Four Null Spacetime Theory A Causal Architecture for Geometry, Gravity, Light and Matter

Four-Null Spacetime is a candidate microscopic framework in which local spacetime structure isbuilt from cells generated by four future-directed null vectors arranged in a regular tetrahedralconfiguration. The central idea is to begin with causal, lightlike structure rather than with anindependently prescribed metric. The mutual relations of the four null generators reconstruct thelocal Lorentzian geometry exactly, while curvature appears through variations of that reconstructedgeometry from cell to cell.The same four-null structure carries substantially more than the metric. It defines a relationaltimelike direction, an exact three-plus-three Hodge-incidence decomposition of six bivector channels,a natural electromagnetic field structure, spinor variables, and a reconstruction of the Dirac operator.In this sense, gravity, electromagnetism and spin- 12 matter are formulated on a common causalarchitecture rather than on separate underlying structures.Dynamics are introduced through a discrete Kirchhoff–Huygens propagation law. For the selectedtwo-shell geometry, the leading finite-cell coefficient is determined exactly, a4 = 51491/600000 . The long-wavelength limit reproduces the established Einstein, Maxwell and Dirac structures in thesectors tested. The framework also predicts finite-cell corrections to wave propagation, including acommon subluminal dispersion for fields governed by the shared Huygens law.The work combines exact analytical results with symbolic and numerical consistency tests. Amongthe principal results are metric reconstruction from null data, a unique relational clock, the exacttetrahedral Hodge-incidence structure, spinor and Clifford reconstruction, two gravitational shearpolarizations, Maxwell gauge structure, Einstein–Maxwell and Dirac curvature couplings, quadrupolegravitational radiation, and finite-cell quantum and thermodynamic tests.The framework proposes physics beyond standard continuum general relativity and quantum fieldtheory at a microscopic cell scale Lc, whose absolute value is not yet fixed. The full nonlinearconstraint problem, ultraviolet completion and quantum Lorentz consistency remain open. Thepresent work therefore does not claim a completed theory of quantum gravity; it establishes andtests a unified causal architecture on which gravity, light and matter can be studied together.This record presents the current consolidated formulation of the Four-Null Spacetime program,including its exact foundations, dynamical construction, physical consequences, testable predictionsand remaining quantum frontier.