Stationary-action principle
= Stationary-action principle
{wiki=Stationary-action_principle}
The Stationary Action Principle, also known as the principle of least action, is a fundamental concept in the field of physics and calculus of variations. It asserts that the path taken by a physical system between two states is the one for which the action integral is stationary (usually a minimum), meaning that any small variation of that path will result in no first-order change in the action.