摘要
The nature of the second law of thermodynamics is the irreversibility of time for the development of macroscopic systems,i.e.,“arrow of time”.However,Carnot theorem did just emphasize“reversibility”.Such a paradox,as the root of puzzledom in thermodynamics for more than 180 years.should be removed by an extended Carnot theorem,which becomes a new starting point for modernization of thermodynamics dissipline.