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Sat Sep 09 2023 09:09:50 (1 hour)

# 1.

Szabó, László E. and Gömöri, Márton and Gyenis, Zalán (2023) Questionable and Unquestionable in Quantum Mechanics. [Preprint]

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Sat Sep 09 2023 09:09:09 (1 hour)

# 2.

Cuffaro, Michael E. (2023) Review of Slobodan Perović’s From Data to Quanta — Niels Bohr’s Vision of Physics. Philosophy of Science. ISSN 1539-767X

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Lu Chen

Fri Sep 08 2023 09:13:43 (1 day)

# 3.

I defend algebraicism, according to which physical fields can be understood in terms of their structural relations without reference to a spacetime manifold, as a genuine relationalist view against the conventional wisdom that it is equivalent to substantivalism, according to which spacetime exists fundamentally. I criticize the standard version of algebraicism that is considered equivalent to substantivalism. Furthermore, I present alternative examples of algebraicism that better implement relationalism and showcase their distinct advantages over substantivalism or its standard algebraic counterpart.

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Jean-Luc Lehners, Jerome Quintin

Fri Sep 08 2023 09:13:42 (1 day)

# 4.

Many cosmological models assume or imply that the total size of the universe is very large, perhaps even infinite. Here we argue instead that the universe might be comparatively small, in fact not much larger than the currently observed size. A concrete implementation of this idea is provided by the no-boundary proposal, in combination with a plateau-shaped inflationary potential. In this model, opposing effects of the weighting of the wave function and of the criterion of allowability of the geometries conspire to favour small universes. We point out that a small size of the universe also fits well with swampland conjectures, and we comment on the relation with the dark dimension scenario.

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Howard M. Wiseman, Eric G. Cavalcanti, Eleanor G. Rieffel

Fri Sep 08 2023 09:13:42 (1 day)

# 5.

A recent paper by two of us and co-workers, based on an extended Wigner’s friend scenario, demonstrated that certain empirical correlations predicted by quantum theory (QT) violate inequalities derived from a set of metaphysical assumptions we called “Local Friendliness” (LF). These assumptions are strictly weaker than those used for deriving Bell inequalities. Crucial to the theorem was the premise that a quantum system with reversible evolution could be an observer (colloquially, a “friend”). However, that paper was noncommittal on what would constitute an observer for the purpose of an experiment. Here, we present a new LF no-go theorem which takes seriously the idea that a system’s having *thoughts* is a sufficient condition for it to be an observer. Our new derivation of the LF inequalities uses four metaphysical assumptions, three of which are thought-related, including one that is explicitly called “Friendliness”. These four assumptions, in conjunction, allow one to derive LF inequalities for experiments involving the type of system that “Friendliness” refers to. In addition to these four metaphysical assumptions, this new no-go theorem requires two assumptions about what is *technologically* feasible: Human-Level Artificial Intelligence, and Universal Quantum Computing which is fast and large scale. The latter is often motivated by the belief that QT is universal, but this is *not* an assumption of the theorem. The intent of the new theorem is to give a clear goal for future experimentalists, and a clear motivation for trying to achieve that goal. We review various approaches to QT in light of our theorem. The popular stance that “quantum theory needs no interpretation” does not question any of our assumptions and so is ruled out. Finally, we quantitatively discuss how difficult the experiment we envisage would be, and briefly discuss milestones on the paths towards it.

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Fri Sep 08 2023 08:44:12 (1 day)

# 6.

Chen, Eddy Keming (2023) Laws of Physics. [Preprint]

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Fri Sep 08 2023 08:42:40 (1 day)

# 7.

Read, James (2023) Review of “Teleparallel Newton-Cartan Gravity”, by Philip K. Schwartz. [Preprint]

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Lu Chen

Thu Sep 07 2023 10:16:22 (1 day)

# 8.

I develop a new view of the structure of space–called infinitesimal atomism–as a reply to Zeno’s paradox of measure. According to this view, space is composed of ultimate parts with infinitesimal size, where infinitesimals are understood within the framework of Robinson’s nonstandard analysis. Notably, this view satisfies a version of additivity: for every region that has a size, its size is the sum of the sizes of its disjoint parts. In particular, the size of a finite region is the sum of the sizes of its infinitesimal parts. Although this view is a coherent approach to Zeno’s paradox and is preferable to Skyrms’s (1983) infinitesimal approach, it faces both the main problem for the standard view (the problem of unmeasurable regions) and the main problem for finite atomism (Weyl’s tile argument), leaving it with no clear advantage over these familiar alternatives.

