Among scientific and skeptical types, clowning on flat-earthers is a pastime as old as Washington Irving. But the fun isn’t just in the myriad ways that you can prove that the Earth is round (er, a roughly spherical ovoid). It’s also in imagining what life would be like if the Earth was actually flat. The problems start with the simple issue of gravity.
Gravity Goes Gonzo
A lot of the strange side effects of a flat Earth would arise directly from the way the disc would experience gravity. This fundamental force of the universe would make its presence known on a pancake planet in several large-scale, undeniable ways. First things first, remember that Earth’s gravity doesn’t pull you down, per se -- it pulls you towards its center of mass. So if you’re standing at the exact center of the disc, you might feel Earthly gravity as normal. But move too far away from the center, and you’ll feel a constant pull drawing you back.
You could imagine that feeling as being akin to standing on a steep hill. And the farther away from the center and towards the edge you went, the steeper that hill would grow. At the very end, it would feel like a nearly vertical wall -- scale that wall and make it to the coin’s edge of the planet, and it will be like standing on normal Earth gravity again. In essence, a flat Earth would feel a lot like a bowl-shaped Earth.
Speaking of that bowl-like effect, it wouldn’t just pull ambulatory beings like humans and animals towards the middle. It would also draw all the water in the world there. As a result, our planet would actually just have one giant ocean, leaving the outer edges of the disc bone dry. Land animals would have to live in a ring around this ocean, leaning ever-so-slightly inward as they did. Because of a phenomenon called negative gravitropism, which causes plants to point their roots towards the center of gravity, all of our trees and shrubs would be leaning too -- but in the opposite direction.
There’s also the matter of what, exactly, is going on in outer space if our planet is flat. In the known model of the solar system, the Earth is round and orbits the sun (also round), which means that it’s under the effects of two vectors of force at once -- the gravitational pull of the sun, which tugs it inward, and forward momentum, which moves it in a perpendicular direction. The combination of those two forces results in a stable, virtually never-ending fall.
But if the Earth is flat, then it’s not orbiting the sun and the moon isn’t orbiting the Earth either. Instead, both the sun and the moon are much smaller than the Earth and move high above the disc as if they were on a carousel centered on the North Pole (the “center of the Earth”). There’s just one issue -- what is keeping them up there? There’s no known force that could levitate two celestial bodies above a high-mass object and keep them moving in a circle in perpetuity.
According to the classic flat-Earth map, the outer rim of the world is a wall of ice that’s commonly called “Antarctica,” and the very center is the North Pole. The idea that the sun spins eternally along that outer rim may explain why the days are so short and the nights so long during certain months as you get close to the Arctic Circle. But it doesn’t explain how that situation flips during the other half of the year, with dark days down south and eternal sunshine on Iceland’s shores.
All this is leaving out the fact that for all intents and purposes, communications satellites would be impossible on a flat Earth. Certainly, we couldn’t launch objects into orbit if we don’t even know what forces are keeping the moon and sun aloft -- our satellites would have to contend with those forces to stay up as well. Since there are, in fact, satellites in orbit (you’re reading this on the internet, after all), we’ve got to conclude that the Earth is still round. Still, it’s fun to speculate about how it might work if it wasn’t.