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arXiv 0704.2567cond-mat.stat-mech
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基于体积熵的热力学第二定律的力学证明

Mechanical Proof of the Second Law of Thermodynamics Based on Volume Entropy

Michele Campisi

摘要:

在以前的工作(M。坎皮西种马。历史。菲尔。M. P. 36(2005)275-290),我们已经基于广义亥姆霍兹定理解决了平衡热力学的力学基础。结果发现,体积熵提供了一个很好的力学模拟热力学熵,因为它满足热定理,它是一个绝热不变量。这个性质解释了克劳修斯原理($S_f \geq S_i$)中的“等于”符号,并表明如果考虑非绝热变换,体积熵可能解释"大于“符号(即熵增加定律)。基于微观(量子或经典)力学的原理,我们证明了,如果初始平衡满足概率降序的自然条件,那么对于绝缘系统上的一些外部功源进行的任意变换,体积熵的期望值不会降低。这可以看作是第二定律的一个严格的量子力学证明。我们讨论了这个结果与最小功原理的关系,并改进了以前的尝试。熵的自然演化是朝着更大的值,因为物质的自然状态是在正温度下。实际上,熵减定律在人工制备的负温度系统中也成立。

英文摘要:

In a previous work (M. Campisi. Stud. Hist. Phil. M. P. 36 (2005) 275-290) we have addressed the mechanical foundations of equilibrium thermodynamics on the basis of the Generalized Helmholtz Theorem. It was found that the volume entropy provides a good mechanical analogue of thermodynamic entropy because it satisfies the heat theorem and it is an adiabatic invariant. This property explains the ``equal'' sign in Clausius principle ($S_f \geq S_i$) in a purely mechanical way and suggests that the volume entropy might explain the ``larger than'' sign (i.e. the Law of Entropy Increase) if non adiabatic transformations were considered. Based on the principles of microscopic (quantum or classical) mechanics here we prove that, provided the initial equilibrium satisfy the natural condition of decreasing ordering of probabilities, the expectation value of the volume entropy cannot decrease for arbitrary transformations performed by some external sources of work on a insulated system. This can be regarded as a rigorous quantum mechanical proof of the Second Law. We discuss how this result relates to the Minimal Work Principle and improves over previous attempts. The natural evolution of entropy is towards larger values because the natural state of matter is at positive temperature. Actually the Law of Entropy Decrease holds in artificially prepared negative temperature systems.

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