3 ms·
If you look closely enough, you will see photons traveling at the speed of light between atoms, getting absorbed by atoms and reemitted later. That's a story w
by cperciva 11y ago
If you look closely enough, you will see photons traveling at the speed of light between atoms, getting absorbed by atoms and reemitted later.
That's a story we tell kids who ask too many awkward questions. If it were true we would see sharp changes in the observed speed of light at wavelengths depending on the absorption spectrum of the material in question.
My understanding is that the real answer involves photons gaining inertia via coupling with particles in the material they are passing through (cf. Higgs) ... but I'm probably mangling that explanation horribly.
- danbruc 11y agoI shouldn't have written »absorbed by atoms and reemitted later«, that is really a different thing, interacting with the atoms is better. The superposition of all possible paths and interactions results in a wave function that effectively travels slower than the speed of light.
- wnoise 11y ago> If it were true we would see sharp changes in the observed speed of light at wavelengths depending on the absorption spectrum of the material in question. Uh, we do. The imaginary portion of the index of refraction near a resonance generally looks roughly like a gaussian, and the real portion does have jumps that look a bit like tanh.
- deleted 11y ago[deleted]