Check the Wikipedia article “Butterfly effect”:
In chaos theory, the butterfly effect is the sensitive dependence on initial conditions; where a small change at one place in a nonlinear system can result in large differences to a later state. For example, the presence or absence of a butterfly flapping its wings could lead to creation or absence of a hurricane.
Although the butterfly effect may appear to be an esoteric and unusual behavior, it is exhibited by very simple systems: for example, a ball placed at the crest of a hill might roll into any of several valleys depending on slight differences in initial position.
The term “butterfly effect” itself is related to the meteorological work of Edward Lorenz, who popularized the term.
The butterfly effect is most familiar in terms of weather; it can easily be demonstrated in standard weather prediction models…