Angular Diameter Distances (Z~1 Peak)

The angular diameter distance D_A(z) reaches a maximum at a redshift of roughly z ~ 1.6 in standard ΛCDM, then turns over and decreases at higher redshift as the angular size of a standard ruler appears to grow again with increasing lookback time. Observational measurements of D_A via BAO, strong lensing, and galaxy size benchmarks show mild but systematic offsets from ΛCDM predictions at redshifts near this peak, with some datasets preferring a peak location or amplitude that is inconsistent with the best-fit cosmological parameters at the one-to-two sigma level. Because D_A is directly sensitive to the expansion history H(z), any systematic deviation encodes information about how the effective expansion rate departs from the ΛCDM trajectory over cosmic time.

In Successive Collision Theory, the effective cosmological term Λ_eff(x,t) is not a constant but a dynamical ratio that grows as the large-scale tensor mesh dissipates through orbital decay of the hierarchical frame structure. At redshifts near z ~ 1, the mesh dissipation has been operating for several billion years and the ratio Λ_parent/λ_local has evolved away from its post-decoupling value. This means the effective expansion rate H_eff(z) follows a trajectory that deviates modestly but systematically from that of a cosmological constant, shifting the location and amplitude of the D_A peak in a direction consistent with the observed mild offsets. The deviation is not a free parameter but is set by the rate of orbital decay in the parent frame hierarchy — a physically determined quantity tied to the same mechanism that explains the Hubble tension's spatial and temporal components.

Furthermore, SCT predicts that the D_A discrepancy should be correlated with large-scale environment: observers embedded in the KBC supervoid measure a locally enhanced Λ_eff that shifts H(z) at all redshifts, systematically biasing the inferred D_A peak position relative to the true global value. The combination of the temporal evolution of Λ_eff and the local void environment produces a coherent pattern of D_A offsets across redshift that ΛCDM with a constant Λ cannot produce. This is mutually consistent with the SCT explanations of the Hubble tension and the BAO scale mismatch, all three effects being manifestations of the same dynamical Λ mechanism operating across different observational windows.