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

by M. Mitchell Waldrop

Basically, Prigogine was addressing the question, Why is there order and structure in the world? Where does it come from? This turns out to be a much tougher question than it might sound, especially when you consider the world’s general tendency toward decay. Iron rusts. Fallen logs rot. Bathwater cools to the temperature of its surroundings. Nature seems to be less interested in creating structures than in tearing structures apart and mixing things up into a kind of average. Indeed, the process of disorder and decay seems inexorable—so much so that nineteenth-century physicists codified it as the second law of thermodynamics, which can be paraphrased as “You can’t unscramble an egg.” Left to themselves, says the second law, atoms will mix and randomize themselves as much as possible. That’s why iron rusts: atoms in the iron are forever trying to mingle with oxygen in the air to form iron oxide. And that’s why bathwater cools: fast-moving molecules on the surface of the water collide with slower-moving molecules in the air, and gradually transfer their energy. Yet for all of that, we do see plenty of order and structure around. Fallen logs rot—but trees also grow. So how do you reconcile this growth of structure with the second law of thermodynamics? The answer, as Prigogine and others realized back in the 1960s, lies in that innocuous-sounding phrase, “Left to themselves …” In the real world, atoms and molecules are almost never left to themselves, not completely; they ar...