Chaos occurs when a
system is very sensitive to initial conditions. Initial conditions are the
values of measurements at a given starting time.
The weather is an
example of a chaotic system. In order to make long-term weather forecasts it
would be necessary to take an infinite number of measurements, which would be
impossible to do. Also, because the atmosphere is chaotic, tiny uncertainties
would eventually overwhelm any calculations and defeat the accuracy of the
forecast. The presence of chaotic systems in nature seems to place a limit on
our ability to apply deterministic physical laws to predict motions with any
degree of certainty.