Dark-energy and matter densities are comparable today (Ω_Λ ≈ 0.69, Ω_m ≈ 0.31), despite evolving completely differently across cosmic history. Λ stays constant in the standard model while matter density falls as 1/a³. The probability of finding Ω_Λ ≈ Ω_m precisely at the present epoch, after billions of years of divergent evolution, is astronomically small without fine-tuning (Steinhardt et al. 1999).
The standard model treats Λ and matter density as two independent components evolving on independent histories. Their present-day comparability is therefore a coincidence requiring tuning of initial conditions, and the model offers no mechanism that would naturally couple their evolution.
SCT replaces the hot-dense-center with a superluminal collision and the thermalized debris field that became our visible universe. From this single change, Λ and matter density stop being independent. The cosmological term becomes Λ_eff(x,t) = κ · U_local(x,t) / U_parent(x,t), where U_local and U_parent are both gravitational binding energies built from the matter distribution itself (P17). The two quantities are coupled at the level of the field equation, not by accident.
As matter clusters into stars, galaxies, and the cosmic web over Gyr timescales, U_local rises in overdense regions and falls in voids, while the parent-frame mesh weakens through ordinary three-body ejection and dynamical friction (P14, P15, P16). The ratio Λ_eff therefore tracks matter clustering by construction. Their present comparability is the natural consequence of that coupling, not an unexplained alignment of two free-floating constants. Add the eternal-cycle context (P26, P27, P28) and there is no preferred cosmic-history baseline against which today looks unusual.
The same mechanism resolves the Hubble tension, the S₈ deficit, the cosmological-constant fine-tuning problem (recid 3), and the dark-energy identity question (recid 5). The coincidence problem is one more observational window onto the same underlying coupling between mesh dissipation and matter binding energy. There is no need to invoke quintessence, tracker fields, or anthropic selection across a multiverse.
Detection of a cosmological-constant-equivalent component at any epoch that is demonstrably decoupled from local matter binding-energy density (showing zero environmental variation when comparing void-direction and overdensity-direction sightlines at > 3σ) would refute the M5 coupling. DESI environment-tagged H(z) measurements can perform this test within the next few years.