It's spacetime curvature. This is an important distinction, because although you can zero out the spatial component of your 4-vector you can't also zero out the

It's spacetime curvature. This is an important distinction, because although you can zero out the spatial component of your 4-vector you can't also zero out the time component. Apparently you can think of the gravitational force as arising from time gradients [1]. Time flows slower closer to the planet, so if your arm is pointing towards the planet then your arm is advancing slightly slower in a particular way and this creates a situation where your arm wants to pull away from you; an apparent force. 1: https://www.youtube.com/watch?v=UKxQTvqcpSg https://www.youtube.com/watch?v=UKxQTvqcpSg