O5 Blind Test — A Pre-Registered Analysis Protocol for the Echo Prediction of Type-B Traversable Singularities

This paper designs a fully pre-registered blind analysis protocol for the upcoming fifth observing run (O5, expected 2028–2031) of LIGO-Virgo-KAGRA, to test the echo prediction of the Type-B traversable singularity in the Order Parameter Spacetime Theory (OPST). The theory predicts that the event horizon is a Type-B traversable singularity characterized by a universal relaxation time τ, independent of the black hole mass and spin, leading to equidistant gravitational-wave echoes with an interval Δt = 2τ. Based on dimensional analysis, the theory gives an order-of-magnitude range for τ of 0.1–1.5 ms. A previous multi-messenger analysis of 17 high-spin binary black hole merger events in GWTC-3 found that the τ values of all 17 events fall within the narrow interval 0.100–0.525 ms (H1 mean 0.206 ms, L1 mean 0.214 ms), providing compatibility support between the data and the theory. However, this result did not pass multiple-comparison correction and lacks blind protection, and was classified as a "suggestive candidate." This protocol defines three independent decisive tests for O5: (1) the echo-interval constancy test (cross-event, cross-detector Δt consistency); (2) the chirp-mode test (testing non-equidistant echo sequences with a drift rate α ≈ 0.55 ms); (3) the fundamental-frequency phase-locking test (phase coherence at Δt₀ = 3.0 ms). All search parameters, template forms, and decision thresholds are frozen before access to the O5 data. Detection thresholds and falsification conditions are pre-specified. This paper is a pre-registered methodology paper and does not report analysis results from O5 data — those will be presented in a follow-up paper after the O5 data release. The SHA-256 hash of the frozen parameter list will be submitted to Zenodo to obtain a timestamp prior to the O5 data release.