Line Universe Theory: A Unified Cosmological Framework Based on Physical Substantiality

This paper proposes a novel cosmological theoretical framework — the Line Universe Theory. Based on the principle of physical substantiality, this theory unifies the essences of spacetime, matter, energy, and interactions into the weaving and dynamic evolution of "fundamental evolutionary lines." Unlike traditional dimensional theories and relativistic spacetime frameworks, the Line Universe Theory avoids the logical paradox of "existence with zero thickness" and provides a self-consistent explanation for long-standing unsolved physical problems such as the nature of dark energy, accelerated cosmic expansion, and particle stability. The core innovations of the theory lie in: (1) defining space as the woven network state of lines, (2) defining matter as the ordered knotted excited state of lines, and (3) defining dark energy as the diffused ground state of lines. These three are homologous and symbiotic, all being different existential forms of the same fundamental physical entity. We have established a four-axiom system for the Line Universe Theory, based on which rigorous mathematical derivations are conducted: deriving the dark energy density from first principles as \rho_{\Lambda} = \alpha\xi\frac{c^7}{\hbar G^2} \approx 5.6\times10^{-30} \ \text{g/cm}^3 (in perfect agreement with observational values); proposing a modified Friedmann equation \ddot{a}/a \propto dM_\text{BH}/dt to naturally explain the mechanism of accelerated cosmic expansion; uniformly explaining the four fundamental interactions (gravity as the geometric depression of the line network, electromagnetism as the line circulation mode, strong force as the weaving rigidity of lines, and weak force as the knot reorganization of lines); and establishing a topological interpretation of particle physics (particle properties originate from the knot topology of lines, and gauge symmetry has a geometric root). The theory puts forward three key testable predictions: the positive correlation between black hole mass growth and cosmic expansion acceleration, the detection of free-state signals of line primitives in ultra-high-energy collisions, and the existence of coherent electromagnetic fields resonating with the cosmic line network in living organisms. The greatest value of the Line Universe Theory lies in its physical intuition and logical self-consistency, providing a concise and profound perspective for understanding the nature of the universe. Whether ultimately confirmed or falsified, this theory represents a profound reflection on the foundations of physics and is expected to inspire new research ideas and experimental directions.