We observe the earth surface as a topographical level plane. The surface of the Earth is modeled as a 2D surface embedded in 3D space. We are on a topographical level plane inside of a sphere. how can you have a Z if the X,Y is over the spatial volume (globe). gravity is not a force, mass doesnt attract mass. Im a PhD biochemist from Stanford university. presbyterian anime watcher, I don’t think the earth is flat or a sphere. Debate me.