One of the world's most celebrated cosmologists presents her breakthrough explanation of our origins in the multiverse. What came before the Big Bang, and what exists outside of the universe it created? Until recently, scientists could only guess at what lay past the edge of spacetime. But as pioneering theoretical physicist Laura Mersini-Houghton explains, today new scientific tools are giving us the ability to peer beyond the limits of our universe and test our theories about what is there. Her ground-breaking research suggests that we sit in a quantum landscape whose peaks and valleys hide a multitude of other universes, and whose nature holds the secret to the origins of existence itself. In recent years, Mersini-Houghton's theory has been spectacularly vindicated with observational evidence, turning the multiverse from philosophical speculation to one of the most compelling and credible explanations of our universe's origins. In Before the Big Bang , she interweaves the story of how she arrived at her breakthrough insights with that of her journey from communist Albania, where she was born and brought up, to the West, showing how her unconventional path helped her to challenge orthodoxies and become one of the most courageous thinkers on the world stage of theoretical physics.