While it may seem indisputable that time flows in a linear fashion (from past to future), there are a number of philosophical and physical objections to this notion. In the quest to make sense of this conundrum, philosophers and physicists confront fascinating and irresistible questions such as whether effects can precede causes, and whether one can travel in time. In this book, eleven eminent scholars who stand at the boundary between physics and philosophy attempt to answer these questions. There are chapters by W. Unruh and H. Price on cosmology; A. Leggett, P. Stamp, and S. McCall on quantum theory; M. Barrett, E. Sober, and L. Sklar on thermodynamics, and P. Horwich and J. Earman on time travel. The book will be enjoyed by anyone of a speculative turn of mind fascinated by the puzzle of time.