Entropy and Disorder, cont.

•Isolated
systems tend toward greater disorder, and entropy is a measure of that disorder

•S = kB ln W

•kB is Boltzmann’s constant

•W
is a number proportional to the probability that the
system has a particular configuration

•This gives
the Second Law as a statement of what is most probably rather than what must be

•The Second
Law also defines the direction of time of all events as the direction in which the entropy of the universe increases