[alan wales - dennis sparkes (OP)]

It should be noted that when photons are travelling in vacuous space they are mass-less and their velocity is that of light (c). Consequently, we hypothesize that when photons move from vacuous space into transparent substances their velocity falls below c and they acquire point mass.

[alancalverd]

You are still laboring under the misapprehension that a photon is a particle. It is a particulate model of electromagnetic radiation.

[Origin]

we hypothesize that when photons move from vacuous space into transparent substances their velocity falls below c and they acquire point mass.

That is not a hypothesis, that is a guess and the evidence does not support that particular guess.