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Lu Chen

Thu Sep 07 2023 10:16:21 (1 day)

# 9.

In this paper, I advance an original view of the structure of space called \textit{Infinitesimal Gunk}. This view says that every region of space can be further divided and some regions have infinitesimal size, where infinitesimals are understood in the framework of Robinson’s (1966) nonstandard analysis. This view, I argue, provides a novel reply to the inconsistency arguments proposed by Arntzenius (2008) and Russell (2008), which have troubled a more familiar gunky approach. Moreover, it has important advantages over the alternative views these authors suggested. Unlike Arntzenius’s proposal, it does not introduce regions with no interior. It also has a much richer measure theory than Russell’s proposal and does not retreat to mere finite additivity.

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Emilio Elizalde

Thu Sep 07 2023 10:16:20 (1 day)

# 10.

Albert Einstein visited Spain only once, precisely one hundred years ago. The circumstances, of a very different kind, of this visit will be explained here. In special, some important events happened to Einstein during that period, which, eventually, were key for converting modern cosmology into a genuine physical theory. Among them is the famous Einstein-Friedmann controversy, first, on the mathematical validity of Friedmann’s equations and, later, their possible usefulness as a reliable tool to describe the real world. A summary of the deepest ideas underlying Einstein’s contributions to the theory of relativity, which he had already completed before his visit, will precede the discussion, also supplemented with a description, in very simple terms, of the three main relativistic theories, namely Galileo’s one, and Einstein’s special and general theory. They pave the way towards a definitive theory of total relativity, so far unattainable. It will be recalled that the most general relativity principle, faithfully reflecting Ernst Mach’s far-reaching ideas, might have much to do with the symmetry-breaking paradigm, a most crucial tool in quantum field theory and high energy physics.

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Hans Christian Öttinger

Thu Sep 07 2023 10:16:19 (1 day)

# 11.

The stochastic nature of quantum mechanics is more naturally reflected in a bilinear two-process representation of density matrices rather than in squared wave functions. This proposition comes with a remarkable change of the entanglement mechanism: entanglement does not originate from superpositions of wave functions, but results from the bilinear structure of density matrices. Quantum interference is not an additive superposition mechanism, but rather a multiplicative phenomenon. The proposed bilinear representation of density matrices is given in terms of two stochastic jump processes. These ideas are illustrated for the Einstein-Podolsky-Rosen and double-slit experiments. The expression of the stochastic nature of quantum mechanics in terms of random variables rather than their probability distributions facilitates an ontological viewpoint and leads us to a two-worlds interpretation of quantum mechanics.

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Emily Adlam

Thu Sep 07 2023 10:16:18 (1 day)

# 12.

Recently there have emerged an assortment of theorems relating to the ‘absoluteness of emerged events,’ and these results have sometimes been used to argue that quantum mechanics may involve some kind of metaphysically radical non-absoluteness, such as relationalism or perspectivalism. However, in our view a close examination of these theorems fails to convincingly support such possibilities. In this paper we argue that the Wigner’s friend paradox, the theorem of Bong et al and the theorem of Lawrence et al are all best understood as demonstrating that if quantum mechanics is universal, and if certain auxiliary assumptions hold, then the world inevitably includes various forms of ‘disaccord,’ but this need not be interpreted in a metaphysically radical way; meanwhile, the theorem of Ormrod and Barrett is best understood either as an argument for an interpretation allowing multiple outcomes per observer, such as the Everett approach, or as a proof that quantum mechanics cannot be universal in the sense relevant for this theorem. We also argue that these theorems taken together suggest interesting possibilities for a different kind of relational approach in which dynamical states are relativized whilst observed events are absolute, and we show that although something like ‘retrocausality’ might be needed to make such an approach work, this would be a very special kind of retrocausality which would evade a number of common objections against retrocausality. We conclude that the non-absoluteness theorems may have a significant role to play in helping converge towards an acceptable solution to the measurement problem.

