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Randall Munroe Of xkcd Answers Our (Not SoAbsurd) Questions10:11 AM SEP 2 By WALT HICKEY

Randall Munroe, the guy behind Internet sensation xkcd, is out with a new book expanding on his recurring “What If?”series. Each week, Munroe tackles an absurd question with as much scientific rigor as possible.

The book comprises more than 50 questions, ranging from the somewhat mundane(“Which U.S. state is actually flown over most?”) to the gruesome (“If someone’s DNAsuddenly vanished, how long would that person last?”) to the intriguing (“When if everdid the sun finally set on the British Empire?”) to the utterly fantastical (“How longcould a nuclear submarine last in orbit?”).

(Full disclosure: I’ve been a fan of the site for a while, as you can tell from the thirdpicture on this page.)

In the book, Munroe relies on estimation techniques, in-depth and esoteric research,and basic physics to tackle questions most folks would never think to ask, and evenfewer folks could even think about answering. Munroe took time off from answering

absurd questions to answer some of mine.

Walt Hickey: You’ve managed to write about lots of complex topics for a general audience. Whom do you write for?What’s the target audience in your head when you’re writing a “What If?”

Randall Munroe: It’s tempting to think of technical audiences and general audiences as completely different, but Ithink that no matter who you’re talking to, the principles of explaining things clearly are the same. The only realdifference is which things you can assume they already know, and in that sense, the difference between physicists andthe general public isn’t necessarily more significant than the difference between physicists and biologists, or biologistsand geologists.

Whether I’m explaining things or solving problems for my own sake, I’m always looking for ways of looking at problems— mental models — that make the answers intuitively clear. Once I’ve hit on one of those, I just try to explain it as simplyand clearly as I can, as if I’ve traveled back a few years in a time machine and I’m giving the executive summary to my

WHAT IF

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past self to save me the trouble of working it out.

WH: In “What If?” you often rely on estimation techniques to develop reasonable answers to pretty complex questions.For example, in the Supernova neutrino radiation question, you reconciled two things that happen at extremely differentorders of magnitude. Of the estimation techniques you use, which do you think is the most applicable for people to applyto their daily life? What’s a technical takeaway you’d like to see people use more?

RM: One thing that bothers me is large numbers presented without context. We’re always seeing things like, “This canalproject will require 1.15 million tons of concrete.” It’s presented as if it should mean something to us, as if numbers areinherently informative. So we feel like if we don’t understand it, it’s our fault.

But I have only a vague idea of what one ton of concrete looks like. I have no idea what to think of a million tons. Is thata lot? It’s clearly supposed to sound like a lot, because it has the word “million” in it. But on the other hand, “TheAdventures of Pluto Nash” made $7 million at the box office, and it was one of the biggest flops in movie history.

It can be more useful to look for context. Is concrete a surprisingly large share of the project’s budget? Is the projectgoing to consume more concrete than the rest of the state combined? Will this project use up a large share of the world’sconcrete? Or is this just easy, space-filling trivia? A good rule of thumb might be, “If I added a zero to this number,would the sentence containing it mean something different to me?” If the answer is “no,” maybe the number has nobusiness being in the sentence in the first place.

One thing that’s been really helpful for me is to memorize random quantities to serve as reference points. I rememberthat Wyoming is the smallest state and has a bit over half a million people, and that New York’s metro area has about 20million. Boston’s has 5 million, and Tokyo’s has 35 million. “One in 100 Americans” is 3 million people, and “1 in 100people” is 70 million. Once I have those reference points, when I hear “10 million people have lost power in the storm,” Iat least have something to compare it to.

But I’m also wary of people saying “everyone should know” some skill from their area of expertise, because people havetheir own stuff to deal with. It’s easy for me to imagine an abstract person and then say, “Wouldn’t it be better if thatperson knew how to program?” And maybe it would. But real people are complicated and busy, and don’t need methinking of them as featureless objects and assigning them homework. Not everyone needs to know calculus, Python orhow opinion polling works. Maybe more of them should, but it feels a little condescending to assume I know who thosepeople are. I just do my best to make the stuff I’m talking about interesting; the rest is up to them.

WH: You draw on lots of research here. At one point, you draw on Intercontinental Ballistic Missile research to talkabout cooking a steak dropped from space. How do you find these sources? Where’s the weirdest corner of JSTORyou’ve been to in researching the book?

RM: I do a lot of Googling. I use ResearchGate and JSTOR and Google Scholar and everything, but I sometimes find amore effective approach is to just Google for my search term plus “PDF.” That turns up a lot of old papers professorsstick up on their personal websites that aren’t indexed anywhere.

One night, I found myself reading all the way through an ancient Xeroxed copy of the “Proceedings of the SecondAmerican Conference on Human Vibration.” Sadly, it was not the fun kind of vibration; it was mostly concerned withthings like long-term injuries from jackhammer use or spinal problems caused by spending all day on hard seats invehicles driving on uneven roads.

