The calculation for mass zeros out as c is a divisor. You get zero for one of the coefficients of the mass calculation, which winds up making the whole thing ze

The calculation for mass zeros out as c is a divisor. You get zero for one of the coefficients of the mass calculation, which winds up making the whole thing zero. The article doesn't have to comment on not-at-rest mass because the math is clear. As for interacting with gravity, photons move through spacetime, and general relativity shows that gravity is the curvature of spacetime, and photons move on the shortest geodesic for that spacetime.