Dropping Science: 'XKCD' Cartoonist Randall Munroe on His New Book

The man behind the popular absurdist Web comic takes on the big question in his new book 'What If'

Randall Munroe, the author.
Courtesy Randall Munroe/Houghton Mifflin Harcourt
Randall Munroe, the author.
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"Stand back, I'm going to try science" is one of the enduring mottos of the XKCD webcomic. That's exactly what cartoonist Randall Munroe has done: applied his physics degree (he's a former employee of NASA) to brilliant stick-figure comics about the Internet, eBay feedback, romance, and bacon. With tens of millions of visitors every month, the 29-year-old Munroe has become the king of the oddball online funny pages. Sometimes the jokes are built on obscure references to logic trees or Linux; there's now a whole ecosystem of other people explaining what he's talking about in case your liberal-arts degree isn't getting the job done.

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The comic also encompasses maps of Internet communities, charts about radiation doses, money, and the metric system, and jaw-dropping formal experiments like "Click and Drag" (where the reader scrolls through a 46-foot-wide comic to explore its world) and the Hugo Award-winning "Time" (a movie released one frame per hour over a period of four months). Since 2012, Munroe has also been answering weekly reader questions about science, ranging from "What would it take to stop an out-of-control freight train using only b.b. guns?" to "What would happen if you tried to hit a baseball pitched at 90% of the speed of light?", now collected in the book What If? (published by Houghton Mifflin Harcourt on September 2nd). A remarkable number of the answers to those questions involve mass carnage. "Whenever I have a couple of questions in a row about things exploding, I then like to look for something different," Munroe says. "If you blow up the world every time, it gets old." 

'What If?' book cover
Photo: Courtesy Randall Munroe/Houghton Mifflin Harcourt

What's the spark behind something like "Click and Drag" or "Time"? Are you consciously trying to expand the boundaries of the medium?
With most of those, I think what really gets me interested in those ideas is noticing some aspect of the whole system that I haven't seen anyone play with before. With "Click and Drag," I felt like the act of exploring Google Maps was really satisfying — you know, zooming way in and following a river. I had never seen anyone make a game, or a panel in a comic, that replicated that.

And then with "Time," I thought about how there was the in-between space between animation, where you get many frames per second, and a daily comic, where you're getting updates every day. I couldn't think of anything that had been done in the in-between space, partially because it's really hard to reach people every hour without the Internet. You have to show up at their house — "Alright, here's the frame for this hour" — and they're like, "Please leave me alone." I wasn't sure how people would consume it, but it's fun to have something where people are figuring out how to read it. Sometimes making something a little bit less accessible and more of a puzzle can make it more appealing.

Have you come up with anything that you've rejected for being too obscure?
Sure. There are plenty of jokes where I'm like, there are five people who are researching this one thing who will get this — maybe I'll keep this to myself.

Are you familiar with the comedy term "one-percenters"? It's what sitcom writers call jokes that only one percent of the viewing audience will get. I feel like XKCD fully commits to the one-percenter.
One percent of the general public is a lot of people. It used to be if you wanted to do a newspaper comic, you had to appeal to a pretty big chunk of the newspaper's readership for them to want to keep you around. Dilbert would be office humor, but even that is pretty widely experienced. One of the nice things about the Internet is you can do a comic that's just for Ph.D. students, or for truck drivers, and you get to reach all of them without having to satisfy the other 99%. 

Image from Randall Munroe's 'What If?'
Conveyor belt, Soulmates (Photo: Courtesy Randall Munroe/Houghton Mifflin Harcourt)

Do you remember the moment when you realized you could make a living doing the strip?
Early on, I put up a couple of T-shirts. I got a few orders; I made a few dollars. And then the orders started to pick up, and in a very short amount of time I realized I was going to have a hard time physically packing and shipping them all, especially if I kept going to my day job. I did the math, and it was like Terry Pratchett said: I was at the point where you realize that every day you go to work instead of staying home and doing your hobby, you're actually losing money. I was working [at NASA] on a contract basis, and I hit the end of a contract right around that point. I could have pushed to get a new contract, but I said, "No, I'll do this for a while."

Tell me a little bit about your work space.
I have the standard cartoonist setup, which is one of those Cintiq tablets, and a laptop. If I'm mostly writing code, I'm on the laptop, and if I'm mostly drawing, I'm on the Cintiq.

How much code do you write these days?
Surprisingly, more and more. I do a lot of code just to try answer questions for myself, and sometimes the result turns into a comic. One example that did not turn into a comic — not yet, anyway — I downloaded the whole Google Books Ngrams corpus, and made some tools to visualize whether there were patterns in what years were mentioned in what years. In the 1930s, did people talk about 1776 more than in the 1980s? And you have to normalize for a bunch of things: everyone talks about the current year the most, and the number 2000 gets mentioned a lot, but how much of that was people talking about the year 2000?

