Interesting question. In my opinion, the vacuum can certainly be used for propulsion. What if I told you that the vacuum is already providing energy for propulsion? I know. You would not believe it. However, have you ever wondered why two bodies in relative inertial motion stay in motion? No, it's not because of momentum. Momentum is just the abstract description of the phenomenon. The truth is that bodies remain in motion because of the energy in the vacuum.
If you truly want to use the vacuum for propulsion, you must first understand the properties of the vacuum, and in order to do that, you must first understand the true fundamental nature of motion. Once you do, you will also know that Aristotle was right about the causality of motion, that the universe is discrete and that, as a result, we are immersed in an immense lattice of energetic particles. No lattice = no motion.
Physics: The Problem with Motion
