Fig. 2
From: Quantum speedup in the identification of cause–effect relations
Spacetime picture of a causal intermediary. Variable A is localized at a point in spacetime, and its causal influences propagate within its future light cone. Variable B is distributed over a section of the light cone of A and intercepts all the influences of A. Every other variable B′ that is affected by A and comes after B must be obtained from variable B through some physical process
