Spacetime Curvature at an Extreme Remove from all sources of Mass-Energy

[geordief]

Can it be tested as to whether the theory of GR still applies in the extreme situation where two bodies (not particles) interact at such a remove from sources of mass-energy that we can ,for all intents and purposes regard them as constituting the entire universe?

 

If we consider only the mass-energy bound up in the two bodies in question is it known/expected that they will curve spacetime in the same way as they do when they are just a part of the overall system of macro objects?

 

It is not possible is it that GR will lose its applicability (or need to be tweaked) as such an extreme situation is approached?

[imatfaal]

The solutions to Einsteins field equations are what are known as vacuum solutions and these are solutions which only deal with the volume with no matter (there is a field but no sources of the field) - ie the most famous one the Schwartzchild Solution is the behaviour in the volume of space outside a non-rotating sphere; it does not deal with that volume of space within which there is matter. So to an extent your question is answered by the fact that currently general relativity only deals with bodies which are the only things in the universe