RELATIVE GEOMETRY. “With information propagation restricted due to matter, the shortest path is around rather than across an obstacle. This property of information exchange implies non-trivial structure of the associated flat space-times, relative to the case without obstacles. We will call this relative geometry, and model it on the connectivity of flat space-time, leaving dt constant.”
https://link.springer.com/content/pdf/10.1007/JHEP07(2019)140.pdf