The End of the Universe Calculator

This research extends the Yuuki Theory (Yuuki Collapse Theory) to cosmological scales, proposing that the "size" of the universe is not determined by causal horizons or the expansion age, but by a finite structural boundary where electron-based mass calibration loses coherence. It reinterprets the universe's extent as a problem of structural sustainability rather than a kinematic or geometric one. Key Concepts of the Theory The Electron as a Universal Ruler: The theory adopts the electron as the universal mass reference, defining a minimal structural unit m_0 where m_e = \sqrt{2} \cdot m_0. Calculated Structural Limit: By calculating the point where the effective structural density \rho_{struct}(r) becomes too dilute to maintain m_0-based calibration, the theory yields a maximum sustainable radius of approximately 387 billion light-years (3.87 \times 10^{11} ly). Orthogonality to Causal Horizons: This radius is independent of the expansion rate or dark energy and does not contradict the observed age of the universe, as structural sustainability and causal reach are considered orthogonal concepts. Compatibility with CMB: The structural edge lies far beyond the last scattering surface; thus, it does not violate Cosmic Microwave Background (CMB) observations regarding early-time density fluctuations. Normalization Limit: The boundary represents a limit where "mass," "energy," and "distance" can no longer be coherently defined in electron-based units, rather than a physical wall or singularity. Conclusion Yuuki Theory concludes that the universe is structurally finite, even if it remains unbounded in geometry. By utilizing the electron as the fundamental unit of physical measurement, the framework provides a unified foundation that connects subatomic particles to the largest astrophysical structures.