What If? (Randall Munroe) Books in Order

The What If? books begin with the kind of question that is easy to laugh at and hard to answer. What would happen if everyone opened their freezer doors at once? Could a person ride a fire pole from the Moon to Earth? How bad would it be to hit a baseball at an impossible speed?

Randall Munroe treats those questions as real problems. He follows the physics, engineering, biology, and astronomy wherever they lead, using calculations, research, diagrams, and stick-figure illustrations to show the results. Sometimes the answer is fairly practical. Quite often, it ends with a warning that the planet, the atmosphere, or the person asking the question would be in serious trouble.

The questions are absurd. The science is not.

The first book, What If? Serious Scientific Answers to Absurd Hypothetical Questions, collects popular reader questions from Munroe's question-and-answer project alongside new material. Each chapter stands on its own, so readers can dip in anywhere. The fun comes from watching a harmless-sounding premise become a chain of real-world consequences, one calculation at a time.

What If? 2 returns to the same format with a fresh set of questions and updated research. It considers extreme buildings, dinosaur-sized meals, geysers, lava, weather, travel, and other ideas that sound simple until basic laws of nature get involved. Munroe's approach is playful, but he does not wave away the difficult parts. He explains why an idea fails, what would happen first, and which detail turns out to matter most.

There is no continuing plot or recurring cast beyond Munroe's visual style and curious point of view. The books work as a series because they share a method: start with a strange premise, gather what is known, make reasonable assumptions, and see how far the consequences go. The answers are full of jokes, but the reasoning stays visible on the page.

Start with What If? for the clearest introduction to the format, then move to What If? 2 when you want more. These are good books for readers who like science without wanting a textbook, or for anyone who has ever interrupted a normal conversation with a question beginning, “Okay, but what if?”