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I Fermat's principle of least time

  1. Jul 24, 2016 #1
    while I was studying "fermat's principle of least time" I was (and still I am) ntrigued by the fact that "out of all possible paths that it might take to get from one point to another, light takes the path which requires the shortest time". this question may be a bit philosophical but: "how" light "knows" and "chooses" (out of all possibilities) the path which requires the shortest time? these days I am also into generic algorithms so I got this silly thought running through my head: what if light is like some kind of super computer which operates with constant CPU speed 300[km/s] and has some generic alghorithm for choosing the best path!?
  2. jcsd
  3. Jul 24, 2016 #2


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    Take a look at the "Derivation" section of the wikipedia article on Fermat's principle: https://en.wikipedia.org/wiki/Fermat's_principle#Derivation

    Fermat's principle follows directly from the fact that light is electromagnetic waves. There's also an explanation based on the theory of quantum electrodynamics; Feynman's "QED: The strange theory of light and matter" includes an excellent and layman-friendly explanation of how this works.
  4. Jul 24, 2016 #3
    thank you!
  5. Jul 24, 2016 #4


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  6. Jul 25, 2016 #5
    oh, wow! many thanks my friend!
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