Book excerpt: From the creator of the wildly popular webcomic xkcd, hilarious and informative answers to important questions you probably never thought to ask Millions of people visit xkcd.com each week to read Randall Munroe's iconic webcomic. His stick-figure drawings about science, technology, language, and love have an enormous, dedicated following, as do his deeply researched answers to his fans' strangest questions. The queries he receives range from merely odd to downright diabolical: - What if I took a swim in a spent-nuclear-fuel pool? - Could you build a jetpack using downward-firing machine guns? - What if a Richter 15 earthquake hit New York City? - Are fire tornadoes possible? His responses are masterpieces of clarity and wit, gleefully and accurately explaining everything from the relativistic effects of a baseball pitched at near the speed of light to the many horrible ways you could die while building a periodic table out of all the actual elements. The book features new and never-before-answered questions, along with the most popular answers from the xkcd website. What If? is an informative feast for xkcd fans and anyone who loves to ponder the hypothetical.