The Time-Symmetric Parity Constraint III : dangerous observations in cosmology – Rest-frame inference and global consistency

Summary – This paper examines a restricted class of cosmological observations that test the internal coherence of the standard cosmological inference framework rather than the numerical values of fitted parameters. These “dangerous” observations include persistent discrepancies in the inference of a unique cosmic rest frame from independent tracers, most notably the non-convergence of matter dipoles with the dipole inferred from the cosmic microwave background. Motivated by recent synthesis and reassessment work in the literature, the analysis focuses on observations that probe a foundational assumption of standard cosmology: that statistical isotropy guarantees a unique kinematic rest frame shared by all sufficiently deep observables. The paper distinguishes these from conventional parameter tensions that can be accommodated by phenomenological extension. The observations are assessed within the framework of the Time-Symmetric Parity Constraint (TSPC), which restricts the class of admissible global spacetime geometries without introducing new dynamical degrees of freedom. Within this framework, the inference from the CMB dipole to a unique global matter rest frame is not mandatory. As a result, several observations that strain the standard model do not, by themselves, contradict the parity-constrained framework. Compatibility is not treated as confirmation. The paper identifies classes of observation that have not yet been fully absorbed by the framework and states explicitly the conditions under which TSPC would be falsified. The emphasis throughout is on restriction rather than accommodation: limiting admissible global geometry rather than extending dynamical freedom to preserve agreement. The entire compendium of TSPC research papers is now to be found at https://spacetimeparity.eu/ Revisions and amendments v.2 Identifier added.