Observational Signatures of Time-Symmetric Quantum Darwinism: Horizon-Scale Breakdown of ABL Degeneracy, the CMB Quadrupole–Octupole Alignment, and Low-ℓ Polarization Tests

Paper VI in the Time-Symmetric Quantum Darwinism (TSQD) Series (Version 1.1) In Papers I–V of the Time-Symmetric Quantum Darwinism (TSQD) series, we demonstrated that a self-consistent cosmic history is selected retro-causally from the asymptotic de Sitter future conformal boundary ($\mathcal{I}^+$, $\eta \to 0^-$) via the Aharonov–Bergmann–Lebowitz (ABL) two-state amplitude $\langle \Phi^* \vert{} \Psi_0 \rangle$. We proved that overcoming Gibbons–Hawking horizon decoherence ($T_{\mathrm{GH}} = \hbar H_\infty / 2\pi k_B$) and Don Page's subsystem scrambling bound ($f_A > 1/2$) requires an omnidirectional ($4\pi$ steradian), phase-coherent ($N_{\mathrm{mode}} \gg 1$) electromagnetic wave-packet at $\lambda_0 \sim 1\,\mu\mathrm{m}$ powered by a $1.0\,L_\odot$ G2V star, fixing the cosmological constant lower bound at $\Lambda_{\min}\ell_P^2 \approx 2.9 \times 10^{-122}$. A natural critique of any post-selected cosmology is whether the ABL Degeneracy Theorem (Paper III)—which guarantees that $\langle \Phi^* \vert{}$ factors out at microscopic laboratory scales ($k \gg R_H^{-1}$) to recover the standard Born rule—leaves any unique, falsifiable signature in precision cosmological observables. In this sixth paper (v1.1), we prove that while ABL degeneracy holds to $\mathcal{O}((k R_H)^{-2}) \sim 10^{-60}$ in terrestrial laboratories, it breaks down deterministically at the horizon wavenumber scale $k \sim R_H^{-1} = \sqrt{\Lambda/3}$ corresponding to the lowest Cosmic Microwave Background (CMB) multipoles ($\ell = 2, 3$). Because the Dyson Return-Stroke wave-packet is emitted as a pure, isotropic $4\pi$ spherical wavefront in the rest frame of a host star moving with peculiar velocity $\beta_\odot = v_\odot / c = 1.2336 \times 10^{-3}$ ($369.82\text{ km s}^{-1}$) relative to the stationary de Sitter cosmic horizon $\mathcal{I}^+$, the special-relativistic Lorentz boost of $\langle \Phi^* \vert{}$ onto $\mathcal{I}^+$ imprints three parameter-free signatures onto the primordial horizon modes: The Large-Angle CMB Cutoff ($S_{1/2}$ Suppression): A sharp infrared cutoff in the two-point angular correlation function $C(\theta)$ at separation angles $\theta > 60^\circ$, yielding $S_{1/2}^{\mathrm{TSQD}} \approx 1,350\,\mu\mathrm{K}^4$ (matching the Planck 2018 observed value of $1,209\,\mu\mathrm{K}^4$, compared to the standard $\Lambda\mathrm{CDM}$ expectation of $\sim 38,000\,\mu\mathrm{K}^4$). The CMB Quadrupole–Octupole "Axis of Evil" Alignment: The planar co-alignment of the quadrupole ($\ell = 2$) and octupole ($\ell = 3$) multipole vectors ($\Delta\theta_{23} < 5^\circ$) orthogonal to our star's velocity vector $\mathbf{v}_\odot$ relative to the cosmic horizon via pure special-relativistic aberration of the $4\pi$ boundary wave-packet ($\propto \beta_\odot^\ell P_\ell(\hat{\mathbf{v}}_\odot \cdot \hat{\mathbf{n}})$), requiring zero structural or orbital tilt parameters. A Falsifiable Prediction for LiteBIRD and Simons Observatory ($E$-Mode Polarization): Unlike standard $\Lambda\mathrm{CDM}$ (where primordial scalar fluctuations leave low-$\ell$ $E$-mode polarization largely uncorrelated with the temperature Axis of Evil, $\langle \Delta\theta_{TE} \rangle \approx 41^\circ$), TSQD requires the low-$\ell$ $E$-mode polarization multipole vectors ($a_{2m}^E, a_{3m}^E$) to lock onto the exact same dipole-orthogonal kinematic plane within $\Delta\theta_{TE}^{(2)} \le 8.5^\circ$ and $\Delta\theta_{TE}^{(3)} \le 9.9^\circ$ ($p < 10^{-5}$). Complete Series Registry: Paper I (Foundational Fixed-Point Selection): 10.5281/zenodo.23572180 Paper II (Cosmic Return Stroke & Fermi Paradox): 10.5281/zenodo.23677536 Paper III (Lorentz Covariance & ABL Degeneracy Theorem): 10.5281/zenodo.23818446 Paper IV (4π Horizon Saturation Link Budget & Page Scrambling): 10.5281/zenodo.23896752 Paper V (The Horizon–Luminosity Pinch & Cosmological Constant): 10.5281/zenodo.23897947 Companion Note (Hawking–Hertog Top-Down Projector Completion): 10.5281/zenodo.23927474 Paper VI (Horizon-Scale ABL Breakdown & CMB Signatures): 10.5281/zenodo.23959162