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A state of disorder and irregularity whose evolution in time, though
governed by simple exact laws, is highly sensitive to starting conditions:
a small variation in these conditions will produce wildly different results.
Long-term behaviour of chaotic systems cannot be predicted. chaos is an
intermediate stage between highly ordered motion and fully-random motion.
For example, in
fluid
flow, a slowly moving fluid exhibits perfectly regular flow; as the fluid
velocity increases, the flow becomes chaotic; and as the velocity increases
still further, the flow becomes fully turbulent
(random).
In a chaotic system, the values of some quantity at two points maintain their
relationship as time passes, even though the exact value of each cannot be
predicted in the future. In truly random motion, there exist no such
relationships.
Chaos is present
in most real systems, such as in
weather
patterns and the motion of planets about the sun; the stable classical
motion widely accepted as the norm in physics is now known to be the exception
rather than the rule.
The underlying structure of chaos exhibits universal features, regardless
of the system in question. The modern theory of chaos is based on the work
of us meteorologist Edward Lorenz (1917-) in 1963, arising from the study
of convection in the atmosphere. Some degree of non-linearity is necessary
for chaotic behaviour. Fractals feature in a
comprehensive description of chaos.
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