David Peat

From Clockwork to Chaos 137The cells in a heated pan of water, or the movement of sand in adesert, are examples of order arising out of chaos. They all occur inwhat scientists call open systems. When energy flows through a system,such as heat in a pan of water, the system can order itself into a stablestructure.A river provides another example of what is termed selforganization.During the summer it flows slowly with hardly a rippleto disturb its surface. Where there is a rock in the river the water dividesand flows gently past the disturbance. But once the spring rainsarrive, the river flows faster. In many ways the movement of particularregions of water appears chaotic and turbulent, but notice what happensas fast-flowing water encounters a rock. Now a vortex appearsdownstream from the rock. It is a stable form that has emerged out ofthe chaotic order. These vortices are remarkably stable. Throw in astone and the vortex may be disturbed for only a moment, but thencontinues as before.A vortex is an example of the way an open system organizes itselfto produce a stable structure. Unlike the pan of water, in which anenergy flow produced stable patterns, this time it is matter—water—that is flowing through the vortex. As long as the river is in spate, thisstructure is remarkably stable. As soon as the flow subsides, the vortexdisappears.Natural and social open systems exhibit many examples of selforganization,systems in which regular behavior and stable structuresemerge out of chaos. These are found in everything from traffic flows,economic systems, the movements of goods and services, to certaintypes of waves in canals and rivers and even Jupiter’s giant Red Spot.Some, like the vortex, are open to a flow of matter, others to a flow ofenergy, or even information.A city can be thought of as a self-organized system that has structureditself over a historical period. It maintains its form by virtue of acomplex network of flows—money, food, energy, people, and information.Provided that these flows are maintained at a certain level, thecity will sustain itself, garbage will be moved, people will have enoughto eat, taxes will be paid, and social services will function. But if anyone of these flows should be interrupted for a long enough period, thecity would collapse and chaos would reign.