辐射场的非平衡性与不可逆性

指出现有文献上的平衡与非平衡辐射的界定条件存在的问题，提出新的更全面的界定条件。证明在真空中的任意辐射场都是不存在熵产生的，其不可逆性只体现在，它只有同物质系统相互作用才可能回复到初态，而后一过程当辐射场与物质系统不全处于平衡态时总熵必定增加，但只就辐射场本身而言，熵则可增可减，可生可灭。辐射场与物质系统的非平衡性及不可逆性具有不同的特征。

Nonequilibrium and Irreversibility of Radiation

The imperfection of the condition to distinquish between equilibrium and nonequilibrium radiation in the references up to now is analyzed in detail, and a new more satisfactory distinquishing condition is presented. By theoretical analysis with concret example, it is shown that the radiation in vacuum (or an isolated radiation system )should be no entropy production, and its irrerversibility is only manifested in the fact that returning to initial state it must interact with matter and increase the total entropy of the radiation and matter when they are not in equilibrium simultaneously. The character of nonequilibrium and irreversibility between radiation and matter are essentially different.