The 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. The effect derives its name from the theoretical example of a hurricane's formation being contingent on whether or not a distant butterfly had flapped its wings several weeks before.
-- Wikipedia
A Sound of Thunder
“A Sound of Thunder” is a science fiction short story by Ray Bradbury, first published in _ Collier’s_ magazine in 1952. As of 1984 it was the most re-published science fiction story up to the present time.[1] It is based on the concept of the butterfly effect, as well as, perhaps, the snowball effect.
-- Wikipedia