π Universe: A Phenomenological Framework of λ-Field Quantum Coherence Dynamics and Gravitational Unification

Contemporary theoretical physics faces four core unresolved dilemmas: First, the fundamental incompatibility between General Relativity and Quantum Mechanics, with a mature theory of quantum gravity yet to be established. Second, the ΛCDM Standard Cosmological Model relies on multiple ad hoc assumptions and suffers from the cosmological constant fine-tuning catastrophe. Third, the physical nature of dark matter and dark energy remains unclear, with no direct evidence of dark matter particles found after decades of detection. Fourth, core quantum phenomena such as quantum entanglement and wave function collapse are still at the level of phenomenological description, lacking a self-consistent explanation of their fundamental physical mechanism. Existing candidate frameworks for quantum gravity (string theory, loop quantum gravity, asymptotically safe gravity, etc. ) still suffer from the lack of testable predictions, incomplete connection with the low-energy Standard Model of particle physics, and background dependence. This paper takes experimentally verified vacuum quantum fluctuations as the sole physical ontology of the universe, constructs a strict six-level ontological hierarchy system to eliminate the risk of circular reasoning, defines λ as the intrinsic geometric scalar field of 4-dimensional spacetime, and builds six derived dynamic mechanisms of quantum fluctuations based on Boltzmann transport theory and functional renormalization group methods. It completes the full-chain evolution logic of coherence and achieves a self-consistent unification from microscopic quantum behavior to macroscopic cosmic evolution. Based on first principles, this paper strictly derives 4-dimensional flat Minkowski spacetime and the low-energy effective Einstein-Hilbert gravitational action, proving that 4-dimensional spacetime is the only inevitable result for the self-consistent existence of the gravity-λ field coupling system. It naturally resolves the cosmological constant fine-tuning catastrophe through the trace anomaly cancellation mechanism, and gives an effective dark energy density matching the observations of the Planck satellite. Based on topological soliton solutions, it explains the origin of matter-antimatter asymmetry and the physical nature of dark matter, and completes the quantitative fitting of the rotation curves of 175 spiral galaxies from the SPARC galaxy database. Fitting based on the SPARC database shows that this model (R²=0. 97) is significantly better than the NFW profile (R²=0. 92). Meanwhile, it presents 13 quantitative predictions with clear 5σ falsification criteria, covering three dimensions: laboratory testable, astrophysical observation, and strong-field gravitational wave test. This paper still has many core problems to be improved. It only provides a self-consistent and testable exploration direction for the grand unification of physics, and does not claim to have solved all core dilemmas. (A full Chinese version of this work is included as an additional file. )