Hi, some researchers have wondered whether the G in F(M,m,r)=GMm/rr was a true constant. I believe an associated problem is the motion of stars on the edge of our galaxy (there are either too fast or too slow...). A nonconstant G was then proposed to explaine this motion. This may relate to dark matter too, I 'm not sure. If someone can brief me of the current state this problem, I'd appreciate it. My related question is more mathematical : What is (are) the proposed alternative(s), for F(M, m, r)? Can we make somekind of an expansion to F so that other terms G2, G3, ...Gn, are introduced? Experimentally (according to fits), what does F look like for these far away stars?