Considering Einstein equations, suppose, for instance, that the RHS, the stress-energy tensor, is uniquely due to the electromagnetic field. Now, if we imagine a quantized version of these Einstein equations, we have a quantum field theory in D dimensions (here the quantum electromagnetic field) as "source" of a "quantum gravity" theory in D dimensions, so we may consider these equations as a kind of "dictionary" between these two theories.
On an other way, there are some holographic dualities, which relates some quantum theory of gravity in a D dimensional space with boundary, with some quantum field theory on the boundary (D−1 dimensions)
So, the question is, if, "skipping gravity", it is possible or not, and how, to directly relate the QFT in D dimensions (source of gravity), and the other QFT (on the boundary) in D−1 dimensions.
This post imported from StackExchange Physics at 2014-08-02 11:04 (UCT), posted by SE-user Trimok