Gravity on a Flat Earth: living in a skewed wonderland

Flat-Earthers often demand visual proof of Earth’s curvature, something you can only see clearly from space. But there’s a much simpler way to demonstrate that Earth can't be flat: gravity itself. The law of gravity is universal and remains consistent for all shapes and forms. Yet, it would manifest itself differently if Earth were flat, continuously reminding us that the world beneath our feet had been transformed. So, let's imagine walking on a flat Earth and experiencing a strange new world created by a touch of scientific imagination.

Fig. 1. If Earth were flat, gravity would cause an environment to tilt toward the ground, clearly revealing the planet's actual shape.

Gravity is always radial, meaning it acts along lines that point toward the center of mass. On the almost spherical Earth, that inward pull points nearly perpendicular to the ground, since every point on the surface is already angled toward the center (Fig. 2, left). However, if Earth were a flat disk, the vector of the gravitational force would not point directly down; it would become more slanted as we travel away from the center of the Earth, wherever it would be (Fig. 2, right). This is why a flat Earth model can't produce the gravitational conditions we experience on the round Earth and take for granted.

Fig. 2. On a round Earth, gravity keeps everyone upright. On a flat Earth, "upright" would become more slanted the closer we get to the edge.

Every object and creature on a flat Earth would be affected by this shift in gravity. Have you noticed that when walking uphill, you tend to lean forward, and when walking downhill, you lean backward? This happens because your body adjusts to the gravitational vector to support your weight. You automatically adjust your posture and muscle tone depending on the surface you’re walking on. You do this subconsciously because if your spine were not aligned with the vector of gravity, you would lose balance and topple.

A climber (Fig. 3, left) is positioned at a sharp angle to the hill. Yet, relative to the flat ground behind him, he remains upright. This illustrates that, despite the change in angle, he keeps his posture aligned with the gravitational vector regardless of his location. If he were holding a plumb line, it would indicate the direction of the gravitational vector and the posture that requires minimal muscle effort to maintain balance. Gravity always pulls the plumb line along the radial vector, showing a vertical orientation of minimal structural strain, whether in a living body or a building.

Fig. 3. Contrary to popular belief, vertical position is determined not by the angle with the ground, but by alignment with the gravitational vector. On a slope, both the climber and the house are still vertical.

On a flat Earth, the upright posture, as well as the upright buildings, would only be possible at the center of the faces and the center of the edges, because only there the radial vector is perpendicular to the surface. The farther we move from those points to the edges, the more slanted the gravitational vectors become, and the more tilted our posture would have to be. Even on a level surface, we'd maintain a tilt as a natural adaptation to the radial lines upon which gravity acts on our body.

In fact, everything would need to adapt, including soil, water, and atmosphere. Trees would lean toward the ground, much like they do on slopes now, and stilt foundations would be necessary to support houses, similar to those built on hills. The hills themselves would pose an unusual challenge for the angled climbers (Fig. 4). Shaped like houses on stilts to bear their weight, they would make ascent feel much steeper than it looks. Conversely, descending would feel like a stroll in the park on our spherical Earth (Fig. 4). This scenario would reverse when moving from the edge toward the center. In this case, climbing up would feel surprisingly easy, while descending would become a dangerous act. This is because the plains on the flat Earth would no longer be level relative to gravity.

Fig. 4. On a flat Earth, the farther you move from the center, the more gravity pulls sideways, making every step feel like walking on a slope

Animals would also walk with their bodies angled to the ground, and even birds would need to keep the angle when flying in the sky, as gravitational vectors extend into space. In our world, when we drop an object from a window, it falls straight down, guided by the gravitational vector, which is perpendicular to the ground. On a flat Earth, the same vector would cause the object to fall diagonally. However, as bizarre as it sounds, this path would appear normal in the skewed surroundings, as it would be consistent with the angled house. Even rain would pour diagonally, and its puddles would drain toward the Earth's center, similar to how they drain now from hills.

Ultimately, everything in such a world—air, water, soil, and even the ground itself—would be pulled along those inward-pointing gravitational vectors. Over time, this constant pull would cause all loose material to migrate toward the center, smoothing out the tilted landscape. The atmosphere would settle into a uniform shell, water would pool symmetrically around the center, and the crust would gradually deform under its own weight. Instead of remaining flat, the surface would slowly reshape itself into the familiar, almost spherical Earth we live on today.

By analyzing such an alternative flat-Earth model, we also gain a fresh, out-of-the-box perspective on our own reality. Imagining how gravity would shape a radically different world helps clarify just how strongly this force governs the behavior of matter, from the atmosphere and oceans to the very form of the planet itself. In exploring the impossible, we deepen our understanding of why the Earth must take the shape it does.