表述热力学第二定律有各种说法,其实质都是指出某种特殊的具体过程的不可逆性。例如克劳胥斯的说法是“不可能把热从低温物体传到高温物体而不产生其他影响。”这种说法是指热传导的不可逆性。既然它是指具体过程的特殊性而言,就必然要有一定的条件。因为“一切个性都是有条件地暂时地存在的”。上述克氏说法的条件是指单纯的热传导过程,没有其他能量形式的转换,而且是指高温物体和低温物体所组成的体系而言的。倘若我们举出一个例子,如将煤和空气一起投入火红的炉子,煤和空气中的氧(我们所考察的系统)便发生化学变化,由于燃烧所释放出来的化学能,使得“体系”加热,即升温,这个过程却是从低温向高温迁移。粗看起来,似乎驳斥了克氏说法,但其实不然,这里已把化学能转化为热的能量转换过程加了进去。前提条件已经不同了,自然就不会有相同的结论。所以不能脱离条件来谈变化,把不同的特殊过程混淆在一起。第二定律的表述形式不管是以什么样的具体说法出现,最终可以归纳成孤立体系中的自发变化是熵增加的结论。严格地讲,自然界中是不存在真正的孤立体系的,因为“每一事物的运动都和它的周围其他事物互相联系着和互相影响着。”例如,地球上的任何体系 The second law of thermodynamics is expressed in various ways, and its essence is to point out the irreversibility of a particular specific process. For example, Clauss said “it is impossible to transfer heat from a cryogenic object to a hot object without any other impact.” This statement refers to the irreversibility of heat conduction. Since it refers to the particularity of the specific process, it must have certain conditions. Because “all personality is conditionally temporary existence.” The above conditions of Karl’s theory refer to the simple heat conduction process, there is no conversion of other energy forms, and the system composed of high-temperature objects and low-temperature objects. If we give an example, if coal and air are put into a fiery furnace, the chemical changes occur in the coal and in the oxygen in the air (the system we are examining), the “system” heats up due to the chemical energy released by the combustion , That is, warming, this process is from low temperature to high temperature migration. Roughly seems to have dismissed Kirschner’s assertion, but it is not true that the energy conversion process of converting chemical energy into heat has been added here. The preconditions have been different, naturally, will not have the same conclusion. Therefore, we can not talk about change from the conditions and confuse different special processes together. No matter what form the second law appears, it can be concluded that the spontaneous change in the isolated system is the conclusion that entropy increases. Strictly speaking, there is no real system of isolation in nature because “the movement of each thing is interrelated and interrelated with everything else around it.” For example, any system on Earth