I hate to have to demolish the world view of all you round-earthers out there, but someone had to say it: the earth is flat. Don't believe me? Hear me out for a second.
The Merriam-Webster Dictionary ascribes the following meaning to the word flat (adjective):
2 a: having a continuous horizontal surface
and the following meaning to the word horizontal:
1 b: parallel to, in the plane of, or operating in a plane parallel to the horizon or to a baseline : level
A man, woman, or child walking upon the earth is attached to its surface by a gravitational pull directed towards the earth's center of mass. This pull defines the direction "down". Any movement perpendicular to "down" takes place in the horizontal plane. The person in question will, in other words, be walking on a flat surface.
This may seem like a word game, but it is actually sort of serious. The earth only seems round to an observer that is outside its gravitational field. But if that observer were to enter its gravitational field, he would see it fold out into a flat surface. It is plausible that every world, such as another universe, would seem round when observed from the outside. But it is only when you enter a world and become affected by its physical laws that you can judge its true shape.
