The butterfly effect is the notion that a small initial factor may have a part in determining greater and unpredictable changes in large, complex systems. The concept of the butterfly effect is from a 1972 talk by meteorologist Edward Lorenz titled “Predictability: Does the Flap of a Butterflies Wings in Brazil Set Off a Tornado in Texas?” The idea that a butterfly flapping its wings could affect weather systems in a distant place illustrates not only the complexity of predicting weather, but also the difficulty of making predictions in chaotic or complex systems in general.
To counter the unpredictability of complex systems, Lorenz recommended the use of multiple predictive models. Rather than try to simulate a weather system’s effect from the best efforts at inputting data on its initial conditions, Lorenz made an average from a number of parallel runs of the simulation. In each of the runs, the initial onset conditions could be modified. This approach proved to be effective enough to still be used by meteorologists today. Lorenz is seen as one of the first experimenters in the field of chaos theory.
The butterfly effect is important because it describes how the inaccuracies of human measurements and failures to account for all initial causal factors make predictions of complex systems, such as the weather, too chaotic for easy simulation or predictions. The butterfly effect plays a part in chaos theory, which deals with the unpredictability of complex systems and is often connected to quantum theory. Concepts like the butterfly effect put in to question the probable determinist mechanical interpretation of the universe.