**The brachistochrone**

This animation is about one of the most significant problems in the history of mathematics: t*he brachistochrone challenge.*

*If a ball is to roll down a ramp which connects two points, what must be the shape of the ramp’s curve be, such that the descent time is a minimum?*

Intuition says that it should be a straight line. That would minimize the distance, but the minimum *time* happens when the ramp curve is the one shown: a *cycloid*.

Johann Bernoulli posed the problem to the mathematicians of Europe in 1696, and ultimately, several found the solution. However, a new branch of mathematics, calculus of variations, had to be invented to deal with such problems. Today, calculus of variations is vital in quantum mechanics and other fields.

(Source: saulofortz)