It is proposed that the Big Bang is not the absolute origin of reality, but a local collapseevent within the arm of a spiral mega-structure of vastly greater scale — a "galaxy ofuniverses". This work develops the complete mathematical chain of the model: thereformulation of the collapsing core at the Planck scale, the shear and winding dynamicsof the spiral arm, the stability validation through the Toomre criterion, the quantumbounce mechanism (Loop Quantum Cosmology) that avoids the classical singularity, thedetermination of the physical scale of the parent galaxy (size, dark-matter halo, number ofarms and number of node-universes hosted), and two observationally falsifiable predictions: the "dark flow" and the search for collisions between bubble universes in the cosmic microwave background. Four conceptual limitations of the model are explicitly identified and addressed, including its epistemological boundary regarding the ultimate origin of the parent structure.