I wasn't able to extract a good enough signal from that noise, but I found patterns of mentions of future years in unexpected places. In the 1930s, there was a string of mentions of the 1980s. That seemed weird to me — why are people in the Thirties talking about 50 years in the future? And it was specifically 50 years — 1932 would mention the early 1980s a lot — but the pattern didn't continue in the Forties. I started seeing other ghosts like this that were kind of inexplicable, and then I realized I was seeing OCR text recognition errors, where the 3 was misread as an 8. This was a really effective method to spot the flaws in the text recognition engine they were using. Which was cool, but wasn't I was looking for. I wrote quite a bit of code in the process, making a useful graphic that I could explore. That was a hundred lines of Python, at least, and a couple of afternoons. I do that kind of thing a lot, and occasionally it turns into a comic. 

Image from Randall Munroe's 'What If?' book
Little Prince, Little Planet (Photo: Courtesy Randall Munroe/Houghton Mifflin Harcourt)

Is there a What If answer that surprised you?
I was really surprised by how little radiation you get if you swim in a nuclear reactor fuel cooling pool. If they have everything perfectly sealed, then you're getting less radiation a foot below the surface than you would be at home in your living room, because the water's protecting you from cosmic rays.

I don't know if this showed up in a What If answer, but it really surprised me that the pools at the bottoms of waterfalls aren't hot. Heat is just kinetic energy, and I thought, okay, water's falling this great height and has enough energy to run hydroelectric plants--there's a lot of potential energy there. And water is heavy, and waterfalls are huge, so there's a tremendous amount of energy being converted as the water falls from the top of Niagara Falls to the bottom, so the water on the bottom has to be pretty hot. I sat down and did the math: the mass of the water times gravity times the height, divided by the specific heat of water to come up with how many degrees the temperature increases per hundred meters. The temperature increase is barely measurable, and the reason is water just has an incredibly high heat capacity, it can soak up more heat per mass than anything except, I think, ammonia.

In school, could you have imagined that this was the use that you would be putting your education to?
Like a lot of physics students, when I wasn't sure what to do, I thought, maybe I'll keep doing physics in school! Because it was the path of least resistance. One of my advisors when I was an undergraduate, the chairman of the physics department, said, "If you're going to go on here, then you need to specialize. You need to pick out something and focus on it than for more than a little bit. You can't just work on a problem, get a little bit of an answer, and then go on to the next one." But in a roundabout way, I found one of the few ways to do exactly that.

When you're talking about pure research, every year it's a longer trip to the cutting edge. Students have to spend a larger percentage of their careers catching up to the people who have gone before them. My solution to that is to tackle problems that are so weird that no one serious has ever spent any time on them.

Is there anything you haven't done yet that you would like to?
Oh, man, a lot of things. I have never seen an aurora. That's pretty high on that list. 

Image from Randall Munroe's 'What If?' book
Pitch, Relativistic Baseball (Photo: Courtesy Randall Munroe/Houghton Mifflin Harcourt)

Do you care whether it's an aurora borealis or aurora australis?
I'll be picky once I've seen both and can compare. There are a few phenomena where there's a 30 or 50% chance that I'll get to see one in my lifetime and I have no control over it. I think about those more, maybe because there's no pressure on me to make them happen. It would be really cool to see a supernova that you can see with the naked eye. They should happen every 100 years or so, but we haven't really had one since two in the 1600s. There was one in 1987, which was in one of the Magellanic clouds, which is sort of in our galaxy. There's a couple supergiant or hypergiant stars that are in danger of at some point blowing up extremely violently. One of them, Eta Carinae, is in the southern hemisphere, and when it goes, which is sometime probably in the next 100,000 years, it'll be brighter than the full moon. You'll see it during the day. It's going to be totally unreal. You'll have to be south of about thirty degrees north to see it--I've talked to friends about this, and we've agreed that if it ever explodes, we drive down to Texas or fly to the Caribbean.

There's one that happened in 2008: we detected this really weak gamma-ray burst, but what was crazy about it was that it was visible with the naked eye, even though it came from the other side of the universe, 4 or 5 billion light years away. There are no other galaxies, even ones immediately adjacent to us, that are bright enough to see with the naked eye--except for Andromeda, which is pretty faint. And this thing was lit up, shining so bright you could see it across the universe. We worked out at one point it was outshining a good 10 or 15% of the rest of the universe combined, for some definition of words in that sentence. If that thing happened anywhere in our galaxy, it could have sterilized the Earth's surface.

There are a lot of events that happen so rarely, we don't really have them in the historic record, but frequently enough that one of them could happen in the next hundred years. A big solar flare knocking out all our communications equipment is high on the list of things that are more probable than most people think. I give it a one in three chance that we'll have a huge global catastrophe from a solar flare.

Are you ready for that?
No, I've run out of pens, so I'd need to make a run to the art store. Of course, then I'd need to start mailing my comic out to people, and that's a huge hassle.