[The Cajun]

wouldn't it be uneffected by any medium that is within our 3Dimen/1temp dimen universe?

Keeping in mind that I'm just a semi-educated Cajun who has been told by various experts that I know just enough to be very dangerous to knowledge in several fields;-)..........I think I've read that there is no way to detect a photon in "flight" until it smashes into something (detector, retina etc. etc.), but that does not mean that something in our universe (gravity) will not effect its' flight path.

[GoLightly]

Many things in this known universe affect photons, which is why "c" is the speed of light in a vacuum. There's supposed to be some kind of fiber that allows light to travel faster than the speed of light, which is like saying that it gets to the end before it leaves. Please, don't ask me to explain how, because it has me totally baffled.