“So you’re saying gravity acts as if it were a rigid “arm” that connects two bodies, as opposed to something that propagates through the intervening space between them? i.e., like flying cars in an amusement park ride physically attached to the rotating mechanism at the center?”
I think that’s a good analogy.
Gravity seems to be a property of matter, like a field of mutual attraction that surrounds all matter in proportion to its static mass, so that there’s nothing that actually ‘travels’ as such but is always present.
I don’t know. It just might not be perceivable in systems as minor as our solar system. Perhaps on much larger scales, a time delay can be detected.
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From nasa.gov:
Satellite observations of Black Holes confirm frame-dragging effect 80 years after prediction
The next time you feel like you’re barely dragging along, blame relativity. You’ll be stretching the point, but it appears that Einstein was right: space and time get pulled out of shape near a rotating body.
Einstein predicted the effect, called ``frame dragging,’’ 80 years ago. Like many other aspects of Einstein’s famous theories of relativity, it’s so subtle that no conventional method could measure it.
Using recent observations by X-ray astronomy satellites, including NASA’s Rossi X-ray Timing Explorer, a team of astronomers is announcing that they see evidence of frame dragging in disks of gas swirling around a black hole. The discovery will be announced today at a meeting of the High Energy Astrophysics Division of the American Astronomical Society in Estes Park, Colo., by Dr. Wei Cui of the Massachusetts Institute of Technology, and his colleagues, Dr. Nan Zhang, working at NASA’s Marshall Space Flight Center, and Dr. Wan Chen of the University of Maryland in College Park.
Frame dragging is one of the last frontiers in relativity. More familiar and already proven are the conversion of mass into energy (as seen in atomic bombs and stars) and back, the Lorentz transformations that make objects near the speed of light grow thinner and heavier and stretch time, and the warping of space by gravity (as seen when light is bent by a massive object).
Einstein also predicted that the rotation of an object would alter space and time, dragging a nearby object out of position compared to predictions by the simpler math of Sir Isaac Newton.
The effect is incredibly small, about one part in a few trillion, which means that you have to look at something very massive, or build an instrument that is incredibly sensitive and put it in orbit.
http://science.nasa.gov/science-news/science-at-nasa/1997/ast06nov97_1/