# Weekly Papers on Quantum Foundations (8)

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Sat Feb 18 2023 03:36:22 (13 hours)

# 1.

Ruiz de Olano, Pablo and Fraser, James D. and Gaudenzi, Rocco and Blum, Alexander S. (2022) Taking Approximations Seriously: The Cases of the Chew and the Nambu-Jona-Lasinio Models. [Preprint]

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Duncan Farrah, Kevin S. Croker, Gregory Tarlé, Valerio Faraoni, Sara Petty, Jose Afonso, Nicolas Fernandez, Kurtis A. Nishimura, Chris Pearson, Lingyu Wang, Michael Zevin, David L Clements, Andreas Efstathiou, Evanthia Hatziminaoglou, Mark Lacy, Conor McPartland, Lura K Pitchford, Nobuyuki Sakai, Joel Weiner

Fri Feb 17 2023 10:32:09 (1 day)

# 2.

Observations have found black holes spanning ten orders of magnitude in mass across most of cosmic history. The Kerr black hole solution is however provisional as its behavior at infinity is incompatible with an expanding universe. Black hole models with realistic behavior at infinity predict that the gravitating mass of a black hole can increase with the expansion of the universe independently of accretion or mergers, in a manner that depends on the black hole’s interior solution. We test this prediction by considering the growth of supermassive black holes in elliptical galaxies over $0<z\lesssim2.5$. We find evidence for cosmologically coupled mass growth among these black holes, with zero cosmological coupling excluded at 99.98% confidence. The redshift dependence of the mass growth implies that, at $z\lesssim7$, black holes contribute an effectively constant cosmological energy density to Friedmann’s equations. The continuity equation then requires that black holes contribute cosmologically as vacuum energy. We further show that black hole production from the cosmic star formation history gives the value of $\Omega_{\Lambda}$ measured by Planck while being consistent with constraints from massive compact halo objects. We thus propose that stellar remnant black holes are the astrophysical origin of dark energy, explaining the onset of accelerating expansion at $z \sim 0.7$.

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Marian Kupczynski

Fri Feb 17 2023 10:32:07 (1 day)

# 3.

We reject unjustified criticism of our published article [2209.07992] by Gill and Lambare [arXiv:2211.02481arXiv:2208.09930]. They completely misinterpret the content and conclusions of this article. They construct a counterfactual probabilistic model in which random variables representing outcomes of four experiments performed using incompatible experimental settings are jointly distributed. Thus, CHSH inequalities trivially hold for all finite samples generated by their model. Their model defines a probabilistic coupling for our model describing only the raw data from Bell tests. The existence of this coupling does not invalidate the derivation of the contextual probabilistic model describing the final data from Bell tests. Only these final data are used to test Bell inequalities. Inequalities cannot be derived because our model violates statistical independence. Our contextual model allows to explain in a local and causal way the violation of inequalities and the apparent violation of no-signaling reported in these experiments.

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Raphael Bousso, Geoff Penington

Fri Feb 17 2023 10:32:07 (1 day)

# 4.

In AdS/CFT, the entanglement wedge EW$(B)$ is the portion of the bulk geometry that can be reconstructed from a boundary region $B$; in other words, EW$(B)$ is the hologram of $B$. We extend this notion to arbitrary spacetimes. Given any gravitating region $a$, we define a max- and a min-entanglement wedge, $e_{\rm max}(a)$ and $e_{\rm min}(a)$, such that $e_{\rm min}(a)\supset e_{\rm max}(a)\supset a$.

Unlike their analogues in AdS/CFT, these two spacetime regions can differ already at the classical level, when the generalized entropy is approximated by the area. All information outside $a$ in $e_{\rm max}(a)$ can flow inwards towards $a$, through quantum channels whose capacity is controlled by the areas of intermediate homology surfaces. In contrast, all information outside $e_{\rm min}(a)$ can flow outwards.

The generalized entropies of appropriate entanglement wedges obey strong subadditivity, suggesting that they represent the von Neumann entropies of ordinary quantum systems. The entanglement wedges of suitably independent regions satisfy a no-cloning relation. This suggests that it may be possible for an observer in $a$ to summon information from spacelike related points in $e_{\rm max}(a)$, using resources that transcend the semiclassical description of $a$.

