[quote name='Chewett' post='24876' date='Feb 7 2009, 10:44 AM']Gravity is easy to exaplain i believe
since any body of mass has gravity i believe that under our ground is a type of metal that is dense enough to have a gravititional force that is large enough that it allows us to walk on this place. however this theory means that unless this layer of metal is resting on another world (box theory) then there could be "things" on the other side of our world.[/quote]
If you want to use gravity as we know it, you'll have to put the center of mass far beneath the surface, to make the gravitational vector as near orthogonal to the surface as possible. And i'd suggest a black hole, that'd be dense enough, and is conform myths in which falling off of a disclike world, you'd fall to your doom.
Of course you'd need some force that keeps the disc from falling towards the black hole. Maybe add a magnetic monopole? (that ought to annoy theorists enough)
