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Main positions:Director, High Performance Computing Platform, PKU
Degree:Doctoral degree
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School/Department:Institute of Theoretical Physics

Lei Yian

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Education Level: Postgraduate (Doctoral)

Administrative Position: Associate Professor

Alma Mater: Peking University

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A Natural Quantum Theory Interpretation of the Kochen–Specker Theorem
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A Natural Quantum Theory Interpretation of the Kochen–Specker Theorem

From the perspective of Natural Quantum Theory (NQT), the **Kochen–Specker **(KS) theorem does not refute the determinism of physical reality. Instead, it reveals an inherent mathematical constraint within the spectral representation framework. The theorem demonstrates that—within the algebraic structure of quantum projections—it is impossible to assign consistent eigenvalues to all observables simultaneously. But this limitation pertains to the representation, not to the underlying physical system itself.

The KS theorem exposes a dilemma of representation—not a crisis of reality.

1. The Mathematical Essence of the Theorem

The KS theorem proves that in Hilbert spaces of dimension ≥ 3:

  • There exists no non-contextual hidden-variable assignment function;

  • It is impossible to assign definite {0,1} values to all projection operators while preserving functional relationships (e.g., orthogonality implies mutual exclusivity);

  • Any attempt to do so leads to logical contradictions.

NQT Interpretation:

This is a structural limitation of spectral decomposition, not a flaw in physical reality.
Just as the Fourier transform imposes a fundamental trade-off between time and frequency resolution—without implying that the signal itself is “uncertain”—the KS theorem reflects constraints inherent to how we represent physical states mathematically, not how they exist.

2. Reinterpreting Contextuality

The conventional reading holds that the KS theorem proves quantum contextuality: measurement outcomes depend on which other compatible observables are measured simultaneously.

NQT Reinterpretation:

What we call “context” is simply the choice of spectral basis:

  • Each measurement setup corresponds to a specific Hamiltonian spectral decomposition;

  • The apparent dependence arises from incompatible projection bases, not from intrinsic indeterminacy in the system.

Signal Processing Analogy:

  • Time domainf(t) → definite instantaneous values

  • Frequency domainF(ω) → definite spectral components

  • **Short-time Fourier transform **(STFT) → a time-frequency compromise

You cannot simultaneously obtain perfect resolution in all representations—but the underlying signal f(t) remains fully deterministic.
Similarly, quantum “contextuality” is a feature of representation, not ontology.

3. The Limitations of Projection Operators

At its core, the KS paradox stems from the algebraic rigidity of projection operators:

  • Orthogonal projectors must satisfy PiPj=0 (for i=j);

  • Completeness requires iPi=I;

  • In dimensions ≥ 3, these constraints make consistent {0,1} assignments mathematically impossible.

NQT View:

Projection operators are tools of spectral analysis, not direct mirrors of physical reality.
Their inability to support global value assignments reflects the inflexibility of the projection formalism, not the absence of definite physical properties.

4. A Three-Layer Ontology in NQT

Natural Quantum Theory distinguishes three ontological levels:

Level Description Deterministic?
I. Physical Reality Actual particle positions, momenta, spin orientations; field configurations ✅ Yes
II. Dynamical Evolution Classical Hamiltonian trajectories; causal, local field dynamics ✅ Yes
III. Spectral Representation Fourier-like decomposition into eigenmodes; yields quantum formalism ❌ Constrained

Crucial insight: The KS theorem applies only to Level III. It places no restrictions on the determinism of Levels I and II.

5. Concrete Example: The Spin-1 KS Paradox

Consider Peres’ famous construction with 33 directions for a spin-1 particle:

  • Standard view: No consistent assignment of squared spin values {+1,0,1} exists → “spin has no definite direction.”

  • NQT view:

    • The physical spin is a continuous 3D magnetic moment vector μ;

    • The contradiction arises when we force this continuous object into discrete, incompatible projection bases dictated by the rotation group’s representation theory;

    • The KS paradox is thus a mathematical artifact of discretization, not evidence of ontological indefiniteness.

Physical picture:
Continuous reality → Discrete spectral projection = Information loss, not ontological randomness.

6. Relationship to Bell’s Theorem

Both KS and Bell theorems are often cited as refutations of “local realism,” but NQT offers a unified reinterpretation:

Theorem Traditional Claim NQT Resolution
Bell Rules out local hidden variables via statistical correlations Correlations arise from field coherence, not nonlocality
KS Rules out non-contextual value definiteness Value indefiniteness is representational, not physical

Both are theorems about the limits of description—not disproofs of an underlying deterministic reality.

7. Experimental Implications and Predictions

NQT makes testable predictions that distinguish it from orthodox interpretations:

  • Smooth transitions under continuous basis changes:
    Measurements should show continuous evolution, not abrupt “quantum jumps,” reflecting the underlying deterministic dynamics.

  • Weak measurements reveal intermediate values:
    These correspond to actual physical quantities, not mere probabilistic mixtures.

  • Topologically protected observables evade KS constraints:
    Quantities like the Aharonov–Bohm phase are basis-independent and thus unaffected by projection incompatibilities.

8. Philosophical Reorientation

Traditionally, the KS theorem is seen as a death knell for naïve realism. NQT proposes a refined ontology:

  • Dynamical Realism: Systems possess definite states evolving deterministically.

  • Representational Relativity: Different spectral bases yield different mathematical descriptions—none is privileged.

  • Pragmatic Measurement Theory: Measurement is a partial projection of reality, not its complete revelation.

Epistemology vs. Ontology

  • The KS theorem is an epistemic limitation: our representational tools cannot capture the whole.

  • It is not an ontological limitation: the system itself remains fully determined.

Key conclusion: Representational incompleteness ≠ ontological indeterminacy.

Conclusion: The True Meaning of KS in NQT

In the framework of Natural Quantum Theory, the Kochen–Specker theorem:

  • Demonstrates the inherent limitations of spectral representation;

  • Does not challenge the determinism of physical reality;

  • Highlights the gap between continuous physical states and discrete measurement outcomes;

  • Supports the view that quantum measurement is an incomplete projection of a richer underlying reality.

Far from proving that “God plays dice,” the KS theorem reveals that our mathematical lenses have chromatic aberration.
Just as a finite-pixel image cannot perfectly encode a continuous scene, a discrete set of projection operators cannot fully capture a continuous physical state.

The “weirdness” of quantum mechanics, then, lies not in nature—but in the choice of representation.
And in recognizing this, we take a step toward restoring causality, determinism, and intelligibility to the heart of physics.

The universe is not uncertain—it is our spectral glasses that blur its edges.