but these nuts move by gravity do they not? and what in the universe is exactly up and down? and why would that matter?
are all celestial bodies then a local up and 'away from them' down?
this analogy hurts my brain. please tell me how to make the hurting stop
No you are right. You can't invoke gravity in an analogy trying to explain gravity.
The same effect could be replicated in a zero-gravity environment using an alternative background force (centrifugal force, vacuum suction, electromagnetism, etc.)
Wouldn't that mean that if gravity was like this analogy, that gravity would still need an external background force to work? And how would you explain the presence of that force?
Not without a bridge for the metaphor to generalize. What parameters map to the nutjar’s selective force, size, and mass?
You need to reread the middle only. It's a kind of "vacuum" effect.
but where in nature is then this vacuum? is it just higher and lower energy density or something? like high and low pressure systems in weather pushing and pulling?
that would or might imply gravity is electromagnetic?
(sorry if this seems really off the charts / missing your point!)
This problem of explaining gravity with gravity is a bit pervasive, and it frustrated the heck out of me as a kid.