Mohan is right.
Just like Heisenderg said "A particle only come into existence as we observe it", so the relationship between the oberver and a particle (as in the sense photons) is parallel. As for its massless property, the photoelectric effect is quite relavent (it states that a photon can knock electrons off a specific material, so that's means photons must have mass), but on the other hand, anything that has a rest mass can not accelerate to, travel and or exceed the speed of light, so the mediator (photon) must be massless. Although there are still many disputes over this theory, I personally think, we should just add our own interpretations in the theories (your theory is just as good as anyone eles, remember that).
"Science is organized knowledge. Wisdom is organized life"
"But although all our knowledge begins with experience, it does not follow that it arises from experience."
"Happiness is not an ideal of reason, but of imagination."
Immanuel Kant