Hello; For something to travel at the speed of light, mass has to be zero. Light is a form of electromagnetic radiation, which travels at 299,792,458 m/s. Because it is a form of electromagnetic radiation, it is carried by the force-carrier particle, the photon. However, photons have a very small mass that is almost zero (but not zero) so it is not massless, but very close to being massless. If light is simply photons, then that means that light cannot reach 299,792,458 m/s; in other words, light cannot reach the speed of light. Where is the error here? Thanks.