Things do not "fall up" because of gravity, an attractive force that pulls objects with mass toward the center of the Earth rather than away from it. Because the Earth is vastly more massive than any object on its surface, its gravitational pull dominates, creating a "gravity well" that draws everything toward its center, which we perceive as "down". While Isaac Newton described this as an invisible force acting between masses, Einsteinās general relativity refined this by explaining that Earth's mass bends the fabric of spacetime, and objects simply follow the shortest path through that curvatureāleading them toward the ground. Ultimately, things don't fall up because there is no mechanism to push them away from the immense mass of the planet.