Conceived and published in recognition of the Bulletin of the Atomic Scientist's 75th year of publication, Now, Then, and the Future consists of two distinct collections of distinguished articles that are meant to comment on one another. The opening section of the book focuses on 21st century challenges and asks a diverse cast of respected strategic thinkers and doers of the 21st century-including two Nobel Prize laureates-to look forward a decade or two, and to answer a general question: Where might the Bulletin and its readers most profitably focus their attention as they work to keep the Doomsday Clock from striking midnight? The book's latter portion of consists of republications of noteworthy pieces that appeared in the Bulletin over the last seven-and-a-half decades. This retrospective is not comprehensive could not possibly be, given the trove of famous authors and weighty subjects the magazine has ushered into print and pixels since 1945. Even so, this portion of the book includes major work by authors so acclaimed as to be easily identified by single names: Einstein, Oppenheimer, Gorbachev, Nixon, Kennedy. As is fitting for the prominence of its expert authors, Now, Then, and the Future begins with a foreword by one of the most influential public intellectuals of modern history, Noam Chomsky.The Bulletin of the Atomic Scientists, founded in 1945, covers nuclear issues, climate change and disruptive technology. Our coverage of these issues is based on a driving belief that humans can successfully manage the technologies they create. The Bulletin is also the nonprofit behind the iconic Doomsday Clock. Notable contributors and figures featured in the Bulletin include Albert Einstein, J. Robert Oppenheimer, Ruth Adams, Stephen Hawking, Christine Todd Whitman, U.S. Secretary of Defense William J. Perry, and multiple Nobel laureates. The Bulletin was founded after World War II by Manhattan Project scientists who "could not remain aloof to the consequences of their work." Our mission is to equip the public, policymakers, and scientists with the information needed to reduce man-made threats to our existence.