is just plain idiotic kookery it should be on wikipedia with wp:due weight. However, I am willing to give it a pause, reconsider and perhaps return to discussion later. Thank you for opinion. --Asterixf2 (talk) 20:55, 8 March 2016 (UTC)[reply]

Due weight is not decided by a wikipedian on a whim, but according to the degree of coverage in the world outside wikipedia. If nobody comments on it, then

DueWeight=0

. Staszek Lem (talk) 00:13, 9 March 2016 (UTC)[reply]

I see you insist on continuing discussion. Most primary sources on physics are not commented on the internet because they are from a very narrow specialized domain. However, if you were to remove such references from wikipedia it would lose a lot of valuable content, impossible to find anywhere. Therefore, I don't agree with your argument. People looking specifically for 'entropic force' would like to find as much information as possible, especially about new approaches that are not discussed in less specific pages on entropy. I heard about theory from a physicist who discussed it and couldn't find information about it on wikipedia. That was my motivation to add it. In my opinion, your argument is again a miss. Please read wp:npov, Wikipedia:Neutral_point_of_view/FAQ#Pseudoscience, wp:due. Another motivation is that evolutionary perspective in physics is underrepresented (censored?) wp:npov. Perhaps I should create a new page on evolution of physical laws as concept became notable in recent years.--Asterixf2 (talk) 12:44, 9 March 2016 (UTC)[reply]

I have reverted ([1]) your last edits because you fail to get wp:CONSENSUS for it here. Continue this and you'll end up blocked for pushing wp:FRINGE and edit warring. - DVdm (talk) 14:05, 9 March 2016 (UTC)[reply]

You failed to recognize that I have not added the content discussed in this section and you reverted other good changes. If you have a prejudice (wp:prejudiced), don't edit this article wp:npov also pls. see wp:notcensored --Asterixf2 (talk) 14:09, 9 March 2016 (UTC)[reply]

See Wikipedia talk:WikiProject Physics#Possible fringe or nonsense at Entropic force. - DVdm (talk) 16:55, 9 March 2016 (UTC)[reply]

re: "primary sources on physics are not commented on the internet" As I see you are thoroughly confused about the ways wikipedia works. Internet is no the only source of wisdom for wikipedia. Please peruse WP:RS. Staszek Lem (talk) 19:51, 10 March 2016 (UTC)[reply]

1. Please do not generalize my position. It is easier to argue against more general points. Please also see: disagreement 2. Please see comment on content not on contributor and avoid personal remarks. 3. Primary source is the most reliable source. 4. for notability please see section above. 5. Thank you for your guidance and cooperation. --Asterixf2 (talk) 17:45, 12 March 2016 (UTC)[reply]

Please do not reinsert text for which consensus not reached yet. You failed to address my major objection: due weight of fringe theories is judged by its coverage in independent sources, not by opinions of wikipedians. See Wikipedia:Fringe theories: " For a fringe view to be discussed in an article about a mainstream idea, reliable sources must discuss the relationship of the two as a serious and substantial matter.". See Wikipedia:Fringe theories#Unwarranted promotion of fringe theories for more detail. Staszek Lem (talk) 16:28, 14 March 2016 (UTC)[reply]

Use separate subsection headings to discuss multiple changes; Keep discussions focused; Avoid excessive emphasis

WP:TALKNO Do not misrepresent other people This thread on talk page is about MET. However in your reply above you are probably talking about my revert of your edit that was not concerned with MET (in particular, I have not added MET even once again since starting this discussion). Therefore your statements may be misunderstood as related to MET. If you would like to discuss other issues/edits please create a new section on talk page to avoid confusing readers.

