Remco van Santen

Quantum mechanics has long been taken either to provide an incomplete description of microscopic reality or to require interpretive supplementation to account for its distinctive features. This paper advances a different diagnosis. It argues that quantum theory is best understood as a formal theory of observability, constrained by the physical requirements of irreversible record formation, rather than as a mechanics of observer-independent entities. The central claim is that observation itself is a physical process governed by thermodynamic constraints. Establishing stable, communicable records requires irreversible energy dissipation, and this irreversibility is not a contingent feature of measurement practice but a necessary condition of observational access. Once this constraint is made explicit and treated as explanatorily prior, characteristic structural features of quantum mechanics—contextuality, probabilistic outcomes, non-commutativity, and the asymmetry between unitary evolution and measurement—emerge as consequences of physically admissible distinction-making rather than as indicators of metaphysical indeterminacy or epistemic limitation. On this basis, the Einstein–Podolsky–Rosen incompleteness argument is re-examined and shown to presuppose reversible access to observer-independent properties, an access condition incompatible with the thermodynamics of observation. Hidden-variable programmes and thermodynamic observability are thus revealed to embody fundamentally different commitments about what physical theories can coherently describe: the former posit underlying mechanisms independent of observation, while the latter ground physical description in irreversible observational processes. The paper proposes a reclassification of quantum mechanics as a complete theory of observability under thermodynamic constraint. This is offered as a contribution to conceptual clarification in the foundations of physics, situated at the intersection of quantum theory, thermodynamics, and the historical debate over completeness, without appeal to consciousness-based or speculative ontologies.

Physics cannot coherently function as an empirical theory without presupposing thermodynamically irreversible observability—that is, observability grounded in thermodynamically irreversible record formation. This is not an interpretive stance or a preference about how to do physics, but a constraint argument: empirical meaning requires stable records; record formation requires physical stabilisation; stabilisation is thermodynamically irreversible. Any theoretical framework claiming empirical content is therefore subject to this physical constraint. This meta-theoretical claim sits one level above standard debates in quantum foundations and quantum gravity. It concerns what must already be true for physics to function as an empirical science. Building on established thermodynamic analysis of observation, the paper argues that modern physics' characteristic foundational difficulties—the quantum measurement problem and the quantum gravity impasse—arise from pursuing ontology prior to establishing the physical conditions under which observations become possible. This is an ordering error, not a missing mechanism. On this basis, quantum mechanics and general relativity are best understood not as rival ontological descriptions requiring unification, but as coordination schemes—formal frameworks for organising empirically established distinctions under different physical constraints while presupposing a shared thermodynamic foundation. Quantum mechanics coordinates which distinctions can be irreversibly established under quantum constraints; general relativity coordinates spacetime structure through invariant relations between recorded events. The paper makes three distinct contributions. First, it demonstrates that general relativity's observables—proper times, coincidence events, causal relations—depend essentially on thermodynamically irreversible measuring systems, which is a dependence not previously recognised as a constitutive thermodynamic constraint parallel to quantum measurement. Second, it shows that the measurement problem and quantum gravity impasse are parallel instances of the same ordering error. Third, it provides a positive framework—coordination schemes grounded in thermodynamic observability—that explains why unification has resisted technical refinement: the frameworks already operate under a shared physical precondition; what differs is the coordination regime, not the ontological status.

Quantum mechanics is not an incomplete mechanics of microscopic entities but a complete physical theory of observability under thermodynamic constraint. The argument rests on a single physical requirement: establishing stable, communicable records requires irreversible energy dissipation, making observation itself a thermodynamically constrained process. Once this irreversibility is taken as explanatorily prior, core structural features of quantum mechanics—contextuality, probabilistic outcomes, non-commutativity, and measurement asymmetry—follow as necessary consequences of physically admissible distinction-making rather than as signs of metaphysical indeterminacy or epistemic limitation. The central claim is that observation itself is a physical process requiring irreversible energy dissipation to establish stable, communicable records. Once this constraint is made explicit, core structural features of quantum mechanics—contextuality, probabilistic outcomes, non-commutativity, and measurement irreversibility—follow as necessary consequences of physically admissible distinction-making, rather than as signs of metaphysical indeterminacy or epistemic limitation. On this basis, the Einstein–Podolsky–Rosen incompleteness argument is re-examined and shown to presuppose reversible access to observer-independent properties, an access condition incompatible with the thermodynamics of observation. Hidden-variable programmes and thermodynamic observability are shown to represent fundamentally different commitments about what physical theories describe, with the former positing observer-independent properties and the latter grounding physics in irreversible observational processes. Quantum mechanics is thus reclassified as a complete theory of observability rather than an incomplete mechanics of microscopic entities. The contribution is one of physical clarification, grounded in information thermodynamics and measurement theory, and does not rely on appeals to consciousness or speculative ontology.