Well, if you
really want to know, maybe look into Sean Carroll's book
From Eternity to Here....
"Carroll argues that "understanding the arrow of time is a matter of understanding the origin of the universe" and in his explanations relies on the second law of thermodynamics, which states that all systems in the Universe tend to become more and more disorganized (increase in entropy). His proposed explanation for the arrow of time is based on ideas that go back to Ludwig Boltzmann, an Austrian physicist of the 1870s."