Talk:Entropy/Archive 1

message: This talk page needs to have stuff dumped into an archive. Any dead arguments, or old and obsolete comments should be archived. Please move all the comments under one header, not only one. perhaps we can have one header that lists the headers in the archive. I've made a link to the non existant archive above. Fresheneesz 00:50, 9 December 2005 (UTC)
thread_title: Talk page needs cleaning

message: I read this article hoping to obtain an intuitive understanding of entropy.  Didn't get it.  And I don't think the problem is that the article is too "hard"; I don't think it would provide an intuitive grasp of the subject to any reader, however sophisticated.  Maybe the topic is too hard.  If nothing else, more examples (and examples less wedded to chemical engineering) would be welcome.
Perhaps it is unclear what I mean by "intuitive understanding".  I mean the ability to answer questions like these:
Consider my coffee cup as a thermodynamic system.  I drop an ice cube into it.  How does this affect the entropy?  I have introduced a big difference in temperature between two parts of the system, so the entropy decreases, right?  But coming at it from a different direction, it seems as though I have added heat to the system, by adding matter to it:  even though the ice is frozen, the ice molecules have some thermal energy.  So the entropy increases, right?
Is entropy meaningful outside the context of thermodynamic machines?  For example, is entropy defined at non-equilibrium states?  (The article sort of gives the impression that it isn't.  But lots of real-world systems are essentially never at equilibrium, so this would be a serious limitation.)
I'm not clear on how entropy, energy, and work are tied together.  How exactly is entropy related to the ability to do work?  The article states that when you reach the maximum entropy state, no more work can be done--states it, that is, but doesn't explain.  What is meant by "can't do work"--can't do significant, macroscopic work?
Can a supply of energy be referred to as "ordered" (i.e., capable of doing work)?  It seems by definition that heat is the only form of energy that increases entropy.  Are all other forms of energy equally "ordered" as far as entropy is concerned?  After some thought, my guess is that all other forms of energy can be used to do work; only thermal energy can become dispersed and unable to do work, and entropy is a function of the distribution of thermal energy in a system.  Am I getting warm?
The article talks about entropy of a system in relation to work done by the system.  What about work done within the system (as, by one part of the system on another part)?  Perhaps an equivalent way to put this question would be:  How does entropy relate to non-thermodynamic properties (like potential energy) of parts of a system?  If my previous guess is right, the only effect on entropy is when activity within the system converts other sorts of energy to "waste heat".
Entropy is defined as a function of the state of a system.  Does it make any sense to compare the entropy of one system to the entropy of some other system that contains entirely different matter?  For example, which has greater entropy: your average rock; or an ice crystal of the same mass at the same temperature?  Is the question meaningful?
Kindly don't answer the questions here, unless you just want to talk them through.  Improve the article instead.  Thanks!  Jorend 05:18, 24 Apr 2005 (UTC)
thread_title:  An intuitive understanding of entropy 

message: * Added Section 3 "Intuition and Entropy" and subsection 3.1 "Entropy in Cosmology"
* Added bullet definition recaps at top for: "thermal energy, thermal work, thermal entropy, statistical thermal entropy, principle of increasing entropy"
sitearm 16:38, 26 July 2005 (UTC)
thread_title:  Additions 

message: I'm not entirely sure what's happened here. The article is at Entropy, but Talk:Entropy redirects to Talk:Thermodynamic entropy. As far as I can see, the article used to be at Thermodynamic entropy; after Entropy was moved to Entropy (disambiguation), Thermodynamic entropy was moved to Entropy. Looks like the talk page was left behind. I'm going to delete the current Talk:Entropy (which is just, and has always been, a redirect) and move Talk:Thermodynamic entropy there to match the article. — Knowledge Seeker দ 06:13, 12 May 2005 (UTC)
thread_title:  Page move 

message: I removed the following,
:In the limiting case of a reversible cycle consisting of a continuous sequence of transformations,
::\oint \frac{dQ}{T} = 0 \,\! (reversible cycles)
:where the integral is taken over the entire cycle, and T is the temperature of the system at each point in the cycle. 
because a heat engine rarely uses a continuum of temperatures, and because it is pointless.Bo Jacoby 11:28, 16 September 2005 (UTC)
thread_title: definition of entropy

