If I dig 2 holes a little space apart, and then they intersect straight down, because of the curvature of the earth, then there is more than one up direction from the center. The closer 2 points at an equal distance down from the surface in separate holes get to the center, the less distance there is between the 2 points. I think that ratio has got to be related to gravity! Can we discuss the ratio and how it's related to gravity? By the way, is gravity different near the center? At the center?