4 ms·
> then you kind of already accept that (ordinary, classical) light somehow knows the time it takes to go along all possible paths, then chooses the minimum But
by EvgeniyZh 3y ago
> then you kind of already accept that (ordinary, classical) light somehow knows the time it takes to go along all possible paths, then chooses the minimum
But it doesn't, minimum (or more precisely extremum) is a local quality. Basically light goes by the path with zero derivative because otherwise neighboring pathes interfere. Feynman lectures touch on it relatively early [1] which I think is nice
[1] https://www.feynmanlectures.caltech.edu/I_26.html#Ch26-S5 https://www.feynmanlectures.caltech.edu/I_26.html#Ch26-S5
- alecst 3y agoIt is not local. That’s what’s wild about it. It’s a minimum over all paths. Re-read that section you posted.
- EvgeniyZh 3y ago> In other words, the principle is that light takes a path such that there are many other paths nearby which take almost exactly the same time. > the wavelength tells us approximately how far away the light must “smell” the path in order to check it. For the same reason, it doesn't even have to minimum at all, it should be extremum.