Time is not what you think it is. Neither are you. Welcome to a world where participants in psychology experiments respond to pictures they haven't seen yet ... where physicists influence the past behavior of a light beam by measuring its photons now ... and where dreamers and writers literally remember their future. This landmark study explores the principles that allow the future to affect the present, and the present to affect the past, without causing paradox. It also deconstructs the powerful taboos that, for centuries, have kept mainstream science from taking phenomena like retrocausation and precognition seriously. We are four-dimensional creatures, and sometimes we are even caught in time loops-self-fulfilling prophecies where effects become their own causes.