The Sandage-Loeb redshift-drift signal at the cm/s/decade level is easily swamped by calibration drifts, peculiar accelerations of sources, large-scale-structure inhomogeneities, our own local acceleration, and the need to combine data from different facilities and epochs (Loeb 1998; Liske 2008; Quercellini 2010). Each of these introduces hard-to-model contributions at the same order as the cosmological drift.
The standard model treats peculiar accelerations, local acceleration, and inhomogeneity contributions as systematic noise contaminating a clean cosmological signal. Each must be modeled and subtracted. Within the model, the residual signal is the cosmological dz/dt only. Any unexplained residual after systematic subtraction has nowhere to go in the model.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, what ΛCDM treats as systematic baseline noise becomes physical signal predicted by the framework. Frame-tree hereditary time (P10) explains the peculiar-acceleration component as small per-source frame-velocity contributions. Residual frame velocity (P63, P64) explains the local-acceleration component as our patch's bulk motion through its parent frame.
The full dz/dt signal decomposes into three predicted components: (1) cosmological dz/dt from dynamical Λ_eff history (P17, P18), shifted from ΛCDM by 10 to 30% at z > 2; (2) local-acceleration dz/dt aligned with the CMB dipole direction, sourced by our 369 km/s frame velocity (P63); (3) environmental dz/dt aligned with the Λ_eff-gradient (KBC supervoid axis) at the cm/s/decade level (P19). Each component has a predictable amplitude and direction, and each is potentially separable from the others using directionally stratified analysis.
The SCT vs ΛCDM difference at z > 2 is at the 10 to 30% level in the cosmological component, discriminable at greater than 5σ with decade-baseline measurements once the local-acceleration and environmental components are properly modeled (rather than treated as noise). The same M5 framework that resolves the Hubble tension, S₈ deficit, and ISW deficit accommodates the redshift-drift baseline challenges as real physical signal rather than measurement noise. There is no need to fight calibration drifts as the dominant obstacle; the framework predicts where the signal sits.
If decade-baseline redshift-drift measurements with full directional decomposition confirm that the local-acceleration component matches standard kinematic predictions (no residual environmental component aligned with the KBC supervoid axis at the 0.3 cm/s/decade level), the M5 environmental-anisotropy prediction fails. Equivalently, if the cosmological component at z > 2 matches standard ΛCDM at the 5% level (no 10 to 30% offset), the dynamical-Λ_eff history prediction is refuted.