"A child's eyes open, and light floods in." Light is one of the most important parts of our lives, through which we perceive the universe around us. L. Riofrio worked as a scientist at NASA in Houston. While studying the Moon at Johnson Space Center, Riofrio found evidence that light is slowing down. In evocative and easy-to-read prose, Riofrio describes the history of light, starting with a child's eyes opening. The book contains just one equation