Maxwell's demon, rectifiers, and the second law: Computer simulation of Smoluchowski's trapdoor

摘要

We have simulated numerically an automated version of Maxwell's demoninspired by Smoluchowski's ideas of 1912. Two gas chambers of equal volume areconnected via an opening that is covered by a trapdoor. The trapdoor can opento the left but not to the right, and is intended to rectify naturallyoccurring fluctuations in density between the two chambers. Our results confirmthat though the trapdoor behaves as a rectifier when large density differencesare imposed by external means, it can not extract useful work from the thermalmotion of the molecules when left on its own.