Book review: What If? (Randall Munroe)

I didn't study economics at high school. I studied the sciences instead, and physics was my favourite among them (in fact, my first stint as a university undergraduate was as a physics major). In physics class, it was easy to get sidetracked thinking of weird and wacky ways to use the formulas we were learning. The hero of these mathematical adventures was 'Frictionless Scott', a fictitious character unaffected by friction, but seemingly able to withstand severe punishment. We once calculated how far Frictionless Scott would move the moon out of its current orbit if he struck it while moving at 10 percent of the speed of light. We also calculated how far Frictionless Scott could hit a golf ball, with his head, while tethered to a one-kilometre-long rope (also frictionless, of course) being spun around on the end of a rotating helicopter rotor. We then calculated how far he could hit a bulldozer under the same conditions. Frictionless Scott took a real beating in my physics class.

Those sorts of absurd questions kept my friends and I entertained in class (and, oftentimes, outside of class). So, I was excited to read Randall Munroe's 2014 book, What If?, which Tim Harford has recommended a few times on his blog. What If provides "serious scientific answers to absurd hypothetical questions", which is pretty much what my friends and I were doing in physics. Some of the questions that Munroe addresses in the book include, "What would happen if you tried to hit a baseball pitched at 90 percent of the speed of light" (a firestorm would engulf the entire city), "Is it possible to build a jetpack using downward-firing machine guns" (surprisingly, yes it is), and "If a bullet with the density of a neutron star were fired from a handgun (ignoring the how) at the Earth's surface, would the Earth be destroyed?" (no, but there would be some weird gravitational effects).

Munroe is the author of the wildly popular online comic XKCD, which I have also been a fan of for a number of years (and which my students may recognise, because I sometimes use those comics in my lecture slides, and there is always at least one XKCD comic posted to my office door (along with sometimes Saturday Morning Breakfast Cereal, or PhD Comics). The humour is the same, albeit in slightly longer form, and illustrated with the same endearing stick-figures.

There's even a little bit of economics in the book, explaining why aliens would be unlikely to be able to detect our radio transmissions (in short, it is expensive to beam signals into space, and advertisers have figured out that it is more effective to concentrate on beaming those signals to potential consumers on Earth).

I really enjoyed this book. Not all of the questions were equally funny - those towards the beginning of the book tended to be better than those towards the end. However, the difference in my reactions was between a mild chuckle and a loud guffaw. If you're looking for a book to break up the monotony of teaching (or learning, or working) online and in-person, then I highly recommend this one. And more to come - I've been reading Munroe's more recent book How To, and I see that there is a sequel, What If? 2, due for release this month!