That light always finds the best path to any destination has puzzled thinkers for centuries. Hero of Alexandria observed that light always takes the shortest path but how does it know that path? It might seem obvious that it is a straight line but how, at each step, does light know what straight is? How light always travels the best path to any destination has always been a mystery and it still is today.
QR3.6.1. A Wave Moves
QR3.6.2. The Physical Law of Least Action
QR3.6.3. The Quantum Law of All Action