Fermat's principle (費馬原理)
Fermat's principle states that "light travels between two points along the path that requires the least time,as compared to other nearby paths."
https://en.wikipedia.org/wiki/Fermat%27s_principle
Fermat's principle (費馬原理)
Fermat's principle states that "light travels between two points along the path that requires the least time,as compared to other nearby paths."
https://en.wikipedia.org/wiki/Fermat%27s_principle