How exactly does gravity work?

[David Lewis]

The only reason that objects follow the curve of a rubber sheet is because of the force of gravity. Take away the force of gravity and all bets are off.

It's a 2D model in 3D space, and you can see all the dimensions. If you are moving in a straight line in a universe that is curved in a dimension you can't see, you would feel a force.

Why does it lose some of its motion through time and gain motion in space?

The extent in one dimension decreases in the dimension it's rotating out of, and simultaneously increases in the dimension it's rotating into.

You cannot remove the planet and keep the curvature of spacetime.

The curvature will remain for a time. As a thought experiment, if you suddenly moved the Sun far away from the solar system, the curvature in the vicinity of Earth would remain unperturbed for about 8 minutes.

 

[Dale]

if you suddenly moved the Sun far away from the solar system,

You cannot do that either.

 

[PeterDonis]

If you are moving in a straight line in a universe that is curved in a dimension you can't see, you would feel a force.

No, you wouldn't. GR models spacetime in the presence of gravity this way (except for the part about being "curved in a dimension you can't see", which is not necessary, curvature can be intrinsic to a manifold and independent of any embedding into a higher dimensional space), and objects moving solely under gravity feel no force.

As a thought experiment, if you suddenly moved the Sun far away from the solar system

As @Dale pointed out, you can't do this. The qualfier doesn't get you off the hook; even in thought experiments, you can't violate the laws of physics, and suddenly moving the Sun far away from the solar system would violate the laws of GR (in this case, local conservation of stress-energy).

 

[Patterner]

You could always build planet sized spaceships.

That's an easy fix! :) Just don't go near any solar systems. Don't want to be causing tidal waves. Or pulling planets out of orbit.

However, setting a “who cares” radius and then asking about a baseball placed there will only lead to “who cares” answers. That is fairly uninteresting for us to write and uninformative for you to read, so I hope you don’t do it.

I will fight the urge. But I'm just trying to understand things. I guess the inverse square law won't let us say there is any distance at which the gravitational effect is 0. But still...

 

[Dale]

I'm just trying to understand things.

If you really do have a strong desire to understand, then you will need to put in some effort learning background concepts. I would recommend learning special relativity first, particularly from a source that teaches about four-vectors and has a strong emphasis on spacetime geometry.

 

[Patterner]

Any sources you particularly recommend?

 

[Nugatory]

Any sources you particularly recommend?

You could do worse than "Spacetime Physics", by Taylor and Wheeler.

 

[Dale]

Any sources you particularly recommend?

I was going to suggest Spacetime Physics also.

 

[A.T.]

Any sources you particularly recommend?

If you want an intuitive grasp of the concepts, with as little math as possible, try:
"Relativity Visualized" by Lewis Carroll Epstein

 

[Patterner]

Checking them out. Thanks.

 

[PeroK]

Checking them out. Thanks.

There are free texts on SR and GR here:

http://www.lightandmatter.com/

 

[Patterner]

Thanks again!