Hi all, I understand the mathematics behind special relativity pretty well, but I only have a bare conceptual understanding of general relativity. My understanding is that energy, momentum and stress (as described in the energy-stress tensor) are what contribute to space-time curvature and hence gravity. (Shortest summary of GR ever? :P) However, my understanding from special relativity is that the energy and momentum possessed by a system are not invariant quantities but are measured differently by different observers. Special relativity has also taught me that space-time intervals are invariant/absolute. That suggests to me that space-time curvature would be absolute too, as well as the logic telling me that gravitational fields should be absolute too - an object can't be a black hole for one observer but not for another... can it? And yet if space-time curvature/gravity is something we can all agree on... how can it come from relative quantities like energy and momentum? Is this a situation like space and time combining to form space-time intervals in special relativity, where relative quantities change for different observers together in such a way that they can be combined into one absolute quantity for all observers? Or is space-time curvature not invariant and something that can be measured differently depending on who's measuring? Thanks!