Refraction

Why does refraction of light occur?
I never understood why it happened, and was only told when and how occurs, but never why.

Other urls found in this thread:

en.wikipedia.org/wiki/Snell's_law
dujs.dartmouth.edu/2013/04/what-causes-ice-to-be-slippery/
youtube.com/watch?v=v1GdgD77AQ4
twitter.com/AnonBabble

Because light oscilates

Care to elaborate?

Light always takes the path of minimum time. Light travels slower in transparent media than in vacuum (superposition of electric fields of atoms).
A good analogy is you're walking along the beach, 20 meters from the water's edge, and you see someone drowning 100 meters further along the shore and 30 meters out.
You want to reach him as quickly as possible.
Do you run directly towards him and begin swimming along the same line? Say you can run 5 times as fast as you can swim. You'll want to minimize the distance (and time) you spend in the water, right?
You could run along the beach until you reached the closest point on land to the victim and THEN plunge into the surf. But your total distance is large. You're traversing two sides of a triangle whose third side it the straight-line path.
If you work it out (calculus, but not difficult) you can find a compromise, the place to enter the water, which minimizes your total time.

Look at the explanation and diagram in >en.wikipedia.org/wiki/Snell's_law
The shortest-time path is the one that light (and you, the would-be rescuer) take.

a rare example of sci actually being a good board

There are a FEW serious people here.
The occasional "thank you" is appreciated. Makes up (somewhat) for the time wasted arguing with Flat-Earthers.

Those are certainly two nice analogies, but they aren't explanations.

Light is a particle. All of it's probabilistic wave distributions are a result of it's oscillation normal to the direction of travel.
Refraction is a wave based probabilistic distribution, so it is a result of light's oscillation.

Light isnt conscious, it cant choose to take the minimum time

But it is absorbed and emitted by atoms in the material. It will go through the material according to the path of least resistance ie least amount of being absorbed/emitted. But not because it wants to, but because energy levels are quantized ie it takes so much energy to be absorbed, its likely that it doesnt get absorbed and keeps travelling. So the path ends up being whatever path has least absorbance.

the time rule is just an illusion of that underlying mechanism

No, it's not an explanation, but the full explanation involving wave-interference is too long to present here and I didn't know what level of detail OP was seeking.

Best explanation of WHY the least time principle works I ever found is in Feynman's Lectures on Physics. That's somewhat technical and I'm sure there are simpler, but still good, ones out there.