Greetings everyone! I am new to the Physics Forums, and I am really glad to have found this place. I just finished Brian Greene's book The Elegant Universe, and needless to say I am a little confused on some things (most things, actually). One of the most interesting topics discussed, I thought, was that of light and its properties. According to the text, light only moves through the three extended spatial dimensions, while ignoring the fourth (time). So, in other words, light isn't affected by time. A photon emitted from a star a billion years ago is still the same "age" today as it was from its initial emission. Does that mean that if one were to see the world through the point of view of a photon, that everything would simply be completely frozen? I guess my question is, if light isn't affected by time, how is it that we are able to measure that in a year it has traveled a light year from us, instead of two, or ten, or an infinite number of light years? Since it is unaffected by time, why doesn't it reach infinity in what would seem to us as an instant?