Timeline for Existence of negative temperatures and the definition of entropy
Current License: CC BY-SA 3.0
9 events
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| Jul 12, 2014 at 0:09 | history | edited | Semola | CC BY-SA 3.0 |
added 255 characters in body; added 6 characters in body
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| Jul 9, 2014 at 20:15 | comment | added | Semola | [...]who would desire to make his life more complicated by introducing misleading notions? Especially when there exist a theory explaining things properly (using the right definition of entropy things works out!). I believe they made a mistake (quite arrogantly), and now they are trying to save the face.I see that even in the sentence "What are we to make of the fact that the Gibbs entropy satisfies certain exact mathematical theorems, as adduced by Dunkel and Hilbert": Dunkel&Hilbert did not show that Gibbs entropy satisfies certain theorems but that their paper was file with basics mistakes. | |
| Jul 9, 2014 at 20:11 | comment | added | Semola | I believe their comment is a way to try to justify the nonsense they published and try to save their faces (my opinion of course). I must admit I am not an expert in their field so they may have at least done some interesting work, but there is no doubt that they wrote misleading things/didnt quite catch what was going on. It's a bit like I am coin an experiment to find the acceleration a of an object of mass m when pushed with force F and then say "oh by the way we have just shown that the law $F=m\cdot a^2$ does not hold". Then they say "certain desired features".. desired by whom? [...] | |
| Jul 9, 2014 at 17:19 | comment | added | alarge | [...] For large systems, the theorems can be used to prove that the Boltzmann entropy acquires certain desired features. But if the exact theorems lead towards nonsensical conclusions (for example that the temperature diverges exponentially with system size), then what they are telling us is that the interpretation is wrong. The original position is seen to become untenable. With our viewpoint, negative temperatures are inevitable in systems with bounded energy spectra." | |
| Jul 9, 2014 at 17:18 | comment | added | alarge | Do you believe what is written in the comment is nonsense? "What are we to make of the fact that the Gibbs entropy satisfies certain exact mathematical theorems, as adduced by Dunkel and Hilbert. Of course we do not dispute these. Rather, we say that for small systems they are evidence of the well-known inequivalence of ensembles, and the difficulty in finding a suitable entropy definition. [...] | |
| Jul 9, 2014 at 17:07 | comment | added | Semola | The mathematicians I am referring to are [Dunkel and Hilbert ](arxiv.org/abs/1304.2066); This article is quite accessible (math is not really hard) and has references to those articles I believe to be wrong and it explains the use of diff. Entropies and temp. To sum up, quoting them "such findings can be attributed to the use of a popular yet inconsistent entropy definition, which violates fundamental thermodynamic relations and fails to produce sensible results for simple analytically tractable classical and quantum systems." Polite way to say 'go back to highschool'. | |
| Jul 9, 2014 at 17:03 | comment | added | Zo the Relativist | It's certainly not theoretically impossible for the energy of a system to be bounded from above but for the entropy to be unbounded, though. | |
| Jul 9, 2014 at 16:57 | comment | added | alarge | Thank you for the answer! Could you perhaps, just to make it unambiguous, write out who or what you mean when you write "that entropy", "original paper" and "those authors" etc? I think I know what you mean, but just in case. Would you also happen to have a reference to the proofs by mathematicians? | |
| Jul 9, 2014 at 16:47 | history | answered | Semola | CC BY-SA 3.0 |