Foundations of Physics最新文献

We revisit the classical adiabatic law from the perspective of Fisher information geometry. While the link between Fisher information and thermodynamic fluctuations is well established, we show here that the adiabatic exponent (upgamma) admits a new interpretation as quantifying the relative stiffness of energy and volume fluctuations. Within this framework, the law (PV^upgamma = mathrm {const.}) emerges as a geodesic constraint in thermodynamic state space, providing a conceptual bridge between microscopic fluctuation geometry and macroscopic dynamical invariants. This reinterpretation elevates adiabaticity from a phenomenological rule to an information-theoretic principle, with potential applications to fluctuation control in cold-atom platforms, quantum metrology, and finite-time thermodynamics. Our present results highlight how classical thermodynamic laws can be rederived as emergent signatures of Fisher-geometric structure, opening a pathway toward unifying epistemic and ontic perspectives on thermodynamic order.

The Aharonov-Bohm (AB) effect highlights the fundamental role of electromagnetic potentials in quantum mechanics, manifesting as a phase shift for a charged particle in field-free regions. While well-established for static magnetic fluxes, the effect’s behavior under time-varying fluxes remains an open and debated question. Employing the WKB method, we derive the AB phase shift for a time-dependent magnetic vector potential, demonstrating that for circular paths in the quasistatic regime, it is proportional to the time-averaged enclosed magnetic flux, (Delta phi _textrm{AB} = frac{1}{T} int _0^T e Phi (t) , dt), with the total phase shift, including kinetic contributions, equaling (e Phi (0)). For non-circular paths, the phase shift depends on both the flux history and path geometry, revealing the effect’s hybrid nature involving gauge potentials and induced electric fields. We verify the consistency of our gauge choice with Maxwell’s equations and discuss the implications for local versus nonlocal interpretations of the AB effect. We also generalize the results to scenarios with nonzero external magnetic fields, where the enclosed flux is through the actual electron paths, and for circular paths of radius R, the AB phase shift is also proportional to the time average of the enclosed flux (Phi _textrm{enc}(R,t)), with the total phase shift depending only on the initial enclosed flux (e Phi _textrm{enc}(R,0)); for general non-circular paths, the external magnetic field affects trajectories and phase accumulation through the Lorentz force, leading to additional path dependence. These findings clarify the role of gauge-dependent potentials and induced fields in the generalized AB effect, offering new theoretical insights and potential applications in quantum technologies.

In this article we develop in detail a causal model of the hydrogen atom, building on the earlier work of Dewdney and Malik in which they outlined a causal model of the hydrogen atom, focusing more on a causal model of angular momentum measurement and of the EPR experiment. We interpret the resulting formulae differently leading to new electron orbits. We develop in detail the relationship between electron orbits, angular momentum and the quantum potential.

We study gravitational back-reaction within the Page-Wootters formulation of quantum mechanics by treating time as a quantum degree of freedom. Our model introduces a distinction between global “coordinate time,” represented as a relational quantum observable, and “proper time,” measured by internal quantum degrees of freedom of physical systems. By coupling mass-energy with coordinate time through a Wheeler-DeWitt-like constraint, we demonstrate the natural emergence of gravitational time dilation. In the presence of a massive object this agrees with time dilation in a Schwarzchild metric at leading order if the interaction strength is taken to be representative of the gravitational coupling G. Additionally, when two particles independently couple to the time coordinate, a Newtonian gravitational interaction arises in the low-energy limit, showing how gravitational potential can emerge from non-interacting quantum systems. Our approach also reveals renormalization features, potentially softening high-energy divergences and suggesting that particles in superposition might introduce quantum corrections to gravitational time dilation.

High-energy colliders enable the testing of quantum mechanics at its most fundamental level, in the presence of strong and electroweak interactions, with systems that consist of qubits (fermions) and qutrits (massive spin-1 bosons). Quantum state tomography at colliders enables the witnessing of entanglement and Bell non-locality, two defining characteristics of quantum mechanics. We offer a comprehensive explanation of the underlying principles and the methods employed to achieve this remarkable feat.

