The seven articles in this book were originally published in Scientific American and bring together issues that are vital to contemporary discussions on extreme physics. Researchers investigate such subjects as a world in which spacetime is a fluid, the constants of nature change with time, and the universe with which we are familiar is just one of a virtually infinite number of universes. Sound too fantastic? Readers will learn that these scenarios reflect the current thinking of today's cutting-edge physicists. They will also learn how researchers are recreating the conditions of the infant universe, why gravity and mass are still surprising, and how physicists could soon use quantum black holes to explore the extra dimensions of space.