With this book and with XKCD, you're a kid with a chemistry set all over again. [Randall Munroe's] enthusiasm for all things scientific is infectious . . . required reading for grown-ups, it's just fun to remember that science is really, really cool ― REGISTER

Smart answers to silly questions: Randall Munroe reveals all ― GUARDIAN

What If? maintains a delightfully free-wheeling tone throughout, especially when complicated calculations lead to whimsical results. Despite all the hard facts and gigantic numbers, it never feels like a textbook-and you don't have to be a rocket scientist to enjoy it ― ENTERTAINMENT WEEKLY

The best bathroom book you'll ever buy...Munroe takes inane, useless and often quite pointless questions asked by real humans (mostly sent to him through his website), and turns them into beautiful expositions on the impossible that illuminate the furthest reaches, almost to the limits, of the modern sciences .The first chapter, "Q. What would happen if the Earth and all terrestrial objects suddenly stopped spinning, but the atmosphere retained its velocity?" ends with the anthropomorphized moon worrying over the state of the Earth, and, with the gravity generated by its own rotation around the Earth, saving our dying planet. The physics are real; so is the emotional content. . . The answers are all illustrated with xkcd's trademark stick figures.. . . . and these are eminently approachable ― NEWSWEEK

Brilliant ― ROLLING STONE

What If? includes old favorites, new inquiries and the mix of expert research and accessible wit that has made Munroe a favorite among both geeks and laymen ― TIME

Munroe's brilliant What-If? column-which features scientifically rigorous, utterly absurd answers to ridiculous hypotheticals-has been on the bestseller lists since it was announced in March. Today, it hits shelves and: It. Is. A. Triumph ― BOINGBOING

[What If?] has solved my annual birthday-present and holiday-gift dilemmas for a large group of people . . . What makes Munroe's work so fantastic is a combination of two elements: his commitment to trying to answer even the weirdest question with solid science, and his undeniable sense of humour. So, here's a "What If?" from me: If everyone on the planet simultaneously bought a copy of this book, stopped what they were doing and read it cover to cover, would modern civilization and our global economy collapse? It's worth trying the experiment. ― HUFFINGTON POST

For the record, I'm loving XKCD's What If -- 'Dear Abby for mad scientists' ― NEIL GAIMAN

Munroe has hit on a wonderful form of science and engineering communication that can do so much-extolling the value of analytical thinking, examining data, and doing back-of-the-envelope calculations-while entertaining readers at the same time . . . an incredibly fun book with quirky, hand-drawn pictures ― AMERICAN SCIENTIST

Randall Munroe is the creator of the webcomic xkcd and bestselling author of What If?, Thing Explainer and xkcd: Volume 0. Randall was born in Easton, Pennsylvania, and grew up outside Richmond, Virginia. After studying physics at Christopher Newport University, he got a job building robots at NASA Langley Research Center. In 2006 he left NASA to draw comics on the internet full time, and has since been nominated for a Hugo Award three times. The International Astronomical Union recently named an asteroid after him: asteroid 4942 Munroe is big enough to cause mass extinction if it ever hits a planet like Earth.