Can anyone briefly explain General Relativity as it relates to black holes?

To me it seems that according to special relativity a less dense but larger mass would curve space-time more so than a more dense smaller mass. What am I failing to see?|||Special Relativity does not describe mass *at all*. It is specially formulated for problems with insignificant mass over the entire problem domain.





GR simply describes how mass over a certain density would be invisible to observers at "infinity". Then it goes on to talk about event horizons (2M), photon spheres (4M if I recall correctly), and the closest possible stable orbit for matter (at 6M). Then it extends to rotating black holes, charged black holes, and interactions between black holes that are close to one another (worm holes and such).





Essentially, it does not matter how dense the source is. The effect at a distance of a stationary mass is pretty much the same no matter what the density of the mass is. If the light or rocket passes through empty space, and well outside 6M, there isn't much difference.