This equation could spell your doom: (bN)(S/N)Z = bSZ. That is, if you ever found yourself in the midst of a zombie pandemic.
That's because the calculation describes the rate of zombie transmission, from one walking dead individual to many, according to its creators, Robert J. Smith?, a mathematics professor at the University of Ottawa who spells his name with a "?" at the end, and his students. Smith's work has inspired other researchers to create zombie mathematical models, which will be published with Smith's work in the upcoming book, "Mathematical Modeling of Zombies" (University of Ottawa Press, 2014).
Though of course done tongue-in-cheek, Smith's study demonstrates why zombies are the viruses of the monster world. Their likeness to viruses makes the creatures ideal subjects for theoretical epidemiological analyses, which can be used to capture the public's imagination as well as explore scientific principles, Smith said. (Zombie Facts: Real and Imagined: Infographic)
As for a zombie apocalypse, Smith's model shows that a zombie infection would spread quickly (with N representing total population, S the number of susceptible people, Z the zombies, and b the likelihood of transmission). It also shows that zombies would overtake the world -- there's no chance for a "stable equilibrium" in which humans could coexist with the undead or eradicate the disease.
Only coordinated attacks against the zombies would save humanity, the model shows.
Epidemiology and 'WWZ'
Models of disease outbreaks, like the one Smith developed, play a prominent role in real-life epidemiology, Smith said.
"Unlike most popular monsters, zombies are inherently biological in nature," said Mat Mogk, founder of the Zombie Research Society. "They don't fly or live forever, so you can apply real-world biological models to them."
Zombies are walking representations of a contagion, because they depict flesh-devouring monsters who spread their affliction by gnawing on the healthy. Some recent zombie flicks, notably "28 Days Later" and "Zombieland," even explicitly portray zombieism as a virus.
"A zombie is a bit like giving a virus legs and teeth," said Ian MacKay, a virologist at the Australian Infectious Diseases Research Centre, University of Queensland, who blogged about "World War Z." "This is basically a virus taking over a host, and spreading very quickly and efficiently. ... It's an extreme virus-transmission event, if you like."
In "World War Z," Brad Pitt plays a U.N. inspector searching the globe for the origin of the zombie outbreak, paralleling the quests of many real-life virus hunters, Mackay said. "Trying to find the index case, or case zero, bears quite a resemblance to conventional epidemiology," Mackay said. The movie is (somewhat loosely) based on Max Brooks' novel of the same name, which included unprecedented, true-to-life detailabout the political, medical and sociological ramifications of a zombie outbreak, earning the thriller a spot on a U.S. Naval War College reading list. (Outbreak! The 5 Most Likely Real-Life Contagions)