• Chrobin
    link
    fedilink
    English
    arrow-up
    19
    ·
    edit-2
    1 year ago

    It does: Light does not follow the path of minimal distance between two points, but the path of minimal time. This is called Fermat’s principle.
    Because water has a higher refraction index than air, light is slower in it and therefore takes a longer time to travel through it. Thus, it takes less time to take a longer path that spends more time in the air.
    Fun fact: The underlying law of this principle is the principle of least action. This is the most basic law of nature we know of and can be used to derive all of physics.

    • 6mementomori@lemmy.world
      link
      fedilink
      English
      arrow-up
      2
      ·
      1 year ago

      I’d add to this that, if I’m not mistaken, it’s because light takes all possible paths and the average measured time is longer

      • crossover@lemmy.world
        link
        fedilink
        English
        arrow-up
        2
        ·
        edit-2
        1 year ago

        The probability of a path it takes is the sum of all possible paths. Richard Feynman uses this exact swimmer in the water example during one of his lectures of physics.