As I said, the matter is unknown.
Strange that you can hypothesise so many explanations for things needed to prop up the Flat Earth with no basis at all.
The one and
only reason gravitation is denied in the flat earth hypothesis[1] is that
it conflicts with the idea of a finite disk earth[2].
At least with gravitation in the Globe model, while there may questions as to the cause of gravitation, it has been verified experimentally many times;
see
What did Henry Cavendish Measure? « on: March 14, 2016, 04:53:13 PM », which everyone conveniently ignores.
Actually, while magnetic and electrostatic forces seem more tangible, can you explain at a fundamental level just why these can attract or repel? Gravitation seems so elusive
simply because it is really such a minute force[3] - but is exactly right to explain gravity, orbital motion etc.
[1] Yes I know you claim a "celestial gravitation" that somehow doesn't cause gravity on earth - are celestial objects composed of a different type of matter?
[2] BTW "TheFlatEarthSociety - the other one" seems to be scrapping the whole idea of UA in favour of an infinite plane earth, which leads to a uniform vertical "gravity"! Ask John Davis.
[3] In particular, while you can "feel" magnetic and electrostatic forces between everyday objects, gravitation is far too weak to sense in this way.