from my understanding, the speed of light is invariant everywhere and to all observers (and this is largely the reason for time dilation but that's beside the point). so how exactly is refraction not an exception to this rule? does passing through transparent/translucent materials slow down photons or is there something im missing?
>The light rays travel like a clean wave through the vacuum.
>They collide against the atoms into the water doing a pseudo-zigzag trajectory. So it travels at the same speed, but with a longer trajectory.
Is this wrong?
> [refractive index] is defined as n = c/v where c is the speed of light in vacuum and v is the phase velocity of light in the medium. For example, the refractive index of water is 1.333, meaning that light travels 1.333 times faster in a vacuum than it does in water.
i am OP. i was responding to ">They collide against the atoms into the water doing a pseudo-zigzag trajectory. So it travels at the same speed, but with a longer trajectory" with an article that i think says he is wrong. but maybe "phase velocity" means something i dont understand
OP here, found a probable answer, but it contradicts a lot of other sources say so im suspicious
tl;dr. light doesn't slow down, it is absorbed and re-emitted by atoms in the material
Water molecules look like Mickey Mouse. Each photon stops at each molecule to see if it's actually Mickey Mouse, but then realized it's not and moves along.
Sixty Symbols had a couple videos on this.
The upshot was that it's really hard to make a good analogy for what's going on but it's definitely not about the photons pinballing from atom to atom.
Refraction dotted not make any sense until you realize that light is a wave. All this "absorbed and remitted" and "zig-zaggy path" stuff are just common misconceptions.
Light travels EVERY path, constructively and destructively interfering with itself. And since it's an electric field, it makes charged particles move, which in turn make their own electric fields which add to and subtract from the original light. What comes out the other end is the SUM of all these interacting fields. So while each component is moving at C, together they add up to a "crest" which is moving less than C. Kind of like how a traffic jam can move at a different speed from the cars that make it up.