I will start by saying I am not a physicist and what I am posting here is pure thought experiment on my part. I was wondering about the nature of gravity, and trying to determine how the force could act to pull two objects together. What physical interaction causes two objects to accelerate towards each other? I came up with the idea that gravity is not a property of mass, and it does not cause objects to pull each other. Instead, what if it is a property of an expanding universe that pushes objects together, and is only affected by mass? For example, take an object in empty space. Imagine that gravity affects this object by pushing equally on all sides. It acts as an equal force coming in from all directions. Take another object and place it near the first. Again, this object experiences gravity as a force coming in from all directions. With two objects, though, the pushing force acting on the faces of the objects that are pointing towards each other will be weaker compared to the forces acting on the rest of the objects, because the mass of each object absorbs some of this force- essentially "blocking" it from reaching the other object. The result here is that the two objects would be pushed together.