In a blog post entitled “Why the Many-Worlds Interpretation of Quantum Mechanics Is Probably Correct,” Sean Carroll explains his strong belief in Hugh Everett III’s theory. It’s obvious that this universe results from a series of events, almost all of which could have produced some other outcome. So, there must be many, many possible universes, maybe not an infinite number, but a lot. Why this universe? Do all of these possible universes exist? The physicist Hugh Everett III thought that they do.