The name was based on 'the half-whimsical belief that a butterfly flapping its wings in Asia could affect the weather in New York a few days or weeks later'. When Lorenz created equations to describe these differences and fed these equations into a computer which graphed the results, he found that these 'chaotic' equations produced evidence of an unusual kind of predictability. But the strange part is that although the line always described essentially the same shape over and over again, it never described exactly the same shape and no point on the graph ever intersected any other point. Since Lorenz's discovery, scientists have found many other of these 'strange attractors', as the phenomena are now called. Plants show similar repetitive structures in, for example, the veins on a leaf or a tree's branching limbs.
All chaotic systems seem to have an unusual sensitivity to initial conditions.
They are systems in which seemingly inconsequential changes turn into major differences in outcome. Scientists have found evidence of 'chaos' in astronomy, epidemiology, meteorology, air turbulence, the stock market and the human body. It is in the study of the human body that some scientists are beginning to realize just how important chaos is. Ary Goldberger of Harvard Medical School believes he has discovered not only that the rhythm of the human heart is chaotic, but that chaos in the heart is necessary. When he compared the variations in the heartbeats of a healthy person to those of one suffering from heart disease, the healthy heartbeat was actually the more chaotic.