Hi All, I was hoping someone could help point me in the right direction. I'm interested in simulations of General Relativity with generic mass distributions that are self gravitating, i.e. that the metric of the space-time being considered is dynamically altered by the distribution of mass whose motion is being goverened by that space-time. Phew! I hope that makes some sense! Basically what I am curious about is that the GR solutions I know of are either vacuum solutions (Schwarschild, Kerr etc) or rely on complete homegenaity and isotropy such as the FLRW solutions. I also know that analytically the 2 body problem is not completely solved, though I think with some approximations can be determined, but certainly the N-body GR problem is far from solved analytically. There are sophisticated Magneto-Hydro-Dynamic simulations of GR modelling such things as Neutron star collapse, but these as far as I have found all assume the 'test fluid' approximations where the underlying space-time is fixed and unaffected by the fluid. Does anyone know of any work performed (references would be great!) on numerical simulations dealing with a full arbitrary GR model where the mass curves the space that then directs the mass to accelerate with the full feed-back between the two. Clearly such a thing would be very hard and require a lot of computation, but I can't find any examples where this possibility is even discussed. If I could even find a source that explains exactly why this could not be done that would be a great help. Can anyone point me in the right direction?