Something massless (like the dot of a laser pointer against the wall). Something slinking around the laws of relativity / inertia by moving the grid, not the ob

Something massless (like the dot of a laser pointer against the wall). Something slinking around the laws of relativity / inertia by moving the grid, not the object on the grid, Alcubierre warp style. Or the textbooks are wrong (it wouldn't be the first time).