The Evaporating Universe: A Unified Scalar Field Cosmology ABSTRACT: We present the Evaporation Universe (EU), a cosmological model where dark matter gradually converts into dark energy through a scalar field φ coupled to neutrinos. A single dimensionless parameter ε = 0.0598 controls both the evaporation rate (Γ = εH) and neutrino mass (m_ν = εφ). KEY RESULTS: - H₀ = 71.30 ± 0.89 km/s/Mpc (reduces Hubble tension from 5σ to 1.3σ) - S₈ = 0.79 (reduces S8 tension from 2.6σ to 0.9σ) - Σm_ν = 0.06 eV (testable by KATRIN) - Physical Law: ε + Ωm × λ = Ω_DM (verified) CONTENTS: - 01_Theory.ipynb: Unified Lagrangian with neutrino coupling - 02_MCMC_Production.ipynb: MCMC with Pantheon+, BAO, H(z) data - 03_Results.ipynb: Tension analysis - 04_Figures.ipynb: JCAP-ready figures WHAT'S NEW IN v2.0: - Unified Lagrangian: L_int = -ε·φ·ν̄ν - Single parameter ε controls evaporation AND neutrino mass - Locking mechanism explains cosmic coincidence - Reorganized notebooks (6 → 4) NOTE: CMB analysis with CLASS will be included in Paper II. Keywords: cosmology, dark energy, dark matter, Hubble tension, neutrino mass