My thesis and first publications, show rigorously that general relativity with acausal structures (specifically time reversing paths) has the same logical structure as quantum theory. It is a very powerful result, because all the equations of quantum theory can be derived given the logical structure (orthomodular lattice of propositions) logical structure. There is no other way to represent probabilities and make predictions.
The publications were technical, but the result can be very simply stated. The mystery of quantum theory is that it is a context dependent theory. We can only assign probabilities when we know about future measurements. General relativity with acausal structures is also context dependent, because future measurements can affect the present state.