The low entropy of the early universe is one of the deepest unsolved problems in cosmology. Penrose (1979) estimated the initial gravitational entropy was suppressed by a factor of 10−10123 relative to a thermally equilibrated universe of the same energy, requiring an extraordinary degree of special initial conditions with no dynamical ex- planation in standard cosmology. We show that the brane-bulk octonionic framework provides a complete and natural resolution through a chain of four connected theorems. Theorem 1 (Bounded Fano Spectrum): The Fano Laplacian of the G2-symmetric parent geometry has only three eigenvalues λ ∈{0, 4, 7} with a nite maximum of 7 (Paper XLII). At the Planck scale, the degrees of freedom of spacetime are restricted to these 14 physical Fano modes (7 matter + 7 colour) a severely bounded, discrete spectrum. Theorem 2 (Negative Temperature at Nucleation): A system with a bounded energy spectrum can occupy negative temperature states: T = (∂S/∂E)−1 < 0 when the population of higher-energy states exceeds that of lower-energy states (pop- ulation inversion). At the moment of the quaternionic black hole collision (Paper I), all available energy is concentrated in the maximum-eigenvalue Fano modes (λ = 7) with zero occupation of the lower modes (λ = 4 and λ = 0). This complete popula- tion inversion corresponds to the limit T →0−on the negative side of the Boltzmann temperature scale the most ordered possible state of the bounded Fano spectrum. Theorem 3 (Minimum Entropy at Nucleation): In the bounded Fano spectrum, T →0−is the state of minimum entropy, not maximum. The entropy at nucleation: Sinit = kB ln Ωinit where Ωinit ≈1 (the unique parent octonion O = H+ ⊕H−, up to zero-energy G2 automorphisms). Thus Sinit = 0, with no ne-tuning. Entropy Reconciliation Note. Three distinct entropy quantities appear in the framework and must not be conated. (1) Physical entropy Sphys = kB ln Ωphys: the G2 automorphisms that relate the seven λ = 7 Fano modes are zero-energy gauge transformations (Paper LIX, Gauge Zero-Energy The- orem). Gauge-equivalent states are physically identical. The 7-fold statistical degeneracy of the λ = 7 level is a gauge degeneracy, not a physical one. There- fore Ωphys = 1 and Sphys = 0 at nucleation this is the claim that the universe began with zero entropy. (2) Fano statistical entropy SFano: this counts all Fano mode occupations including gauge-equivalent congurations. At T →0− 317 Brane-Bulk Octonionic Series B.D....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.