Reference Frames and the Ontology of General Relativity. Re(l)ality: The View From Nowhere vs. The View From Everywhere
Abstract
In General Relativity, the genuine observable quantities are gauge-invariant Dirac observables. One well-known method of constructing them is relational, using reference frames. This leaves open an interpretive question: how should we understand two distinct relational observables defined relative to two distinct frames? I argue that this question admits two equally precise answers, corresponding to two distinct ontologies for relational general-relativistic physics, both expressible within a single fibre-bundle vocabulary. Central to the analysis is a distinction -- building on Wallace (2019) -- between frame-independence and frame-freedom, which disambiguates appeals to perspective-'neutrality'. The View from Nowhere treats relational observables as gauge-invariant partial descriptions on one underlying physical situation, typically formalised as a frame-free gauge equivalence class, and articulates within GR Adlam (2024)'s moderate physical perspectivalism. The View from Everywhere takes each relational description to represent the 'most comprehensive' -- as opposed to partial -- physical situation, rejecting ontological commitment to any shared frame-free reality, and articulates Adlam's strong perspectivalism in a non-solipsistic form. I do not settle the choice between them: each is reconstructed with its ontological commitments and costs made explicit. The framework also exhibits a constructive counter-example to a leading objection to strong perspectivalism -- that it cannot underwrite the structural connections between perspectives without frame-free structures -- by showing that a frame-independent inter-frame translation map fulfils the intended connective function. I conclude by suggesting how the results of this works may also shed light on parallel debates in quantum reference frames and relational quantum mechanics.
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