A revolutionary new account of our universe's creation--and a breathtaking exploration of the landscape from which we sprang--from one of the world's most celebrated cosmologists 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. However, as pioneering theoretical physicist Laura Mersini-Houghton explains, new scientific tools are now giving us the ability to peer beyond the limits of our universe and to test our theories about what is there. Her groundbreaking research suggests that we sit in a quantum landscape whose peaks and valleys hide a multitude of other universes, and whose topography holds the secret to the origins of existence itself. Recent evidence has revealed the signatures of one such sibling universe in our own night sky, confirming Mersini-Houghton's theoretical work and offering humbling proof that our universe is just one member of an unending cosmic family. A mind-expanding journey through the multiverse, Before the Big Bang will reshape our understanding of humanity's place in the unfathomable vastness of the cosmos.