  We formulate the string field theory in zero-dimensional target space
corresponding to the two-dimensional quantum gravity theory defined through
Causal Dynamical Triangulations. This third quantization of the quantum gravity
theory allows us in principle to calculate the transition amplitudes of
processes in which the topology of space changes in time, and to include
non-trivial topologies of space-time. We formulate the corresponding
Dyson-Schwinger equations and illustrate how they can be solved iteratively.
