1963 – USA
‘The behaviour of a dynamic system depends on its small initial conditions’
While working at the Massachusetts Institute of Technology, Lorenz developed a simple computer model to forecast changes in weather at a number of places. In one of his equations he used a rounded number (for example 0.156 127 became 0.156). His model now predicted quite different conditions. He suggested that even a small initial unpredictable condition such as a flapping butterfly could produce a larger global change in weather.
The butterfly effect is one aspect of chaos theory that describes disorderly systems. The behaviour of a chaotic system is difficult to predict because there are so many variable or unknown factors in the system.