A Null-Kinematic Reformulation of Spacetime, Gravity, and Quantum Mechanics - Toward a Unified Framework Based on Directional Indeterminacy

A reformulation of spacetime physics is proposed in which null propagation of physical influence at the speed of light constitutes the fundamental kinematic substrate, and spatial direction is not a primitive observable but an emergent, observation-defined quantity. In this framework, spacetime is flat but dynamically flowing and gravity arises from gradients and accelerations of this flow rather than intrinsic curvature. Special relativity, general relativity in the weak-field regime, and quantum mechanics emerge naturally from the same null-kinematic foundation. Quantum uncertainty is interpreted as a direct consequence of the fundamental unknowability of direction prior to observation. The framework reproduces known experimental results in the weak-field and nonrelativistic limits and suggests clear experimental discriminators distinguishing spacetime flow from curvature-based gravity. This reformulation provides a potential framework for progress toward a unified field theory. This work builds on established results in relativity and quantum mechanics while offering a reinterpretation of their physical content.