Reversing cosmological time to find simpler quantum rules

Wavefunction coefficients describing scalar fields in an expanding power-law universe obey differential equations that can be represented as diagrams called graph tubings flowing through kinematic space. By reversing the direction of that flow and introducing new splitting rules, the authors show that the same differential equations, their singularities, and their local structure emerge naturally from the geometry rather than being imposed. The reframing works beyond individual Feynman diagrams and extends to an entire class of scalar theories, suggesting that the tubing structures—not the differential equations—are the more primitive objects, with time ordering appearing as a derived consequence.