Rococo wrote:It looks like everyone else is happy, but none of these explanations really do it for me. Qaanol's explains the change in wavefront, but not the change in momentum direction, since in any configuration other than an infinite evenly spaced line his cows have a different group velocity and phase velocity.
I'm not really sure how this is a problem, since this is exactly what happens to light in any real medium (it's not even a problem for either or both of them to be greater than c, either). All the cows are is a square wave, really, and square waves are perfectly valid solutions to the wave equation.
With the explanations based on Maxwell's equations, it should be fairly obvious that they generalize almost immediately, since the whole idea that light is an electromagnetic wave is explicitly predicated on the fact that Maxwell's equations immediately give you the wave equation if assume a region with no charge or current density (i.e., free space), and it only takes more massaging to get wave equations in the presence of charge and current.
Also, if you throw momentum over your shoulder (I'm assuming you mean opposite your direction of travel), you don't slow down. You speed up. You do move closer to the perpendicular in the reflection/transmission case, and it is a nice illustration of why the transmitted wave's direction changes, but you need the fact that real media are intrinsically absorptive to account for the missing forward momentum.
Fedda wrote:since I can't get my head around quantum physics which seems to be the proper explanation according to the physicists
This is the ultimate explanation, sure, but you don't need QM to understand and explain refraction. Refraction, reflection, diffraction, and all the rest are properties of all
waves, classical and quantum mechanical.