Large-scale rotational coherence in the diffuse cosmic gaseous medium

This work investigates the hypothesis of the existence of an extremely weak primordial vorticity, preserved and transported within the diffuse cosmic gaseous medium throughout cosmic evolution. Rather than implying a global rotation of spacetime or a measurable metric anisotropy, this vorticity is treated as a collective kinematic coherence of the diffuse medium, capable of retaining directional memory over very large comoving scales. Neutral hydrogen gas, due to its low dissipation and very long relaxation times, provides a particularly sensitive tracer of such primordial coherence. Recent HI observations, notably from MeerKAT, reveal filamentary structures exhibiting coherent rotational signatures on scales of several tens of megaparsecs, which are difficult to attribute solely to local gravitational dynamics. The proposed framework shows that a very low-amplitude initial vorticity component may survive over cosmological timescales and be hierarchically transmitted to cosmic filaments during structure formation. This process leads to a non-zero mean curvature of gaseous filaments, long-range directional continuity, and a strong preferential amplification in weakly virialized environments. Quantitative predictions are derived, including an expected mean filament curvature of ⟨κ⟩ ≈ (3 ± 1) × 10⁻² Mpc⁻¹ and a gas-to-stellar amplification ratio in the range ω_gas / ω_stars ≈ 30–80. These predictions are directly testable using current and forthcoming HI surveys, particularly MeerKAT, ASKAP, and SKA. This work does not claim evidence for a global rotation of the Universe, but proposes that initial cosmological conditions containing a correlational vorticity component may leave observable geometric imprints in the present-day diffuse cosmic medium.