message: I think the entropy and disorder section was getting a little wordy. The  new addition was good in that it introduced the concept of Shannon entropy to the messy bedroom analogy, and I have tried to pare the argument in that section down to a simpler statement. PAR 18:39, 8 January 2006 (UTC)
thread_title:  Entropy and disorder 

message: About the reference to to the book "Entropy: A New World View". The article states it is "a notorious misinterpretation of entropy" and links to Foresight to prove it. But Foresight seems to be full of crap, they state that "Therefore, entropy can decline in a closed system", clearly not understanding what a closed system even is. How can you link to such an unreliable source? The book may over interpret some aspects of the law, but it still have a lot of good points and should not be categorical put down in that way. -- A human 14:21, 16 January 2006 (UTC)
replies: text: I am afraid that you misunderstand Foresight. Actually, Rifkin does not understand what a closed system is. Foresight says "Rifkin declares that the Earth is a closed system, exchanging energy but not matter with its surroundings, and that therefore "here on earth material entropy is continually increasing and must ultimately reach a maximum," making Earth's life falter and die." And in the context of Rifkin's (wrong) closed system definition, Foresight says "Rifkin himself states that "in science, only one uncompromising exception is enough to invalidate a law." This thought experiment, which mimics how natural salt deposits have formed on Earth, invalidates the law on which he founds his whole book. So do plants. Sunlight brings energy from space; heat radiated back into space carries away entropy (of which there is only one kind). Therefore, entropy can decline in a closed system and flowers can bloom on Earth for age upon age." That is meant to prove that Rifkin is wrong. I think that Entropy: A New World View deserves a harsh treatment. Rifkin utterly failed to understand Entropy. -- Shotgunlee 03:11, 17 January 2006 (UTC)
thread_title:  Entropy - A new world view 

message: This is a great article. I'm sure I would only make it worse if i were to try to add my two cents to it. but it would be nice if certain things were ummm aaa mentioned ... maybe dealt with .. maybe added to external links?? 
*Potential energy
*Useable energy
*Gravity
*Spacial distribution of energy
*photons
I have in mind data stuff somewhat like:
*
*
*
*
Context: On evolution "entropy is limited to heat" was changed to "entropy is about useable energy" was changed to "entropy is about spacial distribution of energy"  ... or something like that. WAS 4.250 03:46, 17 January 2006 (UTC)
thread_title: Great article

message: I'm a non-scientist, and this may as well have been in urdu for all I could understand of it. Aren't these articles supposed to be understandable by the average joe like me? ElectricRay 23:29, 22 January 2006 (UTC)
replies: text: I agree; I like that the article goes into detail, but it never comes from a nutshell, layman explanation. j_freeman 19:29, 24 January 2006 (UTC)
thread_title: Way too technical

message: By the conservation of energy, the net energy lost by the environment is equal to the work done by the engine. looks some what vague.What say?--Sahodaran 05:25, 8 February 2006 (UTC)
thread_title: This sentence

message: Anybody interested in joining to do a stub on the term: "corporate entropy"?  I keep coming across the term in many places.  For example, the (1999) 2nd Edition of the book Peopleware has a section on how to fight “corporate entropy”, Google shows all sorts of hits for the term, and you can find it used on many Blogs.  Does anyone know the origin of this term, i.e. who coined it or first used it in application?--Sadi Carnot 19:00, 20 February 2006 (UTC)
thread_title:  Stub proposal 

message: From the article:
If the universe can be considered to have increasing entropy, then, as Roger Penrose has pointed out, an important role in the disordering process is played by gravity, which causes dispersed matter to accumulate into stars, which collapse eventually into black holes. Jacob Bekenstein and Stephen Hawking have shown that black holes have the maximum possible entropy of any object of equal size. This makes them likely end points of all entropy-increasing processes.
What effect does hawking radiation have on this? I'm specifically thinking of the fact that black holes are unstable, and have a limited lifetime - which either contradicts the second law of thermodynamics or the statement that black holes have the maximum possible entropy. Mike Peel 13:18, 17 March 2006 (UTC)
thread_title:  Black holes & entropy