Ever since it was first formulated a century and a half ago, the Second Law of thermodynamics (also known as the "law of entropy increase") has had an air of mystery about it. Why is it true? Is it even always true? In this book, Stephen Wolfram builds on his recent breakthroughs work in the foundations of physics to finally deliver a satisfying resolution to the central mystery of the Second Law, elegantly showing how it emerges as a general feature...