Why do photons travel at the speed $299792458$ m/s?
Is it because they are the particles of which light is made, so they must travel at the speed of light, or is it because they have no mass, which implies that we should not call $299792458$ m/s the "speed of light" but rather the "speed of massless particles"?
In a video, a physicist said that we should not say that photons travel at the "speed of light" but at the "speed of massless particles."
I am a bit confused right now. Is he correct for this reasoning?
Any help is greatly appreciated.
