Considering that various measurements of spatial expansion were not available during the period most of the relativity material was developed and that a theory of gravity is still required I might assume that this material has not been covered. As the only immediately obvious product supplies I will provide a model toward that end.
a) assume a matter and an antimatter field has found opposite direction in space to take
b) provide this dynamic with the provision that spatial expansion did not cease at the end of the expansion epoch but was directed into the development of angular momentum with particle proliferation. Assume that since then our observation of expansion has been regulated and limited.
c) assume that between the matter/antimatter fields there is a gulf. If this gulf were without particle presence it would be without any regulation of time. Due to this factor I believe this gulf will have filled with helium that has entered a superfluid state. Only helium can enter this space due to it’s particular balance of aggregation.
In regard a theory of gravity these are the pivotal factors that require extrapolation.