In defense of coordinates: against Rovelli 1991

Title: In defense of coordinates: against Rovelli 1991

Author: Ding Jia

Abstract: Carlo Rovelli claimed that non-material reference systems must be abandoned in favor of material ones in gravitational physics. I argue that this position is wrong. Analysis of eight standard observations in gravitational physics shows that non-material coordinate systems not only can be used without problem, but are superior to material frames. Beyond empirical evidence, I propose a conceptual framework in which observables are labels for distinguishable outcomes, clarifying why observables need not be point-localized. Furthermore, material reference systems face serious difficulties: they are rarely employed in working physics and become untenable in the quantum regime. Non-material coordinates, by contrast, provide a complete, practical, and quantum-compatible framework for defining observables in gravitational theories.

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• Article v1.0: original version