>Quantum mechanical theory is that a photon has no mass (correct?), however, wasn't it Slater or Bohm who posed that a photon has mass and can be treated much like an electron?
Anything that moves exactly at the speed of light has no rest mass - nowadays this is usually just called "mass". Since it has energy, it also has an associated "relativistic" mass, but what used to be called "rest mass" is zero. I am not so sure about the modern terminology...
>Are photons absorbed or reflected? If that is the case, they would surely not go on forever...
The assumption is that they somehow get "old", so even if they are not absorbed or reflected, they would change their frequency, and eventually die out. As far as I know, there is no evidence for this; but it is a theory sometimes presented to account for the redshift (as an alternative to an expansion of the Universe). However, a reduction in frequency means a distortion in time; any alternative theory, in my opinion, would have to account for that.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)
