Speed of Light: Path in Gravity Well & Denser Medium

[wolram]

The path of light in a known medium in a gravity well is x, is the path of the light still x in
a dencer medium ?

 

[JesseM]

Since light's path can be bent when it travels through a medium in ordinary flat spacetime (see here and here), the answer must be "no". But it would depend on the index of refraction, not the density.

 

[marlon]

Since light's path can be bent when it travels through a medium in ordinary flat spacetime (see here and here), the answer must be "no". But it would depend on the index of refraction, not the density.

Doesn't the deviation of the light's path also depend on the local variation of the medium's density ? Just like in the case of dispersion (ie "white" light splits up into different frequencies when it passes through a medium)?

Or what about absorption of photons by the medium's atoms and the subsequent emission into "other" directions than the incident direction.

My point is, shouldn't we tackle this question from a QM point of view ?

regards
marlon

ps : i do realize that mentioning QM in this subthread is a bit, err, contradictory, but anyhow, what are your thoughts on this ?

 

[JesseM]

Doesn't the deviation of the light's path also depend on the local variation of the medium's density ? Just like in the case of dispersion (ie "white" light splits up into different frequencies when it passes through a medium)?

Well, when I said it would depend on the index of refraction rather than the density, I didn't mean to rule out the idea that the density of the medium could itself influence the index of refraction, it's just that other things would presumably influence it too. I don't know enough to say what physical properties of a medium determine the refraction index, I think you're right that you'd need to get into QM to understand it.