Oh, and it is for sure thick. There is an entire underground world full of nuclear powered bases/condos. All run off the fake nuclear "warheads" we made for them, by the thousands. Connected by vast tunnel networks, with maglev trains and all. Its growing bigger and bigger, the more money\energy we give to the space club agencies. They have access to all the ancient cities and technologies that have already existed, and use it to enslave us on the surface. There are even more mini domes in the deepest crevices of the sea too, like the movie abyss. I guess you could say we're in an orb, with the horizon of the earth right near the middle.