The relationship between space (or spacetime) and matter is giving me some trouble. If the universe was created (all its matter) in a planktime explosion then the force of said matter must be driving the expansion of space itself. I view the matter as pressing against the walls of space and exerting force on them, thusly driving its expansion. Or does space expand without the aid of the matter contained in it? At what rate is spacetime expanding relative to the the matter contained inside? I can't imagine any matter could move faster than this initial spatial expansion. How could matter exist outside of spacetime? I'll save my questions about matter on larger scales (galaxies) moving faster than the speed of light relative to one another for later; if someone can answer the exact rate of expansion of spacetime for me.