The cosmic star formation rate exhibits a marked decline beginning around z ≈ 2 (cosmic noon), transitioning from rising rates at z > 2 to rapidly falling rates at z < 2. The sharp transition is not well explained by ΛCDM galaxy formation models, which predict a smoother more gradual decline driven by environment-dependent quenching and secular evolution (Madau & Dickinson 2014; Smit 2016). The abruptness suggests a global trigger rather than local stochastic processes.
The standard model assumes a smooth FLRW expansion with constant Λ plus standard galaxy-formation physics. Recovering the abrupt z ≈ 2 cliff demands either a global environmental change at that epoch or coincident quenching events across diverse galaxy populations, neither of which is parsimonious within minimal ΛCDM.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field. From this single change, the z ≈ 2 star formation cliff is a mesh-dissipation transition signature. The parent-frame mesh weakens progressively over cosmic time (P14, P15, P16), and the dynamical Λ_eff(x,t) field grows as the mesh-dissipation cascade compounds (P17, P18). At z ≈ 2, the integrated Λ_eff contribution crosses a threshold where it begins suppressing gas inflow into galaxies at the cosmic-average rate.
Before z ≈ 2 (the cosmic-noon era), cascade-seeded structure (P22, P25, P29, P30) provides abundant initial gas reservoirs that fuel rapid star formation. The cascade-deposited gas was concentrated in dense cosmic-web filaments at deposition, allowing efficient star formation at high z. After z ≈ 2, the dynamical Λ_eff suppresses the gas-inflow component that would replenish star-forming reservoirs, leading to the observed abrupt decline. The cliff is the natural transition between cascade-fueled (pre-cliff) and mesh-dissipation-suppressed (post-cliff) star formation.
The same M5 framework that resolves the Hubble tension, S₈ deficit, ISW deficit, and the broader cosmic SFRD shape (recid 111) accounts for the cosmic-noon cliff. The transition timing reflects the balance point where the mesh-dissipation cascade overtakes the cascade-deposited gas reservoir. There is no need to invoke coincident global quenching events or fine-tuned environmental triggers.
If precision JWST + ALMA + Roman SFR surveys at z = 1 to 3 find the cliff fully consistent with environment-dependent quenching predictions of ΛCDM (no global mesh-dissipation transition signature, no environment-correlated cliff timing), the M5 mesh-transition explanation is refuted. The signature SCT prediction is the cliff timing correlating with line-of-sight Λ_eff history rather than with local environmental quenching.