eli5 How does gravity work? Where does it come from?
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People keep saying, “We don’t know where gravity comes from,” but we totally do. If you adhere to Newtonian physics, then sure, there’s no explanation for the source of gravity. But Relativity makes it clear that Newtonian physics is merely a fairly good explanation of how gravity behaves, not an accurate explanation of what it IS.
So in short, gravity is not a force. It’s not even a *thing.* Gravity is a *shape.* We human beings think of shapes as three dimensional, but actual shapes are four-dimensional because they exist in spacetime, not just in space. When we ask where gravity “comes from,” it’s like pointing at a circle and asking, “Where does *roundness* come from?” The fact that gravity seems to *act* is due to the fact that every object in the universe is in motion through spacetime. So what seems stationary to us, because the Earth is our frame of reference instead of an inertial frame of reference, are really just other things following the same path through spacetime as we are. What we perceive as the action of gravity is really our inertia following the curvature of the spacetime around us.
It’s very hard to let go of the idea that everything around us is stationary and that we’re moving through time, but that’s what prevents us from experiencing gravity for what it actually is. We evolved to perceive it as something completely different from reality.
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