Unification of large-angle cosmological anomalies at the causal diamond boundary

The ΛCDM model generally describes the cosmic microwave background (CMB) with precision; however several anomalies persist at the largest angular scales. These include a deficit of low-ℓ power and large-angle correlations, alignment and planarity of the quadrupole and octopole, an even/odd parity asymmetry, and a hemispherical power asymmetry. In addition, the observed dipole in extragalactic source counts exceeds the kinematic expectation by a factor of two or more. Individually, each CMB anomaly carries modest (2–3σ) significance, but considered jointly, the evidence against statistical isotropy may exceed 5σ. Proposed explanations typically treat the anomalies as statistical flukes or invoke modifications to primordial physics.

This work hypothesises that all five anomaly classes can be unified within a single observer-relative recording architecture. The observer's causal diamond is treated as a finite recording aperture whose three-layer architecture (aperture, irreversibility threshold, decoder) channels evidence into a classification organised by tensor rank and perturbation multipole order. ΛCDM is retained, while the anomalies are attributed to the observer-relative quantum measurement process itself.

The derived framework has zero fitted parameters, and is tested against Planck and source-count data across five anomaly channels. An angular filter combined with a signed antipodal operator resolves both the low-ℓ power deficit and the parity asymmetry, shifting the S₁/₂ statistic from the 8th to the 44th percentile and resolving the parity ratio at all tested ℓ_max (2Δln𝓛 = 5.6 vs ΛCDM, ΔAIC ≈ −5.6). A radial recording kernel reproduces the source-count dipole excess, predicting an aperture amplification 𝒜 = 5.0 against a CatWISE measurement of 5.3 ± 1.3, with consistent values across NVSS and RACS. A variance decoder with shared evidence budget enhances quadrupole–octopole alignment by 13.3×. A curl evidence channel recovers the hemispherical power asymmetry axis to within 10° of the data (p = 0.014). A universal finite-recording gain δ* = 1/d = 1/4 compresses the raw anomaly amplitudes (spanning ~93×) to a common implied gain of 0.26 ± 0.01.

The framework yields several clear falsifiable predictions across cosmological observables from the CMB polarisation spectrum to extragalactic source counts. Testing these can determine whether the observer's causal diamond boundary provides a unifying origin for large-angle cosmological anomalies through an observer-relative recording architecture.