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arXiv 1408.6358cond-mat.stat-mech
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热力学第二定律与经典力学和量子力学的关系

On the relation between the second law of thermodynamics and classical and quantum mechanics

Barbara Drossel

摘要:

在统计力学的教科书中,人们经常发现基于经典力学、相空间和遍历性的论点来证明热力学第二定律。但是,经典力学的基本运动方程是确定性和可逆的,而热力学第二定律是不可逆的,不是确定性的,因为它指出,一个系统在接近平衡时忘记了它的过去。我认为热力学第二定律从经典力学的所有“推导”都包含了不属于经典力学的附加假设。玻尔兹曼的H定理也是如此。此外,我认为,在推导第二定律时使用的相空间的粗粒化不能被视为我们对系统微观状态的细节的无知的表达,而是反映了这样一个事实,即系统的状态是通过仅使用有限数量的比特来完全指定的,正如熵的概念所暗示的那样,它与一个封闭系统可以具有的不同微观状态的数量有关。虽然薛定谔方程所描述的量子力学将后一种说法置于坚实的基础之上,但它无法解释第二定律中固有的不可逆性和随机性。

英文摘要:

In textbooks on statistical mechanics, one finds often arguments based on classical mechanics, phase space and ergodicity in order to justify the second law of thermodynamics. However, the basic equations of motion of classical mechanics are deterministic and reversible, while the second law of thermodynamics is irreversible and not deterministic, because it states that a system forgets its past when approaching equilibrium. I argue that all "derivations" of the second law of thermodynamics from classical mechanics include additional assumptions that are not part of classical mechanics. The same holds for Boltzmann's H-theorem. Furthermore, I argue that the coarse-graining of phase-space that is used when deriving the second law cannot be viewed as an expression of our ignorance of the details of the microscopic state of the system, but reflects the fact that the state of a system is fully specified by using only a finite number of bits, as implied by the concept of entropy, which is related to the number of different microstates that a closed system can have. While quantum mechanics, as described by the Schroedinger equation, puts this latter statement on a firm ground, it cannot explain the irreversibility and stochasticity inherent in the second law.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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