An objective world has only one type of movement but virtual worlds always have two. In Figure 5.6, one can move the avatars to the left by moving their pixels left or by moving the forest pixels behind them right. A program can create relative movement by moving the object or its background, as the avatars move relative to the forest in both cases. Programs move images by bit-shifting the foreground or background equally easily. In one case, avatar pixels move across the screen and in the other they keep a center-screen frame of reference as the background pixels scroll behind them.
Our reality also has two movement types, of light that is absolute and of matter that is relative to a frame of reference. Light and matter move differently in our reality just as in a virtual reality. Light moves like a pixel crossing a screen while matter moves like a center-screen image whose background scrolls. Bit-shifting space is the equivalent of moving the zero-point described earlier. The particle model assumes particles are moving on a stationary background but quantum realism adds the option of moving by bit-shifting the background. In a fast car, it isn’t hard to imagine one is still and the world is scrolling by, perhaps because it is actually so.