Does anyone remember this topic Transparency and Refraction, or this one? Not knowing bugged the crap out me. So, I sent him this message on Youtube. Well, they finally got around to addressing some of the confusion. [video=youtube_share;YW8KuMtVpug]http://youtu.be/YW8KuMtVpug[/video] [video=youtube_share;CiHN0ZWE5bk]http://youtu.be/CiHN0ZWE5bk[/video]
Thanks for this. Very thought-provoking. The Merrifield one was good, I thought. (Moriarty in my opinion could not think organise his ideas in a sufficiently linear way to be intelligible.) I quite liked the idea of the "polariton". I can readily see that the effect of moving electrons means moving mass about and hence the combined "particle", composed of the incoming photon plus the fluctuating fields induced by moving the electrons, will effectively behave as if it has mass. From there it is easy to see why the polariton moves with a slower speed than light. I also liked the distinction he drew between the speed of the wave crests (the phase speed) and the speed of a signal sent using the photons (the group speed). The Feynman path integral approach I vaguely understand, qualitatively, but it was not explained why you have to add all these different paths in light in a medium, whereas you don't (apparently) in a vacuum. Or maybe it is that in a vacuum the other paths don't contribute to the final Fourier series sum, whereas in a medium they do (if so how and why?). If any other reader has a succinct explanation of this I'd be interested.
