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, electron charge, electron mass, and electron rest energy all collapse to unity, leaving
only the Planck constant ℏ as the reciprocal of the fine-structure constant α.

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.