Quantum mechanics is widely regarded as the most empirically successful theory in the history of physics. It has enabled the design of transistors, lasers, and atomic clocks, and it provides accurate predictions across domains as varied as spectroscopy and quantum computing. And yet, nearly a century after its formal development, we still do not know what it describes.
At the heart of the problem is ontology: the question of what exists and how. Quantum theory operates with a formalism that yields probabilistic predictions about measurement outcomes, but remains curiously agnostic about what the system is doing when it is not being measured. The ontological commitments of the theory are underdetermined by its predictive success—and the result is a landscape of competing interpretations, each with different implications for the nature of reality.
This post outlines the key ontological problems that quantum mechanics presents, and why none of the mainstream interpretations resolve them without cost. It also sketches a path toward a more relationally grounded account, which will be developed further in the posts to come.
1. The Measurement Problem
At the core of quantum theory is the wavefunction—a complex-valued function that evolves deterministically according to the Schrödinger equation. But when a measurement occurs, the wavefunction appears to "collapse" into a definite outcome, in violation of that same evolution.
If the wavefunction is a complete description of reality, then collapse is a real, physical process—but one not accounted for by the theory’s own dynamics. If, on the other hand, collapse is epistemic (a change in knowledge), then we must explain how our observation transforms the state of a physical system. Either option leads to philosophical discomfort.
2. Nonlocality and Entanglement
Quantum entanglement describes correlations between particles that persist across spatial separation. In experiments such as those testing Bell inequalities, these correlations violate classical expectations and suggest that quantum systems are not composed of independently determined parts.
This raises ontological challenges to any theory built on local, separable entities. It suggests that quantum phenomena are not reducible to the behaviour of isolated components—a serious departure from classical metaphysics.
Worse still, no interpretation of quantum mechanics has managed to explain this nonlocality without introducing its own set of paradoxes. Bohmian mechanics, for instance, embraces nonlocality explicitly, but at the cost of reintroducing a preferred frame of reference—undermining relativistic covariance.
3. The Problem of Identity and Individuation
Quantum particles are often said to be “indistinguishable,” and yet they exhibit stable patterns (e.g. in atomic orbitals or statistical ensembles). If two electrons cannot, even in principle, be individuated by any intrinsic property, in what sense are they two?
This problem goes deeper than mere labelling. The ontology of entities breaks down when quantum identity lacks classical substance. Fermi–Dirac and Bose–Einstein statistics reveal that what we call "particles" behave more like excitations of shared relational fields than self-contained units.
4. The Limits of Particle and Field Metaphors
Quantum theory is commonly taught using metaphors of particles and waves, but neither metaphor captures the theory’s full behaviour. Particles that diffract. Waves that "collapse." Dualities that never settle into unity.
This opens the door to alternative ontologies—ones not based on things in space, but on relations, processes, and transformation under constraint. The challenge is to develop such frameworks without losing empirical adequacy or mathematical precision.
5. The Interpretation Landscape: No Clear Winner
Numerous interpretations of quantum mechanics attempt to resolve these problems, but none do so without cost:
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Copenhagen interpretation avoids ontology altogether—collapsing the question into the observer.
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Many-Worlds solves the measurement problem at the cost of proliferating unobservable universes.
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Bohmian mechanics preserves determinism but introduces hidden variables and preferred trajectories.
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QBism and other epistemic interpretations sidestep reality in favour of subjective expectation.
What all these interpretations share is an inability to resolve the ontological paradoxes without importing new contradictions or speculative machinery.
Toward a Relational Ontology
A relational ontology begins not with substances but with patterned dependencies—systems of potential actualising under constraint. In such a view:
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The wavefunction encodes a structured field of affordance, not a hidden substance.
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Measurement is not collapse, but selection—where systemic tensions precipitate local resolution.
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Entanglement reflects non-separability, not spooky action-at-a-distance.
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Time, space, and individuality emerge from deeper relational coherence, not the other way around.
In the next post, we’ll begin to develop this approach systematically, contrasting relational ontology with classical substance metaphysics and exploring how such a framework might resolve the problems outlined here.
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