DEMONS, ENGINES AND THE 2ND LAW
DEMONS, ENGINES AND THE 2ND LAW
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DOI：
10.1038/scientificamerican1187-108
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发表时间：
1987-11-01
影响因子：
3
通讯作者：
BENNETT, CH
中科院分区：
文献类型：
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作者：
BENNETT, CH
热力学第二定律的一种表现是，像冰箱这样产生温度不均匀的设备需要能量才能运行。相反，存在的温度相等可以被用来做有用的工作，例如蒸汽机，它利用热锅炉和冷冷凝器之间的温差。然而在1871年，苏格兰物理学家詹姆斯·克拉克·麦克斯韦在他的热论中提出，一个小到可以看到和处理单个分子的生物可能不受这一定律的约束。它也许能够在不做任何工作的情况下创造并维持性情上的差异：“……如果我们设想有这样一个人，他的官能十分敏锐，能够跟踪每一个分子的运动轨迹，那么，这样一个人，他的属性本质上仍然和我们自己的一样有限，他就能够做到我们目前所不能做到的事情。因为我们已经看到，在均匀温度下充满空气的容器中，分子的运动速度绝不是均匀的....现在让我们一口构成这样一个容器分为两个部分,a和B,由红利锡安有一个小洞,,,谁可以看到独特的分子,打开和关闭这个孔,以便只允许更快的分子通过从a到B,慢的,只有通过从B到他将因此,没有支出,提高B和tem perature降低的,热力学第二定律相矛盾的。”这种“存在”很快被称为麦克斯韦妖，因为它对事物的自然秩序具有深远的颠覆作用。首要
One manifestation of the sec ond law of thermodynamics is that such devices as refrigera tors, which create inequalities of tem perature, require energy in order to operate. Conversely, an existing in equality of temperature can be ex ploited to do useful work-for exam ple by a steam engine, which exploits the temperature difference between its hot boiler and its cold condenser. Yet in 1871 the Scottish physicist James Clerk Maxwell suggested, in his Theory of Heat, that a creature small enough to see and handle indi vidual molecules might be exempt from this law. It might be able to cre ate and sustain differences in temper ature without doing any work:"... if we conceive a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attri butes are still as essentially finite as our own, would be able to do what is at present impossible to us. For we have seen that the molecules in a vessel full of air at uniform tempera ture are moving with velocities by no means uniform.... Now let us sup pose that such a vessel is divided into two portions, A and B, by a divi sion in which there is a small hole, and that a being, who can see the in dividual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B, and only the slower ones to pass from B to A. He will thus, without expenditure of work, raise the tem perature of B and lower that of A, in contradiction to the second law of thermodynamics." The" being" soon came to be called Maxwell's demon, because of its far reaching subversive effects on the natural order of things. Chief among