Foundations of Physics最新文献

In order to reconcile the entropy reduction of a system through external interventions that are linked to a measurement with the second law of thermodynamics, there are two main proposals: (i) The entropy reduction is compensated by the entropy increase as a result of the measurement on the system (“Szilard principle"). (ii) The entropy reduction is compensated by the entropy increase as a result of the erasure of the measurement results (“Landauer/Bennett principle"). It seems that the LB principle is widely accepted in the scientific debate. In contrast, in this paper we argue for a modified S principle and criticize the LB principle with regard to various points. Our approach is based on the concept of “conditional action", which is developed in detail. To illustrate our theses, we consider the entropy balance of a variant of the well-known Szilard engine, understood as a classical mechanical system.

It is widely accepted that the states of any quantum system are vectors in a Hilbert space. Not everyone agrees, however. The recent paper “The unphysicality of Hilbert spaces” by Carcassi, Calderón and Aidala is a thoughtful dissection of the mathematical structure of quantum mechanics that seeks to pinpoint supposedly unsurmountable difficulties inherent in postulating that the physical states are elements of a Hilbert space. Its pivotal charge against Hilbert spaces is that by a change of variables, which is a change-of-basis unitary transformation, one “can map states with finite expectation values to those with infinite ones”. In the present work it is shown that this statement is incorrect and the source of the error is spotted. In consequence, the purported example of a time evolution that makes “the expectation value oscillate from finite to infinite in finite time” is also faulty, and the assertion that Hilbert spaces “turn a potential infinity into an actual infinity” is unsubstantiated. Two other objections to Hilbert spaces on physical grounds, both technically correct, are the isomorphism of separable Hilbert spaces and the unavoidable existence of infinite-expectation-value states. The former turns out to be quite irrrelevant but the latter remains an issue without a fully satisfactory solution, although the evidence so far is that it is physically innocuous. All in all, while the authors’ thesis that Hilbert spaces must be given up deserves some attention, it is a long way from being persuasive as it is founded chiefly on a misconception and, subsidiarily, on immaterial or flimsy arguments.

We introduce a non-Hermitian operator, and then, we discuss the possibility of finding an Aharonov-Bohm-type effect and persistent currents at zero temperature. This non-Hermitian operator is (mathcal{P}mathcal{T})-symmetric. Further, we study the Aharonov-Bohm-type effect and persistent currents at zero temperature in this (mathcal{P}mathcal{T})-symmetric quantum system in a rotating reference frame.

This study introduces the quantum force wave equation (QFWE) as a general theory of quantum forces (GToQF), a novel framework that redefines quantum forces as emergent phenomena arising from the interaction between quantum particles and curved spacetime. By coupling wave functions to spacetime curvature and gauge fields, the theory establishes a dynamic, bidirectional relationship between quantum states and spacetime geometry. This approach provides a unified description of quantum forces in highly curved and dynamic gravitational fields, extending beyond the limitations of existing theories. The theory offers fresh insights into quantum gravity, quantum field theory in curved spacetime, and particle physics in extreme conditions, serving as a versatile tool for exploring the interplay between quantum mechanics and spacetime structure. This work lays the foundation for the advancement of high-energy physics and cosmology in regimes where spacetime curvature is fundamental.

We explore the dynamical behavior of two f(T, B) gravity models with a scalar field: 1. (f(T,B)=T-gamma logbigg [frac{psi B_{0}}{B}bigg ]) and 2. (f(T,B)=eta T+frac{zeta }{B^{n}}), using the potential (V(phi )=V_{0}(alpha +e^{-beta phi })^{-delta }) and an interaction term (bar{Q} = epsilon H dot{phi }^2). A phase space analysis reveals four fixed points in Model 3.1 (three stable, one saddle) and five in Model 3.2 (four stable), indicating transitions from matter to dark energy dominance. With interaction, Model 3.2 exhibits seven fixed points, including five stable, one unstable (stiff matter era) and one saddle point. Evolution of the deceleration parameter q and the total EoS parameter (omega _{tot}) confirms sustained cosmic acceleration, with present values (q_{0} = -1.005) and (omega _{0} = -0.556) (Model 3.1) and (q_{0} = -1.245) and (omega _{0}=-1.0404) (Model 3.2). Comparisons of our observationally constrained parameters with (Lambda )CDM show strong consistency, supporting the viability of these models in describing the late-time accelerated expansion of the Universe.

