Well we dont know right? There Is this Quasar jet which dissapear for a bit And Is thought to be Faster than c, So we can't see it. You have to understand that heat, visible light, UV, radiowaves, your WiFi, tv signal And more is still "light" you just can't see most of it. Let have this box which can be shielded from everything in universe, but Is still in our universe, if you turn on a flash light in there, surprise you Will see light. But if this box Is not part of our universe, there Will be no light, cuz the energy can't travel thru Space like a wave. There Is no particle in photon, it is energetic Peaks in Space which sometimes act like a particle. if you swoosh a long straight rope, the wave Will travel along the rope, it Is the same with light, the rope Is Space And the wave Is photon.