The radial acceleration relation locks observed dynamics to baryonic gravity with one scale, g-dagger = 1.2 × 10⁻¹⁰ m/s², and 0.13 dex scatter, consistent with measurement error alone, across 153 SPARC galaxies (McGaugh et al. 2016); the baryonic Tully-Fisher relation shows the same zero-intrinsic-scatter discipline. ΛCDM, whose halos scatter in concentration, spin, and history, predicts several times the observed scatter, growing exactly where the data stay cleanest.
Dynamics are supposed to be set by a stochastic dark halo plus a feedback-dependent baryonic history: two noisy ingredients per galaxy. A relation in which the baryons alone predict the dynamics, with no residual diversity, requires the halo to mirror the baryons galaxy by galaxy, fine-tuning the model's own randomness away everywhere.
SCT makes the RAR a law of coherence rather than a conspiracy of halos: the dynamical acceleration is the baryonic acceleration amplified by A(N, σ_v, R), a deterministic function of the baryon distribution and its coherence state (P50, P52, P53). With no stochastic halo in the chain, the scatter budget is measurement error plus coherence-state variation, matching the observed 0.13 dex; the baryons predict the dynamics because the baryons, coherently superposed, are the dynamics (P54). The fixed point A* = 1 + N_eff e⁻¹ = 5.970 anchors the deep-coherence end, and the framework derives the baryonic Tully-Fisher constant at 44.8 solar masses per (km/s)⁴ in agreement with the SPARC calibration.
The acceleration scale reframes: g-dagger marks where the coherent mesh contribution overtakes the local baryonic term, a transition of source bookkeeping rather than a new constant of nature, which is why the cluster-scale relation shows a different effective scale (g-dagger rising to 2.0 × 10⁻⁹ m/s² at cluster virial geometry) where MOND's universal a₀ breaks: the scale is geometric, not fundamental.
This is the same coherence law behind the Ω_DM/Ω_b identity and flat rotation curves. There is no need to invoke halo-baryon conspiracies tuned across 153 galaxies.
The registered kill: RAR residuals must correlate with the coherence diagnostic, σ_v/v_bulk, at more than 2σ across the full SPARC sample, since coherence state is the only physical scatter source SCT permits; no correlation at more than 1σ falsifies the coherence reading of the relation. The cluster hierarchy adds a second: the effective g-dagger must scale smoothly from disks through groups to clusters as virial geometry changes, and a flat or step-function hierarchy breaks the geometric account of the scale.