Please also see WP:AVOIDABUSE Always make clear what point you are addressing, especially in replies, Be concise; Keep the layout clear. --Asterixf2 (talk) 20:33, 14 March 2016 (UTC)[reply]

I was clearly talking about any fringe theories. Staszek Lem (talk) 21:15, 14 March 2016 (UTC)[reply]

As a rough consensus and wp:compromise I propose: "MET is a fringe theory that purports to describe an evolutionary mechanism by which entropic force emerges. Within this framework, it is argued that entropic force not only is not a symptom of other forces but that opposite is true - that other forces are entropic in origin [].". In "Controversial" section of low importance page (ancillary article). Please also see:

Compromise: Negotiation is a cooperative process whereby participants try to find a solution which meets the legitimate interests of both parties, which in the context of Wikipedia involves appropriate mention of all points of view in an article thus improving the quality of the article.,
Not censored: Wikipedia may contain content that some readers consider objectionable or offensive—even exceedingly so.,
wp:due. Moreover, I used two words with low importance connotations 'fringe', 'purports'. --Asterixf2 (talk) 18:31, 12 March 2016 (UTC)[reply]

Please provide independent reliable sources which support your text. Staszek Lem (talk) 16:35, 14 March 2016 (UTC)[reply]

It was never required for anything on wikipedia to have multiple independent reliable sources. This is against wp:notcensored. --Asterixf2 (talk) 20:16, 14 March 2016 (UTC)[reply]

Coverage by independent reliable sources is always required.T R 20:24, 14 March 2016 (UTC)[reply]

Are you sure that one reliable source is not enough by definition of reliable source? I don't see multiple citations by every statement on wikipedia. Please point to guidelines if you have something specific in mind. --Asterixf2 (talk) 20:36, 14 March 2016 (UTC)[reply]

Wikipedia rules require reliable sources independent of the subject. The authors of a fringe theory are obviously not independent of the subject. Staszek Lem (talk) 21:10, 14 March 2016 (UTC)[reply]

Primary source is by definition not independent of the subject. Please see WP:PRIMARYNOTBAD.

No it is not. And...? Staszek Lem (talk) 22:01, 14 March 2016 (UTC)[reply]

In the above discussion it says: "Some time ago people burned Giordano Bruno at stake for saying earth is not a center of universe." Was he guilty? GangofOne (talk) 22:21, 14 March 2016 (UTC)[reply]

Fringe theories

I deleted This piece per Wikipedia:Fringe theories: " For a fringe view to be discussed in an article about a mainstream idea, reliable sources must discuss the relationship of the two as a serious and substantial matter.". See Wikipedia:Fringe theories#Unwarranted promotion of fringe theories for more detail. The references provided are primary sources, expressing fringe opinions of the proponents. As such they do not belong to wikipedia. Staszek Lem (talk) 21:07, 14 March 2016 (UTC)[reply]

See the previous section for more discussion in the subject. Staszek Lem (talk) 21:14, 14 March 2016 (UTC)[reply]

3O request one of you posted a request for a third opinion on this dispute. Unfortunately I have to decline the formal request because there are already four editors involved, and other sources of dispute resolution are also being tried. However, I would note in passing that there is a difference between reliable sources and independent sources, which seems to have been lost in the above discussion. A publication in an academic journal is generally considered reliable, even if the authors are the proponents of the "fringe" theory. Vanamonde93 (talk) 21:48, 14 March 2016 (UTC)[reply]
- Exactly for this reason our policies speak of "independent reliable sources" when both qualifiers are required. For example, WP:FRINGE writes 'Claims must be based upon independent reliable sources.. Staszek Lem (talk) 21:59, 14 March 2016 (UTC)[reply]
  - Those developments from section "Other forces" are generally fringe, but they are important within narrow domain of entropic forces. A person looking for information on entropic forces would like to get information about various perspectives, developments and discussions in this domain. I think that it is better to include more content with wp:due weight. As far as my opinion is concerned, I may change my mind if you provide a convincing argument. Also, I would like to point out that User:Staszek Lem have recently edited the guidelines by specifically adding word 'independent'. Very strict guidelines lead to censorship which violates wp:notcensored Please see his edit. Furthermore, guidelines on wp:fringe clearly say that academic publications are usually the most reliable sources when they are available and arxiv is academic. --Asterixf2 (talk) 22:11, 14 March 2016 (UTC)[reply]
    - I am not objecting fringe theories. I am objecting fringe theories ignored by scientific community. If you claim they are "important within narrow domain of entropic forces", please provide a proof of this. In wikipedia, such a proof is in the form of an independent reliable sources. Of course any kokery is important for a particular krank who promotes it. Staszek Lem (talk) 22:23, 14 March 2016 (UTC)[reply]
    - "Independent" is the very essence of WP:FRINGE guideline. Its lede directly says ' Claims must be based upon independent reliable sources.' I merely added this clarification in another part. Since Asterixf2 contests this, I started the discussion in WT:FRINGE. Staszek Lem (talk) 22:23, 14 March 2016 (UTC)[reply]
      - Thank you for creating discussion. I have commented there. --Asterixf2 (talk) 22:39, 14 March 2016 (UTC)[reply]