Relational Quantum Mechanics posits that facts about the properties of physical systems are relative to other systems. As recently pointed out by Adlam, this gives rise to the question of the relationship between the facts that obtain relative to complex systems and the facts that obtain relative to their constituents. In this paper, I respond to Adlam’s discussion of what she calls the Combination Problem. My starting point is a maximally permissive default view according to which any collection of systems counts as a new system and composites inherit all facts that obtain relative to their constituents. Subsequently, I advance three main claims: First, that Adlam’s arguments in favour of a more restrictive approach are not compelling. Second, that even if they were, she is wrong to claim that a ‘tamed’ version of RQM with postulated links between perspectives is in a better position to support such a restrictive approach. And third, that the possibly most difficult aspect of the Combination Problem in fact pertains to the combination of quantum states and probabilities. While significant challenges for the permissive solution arise here, I argue that they are likely to arise for any plausible response to the Combination Problem. More tentatively, I propose a strategy to mitigate the difficulty based on the observer-dependence of relative quantum state assignments. Along the way, I address crucial foundational issues in Relational Quantum Mechanics, from cross-perspective communication to the link between relative facts and experiences to empirical adequacy.

Given two parties performing experiments in separate laboratories, we provide a diagrammatic formulation of what it means for the joint statistics of their experiments to satisfy local realism. In particular, we show that the principles of locality and realism are both captured by a single commutative diagram in the category of probability-preserving maps between finite probability spaces, and we also show that an assumption of such a diagrammatic formulation of local realism implies the standard CHSH inequality associated with dichotomic random variables. As quantum theory is known not to satisfy local realism, our formulation of local realism in terms of commutative diagrams provides yet another way in which the notion of non-commutativity plays a fundamental role in quantum theory. We note that we do not assume any prior knowledge of category theory or quantum theory, as this work is intended for philosophers, mathematicians and physicists alike.

We provide novel, metatheoretical arguments strengthening the position that the naturalness problem of the light Higgs mass is a pseudo-problem: Under one assumption, no physics beyond the standard model of particle physics is needed to explain the small value of the Higgs boson. By evaluating previous successes of the guiding principle of technical naturalness, we restrict its applicability to non-fundamental phenomena in the realm of provisional theories within limited energy scales. In view of further breaches of autonomy of scales in apparently fundamental phenomena outside particle physics, the hierarchy problem of the Higgs mass is instead reinterpreted as an indication of the ontologically fundamental status of the Higgs boson. Applying the concept of robustness of theoretical elements under theory changes by Worrall and Williams justifies this seemingly contradictory attribution within the effective theories of the standard model of particle physics. Moreover, we argue that the ongoing naturalness debate about the Higgs mass is partly based on the adherence to the methodology of effective theories (often claimed to be universally applicable), for which there is no justification when dealing with presumably fundamental phenomena such as the Higgs mechanism, even if it is embedded into an effective theory.

We propose our account of the meaning of local symmetries. We argue that the general covariance principle and gauge principle both are principles of democratic epistemic access to the law of physics, leading to ontological insights about the objective nature of spacetime. We further argue that relationality is a core notion of general-relativistic gauge field theory, tacitly encoded by its (active) local symmetries.

Some authors in the quantum gravity community endorse, explicitly or implicitly, a radical relationalist view of time which states that the ordinal structure of time is not needed even in our classical theories, especially in general relativity. In this article I analyze this position and the arguments supporting it, and I argue that there are some serious concerns with some of the radical relationalists’ arguments which make it an unattractive position. In this sense, I conclude that the chrono-ordinal structures of our theories play important theoretical and explanatory roles and that they can be taken to be part of the empirical content of our theories.