Wednesday, November 25, 2009

Math Will Save Your Life!

Since my boy Waterborn gave us the Chemistry of Hell I thought I'd share this little nugget in honor of Dr. Ned's Zombie Island.

By Jacob Goldstein

"The zombies are coming! Quick, call the mathematicians!

In particular, you may want to get Robert Smith on the phone. (That question mark isn’t a typo. We’ll explain it later.) He’ll tell you that if you try to quarantine the zombies you won’t catch them all, so “it’s basically humans fighting it out with slightly fewer zombies than there were before.” That’s not what you want, given that you’re dealing with flesh-eating, undead monsters that will either kill you or bite you and turn you into one of them.

If you go for a cure, “unless the cure was 100%, which it would never be in reality, you can’t turn all the zombies back.” You wind up with “this equilibrium where people are always switching back and forth” between human and zombie. Entirely unsatisfactory.

The only solution — and if we haven’t learned this from zombie movies, we haven’t learned a damn thing — is to mount wave after wave of military attacks. That should get rid of the zombies in about a week and a half, according to Smith?’s equations. And who can argue with equations?

(We’ll pause here to address that question mark. Smith? added it to the end of his name when he was 17, in an effort to distinguish himself from the countless Robert Smiths in the world.)

If you want to really get into it, you can read “When Zombies Attack!: Mathematical Modeling of an Outbreak of Zombie Infection,” a chapter in a forthcoming book on modeling infectious diseases.

Be warned: The tone is light, but the mathematics are heavy. This, Smith told us, is the point. The chapter grew out of an assignment he gave a class at the University of Ottawa, where he is an assistant professor specializing in disease modeling.

“I said to the students, you can do anything you want, as long as it’s modeling disease.” When a group of students came back with the idea of a zombie outbreak, he encouraged them, and pushed them to make their models more complex.

One example: Tweaking the math to include a lag time between exposure to a zombie and zombification (a feature common to many diseases). “In Shaun of the Dead, you see that his mother gets bitten by a zombie, and his father gets bitten, and they’re not yet zombies,” he said. “That really affected us — we said, we’ve got to put that latency period in.”

Finally, the students were interested in a mathematical technique that looks at intermittent pulses of activity. So they modeled a human counterattack that came in multiple waves.

“While aggressive quarantine may contain the epidemic, or a cure may lead to coexistence of humans and zombies,” they concluded, “the most effective way to contain the rise of the undead is to hit hard and hit often.” "

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