Null Direction Fields and Topological Imprints in Lorentzian Geometry

This paper shows how differential variations of null direction fields generate topological imprints in Lorentzian geometry, demonstrating that local null generation can accumulate into global structure characterized by the Pontryagin number in four-dimensional spacetimes. This work is licensed under the Creative Commons Attribution 4.0 International (CC BY 4.0) license.