What If?

The stick-figure comics that Randall Munroe draws for xkcd.com draw a huge audience every week, and this book turns his most-asked reader questions into full-length answers. Readers want to know things like what would happen if a baseball were thrown at nearly the speed of light, or how a car at highway speed would fare hitting a speed bump, or how long humans could survive a robot uprising.

To answer them, Munroe builds computer simulations, digs through stacks of declassified military reports, works through differential equations, and speaks with nuclear reactor operators. Along the way he keeps his explanations light and funny, with xkcd comics scattered among the chapters. The answers frequently end in total human extinction or at least a spectacular blast.

The book combines brand-new questions that have never been answered on the website with revised, expanded versions of the site's most popular answers. Munroe, a former NASA roboticist, brings a scientist's habit of careful estimation to every scenario, however absurd it may be.