By most popular accounts, the universe started with a bang some 13.8 billion years ago. But what happened before the Big Bang? And how do we know it happened at all?

Cosmologist Niayesh Afshordi and science communicator Phil Halper offer a tour of the peculiar possibilities: bouncing and cyclic universes, time loops, creations from nothing, multiverses, black hole births, string theories, and holograms.

Incorporating insights from Afshordi's cutting-edge research and Halper's original interviews with scientists like Stephen Hawking, Roger Penrose, and Alan Guth, Afshordi and Halper compare these models for the origin of our origins, showing each theory's strengths and weaknesses and explaining new attempts to test these notions. But most of all, Afshordi and Halper show that this search is filled with wonder, discovery, and community—all essential for remembering a forgotten cosmic past.

Niayesh Afshordi is professor in the Department of Physics and Astronomy at the University of Waterloo and associate faculty at the Perimeter Institute for Theoretical Physics in Ontario, Canada. His prize-winning research focuses on competing models for the early universe, dark energy, dark matter, black holes, holography, and gravitational waves.

Phil Halper is a fellow of the Royal Astronomical Society and a science popularizer. He is the creator of the popular YouTube series Before the Big Bang, which has had several million views. His astronomy images have been featured in major media outlets including The Washington Post, the BBC, and The Guardian, and he has published several papers in peer-reviewed journals.