For the purposes of this question, assume there are gravitons and they are the carrier of the gravitational force. I could use one of the other forces and leave out gravitons, but it's easier for me to envision this question using a very low strength force. Q1) -- For gravity to deflect the path of a photon, does it take many-many interactions with gravitons to do the trick? I mean, the angle a photon is deflected is related to mass (other things the same) and I would think the more the gravitational field is to deflect the photon, the more gravitons it would have to interact with to get the job done .. no one graviton interaction could do the job. Q2) -- If that is true, (and this is really my question), I envision the Universe awash in virtual gravitons. So many more of them than virtual photons, and other virtual particles. I know someone could say "well, it depends on where you are in space .. it might not hold true with very little mass in this part of space". But that's not what I mean .. you might also have to assume all matter/energy/forces pretty evenly distributed thoughout the Universe. Wouldn't there then be upteen magnitudes more virtual gravitons around per volume than virtual photons? I'm going to use the answers as the basis of another question, later.