The Second Law and Boltzmann

The second law is associated with the direction of a process. It defines the fundamental property entropy, S, and states that in any real process the direction of the process corresponds to the direction in which the total entropy increases, that is, the entropy change of both the system and environment should in total result in a positive result or in equation form 

In other words, every process generates entropy. The best interpretation, in our opinion, of this important law is given by adopting a postulate by Boltzmann  

Standard textbooks give ample examples of how Q can be calculated [1]. 

Notice that the direction of the process and time have been determined This has been called the arrow of time [2], Time proceeds in the direction of entropy generation, that is, toward a state of greater probability for the total of the system and its environment, which, in the widest sense, makes up the universe. Finally, we wish to point out that an interesting implication of Equation 2.10 is that for substances in the perfect crystalline state at T = 0 K, the thermodynamic probability Q = 1 and thus S = 0. 

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