Brachistochrone Problem

This is a marble run that visualizes the Brachistochrone Problem, which was a challenge by Johann Bernoulli to the mathematicians of his day to prove that the direct path between two points is always the fastest. Supposedly only a hand full of those mathematicians took the time to think of the problem in a real world context - i.e. taking gravity into account. The importance of the problem today illustrates the need to check our mathematical solutions against real world conditions.