I have the same problem as reenpeery, why can't we just base an idea on that space i.e. the black void of nothing between matter and energy is nothing more than that, an infinite void which could be populated with matter and energy way beyond what we can detect. Or the outer most edges of what we can detect are exactly that the edge of our universe. Is our universe defined by this boundry? ( if it exists ) and the rest is an infinite void? or are we trying to define it as the whole of space? which may be just nothing. I do understand that we detect a background radiation emitting from all directions but this may only show that we are unable to detect further out than the bubble of matter and energy which we are a part of. assuming that there is a way to detect beyond this?