Complexity: The Emerging Science at the Edge of Order and Chaos

by M. Mitchell Waldrop

self-organizing criticality only tells you about the overall statistics of avalanches; it tells you nothing about any particular avalanche. This is yet another case where understanding is not the same thing as prediction. The scientists who try to predict earthquakes may ultimately succeed, but not because of self-organized criticality. They’re in the same position as an imaginary group of tiny scientists living on a critical sand pile. These microscopic researchers can certainly perform a lot of detailed measurements on the sand grains in their immediate neighborhood, and—with a tremendous effort—predict when those particular sand grains are going to collapse. But knowing the global power-law behavior of the avalanches doesn’t help them a bit, because the global behavior doesn’t depend on the local details. In fact, it doesn’t even make any difference if the sand pile scientists try to prevent the collapse they’ve predicted. They can certainly do so by putting up braces and support structures and such. But they just end up shifting the avalanche somewhere else. The global power law stays the same.