2 points
12 points
Photons are born and die at c. They experience no time and have no frame of reference.
3 points
1 point
The speed of light is different depending on the medium though isn’t it? So to change speed I would have thought some acceleration would have to be involved.
I have no idea what I’m talking about though.
2 points
It’s not. The wave front moves slower. Because when light moves through matter it’s getting absorbed and reradiated.