Does anyone else find this statement spooky and questionable like I do?
"Light takes the path between two points that takes the least time"
It looks like it's somehow related to Fermat's principle, but it doesn't quite make sense to me. Doesn't light travel in the direction you point it? (assuming you are sending out light with a laser)
Consider the quiz below:
The explanation to this quiz almost sounds like "even if you pointed the light in direction B, it would bend itself into path A as if it knew it would take less time". But that's not what will happen in reality, no?
In my imagination (informed by some faded shadows of high school physics), if you use a flashlight that radiates light rays in all directions, these light rays will arrive at the water surface at different points, then each light ray will bend itself at a certain angle depending on how it meets the water, and finally travel through water towards the bottom of the pond. And the light ray that happens to travel through path A, will luckily reach the ball. If you were to use a laser, however, it will reach the ball only if you send it on the right path (that is, path A).
And maybe it is not because it takes the least time that light bends the way it does in path A. For some other mysterious reasons, it just bends like that, and when we do the math in hindsight, it turns out to be the fastest of all possible routes from the flashlight to the ball.
Does my attempt to make sense of the puzzle make sense to you? What are your thoughts on this quiz and on Fermat's principle? Would love to hear from you!! And I'd appreciate it if you could share some resources and point me in the right direction :)
Thanks and happy learning!!!
I should mention that I am ok with the "correct answer" being A, but have doubts about the way it was explained, because it sounds like "light will take path A because it takes the least time", and that doesn't make sense.
AND "correct answers" are boring! Many years ago, I learned about how light bends when entering a different medium and I never questioned it, but this quiz got me wondering why it bends the perfect angle that it does, as if it was intelligent.