The nature of "space"

Greetings all! It's been a while since I visited, but I always turn to this forum when I've got a puzzle that I simply can't wrap my head around.With that in mind... the simple question here is this:Is there "space" outside of the known universe?What I mean is that, if you were to journey to the outermost edge of the known universe... the point where all matter in the universe had not expanded past yet... would there just be more empty space beyond that boundary?To give you a little more background, I'm currently in a discussion with a creationist and we are discussing the nature of empty space in the Universe. He is trying to make a point that, as the universe expands, new "space" is "created" between the different stellar bodies.My point is that space itself is nothing but the void... the medium (if you will) that all matter expands into. It is not tangible, but rather it is only identifiable as a lack of anything between the various stellar bodies. A true void.My own problem with this understanding is perhaps due to my current understanding of the nature of the universe. I've never understood that whole "balloon" analogy with everything sitting on the surface of the balloon. Instead, I've always thought of the universe more like a "cloud" containing all matter in the known universe that is constantly expanding in all directions outward.If my own understanding is incorrect, maybe someone here could help put it into better terms.Thanks!