- 56,007
- 138,746
light has no rest mass, it has a force that it can impart that's measured comparable to an exceedingly tiny amount of mass, but it has no mass itself.It has relativistic mass but photons do not have mass.
The problem with light is that it has some very special properties (it moves faster than any real matter could). Therefor the relation p = mv is not well-definied for light (since that only applies to particles with mass)