Chaos, unpredictability and butterfly effect

The movement of a pendulum is one of the most predictable phenomena out there. If we know the length, we can accurately calculate the period of oscillation. Whatever the height from which we launch it (amplitude), its period remains constant, as already observed by the Italian astronomer and physicist Galileo Galilei. In fact, this ingenuity is so precise that it has long been the essential mechanism of many watches.
But not all pendulums are the same. If we now make a two-piece pendulum, that harmonic and regular oscillation will become chaotic and completely unpredictable. One of the pioneers in outlining the unpredictability of complex systems was the American mathematician and meteorologist Eduard Norton Lorenz. In 1961, while running a computer model of weather forecasting, he discovered that meteorology is completely dependent on very slight differences in initial conditions. He called this phenomenon poetically the “butterfly effect” and described it this way: the fluttering of a butterfly in Brazil slightly changes the environment, and in the long run, can cause a hurricane in the United States.
There are many other complex systems that have this unpredictable and chaotic behavior, such as the meanders of a river, the evolution of the stock market, or epidemics, such as the Covid-19. It is not surprising that not even the best mathematical models have so far achieved any remarkable success in predicting their evolution. The complexity is so great that the chaotic two-piece pendulum falls short. We should represent it with a three-piece pendulum. The oscillation that follows is devilishly variable, but hypnotically appealing. Which brings us to another extremely complex system: the human mind.
In ancient Greek the word “psyche” meant soul, spirit or breath, and later evolved to designate the mind, hence terms such as psychology or psychiatry. But originally “psyche” also meant butterfly. The human psyche is unpredictable and probably subject to the butterfly effect. A slight flutter in one of our neurons can trigger a thought with potential to change the world.