I'm extremely uber layman, so forgive me for any ignorance or stupidity and my excessive use of the word "so". I'm failing to understand either what light is or how it can travel through space (or both). I read that light is photons, and photons are particles that have no mass, and are a wave. So my understanding of that is that photons are not so much physical substance as they are energy that effect some aspect of physical substance. So if it was a wave as in sound, it causes vibrations in the air of our atmosphere. A literal wave or ripple comes from vibrations of the surrounding water. So if photons as a "wave" are directly analogous to sound or a ripple in a pond in how they work, then that means that there is some sort of medium or atmosphere that they are effecting, and it is this effect on whatever medium or atmosphere that exists that we are measuring and referring to as photons and light. So if this above is more or less correct, and space is really an empty vacuum apart from the odd rocks and debris, how does light get transmitted by nothing for millions or billions of years? Is there really something there that is transmitting light waves? Or is light really a physical something that is just moving really fast, and my lack of a proper scientific physics-based understanding of what mass really is is messing me up?