Everyone is curious about life in the Universe, UFOs and whether ET is out there. Over the course of his 30-year career as an astrophysicist, Adam Frank has consistently been asked about the possibility of intelligent life in the universe. He takes us on a journey to all that we know about the possibility of life outside planet Earth and shows us the cutting-edge science that has brought us to this unique moment in human history: the one where we go find out for ourselves. Drawing from his own work and that of other scientists studying the possibility of alien life, he brings together the latest scientific thinking, data, ideas, and discoveries to equip us with the critical facts as we stand at what may be the last moment in human history where we still believe we are all alone. This book is about everything we do—and do not—know about life, intelligent or otherwise beyond Earth.