# chaos

Chaos is a phenomenon shown by some dynamical
systems, which consists of a curious, infinitely complex pattern of
behavior that lies just beyond the edge of total order. A system is chaotic
if it is predictable in principle and yet is unpredictable in practice over
long periods because its behavior depends very sensitively on initial conditions.
Despite this unpredictability, however, there are certain constants, such
as Feigenbaum's Constant, and
certain structures, such as chaotic
attractors, that are fixed and susceptible to analysis. The weather,
the movements of a metal pendulum moving over fixed magnets, and the orbits
of closely-spaced moons are all examples of chaotic systems. Although the
ideas behind modern chaos theory were actively studied at some level throughout
most of the twentieth century, the word as a mathematical term dates only from
an article in *American Mathematical Monthly* in 1975 called "Period
Three Implies Chaos."

In everyday language chaos has come to mean the exact opposite of order.
But the Greek root *khaox* means "empty space," specifically the primordial
emptiness that in Greek cosmogony existed before anything else came into
being, and this meaning still persists in archaic usage where it refers
to a canyon or abyss. Later this notion of emptiness was superceded and
chaos came to refer to an aboriginal state of confusion. In this sense, Paracelsus applied the term to describe
air, hence the modern term *gas*. The evolution of the word to mean
disorder before the forces of creation filled the emptiness and established
order led to *chaos* in the mathematical sense, as an unexpected
third state: a deterministic system subject to simple rules that nevertheless
displays infinitely complex behavior.

### Reference

1. Gleick, James. *Chaos: Making a New Science*. New York: Penguin,
1988.