Absoluteness–Relativity Duality of Spacetime: Separation of the Mechanical Rest Frame and Optical Moving Frame

Abstract

Hyoungseok Koh

Quantum mechanics presupposes a fixed background spacetime, whereas Einstein’s special theory of relativity excludes an absolute rest frame. Taking the invariance of the speed of light as the sole first principle, we argue that an absolute rest frame and observer relativity can coexist without contradiction, as a consequence of the operational duality of measuring instruments. In a given reference frame, only points at rest are measured directly with rigid rulers and atomic clocks; a moving point borrows the coordinates of the rest points it passes in its vicinity. In the mechanical rest frame, the rigid ruler and the light ruler, the atomic clock and the light clock, and global synchronization all agree, whereas along the axis of motion of an optical moving frame this agreement breaks down and only perpendicular-plane synchronization holds. Because the rest frame employs rigid rulers, atomic clocks, and light together, it satisfies isotropy and homogeneity, from which the linearity of the coordinate transformation follows. Observer relativity, which arises from the shared use of light, then yields the Lorentz transformation and its inverse. The principle of relativity is therefore not an independent axiom but a measurement-theoretic consequence of light-speed invariance. Observer relativity holds on the foundation of an absolute rest frame, and the spacetime of inertial frames accordingly exhibits an absoluteness– relativity duality of spacetime.

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