Optics: The Principle of Least Time: Feynman's Physics Explained
Here is a completely different way to see physics. Instead of saying light bends because it hits water, we can say light checks all possible paths from A to B and takes the one needing the least time. This single elegant principle gives us both the law of reflection and the law of refraction. It hints at a strange kind of 'purpose' in Nature — a theme that returns, more deeply, in advanced physics.
The big idea
Light travels the path that takes the least time.
Think about it
A lifeguard runs on sand, then swims, to reach a drowning swimmer. Why is the fastest path not a straight line — and how is that like light bending?
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