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Thu Sep 07 2023 04:49:19 (2 days)

# 13.

Kearney, Peter (2020) Decoherence, the measurement problem and realism. [Preprint]

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Thu Sep 07 2023 04:46:35 (2 days)

# 14.

Barandes, Jacob A. (2023) The Stochastic-Quantum Theorem. [Preprint]

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Thu Sep 07 2023 04:37:32 (2 days)

# 15.

Kastner, Ruth and Schlatter, Andreas (2023) Entropy cost of “Erasure” in Physically Irreversible Processes. [Preprint]

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Davide Poderini, Giovanni Rodari, George Moreno, Emanuele Polino, Ranieri Nery, Alessia Suprano, Cristhiano Duarte, Fabio Sciarrino, and Rafael Chaves

Tue Sep 05 2023 18:00:00 (3 days)

# 16.

Author(s): Davide Poderini, Giovanni Rodari, George Moreno, Emanuele Polino, Ranieri Nery, Alessia Suprano, Cristhiano Duarte, Fabio Sciarrino, and Rafael Chaves

Quantum Darwinism offers an explanation for the emergence of classical objective features (those we are used to at macroscopic scales) from quantum properties at the microscopic level. The interaction of a quantum system with its surroundings redundantly proliferates information to many parts of the…

[Phys. Rev. A 108, 032201] Published Tue Sep 05, 2023

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Tue Sep 05 2023 06:48:07 (4 days)

# 17.

Barandes, Jacob A. (2023) The Stochastic-Quantum Correspondence. [Preprint]

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Tue Sep 05 2023 06:42:53 (4 days)

# 18.

Fraser, James D. (2023) Infinite Scale Scepticism: Probing the Epistemology of the Limit of Infinite Degrees of Freedom and Hilbert Space Non-Uniqueness. [Preprint]

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Tue Sep 05 2023 05:00:22 (4 days)

# 19.

Krause, Décio (2023) The underlying logic is mandatory also in discussing the philosophy of quantum physics. [Preprint]

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Sun Sep 03 2023 11:36:34 (5 days)

# 20.

Giovanelli, Marco (2023) Cassirer and Energetics: An Investigation of Cassirer’s Early Philosophy of Physics. British Journal for the History of Philosophy. ISSN 1469-3526

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Sun Sep 03 2023 11:34:35 (5 days)

# 21.

Giovanelli, Marco (2023) Relativity Theory as a Theory of Principles. A Reading of Cassirer’s Zur Einstein’schen Relativitätstheorie. [Preprint]

quant-ph>arXiv:2308.11262

Superdeterminism Without Conspiracy

Superdeterminism — where the Measurement-Independence assumption in Bell’s Theorem is violated — is typically treated with derision as it appears to imply contrived conspiratorial correlations between properties λ of particles being measured, and nominally accurate measurement settings x and y. Based on an analysis of Pearlean interventions needed to determine whether x and y are free variables, we show that whilst conspiracy implies superdeterminism, superdeterminism does not imply conspiracy. In conspiratorial superdeterminism these interventions are consistent with physical theory; in non-conspiratorial superdeterminism they are inconsistent. A non-conspiratorial locally-causal superdeterministic model is developed, based in part on the generic properties of chaotic attractors and in part on an arbitrarily fine discretisation of complex Hilbert Space. Here the required interventions are inconsistent with rational-number constraints on exact measurement settings X and Y. In this model, hidden variables λ are defined as the information, over and above the freely chosen determinants of x and y, which determine X and Y. These rationality constraints limit the freedom to vary x and y keeping λ fixed. These constraints disappear with any coarse-graining of λ and hence X. We show how quantum mechanics might be `gloriously explained and derived’ as the singular continuum limit of a superdeterministic discretisation of Hilbert Space. We argue that the real message behind Bell’s Theorem is the need to develop more holistic theories of fundamental physics — notably gravitational physics — some ideas for moving in this direction are discussed.