Paper XXVI: The Sump Mechanism: Dark Energy Without a Cosmological Constant

The sump mechanism is identied as the physical origin of dark energy: the ongoing inward collapse of the 5D gravitational extrusions of the two parent black holes onto the brane generates a constant inward pressure Λ_opp(t) that opposes the nucleation tension Λ_nucleation. Dark energy is the residual net tension Λ_net(t) = Λ_nucleation - Λ_opp(t) > 0, not a cosmological constant. The dark energy equation of state w_e(t) is dynamical: since dΛ_opp/dt < 0 (the H−extrusion continues to collapse), w_e crosses -1 from above at a phantom-crossing redshift z_cross ∼0.3-0.5. This is conrmed by DESI DR2 (2025) at 4.2σ, which nds w0 > -1, wa < 0, consistent with the sump prediction (Prediction 60, new conrmation). No cosmological constant is required; no vacuum energy ne-tuning problem exists in the framework. Part of the One-Octonion Brane-Bulk Framework series. Anchor DOI: 10.5281/zenodo.19120873. Community: one-octonion-brane-bulk. Author: Bharathi Dasan Jagadeesan, M.D., University of Minnesota. ORCID: 0000-0002-1143-941X.