light is a primary particle, and really, practically speaking a variant of electrons, alpha and beta particles and gamma/x/cosmic ray. really they are all photons, with different affinities, all can travel in vacuum.

i have a theory that space itself is expanding and matter especially these radiative particles, are doing two things: a) riding the wave of the constant expansion of the neutral particle (aka space) and composed of disturbances overlaid on them, and b) no particle in the universe is actually moving, but rather, space is either expanding in one direction (radiative particles) or in all directions (inert matter particles and gravitons). ok, i will let you read my recent posts to explain what i think gravity is conducted by, and its relation to matter. the expanding space thing isn't something i talk about so much these days but it's the premise of my model.

everything is at the center of the universe, subjectively, which is moving around them, by this mechanism. just as a circle has no point on it that can be called a center (and thus it has infinite symmetries) space itself is a looped manifold as well, folded through the fourth dimension, also. although the universe does have a beginning, it has no end. as Lao Tzu said. one gives way to 2, which gives way to 3, which leads to all things. all starts with singularity, and "ends" in infinity.