The Butterfly effect was coined by scientists who discovered that small changes can have dramatic consequences over long distances (both in space and time). A hurricane in the U.S. may have been set off by the flap of a butterfly wing in Honk Kong. The film applies this idea to the life of individual people. The first third of the movie is not very exciting, but then the drama picks up as we are suddenly drawn into different possible realities. The main character has problems with memory either because of a genetic predisposition or childhood mistreatment. As he is trying to remember what happened, we are presented with different versions of the past and we no longer know which one is true. Small changes in childhood events lead to very different adult lives.