Nonfiction
Interview: Brian Greene
Because there isn’t just one flavor of parallel universe—there’s a version that comes out of quantum mechanics, there’s a version that comes out of cosmology, a version that comes out of string theory, and so forth. But one thing that they do share is it’s pretty tough, if not impossible, to go from one universe to another in any of these versions—in any conventional notion of what it would mean to travel from one universe to another.