We earthlings have long fantasized, feared and hoped that we’re not alone in the universe. Yet somehow, our dreams of alien life only seem to feature the UFO-flying variety of creature. In “Life Everywhere: The Maverick Science of Astrobiology,” astronomer David Darling contends that “life” encompasses more than E.T. and the green-skinned go-go girls of “Star Trek.” Bacterial life-forms from other planets have the potential to profoundly affect our understanding of the cosmos, as well as ourselves. Darling expertly explores the accomplishments and goals of this young, controversial science and looks with great optimism to the possibility of discovering life on Mars, on the moons of Jupiter and even on planets outside our solar system.