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← openxiv:gr-qc.2026.00003 · gr-qc

The predictive content of Spectral Causal Theory

Explainer at the level of an undergraduate in the field. Read the original paper.

Assumes 1–2 courses of background. Domain terms may appear without definition.

This paper catalogs the empirical predictions of Spectral Causal Theory (SCT), a one-loop gravitational effective field theory derived from the Chamseddine–Connes spectral action S = Tr f(D²/Λ²) of a noncommutative spectral triple that already encodes the Standard Model gauge group and particle content. The framework is an EFT in the Wilsonian sense: a cutoff scale Λ separates a UV completion (the spectral action itself) from an IR effective theory whose form factors are computed diagrammatically. The central distinction is between cutoff-independent predictions (determined entirely by the universal Seeley–DeWitt a₄ coefficient and the SM matter content) and cutoff-dependent ones (sensitive to the shape of the cutoff function f). The cutoff-independent sector is rigid: - Weyl-squared coefficient α_C = 13/120 - Ratio c₁/c₂ = −1/3 (frozen under matter-only one-loop RG flow at conformal coupling ξ = 1/6) - Gravitational wave speed c_T = c - No scalar gravitational mode at ξ = 1/6 - Starobinsky inflation excluded in the standard spectral action because α_R(ξ = 1/6) = 0 - Logarithmic black hole entropy correction c_log = 37/24 (conditional) For Schwarzschild black holes, modal stability of quasinormal modes is proven analytically (V > 3f/r² > 0 for ℓ ≥ 2) and frequency shifts are bounded by δω/ω ~ c₂(ω/Λ)² ~ 10⁻²⁰ for stellar BHs — fifteen orders below LIGO sensitivity. Tidal Love numbers are k₂ ≠ 0 (qualitatively distinct from GR's k₂ = 0, but unmeasurably small). The paper then benchmarks SCT against five competing quantum gravity programs (LQG, asymptotic safety, CDT, string theory, infinite-derivative gravity) across nine quantitative axes. Three discriminating observables and five falsification criteria are identified, each with a stated verification status (proven / verified / established / conditional).

AI-generated · created 2026-05-21

Explainers are best-effort summaries — they round corners. For the authoritative claims, read the paper itself.