what is the observed distance range of gravity?

No such data exists. Newton and Einstein treat gravitational force as if it has infinite range.

The sizes and shapes of the various types of galaxies, and the observed orbital velocities of stars in them at various distances from their cores, can be interpreted as evidence for a limited range of gravitational force. Based on this interpretation, some alternative theories either postualte or deduce a limited range for gravitational force.

One of them is DRP, which uses a particle based LeSagian model for gravitational force. It deduces that the range of gravitational force is on the order of a few kiloparsecs.

It seems you could say all gravity force is local and not go too far wrong. The force centers on mass and is very weak so any large mass has its own domain.

Larry, I believe Tom had calculated somewhere around 21 kiloparsecs from galaxy data....I can't put a finger on the source at the moment, but that is what comes to mind....

Mark Vitrone

I forget which author it was (probably Tom) in Pushing Gravity who gave the mean free path of gravitons as being about 1 or 2 kiloparsecs. Tom also discussed it somewhere on this messageboard as well. The mean free path is the distance a graviton travels, on average, before colliding with another graviton, and is thus the limiting factor for the effective range of gravity.

>> The force centers on mass and is very weak so any large mass has its own domain.

Well, the most massive body in the neighborhood dominates all other bodies because the gravitational forces net out in it's favor but each body still 'feels' the gravitation of all the others within range of a couple of kiloparsecs.

No great thing was ever created suddenly - Epictitus

Tom discusses this in Ch 4 (pg 79 in both editions). He concludes that the mean free path of gravitons appears to be about 2 kiloparsecs, but does not specify a value for the "range" of the force. After traveling two or three mean free path lengths the vast majority of gravitons will have interacted with at least one other graviton and will no longer convey any information about the last mass they encountered.

So, gravitational force should begin to deviate from the inverse square model almost immediately, probably within our solar system. But we will need better measuring devices than we have to detect this small variation. It is likely that some amount of gravitational force can still be detected as far out as 21 kiloparsecs (again, our instruments will influence this). I guess we ought to try to define what we mean by the "range" of gravitational force so that we can be sure we are talking about the same thing. First detectable deviation from inverse square? Maximum distance for detection of any effect? Or some middle ground, like mean free path?

Of course, this sort of thing is just one level above rank speculation. Until we can actually detect gravitons and actually measure the mean free path of their flight, we must admit to ourselves that we do not really know.

Even defining gravity is impossible-all that is known for sure is its a predictable force.