How did the universe begin? Did it have a beginning at all? These questions may have been the subject of speculation and debate for millennia, but they have not been widely discussed for the past forty years.

According to this new idea, there was a big bang, but this was not the beginning of space and time. In fact, in the version proposed by Neil Turok and myself, the big bang has occurred myriad times in our universe's past, repeating at regular intervals during which galaxies, stars, planets, and life form anew. The result is a "cyclic universe" in which cycles extend far into the past and into the future—and perhaps forever.