First, let me say I love astronomy cast. I discovered it only last week or so, and I've already listened through all of them. I'm going to have to listen to some of them again though... some of these concepts are hard to grasp.
Anyway, I have a couple of questions.
fist... Let's imagine we're a photon traveling through a vacuum. Since we are traveling at the speed of light (duh), and time slows down the faster you go, does that mean that photons "experience" no time? or I guess I should say they experience a fraction of a second as an infinity of time... or how does that work?
second... I hear photons are massless, because if they had any mass, it would have to be infinite because of the speed it's traveling at. How is it that photons can push things with light pressure?
and finally... if the universe is expanding and the further away a star is the faster it appears to be expanding, how does that affect light? shouldn't it appear to slow down because it has to travel longer? it's kind of like a treadmill. The space is "pushing" the photon out as it expands, so shouldn't it affect the APPARENT speed of light?
I have more questions, but I guess I'll save those for later :P