Causal Quantum Relativity: Deriving Quantum Mechanics, General Relativity, and Standard Model Gauge Structure from Discrete Causality

We present Causal Quantum Relativity (CQR), a framework that unifies quantum mechanics, general relativity, and the Standard Model gauge group SU(3)\,x\,SU(2)\,x\,U(1) from two axioms: (1) spacetime is a locally finite partial order (causal set), and (2) the Planck length is dynamic, increasing with local energy density. Quantum mechanics emerges from the path sum over causal histories, with interference forced by the combinatorics of discrete causality. General relativity is recovered via the Benincasa--Dowker--Glaser action in the continuum limit. The gauge group is derived through two independent mechanisms: branchial fiber bundles (building on Gorard's framework) and noncommutative geometry (building on Connes' spectral triples), both yielding SU(3) from three spatial dimensions. Black hole singularities are resolved by finite causal depth and unitarity is preserved via an explicit S-matrix through the causal bottleneck. We derive the observed CMB amplitude from Poisson statistics of causal set growth, and show that the spectral index is achievable through chaotic amplification and causal knot formation. Crucially, CQR makes specific falsifiable predictions that distinguish it from competing quantum gravity approaches: gravitational wave echoes at approximately 10\,ms delay (testable with current LIGO/Virgo sensitivity), modified Hawking spectra with Planck-scale UV suppression, vanishing linear Lorentz violation with quadratic corrections, and density-dependent QED radiative corrections in extreme astrophysical environments. The combination of vanishing linear Lorentz violation with GW echoes uniquely identifies CQR among quantum gravity approaches. All results follow from the two axioms without additional postulates. Open problems include the fermion mass hierarchy and cosmological constant, which are shared challenges across all approaches to quantum gravity.