In short, even though photons have no mass, they still have momentum proportional to their energy, given by the formula p=E/c. Because photons have no mass, all of the momentum of a photon actually comes from its energy and frequency as described by the Planck-Einstein relation E=hf.

From here: https://profoundphysics.com/if-photons-have-no-mass-how-can-they-have-momentum/

Essentially, momentum is a function of energy, not mass. It's just that massive objects have way more momentum than massless ones.

[–] [email protected] 16 points 3 months ago* (last edited 3 months ago)

Essentially, momentum is a function of energy, not mass.

Thanks! That's the critical piece of information.