Jeff▲Relf wrote:
So ( to recap ) you don't know if Einstein explicitly said
something like: “ Photons have no rest mass. ”.
I can't believe he was silent on this matter.

Look into his writing on GR. I'm pretty sure he said that light follows
a null geodesic -- that is, for instance, implicit in his computation of
the deflection of light by the sun. It directly follows from Maxwell's
equations and basic GR. Any object that follows a null geodesic
inherently has no mass.

Worrying about what this or that eminent scientist said is of little
use, ESPECIALLY when said scientist died well before the modern
vocabulary we use today was established.


Tom Roberts