By the "standard model", thickness beyond whatever's necessary to make the pizza structurally sound (and allow mining and such) is immaterial. No-one lives on t

By the "standard model", thickness beyond whatever's necessary to make the pizza structurally sound (and allow mining and such) is immaterial. No-one lives on the sides, and there's nothing on the bottom. Or, alternately, the bottom extends infinitely to compensate for the complete lack of turtles. Take your pick - both work. Don't worry about the mass of the earth, since gravity isn't a thing; the appearance of gravity is due to density (somehow) or to the ever-accelerating vertical ascent of the Earth and the nice space-like ceiling and its lights and other decorations (moons and such). If there was any of that so-called "gravity" that NASA ordered Newton and Einstein to make up plausible math for, the Earth would either have to extend to an infinite plane (which does bad things for fitting the dome sky) or anything not in the centre of the Earth would have a distinct lean to it. (Although perspective and atmospheric refraction would probably make things look vertical, just as it works to make the sun appear to rise and set as it travels in its circle over the disc and causes ships to appear to disappear from the bottom up over the horizon. Which ships clearly don't, because Nikon P900.) And don't bother mentioning that density differences need gravity to work as an up/down mechanism, since your so-called "gravity" is just density. (Yes, that will be the answer you get.) The key terms to remember are density, perspective and refraction. These explain any sphere-like or broadly heliocentric behaviours you may observe. And no, you can't just go to Antarctica to prove that it's just another continent, because there are armed forces keeping you away from the ice wall.