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WH: What’s the deal with Goku? Why does everyone seem to care so much about him?

RM: As far as I can tell, he’s one of those characters who is almost infinitely powerful; Superman and the Hulk are twoother well-known ones, and I get a lot of “What If?” questions about all three. When you’re told that someone is almostinfinitely powerful, you naturally wonder what their limits actually are. This is an impulse not limited to superherocomics. It’s the same idea that’s behind the old question, “Can God make a rock so heavy He can’t lift it?”

I also get a lot of questions about these characters fighting each other; I guess pitting near-omnipotent charactersagainst each other is another natural impulse. (At least, when the characters are both superheroes; I’m not sure anyone’sasked the question, “What if the God of the Old Testament fought Goku?”)

I don’t think science has much to say about that kind of superhero showdowns. In the end, we’re talking about fictionalcharacters whose abilities are often loosely defined and vary from story to story. And besides, answering the question“Who would win if Character X fought Character Y?” is practically the whole purpose of the superhero comics industryalready; I don’t think they need any more help from me.

WH: A whole set of “What Ifs?” touch on what it would be like to go to or return from space. The Curiosity rover alsoappears to be a recurring figure. How did your experience at NASA influence the “What If?” estimates? What do youmake of the state of space exploration?

RM: I think space is interesting because it’s defined by the presence (or absence) of such simple and common things —like distance, speed, light, heat, air and gravity — but in such bafflingly unfamiliar amounts and arrangements that wehave no intuition about how they behave. I have a lot of fun trying to develop that intuition, trying to figure out how toget an Earth brain to think coherently about space’s staggering speeds and distances.

Funding space exploration has never been politically popular — even in the Apollo days, which a lot of people don’trealize — so following that side of things can be frustrating. But the science is really fun to follow. I’m looking forward togetting pictures from the surface of a comet later this year. Then next year, we’ll finally get pictures of Pluto, which I’mexcited about, and pictures of Ceres, which I’m even more excited about.

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WH: Lots of the submitted questions involve the questioner wiping out life on Earth or just straight up destroying it.Why do you think your readers keep asking you about what are essentially blockbuster movie climaxes?

RM: We collectively spends millions of hours watching GIFs of people falling off treadmills and walking into screendoors, so I think it’s not really a surprise that we’d be interested in seeing an entire planet crash into something.

Some of my favorite questions come from kids. I think sometimes adults put too much effort into crafting a scenariodesigned to cause as much destruction as possible. At that point, if I answer it, I’m effectively just illustrating what theynarrated, which means there are no surprises. Whereas little kids will just submit weird, straightforward questions (like“What if I built a million-story building?”). I like that, because then when I try to answer them, it often takes me off insome unexpected direction.

WH: Which takes more work, an xkcd strip or a “What If?” What’s the process with a “What If?” You seem to talk topeople when you’re feeling out a problem, like a friend who works in a nuclear facility or a physicist who knowssupernovae. How do you go about figuring out an approach?

RM: It varies from question to question. Often, I start by just thinking about them for a while, or doing somecalculations, before I start on the research at all. I like trying to figure out whether there’s a way to derive the answerpurely from information I already have.

“What If?” articles usually take more time than xkcd comics, but some individual comics are definitely exceptions tothat.

WH: You touch on climate change quite a bit in the book. Why do you think people are reticent to listen to whatscientists have to say about climate change?

RM: This is a pretty big question, and it’s a political and sociological one, so it’s not really my area of expertise. But Ithink there are lots of reasons why people might have a hard time grappling with the idea of climate change. Amongother things, climate change is a global, general, and long-term threat, and we’re better at worrying about things that arelocal, specific and immediate.

The science on human-caused climate change is pretty unanimous, yet the public — and our political leaders — have theimpression that it’s a hugely controversial idea and are split deeply split on whether they believe it’s happening at all.That situation — the vast gulf between what the science says and what the public thinks it says — is a political and socialproblem, not a climate science problem. So maybe we shouldn’t be counting on climate scientists to figure out how to fixit.

WH: Which Google search that you had to make for the book do you think is most likely to put you on some type ofgovernment watch list?

RM: For several calculations, I’ve looked up the street prices of hard drugs, and I’ve also Googled for a lot of phrases like“plutonium suppliers.”

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But if I’m on a watch list, it’s probably for something more mundane, like the time I flooded the Library of Congress webinterface with requests for random catalog numbers to try to get a statistical sample of items in its collection. After I hadbeen sending requests for 10 or 15 minutes, I found I was abruptly blocked from the entire Library of Congress website. Istill feel bad about that; I’d never been kicked out of a library before. So if anyone from the Library of Congress isreading this, I’m sorry. I just wanted to tell people about the cool stuff you have.

“What If? Serious Scientific Answers to Absurd Hypothetical Questions” by Randall Munroe is available now.

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WALT HICKEY @walthickey

Walt Hickey is FiveThirtyEight’s lead writer for lifestyle.

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