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By Fermat's principle, a ray of light has to know where it will ultimately end up before it can choose the direction to begin moving in.

So either something is computing it or some exploration is happening at quantum level and we just see the final result.

by MeteorMarc9 hours ago|

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Fermat's principle is an outcome of constructive interference of waves. It works both for classical and quantummechanical descriptions. E.g. check https://phys.libretexts.org/Bookshelves/University_Physics/U...

by pava08 hours ago|

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> a ray of light has to know where it will ultimately end up before it can choose the direction to begin moving in

A ray of light doesn't know or choose because it has no agency, just like an apple doesn't know or decide to fall because of gravity. It's an anthropomorphization.

by sumitkumar9 hours ago|

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True, so the interference is the "computation"(heavy emphasis on quotes) which gives rise to the principle.

by embedding-shape9 hours ago|

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> a ray of light has to know where it will ultimately end up before it can choose the direction to begin moving in

I'm no physicists, so I guess I'll ask it: Why?

Also related, why do some ray of light then "see" a black hole yet decide to head into them anyways, if they saw it before they went in that direction? Seems like a dumb move :)

by lloeki8 hours ago|

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Its future isn't over there because it moves in that direction, instead it moves in that direction because its future lies over there.

Relatedly:

> [General Relativity] basically says that the reason you are sticking to the floor right now is that the shortest distance between today and tomorrow is through the center of the Earth.

https://physics.stackexchange.com/questions/250800/gr-and-my...