Foundations of Physics最新文献

Using the position as an independent variable, and time as the dependent variable, we derive the function ({mathcal{P}}^{(pm )}=pm sqrt{2m({mathcal{H}}-{mathcal{V}}(q))}), which generates the space evolution under the potential ({mathcal{V}}(q)) and Hamiltonian ({mathcal{H}}). No parametrization is used. Canonically conjugated variables are the time and minus the Hamiltonian ((-{mathcal{H}})). While the classical dynamics do not change, the corresponding Quantum operator ({{{hat{mathcal P}}}}^{(pm )}) naturally leads to a 1/2-fractional time evolution, consistent with a recent proposed space–time symmetric formalism of the Quantum Mechanics. Using Dirac’s procedure, separation of variables is possible, and while the two-coupled position-independent Dirac equations depend on the 1/2-fractional derivative, the two-coupled time-independent Dirac equations lead to positive and negative shifts in the potential, proportional to the force. Both equations couple the (±) solutions of ({{{hat{mathcal P}}}}^{(pm )}) and the kinetic energy ({mathcal{K}}_{0}) (separation constant) is the coupling strength. Thus, we obtain a pair of coupled states for systems with finite forces, not necessarily stationary states. The potential shifts for the harmonic oscillator (HO) are (pm {hbar {omega}} /2), and the corresponding pair of states are coupled for ({mathcal{K}}_{0}ne 0). No time evolution is present for ({mathcal{K}}_{0}=0), and the ground state with energy ({hbar {omega}} /2) is stable. For ({mathcal{K}}_{0}>0), the ground state becomes coupled to the state with energy (-{hbar {omega}} /2), and this coupling allows to describe higher excited states in the HO. Energy quantization of the HO leads to the quantization of ({mathcal{K}}_{0}=k{hbar {omega}}) ((k=1,2,ldots)). For the one-dimensional Hydrogen atom, the potential shifts become imaginary and position-dependent. Decoupled case ({mathcal{K}}_{0}=0) leads to plane-waves-like solutions at the threshold. Above the threshold (({mathcal{K}}_{0}>0)), we obtain a plane-wave-like solution, and for the bounded states (({mathcal{K}}_{0}<0)), the wave-function becomes similar to the exact solutions but squeezed closer to the nucleus.

This paper discusses the question of stable facts in relational quantum mechanics (RQM). I examine how the approach to quantum logic in the consistent histories formalism can be used to clarify what infomation about a system can be shared between different observers. I suggest that the mathematical framework for Consistent Histories can and should be incorporated into RQM, whilst being clear on the interpretational differences between the two approaches. Finally I briefly discuss two related issues: the similarities and differences between special relativity and RQM and the recent Cross-Perspectival Links modification to RQM.

This paper presents a hydrodynamical view of the Aharonov–Bohm effect, using Nelson’s formulation of quantum mechanics. Our aim is to gain a better understanding of the mysteries behind this effect, such as why in the prototype Aharonov–Bohm system with a cylinder the motion of a particle is affected in a region where there is no magnetic field. Our main purpose is to use Nelson’s formulation to describe the effect and demonstrate that it can be explained by the direct action of the current surrounding the magnetic field region. Although conventional theories try to present vector potentials as more physically significant than magnetic fields, our purpose is to demonstrate that such debate regarding the comparison between vector potentials and magnetic fields should not exist at all; within our context, magnetic fields and vector potentials serve as tools for finding other fundamental hydrodynamical quantities that arise from the interaction between the quantum background fields described by Nelson’s quantum theory, and thus, play a secondary role at the explanation of this phenomenon. So, in this paper, we do not intend to participate in a debate regarding whether we should give a local (based on e/m forces and e/m fields) or non-local (based on vector potentials) description of the phenomenon. Finally, we investigate the relationship between hidden variables and quantum fluctuations, their role in this phenomenon and their connection with the gauge transformation of the vector potential, that plays a leading role in quantum AB systems.

In a recent paper (Found Phys 54:14, 2024), Carcassi, Oldofredi and Aidala concluded that the (psi)-ontic models defined by Harrigan and Spekkens cannot be consistent with quantum mechanics, since the information entropy of a mixture of non-orthogonal states are different in these two theories according to their information theoretic analysis. In this paper, I argue that this no-go theorem for (psi)-ontic models is false by explaining the physical origin of the von Neumann entropy in quantum mechanics.