Staszek Lem have you tried looking for reliable independent sources for the statements you have deleted? Even the Matt Visser article cited in the same section already serves as a reliable independent source for the statement that people have suggested entropic descriptions of EM and other gauge forces. (Which is about all that can be reliably said on the topic.T R 10:31, 15 March 2016 (UTC)[reply]

did you? Staszek Lem (talk) 19:30, 15 March 2016 (UTC)[reply]

yes.T R 19:49, 15 March 2016 (UTC)[reply]

Great. Finally something useful out of this bickering. Staszek Lem (talk) 22:32, 15 March 2016 (UTC)[reply]

For some people those topics were obviously and objectively important for the article and it literally does not matter if there are independent secondary sources found and mentioned or not. However the mentioned Visser content was added by me. --Asterixf2 (talk) 10:07, 16 March 2016 (UTC)[reply]

Sorry but you are very wrong there. Independent secondary sources are vital. If an physics idea was published and nobody bothered to respond to it in the physics literature, then obviously it is not worth mentioning (since quite clearly nobody cares). The only way to show that an idea is objectively and obviously important to a subject is to find an reliable independent source that comments on its relevance. Without the relevance to the subject is neither "obvious" nor "objective". This should not be a hard concept to grasp. Being new earns you some slack, but the sooner you come to grips to such basic and obvious editing principles, the more useful you will be as a Wikipedia editor.T R 11:28, 16 March 2016 (UTC)[reply]

But you are talking about something else than I did. I was not talking about showing something to others. For example a person that does not have even a basic general knowledge in zoology (or worse, that have a certain prejudice) could be tempted to delete various statements or sections in articles from this domain by judging them as fringe that is not accompanied by independent secondary sources (requiring effectively 2 reliable sources per claim). Such a behavior would not be constructive. And last but not least "obvious" and "objective" were assumptions about judgement of editors for the sake of argument. There is a lot of articles with plenty of knowledge without references and this knowledge is very appropriate for encyclopedia when written by a person that is qualified to do so. Furthermore, there is even a template ^{[citation needed]}... Wikipedia should not be overly prohibitive. Please also see WP:IMPERFECT and WP:PRESERVE. --Asterixf2 (talk) 14:37, 16 March 2016 (UTC)[reply]

On the other hand, if such "knowledge without references" is challenged for secondary sources by anyone, and none is or can be given, then that content will be removed, whether it was "written by a person that is qualified to do so" or not, because Wikipedia has no means to verify that qualification. The ultimate deciding factor will always be wp:consensus. For failing or refusing to accept that policy, a plethora of highly qualified content providers with spectacular credentials are now living with a permanent Wikipedia block or ban. - DVdm (talk) 15:01, 16 March 2016 (UTC)[reply]

I don't agree with how you approach and interpret policies in general, but I agree about consensus.--Asterixf2 (talk) 15:16, 16 March 2016 (UTC)[reply]

That sounds familiar. - DVdm (talk) 15:42, 16 March 2016 (UTC)[reply]

