There really isn’t much to say about this one, except that if you’re a fan of xkcd and its blend of science, geekiness, humor and pathos, What If? delivers these in spades. In it, Munroe plumbs obscure research papers and runs computer simulations that get him banned from Wolfram Alpha in order to research answers to absurd hypothetical questions that readers pose to him on his website.
A lot of these questions tend to fixate on solutions that would cause thermonuclear explosions or other terrible outcomes, but that’s really what makes the book interesting. When people think in extremes, physical reality, and its range of potential outcomes, runs far, far wider than the narrow bounds within which life can thrive or even survive. One of my favorite questions asked how close one would have to stand next to a supernova to be killed by neutrino radiation. Now, as Munroe explains, neutrino radiation is usually so insubstantial that billions of such particles routinely pass through the earth, with only one or two being picked up by sensors that have to be located at the bottom of oceans. It turns out, however, that supernovae are such titanic outpourings of energy that discounting the other things that a supernova could produce that would get you incinerated into a crisp, you could be 2.3 AU away from the supernova – which is slightly closer than the mean distance of the dwarf planet Ceres to the Sun – and get killed by neutrino radiation. You can absolutely get knocked down by a feather if it goes fast enough.
Now, not all questions pack that kind of sensawonder punch that the above question did. Indeed, many questions were about probabilities of extremely unlikely events; queries that nominally would lead to incredulous and short answers. Munroe, however, often goes the extra mile and ponders interesting tangential issues to the questions – improving upon them and making them more interesting than they ordinarily would be. For example, the commonly asked question – what would happen if the sun suddenly disappeared – has been done ad nauseum elsewhere, usually with something about how the gravitational pull would take 8 minutes to get here, or some such thing. Munroe looks at the bright side of such a disappearance, commenting on the good things that the lack of a sun would bring to human civilization – such as improved satellite service and cheaper trade – in the brief day or so before we all froze to death. Most of the answers that Munroe offers are instructive and enlightening in their own way, even if they are ultimately used to craft a fun but pointless answer to an interesting but absurd questions.
The book is also peppered with illustrations that, in classic xkcd fashion, serve as surprisingly clear conduits and visual aids to the answers in the book. They feature many of xkcd’s recurring cast, acting out some of the absurd hypothetical scenarios alluded to in the book.
Strictly speaking, of course, most of the content in What If? is available on the xkcd what if? section of the website. I bought this book because I like xkcd and want to support it in a limited fashion. It’s also easier to browse that way, to be honest.
I give this book: 4.5 out of 5 neutron star-density bullets