[kevinpet]

I think what he's getting at is that there's this value "c" that's really important to physics appearing in equations like e=mc^2 and determining the absolute upper bound on speed, and by the way, we used to assume that photons traveled at c, rather than their actual rate of 99.9975% of c.

I don't know whether changing c by this amount would break many experimental results. Adding a rest mass to photos sounds potentially revolutionary.