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

Four Null Spacetime Theory is an ongoing research program that investigates whether spacetime, gravity, electromagnetism, gauge fields and quantum matter can be formulated within one common causal architecture. Its starting point is a minimal cell built from four lightlike directions. From these same four generators, the framework reconstructs the spacetime metric, defines a relational clock, produces a six-channel bivector structure, supports differential and gauge operations, and provides the geometric ingredients needed for spinor and gravitational dynamics. The central idea is not that all fields are identical, but that different physical sectors occupy different mathematical representations of the same underlying structure. Gravity is carried by deformations, expansion, shear and null constraints of the causal geometry; electromagnetism and gauge fields use link phases and bivectors; spin-1/2 matter uses the same metric and directional structure through the Dirac and overlap operators. Quantum theory is then built on these common ingredients rather than on a separate background. The program has developed substantial links to quantum field theory, including chiral overlap fermions satisfying the Ginsparg-Wilson relation, gauge-covariant QED, a transverse massless photon, the one-Dirac-fermion vacuum-polarization logarithm, Lorentz-compatibility tests using the highly symmetric F4 root-system / 24-cell lattice, a classical Yang-Mills limit, an Abelian Higgs mechanism, and a lattice-gravity sector with the Fierz-Pauli infrared limit and two healthy low-energy graviton modes. The master manuscript brings these branches together while clearly separating exact results, analytical derivations, strong numerical evidence, conditional results and open problems.