A model of irreversible deterministic quantum dynamics

Fabio Benatti, Roberto Floreanini B

Marriam Naeem

Deterministic microscopic laws constrain physical systems through conservation laws and boundary conditions, yet macroscopic evolution routinely exhibits irreversible collapse, destruction, and path dependence. We analyze deterministic classical and quantum systems admitting multiple metastable macroscopic trajectories under fixed global constraints and show that deterministic dynamics generally underdetermine macroscopic history. We introduce a distinction between constraint-defined macroscopic equivalence classes, fixed by invariant quantities, and metastable macroscopic trajectories, defined by dynamical stability. Using stability and basin-of-attraction arguments, we characterize collapse as a deterministic loss of metastability in which an entire macroscopic trajectory becomes dynamically inaccessible without violation of microscopic reversibility or conservation laws. Irreversible destruction corresponds to elimination of physically realizable paths rather than loss of information or coarse-grained inaccessibility. We show that explanations based solely on coarse-graining or decoherence are insufficient to account for such trajectory elimination, as they preserve admissibility of erased histories. In contrast, instability-driven trajectory destruction constitutes an ontic dynamical process, directly realized in many-body and condensed matter systems. The framework provides a unified account of irreversible macroscopic change and causal differentiation within deterministic dynamics, without invoking stochasticity, modified laws, or observer-dependent mechanisms. Deterministic laws constrain admissible macroscopic states, while instability and metastability govern the physically realizable histories connecting them.

Marriam Naeem

A longstanding tension in the foundations of physics concerns the coexistence of deterministic(or unitary) dynamics with the apparent reality of choice, causation, collapse, and irreversible destruction. Standard responses either deny the physical significance of freedom, modify dynamicallaws, or relocate the problem to metaphysics. This paper identifies a structural distinction betweenmetastable macroscopic trajectories (paths) and globally constrained end states (attractors) and argues that its absence underlies much of the tension. We show that local degrees of freedom can alter,destabilize, and irreversibly eliminate particular trajectories without modifying the global attractorfixed by deterministic constraints. Collapse is thereby interpreted as loss of metastability ratherthan as a violation of determinism or unitarity. On this basis, we provide a structurally consistentaccount of causal efficacy, historical collapse, and responsibility within fully deterministic dynamics. We further extend this analysis to quantum mechanics, arguing that decoherence generatesmetastable macroscopic sectors within globally unitary evolution and that ontological commitmentattaches to dynamically persistent structure rather than to arbitrary Hilbert-space decomposition.The framework introduces no stochastic postulates and no modifications of physical law, but insteadclarifies the structural level at which freedom, collapse, and irreversibility operate.

Stig Stenholm

Silvio Bergia, F. Cannata, Bruno Giorgini +1 more

Abderrahim Lyoubi-Idrissi

The collapse of the wave function remains one of the deepest puzzles in quantum mechanics. The Schrödinger equation is unitary and time-reversal symmetric, yet measurement requires an additional postulate that is neither—and we have no physical explanation for why. Existing interpretations either deny that collapse is real (Many-Worlds), treat it as purely subjective (QBism), or add stochastic noise by hand without deriving it from fundamental principles (GRW, CSL). We demonstrate that collapse is a real physical process requiring fundamentally irreversible dynamics. No purely unitary, time-symmetric theory can account for the objective suppression of macroscopic superpositions—irreversibility must be built into the dynamics from the start. We introduce a minimal extension of quantum mechanics through coupling to a universal scalar field (the I-field) governed by an explicit time-asymmetric field equation. Collapse emerges objectively through deterministic dissipative dynamics, with no reference to observers, measurement devices, or stochastic noise. By integrating out the I-field degrees of freedom, we derive effective Lindblad dynamics for quantum systems. The collapse rate scales quadratically with system mass, ensuring microscopic quantum coherence remains intact while macroscopic superpositions are dynamically suppressed. Unlike stochastic collapse models (GRW/CSL), the mechanism is deterministic and produces no spontaneous heating. Unlike gravitational collapse proposals (Diósi-Penrose), it provides explicit field equations rather than heuristic arguments. Unlike environmental decoherence, the irreversibility is fundamental rather than effective. The theory respects relativistic causality and makes testable predictions for current and near-future experiments in matter-wave interferometry, optomechanical systems, and molecular interferometry. Observation of mass-dependent decoherence without accompanying stochastic heating would provide strong evidence for the I-field mechanism. The framework establishes irreversibility as a fundamental interaction rather than an emergent phenomenon, providing a unified physical origin for both wave function collapse and the quantum arrow of time.