What If? author and XKCD creator Randall Munroe previews his next book

After Randall Munroe's blockbuster science book What If? spent 64 weeks on the New York Times best-seller list, he knows his readers still have lots of questions. The author, who is also the creator of the hugely popular webcomic XKCD, fielded queries ranging from the curious to the absurd and compiled them all into the follow-up book What If? 2 — and EW has the exclusive first details, starting with the cover reveal above.

Munroe promises to cover everything from thermodynamics to swing-set physics to what would happen if you "rode a fire pole from the moon back to earth," all of it told through his signature stick-figure comics. The book won't hit shelves until Sept. 13, but to tide you over until then, the author answered our burning questions about his reading background and how he gets it all done.

What is the first thing — ever — that you remember writing?

The first thing I remember writing down was a sentence I copied out of a book I found on the shelf of my first-grade classroom. The book was titled I Can Read About Horses, and one page said, "The fastest horses are called thoroughbreds. A champion thoroughbred can run a mile a minute." I carefully copied "A CHAMPION THOROUGHBRED CAN RUN A MILE A MINUTE" onto a piece of paper and was very proud of myself.

I later learned that thoroughbreds can't run anywhere near 60 miles per hour — Secretariat only ran about 40 — although quarter horses can get close to those speeds partway through their sprints. (I love that the very first fact I wrote down is still sending me down research rabbit holes decades later.)

Which book is at the top of your current to-read list?

My friend Janelle Shane just recommended the short story And Then There Were (N-One), by Sarah Pinsker, so I think that's next on my list.

Where do you write?

I have a regular desk, but I do a surprising number of calculations on my phone while I'm walking or hanging out with friends. It's an awful way to do math, typing into an input box on a tiny screen with a cursor that's hard to move around, but sometimes a weird question comes up in conversation (like "How many calories would the sandworm monsters in Tremors have to burn to dig those tunnels?") and I get so curious about the answer that I can't pay attention to anything else until I figure it out.

Which book made you a forever reader?

I'll always have a soft spot for A Wrinkle in Time, by Madeleine L'Engle. It really conveyed the sense that when you're sitting in your house on a stormy night, you're also sitting on the brink of a vast, scary, beautiful universe — and the hope that if you think about it all hard enough, maybe someday you can understand how it works.

If you could change one thing about any of your books, what would it be?

In Thing Explainer, I explained how things worked using only the thousand most common English words. It was a fun challenge, but the thing that bugged me most was that none of the words for "rope" made the list. Rope, string, cable, and wire were all just barely outside the top 1,000. Try describing how a sailing ship works without any of those words! I'd like to get people to say "rope" or "string" just a little more often so one of them can make the top 1,000 and make that challenge easier.

What is your favorite part of What If? 2?

I've gotten a few questions from little kids. The questions from kids are always my favorites, because they ask simple, straightforward questions that have extremely dramatic consequences. One of the most catastrophic scenarios in the book is a question from a kid about soup.

Write a movie poster tag line for the book:

I'm torn between "What If? 2: What if" and "What If? 2: What else." I think I'd just go with "What If? 2: This fall, you'll — KABOOM — learn what — PEW PEW PEW — happens when — [rest of sentence inaudible due to explosions]."

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