The Persistent Return of Torsion – Structural constraints on geometric approaches to symmetry breaking

Description – Torsion has repeatedly appeared in geometry-based attempts to unify gravitation with particle physics, despite wide variation in mathematical formulation and physical interpretation. This paper examines the persistence of torsion from a structural perspective, asking why it continues to be invoked across otherwise distinct unification frameworks. The analysis shows that once curvature, gauge connections, and topology are assigned their established roles within relativistic field theory, the remaining local geometric freedom of spacetime is sharply limited. Torsion then emerges as one of the few residual degrees of freedom available. In many unification attempts, torsion is subsequently asked to assume the functional role normally played by scalar order parameters in spontaneous symmetry breaking. When treated in this way, additional dynamics and excitations are introduced to legitimise its background value, leading to the reappearance of scalar-like degrees of freedom in geometric form. It is argued that this pattern reflects a structural bottleneck rather than cumulative theoretical progress. Efforts to avoid fundamental scalar fields tend to relocate scalar behaviour into geometric language, expanding the space of admissible models while weakening predictive closure. This proliferative strategy is contrasted with constraint-based approaches that restrict admissible geometries from the outset rather than introducing new local structure. The Time-Symmetric Parity Constraint is cited as an example of the latter strategy, not as a proposed solution, but as a contrasting response to the same underlying difficulty (https://doi.org/10.5281/zenodo.17456148). The entire compendium of TSPC research papers is now to be found at https://spacetimeparity.eu/ Revisions and amendments – v.1 Further citations added. v.2 Identifier added.