How do you define time? Is it an illusion? Can a measurement made at one location influence a measurement made a million miles away, before a light signal can get there? Why doesn’t the wind blow directly from a high-pressure region toward one of low pressure? Why are there pressure differences between different regions of the earth anyway? Is a vacuum nothing? What’s waving when a light wave passes through a vacuum? Why doesn’t the earliest sunset occur on the first day of winter? These questions, as well as many others are discussed in this book. It is a story of the questions that certain scientists were puzzling over, as well as the questions that their theories created. It helps us understand their theories, and appreciate their accomplishments, if we try to imagine their thoughts as they worked out their theories.