A normal pendulum swings back and forth Steadily and predictably.
But what happens when you attatch a second pendulum to it?
What do you think, will both double pendulums move in the same way?
Hold the longer pendulum and set the short one in motion.
Now let the longer pendulum go. What happens?
Based on his calculations in the field of astronomy, the French physician and mathematician Jules Henri Poincaré (1854-1912) posed the question if all physical phenomena are predictable. In his bestseller “Science and Method” (1912) he gave the following answer: „It is possible, that small differences in the initial circumstances lead to big differences in the results (…) prediction becomes impossible and we are left with a random phenomenon.“