Cosmic-web filaments exhibit clear axial density gradients with one end systematically denser (more thermalized gas, higher galaxy count, higher metallicity, hotter X-ray emission) than the other (Cautun 2014; Bonnaire 2020; Gouin 2023). The gradient direction is not determined by the gravitational pull of the more massive endpoint cluster, and Tudorache 2025 detected coherent bulk angular momentum along the filament axis at amplitudes 10 to 20 times above tidal-torque-theory predictions.
The standard model assumes filaments form symmetrically from Gaussian initial conditions plus tidal-shear fragmentation. Late-time accretion biases toward the more massive endpoint plus AGN feedback are invoked to explain asymmetries, but neither mechanism reproduces all three correlated signatures (density gradient, bulk rotation, metallicity gradient) pointing in the same direction. The model has no place for a coherent directional formation history.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, each filament is the fossil record of a cascade-stream worldline, depositing plasma continuously along its propagation path (P22, P34, P38). Filaments are not condensations from tidal shear; they are direct geometric products of cascade-stream propagation, with the leading edge of the stream depositing more matter than the trailing edge through progressive thermalization.
Pre-existing matter from prior cascade cycles (P25) supplies the baryon budget that gets deposited continuously along the stream. The cascade epoch operated above the QCD scale, so no metals were present during deposition itself; metallicity gradients emerge later from differential star formation along the stream. Higher-density regions (the leading edge) reach star-forming densities sooner and produce metals earlier; lower-density regions (the trailing edge) lag behind. Angular-momentum inheritance (P31, P32) gives the entire filament its bulk rotation J = μ(b × v_rel) from the cascade impact-parameter geometry, naturally producing the Tudorache 2025 110 km/s rotation at 10 to 20 times tidal-torque amplitude.
The three correlated gradients (density, rotation, metallicity) are uniquely SCT-predicted from one cascade-stream-trail mechanism. The same M4 framework that produces the cosmic-filament J-vector inheritance (recid 83), the gigaparsec ring-and-arc structures (recid 85), and the cosmic-web morphology produces the asymmetric filament structure. There is no need for late-time accretion fine-tuning or AGN-feedback prescriptions calibrated separately for each filament.
If precision DESI + Euclid + SKA filament surveys find the three gradients (density, rotation, metallicity) point in unrelated directions across a population of filaments, or that the bulk-rotation signal is fully reproducible by tidal-torque-theory at the 1% level, the M4 cascade-stream-trail explanation is refuted. The signature SCT prediction is that all three gradients align with the cascade impact-parameter direction inherited from the parent stream.