This is a theory describing the strange, confusing and unpredictable results. Chaotic systems follow precise laws, but their irregular behavior can appear to be strange, chaotic and random to a normal observer. Chaotic behavior is common in systems as varied as electric circuits, measles outbreaks, lasers, economy, weather, traffic jams, earth quakes, clashing gears, heart rhythms, electrical brain activity, fluids, animal populations, and chemical reactions. It is suspected that even economic systems, such as the stock exchange, may be chaotic. The field of chaos is evolving rapidly.

The dynamic nature of the universe has led to a great deal of scientific research dedicated to analyzing change. Until recently, it was believed that if the dynamics of a system didn't follow precise laws, it was due to random external influences. Therefore, scientists concluded that if random influences could be eliminated, then the behavior of all such systems could be predicted. It is now known that many systems can exhibit long-term unpredictability even in the absence of random influences. Such systems are called chaotic. Even very simple systems, such as a pendulum, exhibit chaos.

The unpredictability of chaotic systems are caused by their sensitivity to their conditions, such as their initial position and velocity. Two identical chaotic systems set in motion with slightly different initial conditions can quickly exhibit motions that are quite different. French mathematician Henri Poincaré concluded that he could not prove the solar system to be completely predictable. He was the first to state the defining feature of what later became known as chaos: “It may happen that small differences in the initial conditions produce very great ones in the final phenomena. A small error in the former will produce an enormous error in the latter. Prediction becomes impossible. …”

The ramifications of Poincaré's discovery were not fully appreciated by most scientists until computers allowed them to easily model and visualize chaotic systems. Before then, however, pioneering scientists and engineers at NASA used Poincaré's work to send people and satellites into orbit. Edward Lorenz, an American meteorologist, discovered in the early 1960s that a simplified computer model of the weather demonstrated extreme sensitivity to the initial measured state of the weather. He demonstrated visually that there was structure in his chaotic weather model that, when plotted in three dimensions, fell onto a butterfly-shaped fractal set of points of a type now known as a strange attractor. Lorenz rediscovered chaos and proved that long-range forecasting of the weather was impossible.

By the early 1980s, experiments regularly showed that many physical and biological systems behave chaotically. One of the first such systems to be discovered was the dripping water faucet. Under certain conditions, the timing between water drops from a leaking faucet demonstrates chaotic behavior, making the long-term prediction of the timing of drops impossible.

According to recent evidence, Poincaré's observations concerning the unpredictability of the solar system appear to be correct. Observations and computer simulations of the irregular tumbling motion of Hyperion, a potato-shaped moon of Saturn, have provided the first conclusive proof that objects in the solar system can behave chaotically. Recent computer simulations have also shown that the orbit of Pluto, the outermost planet of the solar system, is chaotic.