http://en.wikipedia.org/wiki/Image:Spacetime_curvature.png The picture linked above shows the spacetime curvature. Apparently, it's a 3d model. But it's not! What i think (and basically trying to find out about) is that space itself is imagined as the 2d grid. What the earth does is bends it into the 3rd dimension. So, with an actual 3d grid, wouldn't this actually be bending not space [3rd dimension] but time [4th]? instead of bending the 2nd dimension into the 3rd, i think it would bend the 3rd into the 4th.