Foundations of Physics最新文献

Over the past decade, the physics literature on torsionful non-relativistic gravity has burgeoned; more recently, philosophers have also begun to explore this topic. As of yet, however, the connections between the writings of physicists and philosophers on torsionful non-relativistic gravity remain unclear. In this article, we seek to bridge the gap, in particular by situating within the context of the existing physics literature a recent theory of non-relativistic torsionful gravity developed by philosophers Meskhidze and Weatherall (Philos Sci, https://doi.org/10.1017/psa.2023.136, 2023) we also discuss the philosophical significance of that theory.

Of the many ways of getting at the core of the weirdnesses in quantum mechanics, there’s one which traces back to Schrödinger’s seminal 1935 paper, and has to do with the apparent fuzzy nature of the reality described by the formalism through the wavefunction (psi). This issue, which I will be calling the Determinacy Problem, is distinct from the standard measurement problem of quantum mechanics, despite Schrödinger himself ends up conflating the two. I will argue that the Determinacy Problem is an exquisitely philosophical problem, for as it is standard when facing any phenomenon which appears to have indeterminate or fuzzy characteristics, the solutions available are to either blame the deficiencies of our language, or our lack of knowledge, or to blame the world itself. These three attitudes can already be found in the literature on quantum mechanics, either explicitly or implicitly, and they appear to motivate three very distinct research programs: high-dimensional realism, primitive ontology, and quantum indeterminacy.

There is solid consensus among physicists and philosophers that, in gauge field theory, for a quantity to be physically meaningful or real, it must be gauge-invariant. Yet, every “elementary” field in the Standard Model of particle physics is actually gauge-variant. This has led a number of researchers to insist that new manifestly gauge-invariant approaches must be established. Indeed, in the foundational literature, dissatisfaction with standard methods for reducing gauge symmetries has been expressed: Spontaneous symmetry breaking is deemed conceptually dubious, while gauge fixing suffers the same limitations and is subject to the same criticisms as coordinate choices in General Relativity. An alternative gauge-invariant proposal was recently introduced in the literature, the so-called “dressing field method” (DFM). It is a mathematically subtle tool, and unfortunately prone to be confused with simple gauge transformations, hence with standard gauge fixings. As a matter of fact, in the physics literature the two are often conflated, and in the philosophy community some doubts have been raised about whether there is any substantial difference between them. Clarifying this issue is of special significance for anyone interested in both the foundational issues of gauge theories and their invariant formulation. It is thus our objective to establish as precisely as possible the technical and conceptual distinctions between the DFM and gauge fixing.

The spin-j Einstein–Podolsky–Rosen–Bohm experiment is examined in the context of how the quantum theoretic probability distributions for the spin measurement outcomes are to be coarse-grained in order to yield classical behavior in the (j rightarrow infty ) limit. A coarse-graining protocol is found that can be viewed as imperfection either in the detection process or in state preparation process, and is in both viewpoints minimal in the sense that it is no more than what is needed to wash out the execess quantum correlations. In the first point of view the coarse-grained distribution can be written in terms of a Bell-type factorizable hidden variable model wherein the conditional distributions for the spin measurement outcome of each particle is not just nonnegative but actually attains the value zero for some choice of measurement axis. In the second point of view the coarse-grained distribution arises from a spin state whose Wigner function is not just nonnegative but actually attains the value zero for some spin orientations. That such a remarkable dual interpretation should be possible suggests that this type of complementary coarse graining is an intrinsic aspect of how classicality is obtained in the large j limit, but this conclusion remains speculative.

Recently, the correspondence between the air track scenario and quantum database search algorithm was revealed. The conservation laws of linear momentum and nonlinear kinetic energy in the former case, which involve sequential elastic collisions, have their analogs in the latter case. Obviously, probability normalization combined with the Born rule serves as an analog for kinetic energy conservation. Here we explore the linear conservation laws in a generic quantum database search. Regarding the non-uniform distribution of the marked state, the uneven state is initially prepared. In this way, the Grover diffusion operator results in a linear but nonphysical conservation law. On the other hand, in the CTC-assisted database search with the vast reduction of query complexity, the nonlinear instead of linear conservation laws are found. Finally, we conjecture that there are no conservation laws in the generalized Grover’s algorithm including the imaginary number i.

Recently, in Found. Phys. 53: 64 (2023), it has been argued that there is no reality to the PBR theorem. In Found. Phys. 54: 36 (2024), Hofer-Szabó has commented that the argument is flawed and that PBR theorem remains in tact. Here we reply to Hofer-Szabó by showing that his counterargument does not hold up, concluding that the PBR theorem has been disproved.

I analyze the possibility of free-will in the many-worlds interpretation (MWI), arguing for their compatibility. I use as a starting point Nicolas Gisin’s “The Multiverse Pandemic” (preprint arXiv:2210.05377, 2022, after Gisin, N., “L’épidémie du multivers”, in “Le Plus Grand des Hasards”, Belin, Paris, 2010), in which he makes an interesting case that MWI is contradicted by our hard to deny free-will. The counts he raised are: (1) MWI is deterministic, forcing choices on us, (2) in MWI all our possible choices happen, and (3) MWI limits creativity, because everything is entangled with everything else. I argue that each of these features of MWI is in fact compatible with more freedom than it may seem. In particular, MWI allows compatibilist free-will, but also free-will very much like the libertarian free-will defined by Chisholm. I argue that the position that alternative choices exist as possibilities does not make sense from a physical point of view, but MWI offers a physical ground for alternatives.

In this paper we present a discussion of the basic aspects of the well-known problem of prediction and inference in physics, with specific attention to the role of models, the use of data and the application of recent developments in artificial intelligence. By focussing in the time evolution of dynamic system, it is shown that main difficulties in predictions arise due to the presence of few factors as: the occurrence of chaotic dynamics, the existence of many variables with very different characteristic time-scales and the lack of an accurate understanding of the underlying physical phenomena. It is shown that a crucial role is assigned to the preliminary identification of the proper variables, their selection and the identification of an appropriate level of description (coarse-graining procedure). Moreover, it is discussed the relevance, even in modern practical issues, of old well-known fundamental results, like the Poincaré recurrence theorem, the Kac’s lemma and the Richard’s paradox.

In this paper, we investigate similarities and differences between the main neo-Copenhagen (or “epistemic–pragmatist”) interpretations of quantum mechanics, here identified as those defined by the rejection of an ontological nature of the quantum states and the simultaneous avoidance of hidden variables, while maintaining the quantum formalism unchanged. We argue that there is a single general interpretive framework in which the core claims that the various interpretations in the class are committed to, and which they emphasize to varying degrees, can be represented. We also identify, however, remaining differences of a more substantial nature, and we offer a first analysis of them. We also argue that these remaining differences cannot be resolved within the formalism of quantum mechanics itself and identify the more general philosophical considerations that can be used in order to break this interpretation underdetermination.