The World Science Festival likes to tackle big ideas, and this year was no exception, with a session devoted to everything—more specifically, why our Universe is here and whether it might be part of a larger whole. This isn't the easiest of topics, even for someone who's followed science carefully for the last few years, but the panelists did an admirable job of making their presentations reasonably approachable. It seems that the easiest way to explain the existence of our Universe may involve a process that will inevitably produce an infinite number of other universes. The details, however, are considerably more complicated.

For the topic at hand, however, the use of the term "universe" also gets a bit slippery. Does it mean our own, familiar universe, which may be one of an infinite number of similar items? Or does it apply to the larger whole, within which those items are an inevitable result of the process of inflation?