Butterfly Effect Very few people are afraid of butterflies…but maybe more should be. The movie The Butterfly Effect (which opened in theaters nationwide on January 23) may not include any nefarious insects, but it is based in part on a concept from chaos theory that suggests that something as subtle as the flap of a butterfly's wings in Brazil could trigger a tornado in Texas.

The term "butterfly effect" was coined by meteorologist Edward Lorenz, who discovered in the 1960's that tiny, butterfly—scale changes to the starting point of his computer weather models resulted in anything from sunny skies to violent storms—with no way to predict in advance what the outcome might be.

In the movie The Butterfly Effect, actor Ashton Kutchner plays a man who has found a way to travel back in time to his youth. Each time he returns to his childhood, he makes minuscule changes that radically alter his life in the present, inevitably leading to (you guessed it) terrifying results.

Human time travel is a purely fictional concept, but according to Rutgers biophysicist Troy Shinbrot, the idea that small changes can lead to dramatically different outcomes is firmly rooted in the physics of chaos theory, at least for some systems.

"If you're willing to suspend your disbelief long enough to accept the possibility of time travel," says Shinbrot, "then, yes, the movie sounds like it has a reasonably plausible premise, from a physics point of view."

Shinbrot should know—his PhD dissertation at the University of Maryland was based on groundbreaking butterfly effect experiments.

Scriptwriters, it seems, have found that the butterfly effect is a useful tool for establishing dramatic tension.

For scientists like Shinbrot, it can be a useful tool for manipulating chaotic systems. In fact, Shinbrot's dissertation was part of an effort to learn how to make small adjustments to a chaotic system to choose the system's outcome.

"NASA currently directs trajectories of spacecraft using the butterfly effect," says Shinbrot. "The first example that I know of was the International Cometary Explorer. They used the fact that the butterfly effect applies to trajectories in the solar system. With tiny amounts of hydrazine fuel, they created little puffs that steered the spacecraft halfway across the solar system to meet up with comet Giacobini-Zinner That's how they achieved the first ever scientific cometary encounter."

In order to make use of the butterfly effect, NASA scientists must study highly accurate models of satellites in the solar system.

As for the adventures Kutchner faces in The Butterfly Effect, says Shinbrot, "If he had a better model for the system that is his life, perhaps he could have chosen better outcomes. But then the movie wouldn't be very interesting."

—Adapted from Physicscentral.com

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