We show that the electromagnetic radiation field, conventionally introduced as a perturbation in quantum mechanics, is actually at the basis of the operator formalism. We first analyze the linear resonant response of the (continuous) variables x(t), p(t) of a harmonic oscillator to the full radiation field, i.e. the zero-point field plus an applied field playing the role of the driving force, and then extend the analysis to the response of a charged particle bound by a non-linear force, typically an atomic electron. This leads to the establishment of a one-to-one correspondence between the response functions and the respective quantum operators, and to the identification of the quantum commutator with the Poisson bracket of the response functions with respect to the normalized variables of the driving field. To complete the quantum description, a similar procedure is used to obtain the field operators as the response functions to the same normalized variables. The results allow us to draw important conclusions about the physical content of the quantum formalism, in particular about the meaning of the quantum expectation values and the coarse-grained nature of the quantum-mechanical description.

First of all we shortly illustrate how the symplectic quantization scheme (Gradenigo and Livi, Found Phys 51(3):66, 2021) can be applied to a relativistic field theory with self-interaction. Taking inspiration from the stochastic quantization method by Parisi and Wu, this procedure is based on considering explicitly the role of an intrinsic time variable, associated with quantum fluctuations. The major part of this paper is devoted to showing how the symplectic quantization scheme can be extended to the non-relativistic limit for a Schrödinger-like field. Then we also discuss how one can obtain from this non-relativistic theory a linear Schrödinger equation for the single-particle wavefunction. This further passage is based on a suitable coarse-graining procedure, when self-interaction terms can be neglected, with respect to interactions with any external field. In the Appendix we complete our survey on symplectic quantization by discussing how this scheme applies to a non-relativistic particle under the action of a generic external potential.

If an asymmetry in time does not arise from the fundamental dynamical laws of physics, it may be found in special boundary conditions. The argument normally goes that since thermodynamic entropy in the past is lower than in the future according to the Second Law of Thermodynamics, then tracing this back to the time around the Big Bang means the universe must have started off in a state of very low thermodynamic entropy: the Thermodynamic Past Hypothesis. In this paper, we consider another boundary condition that plays a similar role, but for the decoherent arrow of time, i.e. the subsystems of the universe are more mixed in the future than in the past. According to what we call the Entanglement Past Hypothesis, the initial quantum state of the universe had very low entanglement entropy. We clarify the content of the Entanglement Past Hypothesis, compare it with the Thermodynamic Past Hypothesis, and identify some challenges and open questions for future research.

The PBR theorem is widely seen as one of the most important no-go theorems in the foundations of quantum mechanics. Recently, in Cabbolet (Found Phys 53(3):64, 2023), it has been argued that there is no reality to the PBR theorem using a pair of bolts as a counterexample. In this addendum we expand on the argument: we disprove the PBR theorem by a generic counterexample, and we put the finger on the precise spot where Pusey, Barrett, and Rudolph have made a tacit assumption that is false.

In quantum foundations, there is growing interest in the program of reconstructing the quantum formalism from clear physical principles. These reconstructions are formulated in an operational framework, deriving the formalism from information-theoretic principles. It has been recognized that this project is in tension with standard ψ-ontic interpretations. This paper presupposes that the quantum reconstruction program (QRP) (i) is a worthwhile project and (ii) puts pressure on ψ-ontic interpretations. Where does this leave us? Prima facie, it seems that ψ-epistemic interpretations perfectly fit the spirit of information-based reconstructions. However, ψ-epistemic interpretations, understood as saying that the wave functions represents one’s knowledge about a physical system, recently have been challenged on technical and conceptual grounds. More importantly, for some researchers working on reconstructions, the lesson of successful reconstructions is that the wave function does not represent objective facts about the world. Since knowledge is a factive concept, this speaks against epistemic interpretations. In this paper, I discuss whether ψ-doxastic interpretations constitute a reasonable alternative. My thesis is that if we want to engage QRP with ψ-doxastic interpretations, then we should aim at a reconstruction that is spelled out in non-factive experiential terms.