The argument of editor credentials works two ways. Sometimes an editor comes along that is extremely well-versed comes along who recognized that a statement sourced by a primary mostly-ignored-by-the-literature-source is total and utter gooblycock that is completely unrepresentative of the vast literature on the subject. It is good of such an editor removes such misinformation.T R 20:06, 16 March 2016 (UTC)[reply]

Per WP:ONEWAY this would not be appropriate material at Coulomb's law, but as it is here under a section heading that specifically marks the results as doubtful, I think its appropriate. Someone looking for information on entropic forces could find the mathematical line of argument useful whether or not electrostatic attraction is "actually" entropic. Rhoark (talk) 15:04, 24 March 2016 (UTC)[reply]

lead is faulty

The lead of this article is faulty. It is not a summary of the content of the article. Instead it is an attempt to argue a case for the validity of the concept 'entropic force'. The lead is not a place to argue for the basis of an article. It is a place to summarize such argument as may be in the body of the article.

The attempt at argument in the lead is faulty as an attempt at argument, irrespective of whether such an attempt should be in the lead. Currently, the lead reads:

In physics, an entropic force acting in a system is a force resulting from the entire system's thermodynamical tendency to increase its entropy, rather than from a particular underlying microscopic force.^[1]

For instance, the internal energy of an ideal gas depends only on its temperature, and not on the volume of its containing box, so it is not an energy effect that tends to increase the volume of the box as gas pressure does. This implies that the pressure of an ideal gas has an entropic origin. ^[2]

What is the origin of such an entropic force? The most general answer is that the effect of thermal fluctuations tends to bring a thermodynamic system toward a macroscopic state that corresponds to a maximum in the number of microscopic states (or micro-states) that are compatible with this macroscopic state. In other words, thermal fluctuations tend to bring a system toward its macroscopic state of maximum entropy. ^[2]

^ A history of thermodynamics: the doctrine of energy and entropy by Ingo Müller, p115
^ ^a ^b Taylor; Tabachnik (2013). "Entropic forces—making the connection between mechanics and thermodynamics in an exactly soluble model". European Journal of Physics. 34 (3).

Broadly speaking, that is nonsense. In a nutshell, it puts the cart before the horse. Thermodynamics does not explain the effects of forces; it describes them. Forces explain the effects that are described by thermodynamics. The faulty argument offered in the lead seeks to explain the effects through thermodynamics.

The first sentence of the lead contains this: "the entire system's thermodynamical tendency to increase its entropy". That is nonsense. A system does not have a tendency to increase its entropy. Entropy is a state variable or state function. It is defined only for a system that is accepted as being in its own state of internal thermodynamic equilibrium. Such an equilibrium is determined by the state variables and by the walls and surrounding physical conditions. If the entropy happens to be a state variable, it is given and it is nonsense to talk of its changing. If the entropy is a function of state, it is determined by the given state variables, the walls, and the surrounding conditions. It can change if those factors are changed by an external agency, but not as a result of the agency of the system. A system in its own state of internal thermodynamic equilibrium is not an agent; it has no agency. The phrase 'tendency to increase its entropy' mistakenly attributes agency to the system.

Similar argument could be offered to impugn the rest of the lead, but I think the above sample is probably enough.

I do not intend to try to edit this article, because I think it would cause me much misery to do so. But I offer the above opinion for local editors to include in their deliberations. It will be very hard for editors to find explicit reliable sources on this topic. None of the sources offered so far is reliable for the purpose of validating a notion of 'entropic force'. Reliability of sources is not determined only by such criteria as whether they are primary or secondary, or refereed or not. A source that says black is white is not reliable, no matter by what criteria it is assessed. There is an obligation that material that is posted in articles be reliably sourced. If reliability of sources for a topic cannot be assessed by a Wikipedia editor, he should not muddle on and hope for the best; he should remain silent on that topic. There is no obligation to report on anything in Wikipedia. Chjoaygame (talk) 20:53, 26 March 2016 (UTC)[reply]

