Our understanding of ourselves and the cosmos has advanced immeasurably over the last five hundred years of modern science yet many fundamental mysteries of existence persist. How did our Universe begin if it even had a beginning How big is it Whats at the bottom of a black hole How did life on Earth arise Are we alone Is time travel possibleThese mysteries define the threshold of the unknown. To explore that threshold is to gain a deeper understanding of just how far science has progressed. In The Known Unknowns bestselling popular science writer Lawrence Krauss explores sciences greatest known unknowns. Covering time space physical law life and consciousness Krauss introduces readers to the topics that will shape the state of science of the next few decades and invites us to ponder and appreciate the universe in which we live.