> But how would a theoretical graviton explain this effect? there would be more gravitons if the field is stronger. No gravitons in the empty space. Gravitons

> But how would a theoretical graviton explain this effect? there would be more gravitons if the field is stronger. No gravitons in the empty space. Gravitons are quantas of the always attractive forces. So traveling in the gravitation field, photon constantly absorbs and emits gravitons, more gravitons - more interactions, thus "bending" photon trajectory in the presence of the gravitation. If you a bit math inclined, you could look at Feynman's lectures on gravitation (Caltech, fall semester of 1962). They are quite outdated, a lot of mistakes - he was building it as he is preparing lectures, but approach itself is very interesting He starts with MICROSCOPIC description - lets introduce gravitons, we want bosons which always attract, so no spin 1, only spin 0 or 2. Dropped spin 0 (don't remember why) and start building interaction diagrams form spin 2 bosons like in any standard quantum field theory. Discussed exactly the topic of "trajectory bending", got to quasi-classic limit and showed that this is Einstein field eqs, got to weak field limit and Newton, ... And all this (even his mistakes) in beautiful style and logic.