@Chjoaygame: OK, so here goes. The conventional microscopic explanation of pressure is that it is due to the velocity of atoms hitting the walls of a box. By Newton's law of the conservation of momentum, each collision transfers a minute momentum impulse to the wall, generating a force, or a pressure, on average. All this is still true. However, there are more basic questions: where does velocity come from? Why do particles move? What is momentum, anyway? Both special relativity, and general relativity have something to say about these "more fundamental" questions. "But wait", you say, "what does general relativity got to do with it?" Well, we've got Hawking radiation for starters, and the Unruh effect, it's generalization to accelerated frames of reference. The quantum mechanical vacuum appears to be this rather complex thing that isn't understood, but in some ways, it behaves like an ideal gas, in other ways, like a superfluid (from the RHIC results on heavy ion collisions, but also because its a superconductor for color charge). This goes back to at least Dirac in the 1930's, 1940's (the Dirac sea). This culminates with Verlinde's ideas about entropic origins of gravitation. "But wait", you say, "what does this have to do with ordinary, conventional gas in a box?" Well, so again: we have 19th century laws of thermodynamics, such as "G = H-TdS" relating the Gibbs free energy G to the enthalpy H to the entropy S and these are used happily by chemists and materials scientists everywhere to design the latest and greatest metallic alloys and petroleum crackers and whatnot. So these laws also are "still true", and they seem to say that pressure is due to a change in entropy. So we've got two ends of a 19th-century stick here: one end of the stick is talking about ergodicity, and the other end is talking about the fundamental structure of space and time. "But wait", you might say, "joining up these two ends is just speculative work by over-edumacated theoretical particle physicists" which would be true, except the arrow of time does seem to have something to do with ergodicity, the so called "second law of thermodynamics" that relates time to entropy. "But wait" you say, "the second law is just an ordinary law." So why then is it that entropic forces seem to actually explain plain-old polymers in water? And then there's the bridge to particle physics, by means of the Casimir effect, which says that a "field", a bunch of waves/particles confined by boundaries, cause a force to be exerted on the boundaries: a pressure. Unlike the ideal gas, you can't explain the Casimir force with an "its just the pressure of particles bouncing off the walls", in part because this "pressure" depends on the shape (square boxes and round radar cavities experience distinct Casimir forces) and on the particles (spin-1/2 particles pull inwards, the Casimir force is used to explain quark confinement, see the chiral bag model for details.)

The current forefront of theoretical physics is in complete befuddlement about these seemingly "accidental" relationships between "unconnected" ideas. No one can quite figure out what it is, but it's got something to do with entropy: of the relative arrangement of "things" with regard to other "things", and somehow "time". Anyone who is complaining about the lack of progress in physics is simply asleep at the wheel: there could not be a more exciting time in physics, than now. Physics today is much like physics at the end of the 19th century: a bunch of disconnected ideas that have some unclear, befuddled relationship with each other, but what? This was right before the birth of both quantum mechanics and of relativity at the dawn of the 20th century. Lord Kelvin with his "nothing left to be done in physics" speech be damned. Once the dam breaks, no one will be complaining about the "lack of progress in physics" any more.

I don't know how to convert the above into a Wikipedia article. Maybe it should be a blog post. I dunno. Anyway, entropic force is the tip of the spear. 67.198.37.16 (talk) 21:36, 18 May 2024 (UTC)[reply]

Looking again at the lead, in particular at the reference to Ingo Müller p. 115, I see it as not a secondary source, and so not by itself a reliable source. I see it as argumentative on the part of its author, Müller, not his summary report of other authors' works. Thus it is a primary source. Müller's argument is hardly more than a word game. It boils down to this: 'let us define temperature as the type specimen of an entropic force'. Again, the lead is not the place for primary argumentation that is not a summary of the content of the article. I think the existence of this article is precarious.Chjoaygame (talk) 15:17, 5 November 2024 (UTC)[reply]

What?

