The Dynamics of Discrete Fact: A Phase-Transition Theory of Wavefunction Collapse

The quantum measurement problem—the absence of any dynamical mechanism connecting continuous wavefunction evolution to discrete empirical outcomes—has persisted since the foundations of quantum theory. Decoherence explains interference suppression but cannot explain outcome selection: the diagonal density matrix remains an improper mixture until one outcome is actualized. We propose that collapse is a physical phase transition in the coupled system–apparatus field. The order parameter ψ, constructed as a coarse-grained collective coordinate of apparatus degrees of freedom, evolves under Ginzburg–Landau dynamicswith a symmetry-breaking potential. When the coherence pressure γ exceeds a critical threshold γc, the symmetric phase(superposition) becomes unstable and the field crystallizes into one of the discrete stable minima (eigenstates). We derive the critical coupling from microscopic system–apparatus Hamiltonians, obtaining γc ∼ (√Ng)−1 where N is the number of apparatus degrees of freedom and g is the coupling constant. This scaling explains why macroscopic apparatus collapse wavefunctions while microscopic interactions preserve coherence. The Born rule Pn = |cn|2 is preserved through this dynamical selection mechanism: attractor basin geometry under probability-conserving flow converts probabilistic weights into definite outcomes without altering the underlying probabilities. The theory yields four falsifiable predictions absent from standard quantum mechanics: critical slowing near γc, hysteresis in the collapse–recoherence cycle, metastable supercooled superpositions, and transient Jacobian spikes at the moment of collapse. We provide quantitative estimates for superconducting qubit readout, predicting collapsetimes of order 100 ns with critical slowing observable within current experimental precision. This framework provides a concrete existence proof, within a controlled effective-theory regime, that collapse dynamics can be constructed from standard quantum mechanics plus statistical mechanics, requiring no modification to the Schr¨odinger equation.