Foundations of Physics最新文献

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.

Hardy’s (psi)-ontology theorem proves the reality of the wave function under the assumption of restricted ontic indifference. It has been conjectured that restricted ontic indifference, which is a very strong assumption from the (psi)-epistemic view, can be derived from two weaker sub-assumptions: an ontic state assumption and a locality assumption. However, Leifer argued that this derivation cannot go through when considering the existence of the vacuum state in the second-quantized description of quantum states. In this paper, I present a new analysis of Hardy’s theorem. First, I argue that the ontic state assumption is valid in the second-quantized description of quantum states. Second, I argue that the locality assumption is a locality assumption for product states and it is weaker than the preparation independence assumption of the PBR theorem. Third, I argue that Leifer’s objection to the derivation of restricted ontic indifference is invalid. Finally, I argue that although the vacuum state is irrelevant, the existence of the tails of the wave function will block the derivation of restricted ontic indifference from the ontic state assumption and the locality assumption.

Aurélien Drezet has attempted in Found. Phys. 54(1), 5 (2023) to defend Relational Quantum Mechanics (RQM) against our recent critique, entitled Relational Quantum Mechanics is incompatible with quantum mechanics, published in Quantum 7, 1015 (2023). Drezet not only misrepresents our work, but he also misconstructs the very theory (RQM) that he claims to defend.

We study implications of Leibnizian ideas such as the identity of indiscernibles, and variety (due to Barbour and Smolin) in the context of Wolfram Model, which has been put forward in 2020. We have provided (at the moment) speculative interpretations for Leibnizian and non-Leibnizian hypergraphs. We introduced an action based on variety, to select paths where it is maximized. The specific universe which is of concern here is the one with name ‘wm1268’ from the Registry of Notable Universe Models, which is used as a test case in the present study.

We have revised the problem of the motion of a heavy symmetric top. When formulating equations of the Lagrange top with the diagonal inertia tensor, the potential energy has more complicated form as compared with that assumed in the literature on dynamics of a rotating body. This implies the corresponding improvements in equations of motion. Using the Liouville’s theorem, we solve the improved equations in quadratures and present the explicit expressions for the resulting elliptic integrals.

We investigate a model of becoming—classical sequential growth (CSG)—that has been proposed within the framework of causal sets (causets), with the latter defined as order types of certain partial orderings. To investigate how causets grow, we introduce special sequences of causets, which we call “csg-paths”. We prove a number of results concerning relations between csg-paths and causets. These results paint a highly non-trivial picture of csg-paths. There are uncountably many csg-paths, all of them sharing the same beginning, after which they branch. Every infinite csg-path achieves in the limit an infinite causet, and vice versa, every infinite causet is achieved in the limit by an infinite csg-path. However, coalescing csg-paths, i.e., ones that achieve the same causet even after forking off at some point, are ubiquitous.

We provide the construction of a de Broglie–Bohm model of the N-body system within the framework of Pure Shape Dynamics. The equation of state of the curve in shape space is worked out, with the instantaneous shape being guided by a wave function. In order to get a better understanding of the dynamical system, we also give some numerical analysis of the 3-body case. Remarkably enough, our simulations typically show the attractor-driven behaviour of complexity, well known in the classical case, thereby providing further evidence for the claim that the arrow of complexity is the ultimate cause of the experienced arrow of time.

A classification of different interpretations of the quantum formalism is examined and the concept of perspectival interpretation is presented. A perspectival interpretation implies that the truth is relative to the observer. The degree to which Convivial Solipsism and QBism in its different versions are perspectival is examined.

The persistent challenge of formulating ontic structuralism in a rigorous manner, which prioritizes structures over the entities they contain, calls for a transformation of traditional logical frameworks. I argue that Univalent Foundations (UF), which feature the axiom that all isomorphic structures are identical, offer such a foundation and are more attractive than other proposed structuralist frameworks. Furthermore, I delve into the significance in the case of the hole argument and, very briefly, the nature of symmetries.