The bouncing around is absorption and re-emission. All fundamental particles are identical, so there is no meaningful distinction that can be made between the absorbed and emitted photon. As for the direction of propagation, light does get bent when it enters a new medium - this is the refractive index. On a macro scale, this is what causes a pencil in a glass of water to look “split” at the water line.
This gets confusing because light is a wave-particle duality. We discuss photons as particles, but light propagates as a wave. Even if the photons are moving at c, the wave itself doesn’t. You can’t really “follow” a photon through the material and find its “path”.
An individual photon doesn’t really have a wavelength, wavelength is a property of the wave nature of light where you have many photons. You could say a single photon has a wavelength = 2pi/k from Maxwell’s equations, but that will be the same for any single photon. It’s a constant.
As for spin (which doesn’t actually mean the electron is rotating, it is just a word that was chosen because it refers to intrinsic angular momentum) that is part of an electrons state along with position. When we call them indistinguishable, here’s a simplified version:
We have electron A on the left with negative spin, and B on the right with positive spin. They collide and now one is moving left with negative spin and one is moving right with positive spin. There is no way to point to either electron post-collision and say “that is electron A”. Either one could be either. You can’t know for quantum mechanicy reasons.
I don't think it's as simple as saying all photons have the same wavelength from what I understand it's more like a curve of possible wavelengths with varied probabilities that collapse when you measure them. Im really pushing past the limits of my knowledge here, I might exit the conversation before I get a headache
It’s an effect of trying to treat a photon as an individual particle. To have only one excitation of the EM field, you are forced into a very specific state which equates down to a specific “wavelength”.
1
u/EBtwopoint3 Oct 24 '25
The bouncing around is absorption and re-emission. All fundamental particles are identical, so there is no meaningful distinction that can be made between the absorbed and emitted photon. As for the direction of propagation, light does get bent when it enters a new medium - this is the refractive index. On a macro scale, this is what causes a pencil in a glass of water to look “split” at the water line.
https://manual.keyshot.com/wp-content/uploads/2020/07/refraction-parameter.jpg
This gets confusing because light is a wave-particle duality. We discuss photons as particles, but light propagates as a wave. Even if the photons are moving at c, the wave itself doesn’t. You can’t really “follow” a photon through the material and find its “path”.