Flat earth theory is a subset of ether theory and the of new radical chronology of history. Since most FE are atheists, they do not accept the stationary disk model which is covered by a dome. That is why they have put forth alternatives: UA (universal acceleration), where the Earth is moving upwards at a certain speed, and the IP (infinite plane) conjecture. As soon as these two hypotheses are brought up in a debate, their conceptual weaknesses become clear very fast. FE needs ether theory in order to function properly.