After re-reading the 1st paragraph or two several times I realised this article is almost incomprehensible. Please make it at least readable by humans ? 178.255.168.77 (talk) 21:05, 4 May 2016 (UTC)[reply]

Agreed, this article is basically only readable to people that already understand entropic forces at a very high statistical mechanics level. I'll write down my thoughts for improvements, and then maybe I or someone else interested can start on them.

I propose an into rewrite that emphasizes the most common cases, such as pressure and springyness of chain molecules.
Considering entropic forces are common in in high school chemistry, I think the target audience for this article should be high school level, and the higher level definitions, such as the general mathematical form based on the Canonical Ensemble be moved further down. In practice very few people even use that formulation, usually relying on measured entropy values or problem specific calculations such as the ideal gas law.
I think the order of the examples should be by accessibility and obviousness, so the reader can build up to the harder ones. I would propose that ideal gas pressure come first, followed by the polymer chain model. Both involve consistent forces at the macroscopic scale (as opposed to say Brownian motion or diffusion where the "force" is a bunch of un-unified momentum exchanges). The hydrophobic and colloid example should be rewritten so that they can be understood easily without much background, but until then, let's keep them at the end because they are the hardest to understand.
We should probably add an example for osmotic pressure, as that connects world of macroscopic entropic forces of pressure with the microscopic world of diffusion.
The hydrophobic example and colloid example are impressively detailed, but only understandable to someone who has a wide ranging knowledge. They are also potentially a little confusing because there is a clear enthalpy effect involved as well (the hydrogen bonds squeeze out the nonpolar molecules).
I think adding the example of nonpolar large molecules condensing in a field of small molecules (macromolecular crowding) would be helpful. It is driven by the same entropic force of the hydrophobic example, but if all of the molecules involved are non-polar, it becomes clear that crowding causes condensation even in the absence of intermolecular attractions between solvent molecules. We could include a link to Depletion Force, but that seems to be limited to systems with 3 species, a big solute, little solute, and and littler solvent. I don't know what the name is for a depletion force that only involves two species, so help would be appreciated if anyone knows.

--Anuran (talk) 00:14, 29 April 2021 (UTC)[reply]

Colloids

I broadened the scope of the previous section on "Directional entropic forces" to discuss colloids more generally (and renamed it accordingly) because entropic forces are important there beyond just for directional entropic forces, and they weren't discussed elsewhere in the page. I migrated and edited version of the discussion of directional entropic forces to the page on depletion forces where they enter a bit more naturally. Entrophys (talk) 15:08, 14 June 2016 (UTC)[reply]

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Recent additions

Lvilench, I have reverted your recent additions for five reasons:

You shouldn't be adding content about your own work
You certainly shouldn't be adding content about your own original research
The lead should summarise the rest of the article, it's not the place for new content
You need to cite references in the approved way, see Help:Referencing for beginners (and they should't be to your own work)
You should not be adding material with so many redlinks

Maproom (talk) 20:07, 1 October 2018 (UTC)[reply]

Comparison with Maximal Entropy Random Walk?

I have worked on MERW (Maximal entropy random walk) which is also dynamics accordingly to the (Jaynes) maximal entropy principle. I have recently found this "Causal Entropic Force" PRL paper - at first I thought it is the same, but then realized they are quite different philosophies.

It would be interesting to understand this difference, especially which one suits physics best?

In standard diffusion (GRW) we choose single step accordingly to maximal entropy principle: e.g. using uniform distribution among single steps. We assume that the walker indeed makes random steps according to this distribution ("drunken sailor"). It has no localization property, e.g. for [0,1] range it predicts uniform stationary probability distribution rho=1 (e.g. wrongly predicts that semiconductor is a conductor).

