Reports of UFOs were once ridiculed by government officials and military officers to discourage public interest in sightings of experimental aircraft and weapons tests over restricted areas of the United States, but public and private attitudes have slowly begun to shift. This groundbreaking volume focuses on the political, scientific, social, and security impacts of UAP (Unidentified Anomalous Phenomena) sightings that seem to defy both easy explanation and known physical principles. A pioneering, multidisciplinary effort, this book explores the big questions surrounding UAPs by offering a scientific assessment of the relationship between UAPs and the ongoing effort to search for extraterrestrial intelligent life, analyzing the security implications that have followed UAP sightings, and carefully thinking through the limits of our ability to understand the social implications of finding that humans are not the only intelligent life in the universe. The editors and contributors consider the profound effects that might follow if we are forced to overturn our assumptions about the nature of the cosmos and the human place within it.