The New Field of Complexity

If the basic rules of chemistry are any guide, life should not exist. Scientists showed in the 1950s that shooting an electric spark through a soup of chemicals -- thus simulating lightning strikes on the primordial planet earth -- could produce simple organic compounds. But complex, self-reproducing chemicals like dna? They shouldn't have arisen in a trillion years. At an even deeper level, the second law of thermodynamics dictates that the universe should inexorably move toward disorganization. Cups of tea always cool off; they never spontaneously get hotter. Iron rusts, but rust never turns into iron.

Yet over the eons, a chaotic universe organized itself into stars and galaxies and planets. And at least one planet, our own, is now bursting with life in bewildering varieties, filled with organisms that have arrayed themselves into ecosystems, communities and complex societies. How did this happen? That is the question posed by a brand-new field of science known as complexity.

The central idea is that self-organization is almost inevitable in a wide range of systems, both natural and man-made. The consistent shape of sand dunes marching across a desert, the evolution of complicated body parts such as eyes and kidneys, the equilibrium between supply and demand in a functioning economy and the existence of life itself -- all these may be expressions of this single principle.

The theory is compelling enough to have spawned its own research center, the Santa Fe Institute in New Mexico. And while some scientists dismiss complexity as just a trendy buzz word used to attract grant money, the field has drawn not only young hotshots but also Nobel laureates in physics, including Philip Anderson and Murray Gell-Mann, and Economics laureate Kenneth Arrow.

Complexity has been around for more than a decade, and its roots go back even further, but it is surging in popularity thanks largely to two popular books. They are, confusingly, Complexity, by M. Mitchell Waldrop, and Complexity, by Roger Lewin; both authors formerly wrote for the journal Science. Like James Gleick's wildly successful 1987 book Chaos, each volume attempts to convey to lay readers the basics of the science as well as the excitement it is generating among its practitioners. (Mini-review: Waldrop's book, a straightforward, detailed account, succeeds admirably; Lewin's, a chatty personal memoir, does not.)

Complexity theory and chaos theory share more than the attention of enterprising writers; they are scientific first cousins. The essence of chaos theory is that certain phenomena involve so many factors that they are inherently unpredictable; although a scientist may be able to project the pattern of a swinging pendulum or a flying cannonball, it is impossible to determine how far apart two leaves will be after they go through a waterfall or exactly what the weather will be a month from now. Reason: in systems governed by the mathematics of chaos, small events have big consequences. For instance, even the random firing of just a few neurons, say chaos theorists, can throw a normally beating heart into wildly irregular fibrillation. The best that scientists can do is recognize that the world's chaos follows certain patterns.