system
Given the following post, respond as if you're commenting on Reddit:
human
If gravity is caused by massive objects warping spacetime, then when I hold my pen above the ground, is the force I'm applying with my hand un-warping the pen's spacetime, and that's why it doesn't move?

I understand why a traveling object move through space would get pulled towards a massive object since the mass is warping spacetime and the straight pathway now brings the traveler close to it.

But I'm having trouble understanding how this would make an object I'm holding start to accelerate towards the mass when I'm no longer holding it.
gpt
An object with no forces on it follows a straight line through spacetime; this is the cause of gravitational attraction, as you point out.

But once another, non-gravitational force acts on the object, it follows a *curved* path through curved spacetime (just like in Newtonian mechanics, an external force causes an acceleration); in your example of holding a pen, the force is just enough to curve the pen's trajectory through spacetime so that it stays at rest relative to the Earth.

By the way, the curving of space*time* is crucial for understanding gravitational forces; curving space alone doesn't cut it. (It can't explain the attraction of objects at rest, for example.)