I found out about this book when I sent a friend of mine my recent Imaginary Number Day article. She (a math major in college) replied that it made her day and let me know that this book recently came out. I've been familiar with Monroe since my grad school days, and he creates a popular webcomic called xkcd, which has a strong following by the extreme-math-or-science-nerd niche. (Monroe left a job at NASA to write XKCD full-time).

What If? 2 is the second book along the same lines as the subtitle promises: "Additional serious scientific answers to absurd hypothetical questions". That is precisely what this book is, a series of precise calculations and answers to ridiculous questions. As an example, here are a few questions I specifically enjoyed:

• What would happen if the Solar System was filled to soup out to Jupiter?
• If a T. Rex were released in New York City, how many humans a day would it need to consume its needed calorie intake?
• Can all the world's bananas fit inside all the world's churches? (Okay, for this one I'll give you the answer–yes)
• How many people would it take to build Rome in a day?

All of these, and more than 60 other questions are carefully explored and explained, often resulting in either ridiculous situations or apocalyptic disaster. Either way, Monroe's writing is always clever and the questions are fun to ponder. For someone who is an ENFP/Type-7 former scientist, this book is perfect zaniness for me.