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The article you link starts off by defining mass as rest mass. I think the article shows very clearly that photons have no rest mass, using several different ar
by mnw21cam 3y ago
The article you link starts off by defining mass as rest mass. I think the article shows very clearly that photons have no rest mass, using several different arguments.
However, a photon has energy, so therefore it must have not-at-rest mass. The article doesn't really comment on not-at-rest mass. We know photons interact with gravity because of gravitational lensing.
- slowmovintarget 3y agoThe 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.