In MERW we maximize average entropy production, or equivalently: assume uniform (/Boltzmann) probability distribution among paths. I see it as effective model: used only by us as safest assumption for object having a complex path we know nothing about. It has Anderson localization property (preventing conductance in semiconductor), e.g. predicting rho ~ sin^2 stationary probability distribution for [0,1] range, exactly as predicted by quantum mechanics: of ground state, what is generally true (we get the same formulas). It gives simple combinatorial explanation of Born rules (rho~psi^2), what e.g. allows for constructions of Bell violation.

If I properly understand, in this entropic force the object analyses space of future trajectories, what leads to force giving tendency to maximize this space of future trajectories?

Does it have a physical realization? Where exactly? Does it agree with quantum predictions (localization) - e.g. for [0,1] it should repel from boundaries, but is its stationary probability density exactly sin^2 as in QM? --Jarek Duda (talk) 13:32, 17 December 2019 (UTC)[reply]

@Jarek Duda: take a look at Casimir effect as the bridge to causal entropic force. Conventional Casimir effect is done using a boring old expansion in terms of standing waves/normal modes in a cavity. I would like to suggest a very different approach: there has been work on semi-classical (first order in hbar) expansions to quantum gas in a box. The wave-functions are then explicitly fractal space-filling curves evolving with

\exp(-iEt/\hbar )

dynamics, and so have constructive/destructive interference (e.g. if half of the box is empty, the wave functions are there, but interfere destructively, thus "empty"). I don't know how to relate a space-filling curve into a random walk, but it seems that one should be relatable to the other. Even if the box is completely empty, one should be able to perform a Casimir sum over states, which (I believe) should be equal to the entropic force. But I don't know how to do this calculation. 67.198.37.16 (talk) 22:16, 18 May 2024 (UTC)[reply]

Casimir effect is just a difference of field pressures due to boundary conditions, recreated already in hydrodynamics ( https://pubs.aip.org/aapt/ajp/article/77/12/1095/1042888/A-water-wave-analog-of-the-Casimir-effect , https://www.youtube.com/watch?v=lyXIHlulSQY ).

From random walk perspective, the basic question is e.g. of stationary probability distribution in [0,1] range - standard diffusion, chaos predict uniform rho=1 distribution, while QM and maximal entropy random walk predict rho~sin^2. Jarek Duda (talk) 07:45, 19 May 2024 (UTC)[reply]

My PhD thesis was on the Casimir effect. ☺ You posed a question. I was just offering up something to think about. 67.198.37.16 (talk) 05:01, 21 May 2024 (UTC)[reply]

article lacks a Wiki-reliable source

I have disagreed with Staszek Lem on occasion, but I can hardly disagree with his words lifted from above on this talk page:

If a fringe theory is known only from primary sources, it is no allowed in wikipedia. We don't want kooks to flood wikipedia with nonsense. We discuss only those fringe theories which are widely discussed in reliable sources. Without secondary sources wikipedians cannot judge whether it is just plain idiotic kookery or a reasonable fringe theory. Staszek Lem (talk) 19:38, 8 March 2016 (UTC)

Indeed, I can only endorse his words. This article is kookery that relies on a few primary sources, and lacks suitable secondary sources. I am not saying that it is 'idiotic kookery', but I am saying that it is kookery.

Entropy is an extensive state variable of a thermodynamic system. The second law of thermodynamics tells us that energy tends to spread through all available paths. Entropy is a measure of the extent of spread of energy, relative to temperature, its conjugate intensive state variable. The several intensive state variables, such as temperature, pressure, and concentration, can be thought of as 'driving' the spread of energy. I think it is not supported by adequate secondary sources to elevate this into an article on 'entropic force'. I think this article should be deleted.Chjoaygame (talk) 10:29, 30 July 2024 (UTC)[reply]

[1] A history of thermodynamics: the doctrine of energy and entropy by Ingo Müller, p115

[Taylor_2013-2] Taylor; Tabachnik (2013). "Entropic forces—making the connection between mechanics and thermodynamics in an exactly soluble model". European Journal of Physics. 34 (3).

[1]

[2]