Space-Time Unit System for Unifying Gravitational Mechanics, Electromagnetism and Quantum Physics

This study re-examines the roles of the gravitational constant G, the vacuum permittivity ε₀, and the vacuum permeability μ₀ while preserving the historically established forms of physical laws, and attempts a redefinition of two fundamental SI units: the Coulomb and the kilogram. As a result, both the Coulomb and the kilogram are shown to be expressible solely in terms of length (meter) and time (second). Furthermore, transforming to the Space–Time Unit System yields a fundamental relation between the electron mass m₀ and the electron charge e₀, m₀ = e₀ c from which a new dimensionless constant β inevitably emerges, linking classical mechanics with electromagnetism. This work positions β as a new universal constant, standing alongside the fine-structure constant α. In the corresponding natural-unit formulation, the classical electron radius arises naturally as the fundamental length scale. By adopting this length as the reference unit, the speed of light, the elementary charge, the electron mass, Planck’s constant, and the electron rest energy all collapse to unity, while quantum interactions are characterized by the inverse fine-structure constant α, which appears in conjunction with ℏ. The Space–Time Unit System presented here reconsiders the structure of physical units from first principles, revealing a new universality that spans classical mechanics,electromagnetism, and quantum mechanics, and extending the conceptual foundation of natural unit systems.