Every year John Brockman, editor of the online salon Edge, puts forth a question that he hopes will inspire fascinating answers from leading scientists and thinkers, such as Steven Pinker, Jared Diamond, and Sherry Turkle. He has done it again. This time he asked, "What is your favorite deep, elegant, or beautiful explanation?" A multiplicity of answers are offered in the compact, accessible essays that form "This Explains Everything: Deep, Beautiful, and Elegant Theories of How the World Works" (Harper), edited by Brockman. If you want to increase the intellectual heft of your reading while keeping it entertaining, "This Explains Everything" will do nicely.