Your question is in fact a very profound one, and one that physics (not to mention philosophy) is still grappling with. Although "removing everything that occupies a given space" sounds simple, it is anything but. Remember that what occupies space are energy fields, gravitational, electromagnetic, and so on. How would you go about "blocking" gravitational fields? And it gets worse. Space, like time, is something that we measure only with reference to objects or processes. What is a meter? It is the length of an actual object. There seems to be no way to get around this, believe me people have tried. We know that neither space nor time are constant, but change depending on our frame of reference. If we did manage to remove all matter and energy in a given space, how would we then go about measuring how much space there was there?<br /><br />I am not trying to be obtuse. Niels Bohr tried to tell us that science is not concerned with how things actually are, whatever that means. It is concerned with what we can perceive, what we can measure. This is a hard pill for many to swallow, myself included. But if anyone can demonstrate that space, time, or anything else is "out there," independent of our measurement of objects and/or processes, I would like to hear it. Our present model divides the universe into two "things," matter/energy and space/time. But this is nothing more than a convenience, a model to help us think about our universe. My personal view is that both are expressions of something more fundamental.