In the Beginning

Fans of The Big Bang Theory will know that “our whole universe was in a hot, dense state”— which is indeed how scientists often describe the earliest moments of the cosmos. The devil, though, is in the details. We’re pretty confident in the big bang model of cosmology (now slightly harder to google, thanks to the TV show), which says that the universe came into existence a bit less than 14 billion years ago and has been expanding and cooling ever since. But what was it, exactly, that banged? Was it a single bang? Could there have been multiple bangs leading to multiple universes? What, if anything, came before?

This is where Niayesh Afshordi and Phil Halper pick up the story in Battle of the Big Bang. Afshordi is an astrophysicist at the University of Waterloo and an associate faculty member at the Perimeter Institute for Theoretical Physics, and Halper is a science popularizer and YouTuber. They make a good pair: Afshordi handles the overall...