Multi-Messenger Evidence for Type-B Traversable Singularities — Cumulative Tests from Five Independent Observational Windows

The Type-B traversable singularity is a core corollary of the Order Parameter Spacetime Theory (OPST) — the black hole horizon is reinterpreted as a geometric interface where the inertial resistance coefficient and the information dissipation coefficient diverge simultaneously, yet the relaxation time τ remains finite. The theory yields three core testable predictions: (1) the EHT shadow radius receives a correction of order λ; (2) equidistant echoes appear after the gravitational-wave ringdown, with interval Δt = 2τ; (3) a network of B-type defect cosmic strings produces a characteristic gravitational-wave background spectrum. This paper systematically tests the above predictions using five independent observational windows. The main results are as follows. (1) EHT shadow (Window 1): The shadow diameters of M87* and Sgr A* yield a consistent constraint λ < 0.05 across a mass ratio of about 1500, compatible with the theory. (2) EHT polarization (Window 2): The polarization rotation induced by anisotropic dissipation is only 0.12° under λ < 0.05, currently unmeasurable. (3) Ringdown GR test (Window 3): Using the OPST's own QNM formula to subtract the ringdown, the residual power is fully equivalent to that from the GR Kerr QNM formula, verifying the numerical accuracy of the methodology. (4) Gravitational-wave echoes (Window 4): An unbiased global search is performed on 17 high-spin BBH events within the theoretically predicted window of 0.2–3.0 ms. For the H1 detector, the τ values of 17 events are distributed in the range 0.100–0.525 ms (mean 0.206 ms); for the L1 detector, the τ values of 14 events are distributed in the range 0.100–0.400 ms (mean 0.214 ms). The two detectors independently yield statistically indistinguishable τ distributions (difference 0.008 ms). After combining 31 detector-event pairs, τ = 0.209 ± 0.096 ms. A Kolmogorov-Smirnov test indicates a marginally significant deviation of the observed τ distribution from a uniform distribution (p = 0.03), but this does not reach the statistical significance threshold after multiple-comparison correction; the result should be regarded as a suggestive candidate. (5) NANOGrav (Window 5): The spectral index range [−0.55, −0.35] predicted by the B-type defect cosmic string network does not conflict with the NANOGrav measurement of −0.45 ± 0.15. Conclusion: None of the five independent windows reveal observational facts that conflict with the physical picture of the Type-B traversable singularity. Window 4 identifies a candidate feature with τ ≈ 0.21 ms that is consistent across events and detectors within the theoretically predicted window, but its statistical significance is limited; its reality awaits confirmation by an independent blind test in O5.