I've never heard of that effect being used for any form of interstellar travel.
There are 5 or six main forces that connect at different points that are observable. E-MC^2 is just one of those points, defining the connection between mass, light, and energy transference. What Einstein is describing is the "observation" of these 5 or 6 forces to each other. Since light observes and respects empty space, and so does magnetism, there must be a value, or group of information stored somewhere that tells the other forces what is going on in this spot. Some people call this scaffold energy, because it acts as a scaffold to everything else. Please send Noble Prize right away, thanks Royal Swedish Academy of Science.
