ABSTRACT
Systems with an irregular, non periodic, “chaotic” time evolution are frequently encountered in physics, chemistry, and biology. Think for example of the smoke rising in still air from a cigarette. Oscillations appear at a certain height in the smoke column, and they are so complicated as to apparently defy understanding. Although the time evolution obeys strict deterministic laws, the system seems to behave according to its own free will. Physicists, chemists, biologists, and also mathematicians have tried to understand this situation. We shall see how they have been helped by the concept of strange attractor, and by the use of modern computers.
