Wrong again

As noted in previous posts, it is remarkable how much wrong ideas we carry around in our heads.  This was noted in relation to the mis-perception that people have about the Hydrox cookie.  A more high-brow example is our misunderstanding of the so-called “butterfly effect” that was proposed by MIT meteorologist Edward Lorenz.  An article in The Boston Globe observes that the common and popular understanding of the “butterfly effect” is reflected in such moments as this from a Hollywood movie:  “In 1990’s ‘Havana,’ Robert Redford, a math-wise gambler, tells Lena Olin, ‘A butterfly can flutter its wings over a flower in China and cause a hurricane in the Caribbean. They can even calculate the odds.’”

The writer points out, however, that there is a problem with this.

They get his insight precisely backwards. The larger meaning of the butterfly effect is not that we can readily track such connections, but that we can’t. To claim a butterfly’s wings can cause a storm, after all, is to raise the question: How can we definitively say what caused any storm, if it could be something as slight as a butterfly?

As a low-profile assistant professor in MIT’s department of meteorology in 1961, Lorenz created an early computer program to simulate weather. One day he changed one of a dozen numbers representing atmospheric conditions, from .506127 to .506. That tiny alteration utterly transformed his long-term forecast, a point Lorenz amplified in his 1972 paper, “Predictability: Does the Flap of a Butterfly’s Wings in Brazil Set Off a Tornado in Texas?”

In the paper, Lorenz claimed the large effects of tiny atmospheric events pose both a practical problem, by limiting long-term weather forecasts, and a philosophical one, by preventing us from isolating specific causes of later conditions. The “innumerable” interconnections of nature, Lorenz noted, mean a butterfly’s flap could cause a tornado – or, for all we know, could prevent one. Similarly, should we make even a tiny alteration to nature, “we shall never know what would have happened if we had not disturbed it,” since subsequent changes are too complex and entangled to restore a previous state.