SSDD brings up a valid point. photons do exist all along their flight path until a bit of matter 'puts them to the test' and condenses a probability wave into a discrete particle. it is very conceivable that all photons start as virtual photons.
but the evidence seems to suggest that radiative photons have their energy prepaid by matter trying to shed energy. unlike reactive photons in electric and magnetic fields that are virtual photons which probe the surroundings looking for partners to swap force with. if a virtual photon finds no partner it simply ceases to exist and no energy bill needs to be paid. while virtual photons exist for only a very short time, in the photon's reference frame it exists at all points of it's path.
there is a fundemental difference between radiative and reactive photons. the reactive photons have an extra characteristic of being either attractive or repulsive.
but the evidence seems to suggest that radiative photons have their energy prepaid by matter trying to shed energy. unlike reactive photons in electric and magnetic fields that are virtual photons which probe the surroundings looking for partners to swap force with. if a virtual photon finds no partner it simply ceases to exist and no energy bill needs to be paid. while virtual photons exist for only a very short time, in the photon's reference frame it exists at all points of it's path.
there is a fundemental difference between radiative and reactive photons. the reactive photons have an extra characteristic of being either attractive or repulsive.