You are reading the word "now" right now. But what does that mean? What makes the
ephemeral moment "now" so special? Its enigmatic character has bedeviled philosophers, priests, and modern-day physicists from Augustine to Einstein and beyond. Einstein showed that the flow of time is affected by both velocity and gravity, yet he despaired at his failure to explain the meaning of "now." Equally puzzling: why does time flow? Some physicists have given up trying to understand, and call the flow of time an illusion, but the eminent experimentalist physicist Richard A. Muller protests. He says physics should explain reality, not deny it. In "Now: The Physics of Time," Muller does more than poke holes in past ideas; he crafts his own revolutionary theory, one that makes testable predictions. He begins by laying out a firm and remarkably clear explanation of the physics building blocks of his theory: relativity, entropy, entanglement, antimatter, and the Big Bang. With the stage then set, he reveals a startling way forward. Below is an excerpt from Muller's "Now: The Physics of Time" (W. W. Norton & Company, 2016). https://www.livescience.com/56183-book-excerpt-now-the-physics-of-time.html