What if the vacuum of space rather than being nothing is something? Maybe it's dark matter or something we can't comprehend. Let's call it "nothingness." I imagine "nothingness" to be similar to a 3D fabric,both very ordered and very consistent. What if when a planet is hanging out in space it is displacing the "nothingness" ? The nothingness has nowhere to go and gets pushed back, away from the planet. The larger and denser the planet is the more completely the "nothingness" is displaced. Think of a rock and a sponge of similar size in a bucket of water. . The rock is much denser and less porous than the sponge so it displaces more water. but the "nothingness" is interlocked with all of the adjacent "nothingness" so while it is displaced it develops tension. The greater the size and density the more displacement occurs and the greater the tension is. The "nothingness" knows where it should be like memory foam and wants to return to its normal position creating an invisible pressure or tension that is exerted equally around the entire planet pressing in toward the core strongest at the median surface elevation. As an object moves farther away from the planet the distorted structure of the "nothingness" begins to return to normal structure no longer being stretched or compressed and no longer forcing objects toward the planet.