This paper discusses perspectivism and relationalism in the two versions of Relational Quantum Mechanics (RQM): that initiated by Rovelli (Int. J. Theor. Phys., 35(8), 1637–1678 1996) and the other, by Adlam and Rovelli (Philos. Phys., 1(1) 2023). To this end, we offer a substantial discussion of this interpretation. We investigate the issue of the disagreement of results between different observers; distinguish four senses of agreement: strong, weak, very weak, and perspectival; and argue that the old version guarantees only the very weak and perspectival agreement, whereas the new version guarantees the weak agreement as well. The problem that individuals in RQM need to be propertyless when they do not interact is also investigated. Concerning the issue of probabilities in RQM, we argue that to express probabilities involving events relative to different systems, a new kind of probability spaces needs to be devised. The final problem that we identify concerns underspecified dynamics; we argue that some additional postulates are indispensable to make RQM’s dynamics fully specified. The last two points lead to the conclusion that, contrary to declarations of RQM proponents, this interpretation requires some modifications of quantum formalism and not merely conceptual changes. Finally, concerning the problem of testimony, while the new version of RQM was devised to solve it, we argue that in the old version, this problem can be alleviated to the extent that perspectivism permits.

Theories and models based on fractional differential equations have been developed in many different fields with the motivation to fit experimental data up to now unfitted by theories and models based on differential equations of integer orders. The experimental estimation of the equation’s parameters has a finite precision, and then such parameters emerge to be always rational numbers; as a consequence of this, there is always a pair of fractional and non-fractional equations that admit the same solution. This means that classical theories and models can be generalised into more cumbersome differential equations of integer order, with the same experimental support of the generalisation into fractional differential equations. This makes questionable the experimental corroboration of phenomena with fractional nature. But, notwithstanding this corroboration failure, the fractional generalisation can be checked against a theoretical suitability criterion consisting in preserving mathematical and physical characteristics of the original problem, a criterion that is not met by the non-fractional generalisation. This statement is first illustrated for the cases of fractional diffusion and fractional Schrödinger equation. Later the general case of a nonlinear fractional differential equation is analysed in detail.

This study investigates the Noether symmetries and geometric properties of the Melvin magnetic spacetime, focusing on the associated first integrals and conservation laws. The analysis begins with a detailed examination of the Noether symmetries, identifying the corresponding infinitesimal generators and their commutation relations. These symmetries yield first integrals that are crucial for understanding the dynamical properties of the spacetime, including Lagrangian invariance, angular momentum, generalized momentum, energy, and linear momentum along the z-axis. The study further delves into the geometric structure of the spacetime, using the vielbein formalism and Cartan structure equations to describe the underlying spin connections. Finally, perturbation and stability analysis is conducted on the effective potential governing the motion of a test particle, comparing unperturbed and perturbed potentials to explore the impact of metric perturbations on the stability of circular orbits. The results provide valuable insights into the stability characteristics of the Melvin magnetic spacetime under small perturbations.

Sebens and Carroll (Br. J. Philos. Sci. 69(1), 25–74 1) propose that self-locating uncertainty, constrained by their quantum-specific Epistemic Separability Principle (ESP-QM), derives Born rule probabilities in Everettian quantum mechanics through a global branching model. This paper argues that their approach fails due to the loss of local amplitude information in global branching, particularly evident in an EPR-Bohm setup, where distant observers like Bob are assigned pure local states lacking the amplitude coefficients essential for Born rule probabilities. This flaw undermines the quantitative link to the Born rule, rendering their derivation empirically inadequate. Additional inconsistencies of global branching, including conflicts with decoherence dynamics, relativistic constraints, and limitations on superposition measurements, further weaken the model. Defenses invoking global amplitudes or benign non-locality fail to resolve these issues. This analysis underscores the need to reconsider branching mechanisms to secure a robust foundation for Everettian probabilities.

This paper develops an agent-centric account of measurement that treats the preferred-basis problem as fundamentally perspectival. On this view, the system–apparatus–environment decomposition and the observables that are apt to become classically robust are determined by the physical constitution and epistemic constraints of an embodied class of agents. Decoherence then stabilises those agent-specified observables, yielding facts that are stable for us without positing an absolute, observer-independent basis. On this picture, ‘measurements’ are public not because they are metaphysically privileged, but because agents like us share the relevant sensorimotor and operational structure. I motivate this account through a discussion of two recent no-go results for relational quantum mechanics (RQM) [1, 2], and a subsequent response [3]: my aim is not to defend RQM per se, but to refine the relational insight with a principled account of basis selection rooted in embodiment. I provide a phenomenological gloss, drawing on body-schema considerations, to argue that quantum mechanics is best understood as an idiosyncratically human description of interactions with the physical world—a structurally constrained, agent-indexed framework within which classicality emerges.