Theodore Gray is the author of "The Elements: A Visual Exploration of Every Known Atom in the Universe"; "Theo Gray's Mad Science: Experiments You Can Do At Home, But Probably Shouldn't"; "Mad Science 2: Experiments You Can Do At Home, But Still Probably Shouldn't"; and "Popular Science" magazine's "Gray Matter" column. With his company Touch Press, Gray is the developer of best-selling iPad and iPhone apps, including "The Elements", "Solar System", "Disney Animated", "The Orchestra", T"he Waste Land", and "Skulls" by Simon Winchester. He lives in Urbana, Illinois.