other words, if the expansion rate and the gravitational force had not been very precisely balanced indeed, the universe would have been either very short-lived or very dull. The other thing that’s just right about the big bang is the smoothness or evenness of the “explosion,” what scientists call its isotropy. Back in the 1980s, cosmologists figured out that if the universe did begin with a big bang, it would have needed to result in an almost, but not quite, perfectly isotropic distribution of