It is like the surface of an orange: if you look at it close up, it is all curved and wrinkled, but if you look at it from a distance, you don’t see the bumps, and it appears to be smooth. So it is with space–time. On a very small scale, it is ten–dimensional and highly curved. But on bigger scales, you don’t see the curvature or the extra dimensions. If this picture is correct, it spells bad news for would-be space travelers.
