Foundations of Physics最新文献

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.

Contemporary perspectivism is viewed as a framework of scientific inquiry concerning the origin, generation and systematization of scientific knowledge of nature by focusing on the conditions under which such knowledge may arise in perspectivist terms and investigating the essential ramifications of these conditions. To this end, we develop the conceptual, methodological and semantic framework of contemporary perspectivism according to the norms of the proposed endo-theoretic approach. Implementation of the preceding three-fold scheme in quantum mechanics implies that the global structure of a quantum algebra of events can be consistently comprehended through a multilevel structure of locally variable Boolean perspectives, interconnected in a category-theoretic environment, yielding jointly all the information encoded in the former. In this respect, the proposed approach validates the perspectivist/contextual nature of quantum mechanics at a fundamental level of discourse. Furthermore, due to its general character, it may acquire the form of a theoretical pattern of scientific inquiry in the natural sciences, especially when dealing with complex trans-perspectival phenomena, the analysis of which requires the use of information resulting from more than one perspective. Finally, in the appendix, we provide a concise comparative assessment between our perspectivist framework of quantum theory and Rovelli’s relational interpretation of quantum mechanics.

In this investigation, we attempt to establish a mathematical formulation for teleological explanation, based on path integral interference and information modulation mechanisms. A central hypothesis proposed is the mechanism-intent duality, which posits that a complete description of a physical system must involve both its structural mechanism and intrinsic purpose. Using the interference mechanism of the probability amplitude path integral as the mathematical foundation, the selection of actual paths is viewed as the result of information modulation by both purpose and natural laws. From the perspective of phase modulation, purpose and natural law are demonstrably equivalent in effect, and natural laws are interpreted as various objectively existing combinatorial forms of intrinsic purposes. Finally, we propose and analyze a thought experiment called the “drop arrow”, and examine classical cases such as free particle motion and the harmonic oscillator. This theoretical framework attempts to offer a possible approach to unifying matter, consciousness, and natural law.

We hypothesize that the binding interactions among the components of bound systems and the background fields, sometimes known as virtual particle exchange, affect the state of the systems as do typical scattering interactions. Then with the assumption that the interior environment of unstable particles is disordered, we derive in the limit of continuous binding both an exactly exponential non-decay probability and Fermi’s Golden Rule for the decay rates. The result suggests resolutions to several long-standing theoretical challenges associated with exponential decay in quantum mechanics, without appealing directly to non-Hermitian, approximate Hamiltonians or complex energies. It also contributes to a conceptual understanding of the apparent continuum between controlled interactions that induce deviations from exponential decay, such as those in the Quantum Zeno Effect, and the uncontrolled internal dynamics of excited atoms and nuclei, which exhibit no such deviations. Finally, we examine how the binding interactions responsible for the general exponential character of decay for bound systems differ from the couplings with decay products that control decay rates, providing insight into challenges in quantum computing and information processing.

We use the framework of Empirical Models (EM) and Hidden Variables Models (HVM) to analyze the locality and stochasticity properties of relativistic quantum theories, such as Quantum Field Theory (QFT). First, we present the standard definition of properties such as determinism, no signaling, locality, and contextuality for HVM and for EM and their relations. Then, we show that if no other conditions are added, there are only two types of EM: An EM is either classical, by which we mean that it is strongly deterministic, local, and non-contextual; Or else an EM is non-classical, in which case it is weakly deterministic, non-local and contextual. Consequently, we define criteria for an HVM to be Lorentz invariant and prove that Lorentz invariance implies parameter independence. As a result, we show that a Lorentz invariant and contextual model (e.g., relativistic quantum theory) must be genuinely stochastic i.e., it cannot have a deterministic (strong or weak) HVM. This proof is an improved version of a theorem we proved previously, and it has a wider scope. Finally, we discuss Bell’s definition of locality and show that it is equivalent to non-contextuality. We argue that Bell’s justification for this definition tacitly assumes non-contextuality (which is equivalent to strong determinism). We propose an alternative definition of locality for contextual and relativistic theories that accounts for correlations that result from common history and renders QFT a local theory.

We propose two quantum experiments – modified Bell tests – that could detect contextual hidden variables underlying quantum mechanics. The experiments are inspired by hydrodynamic pilot-wave systems that mimic a wide range of quantum effects and exhibit a classical analog of contextuality. To justify the experiments, we show that contextual hidden variables are inevitable and ‘physics as usual’ if a unification between quantum mechanics and general relativity is possible. Accordingly, contextual theories can bypass Bell’s theorem in a way that is both local and non-conspiratorial. We end with a note on the relevance of exploratory experiments in the foundations of quantum physics.