送交者: gyro 于 2010-05-26, 15:45:32:
回答: gyro, 这段文章有关布朗运动的研究历史的讨论该怎么评价? 由 Amsel 于 2010-05-26, 15:11:16:
I think what this means is the following. We know that thermodynamics is applicable to macroscopic systems, and we know that it is not applicable to individual molecules because thermodynamics laws arise as average statistical properties of many molecules. It does not make sense to apply thermodynamics to individual molecules. But what is the critical size for the applicability of thermodynamics? The fact that Brownian motion exists and can be observed under a microscope indicates that a micro-meter sized particle cannot be considered a macroscopic object, and thermodynamics should not be applied to such particles.
If Eistein thinks measurement of Brownian velocity is impossible, this quoted sentence is not where he expressed his opinion.