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Matthew J. Lake, Marek Miller, Ray Ganardi, Tomasz Paterek

Fri Feb 17 2023 10:31:55 (1 day)

# 5.

In this short note we show how the Generalised Uncertainty Principle (GUP) and the Extended Uncertainty Principle (EUP), two of the most common generalised uncertainty relations proposed in the quantum gravity literature, can be derived within the context of canonical quantum theory, without the need for modified commutation relations. A GUP-type relation naturally emerges when the standard position operator is replaced by an appropriate Positive Operator Valued Measure (POVM), representing a finite-accuracy measurement that localises the quantum wave packet to within a spatial region $\sigma_g > 0$. This length scale is the standard deviation of the envelope function, $g$, that defines the POVM elements. Similarly, an EUP-type relation emerges when the standard momentum operator is replaced by a POVM that localises the wave packet to within a region $\tilde{\sigma}_g > 0$ in momentum space. The usual GUP and EUP are recovered by setting $\sigma_g \simeq \sqrt{\hbar G/c^3}$, the Planck length, and $\tilde{\sigma}_g \simeq \hbar\sqrt{\Lambda/3}$, where $\Lambda$ is the cosmological constant. Crucially, the canonical Hamiltonian and commutation relations, and, hence, the canonical Schr{\” o}dinger and Heisenberg equations, remain unchanged. This demonstrates that GUP and EUP phenomenology can be obtained without modified commutators, which are known to lead to various pathologies, including violation of the equivalence principle, violation of Lorentz invariance in the relativistic limit, the reference frame-dependence of the `minimum’ length, and the so-called soccer ball problem for multi-particle states.

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Matthew J. Lake, A. Watcharapasorn

Fri Feb 17 2023 10:31:54 (1 day)

# 6.

The purpose of this paper is to challenge the existing paradigm on which contemporary models of generalised uncertainty relations (GURs) are based, that is, the assumption of modified commutation relations. We review an array of theoretical problems that arise in modified commutator models, including those that have been discussed in depth and others that have received comparatively little attention, or have not been considered at all in the existing literature, with the aim of stimulating discussion on these topics. We then show how an apparently simple assumption can solve, or, more precisely, evade these issues, by generating GURs without modifying the basic form of the canonical Heisenberg algebra. This simplicity is deceptive, however, as the necessary assumption is found to have huge implications for the quantisation of space-time and, therefore, gravity. These include the view that quantum space-time should be considered as a quantum reference frame (QRF) and, crucially, that the action scale characterising the quantum effects of gravity, $\beta$, must be many orders of magnitude smaller than Planck’s constant, $\beta \sim 10^{-61} \times \hbar$, in order to recover the present day dark energy density. We argue that these proposals should be taken seriously, as a potential solution to the pathologies that plague minimum length models based on modified commutators, and that their implications should be explored as thoroughly as those of the existing paradigm, which has dominated research in this area for almost three decades.

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Fri Feb 17 2023 06:49:10 (1 day)

# 7.

Snoke, David (2023) Mathematical formalism for nonlocal spontaneous collapse in quantum field theory. [Preprint]

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Roberto Casalbuoni, Daniele Dominici, Massimo Mazzoni

Thu Feb 16 2023 12:03:30 (2 days)

# 8.

The history of the Institute of Physics at the University of Florence is traced from the beginning of the 20th century, with the arrival of Antonio Garbasso as Director (1913), to the 1960s. Thanks to Garbasso’s expertise, not only did the Institute gain new premises on Arcetri hill, where the Astronomical Observatory was already located, but it also formed a brilliant group of young physicists made up of Enrico Fermi, Franco Rasetti, Enrico Persico, Bruno Rossi, Gilberto Bernardini, Daria Bocciarelli, Lorenzo Emo Capodilista, Giuseppe Occhialini and Giulio Racah, who were engaged in the emerging fields of Quantum Mechanics and Cosmic Rays. This Arcetri School disintegrated in the late 1930s for the transfer of its protagonists to chairs in other universities, for the environment created by the fascist regime and, to some extent, for the racial laws. After the war, the legacy was taken up by some students of this school who formed research groups in the field of nuclear physics and elementary particle physics. As far as theoretical physics was concerned, after the Fermi and Persico periods these studies enjoyed a new expansion towards the end of the 1950s, with the arrival of Giacomo Morpurgo and above all, that of Raoul Gatto, who created the first real Italian school of Theoretical Physics at Arcetri.

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Thu Feb 16 2023 03:29:47 (2 days)

# 9.

Tasdan, Ufuk I and Thebault, Karim P Y (2023) Spacetime Conventionalism Revisited. [Preprint]

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Tatsuaki Okamoto

Wed Feb 15 2023 09:46:53 (3 days)

# 10.

This paper presents a new hypothesis on a macro law in the universe, the law of increasing complexity, to formulate the assumption that the universe we observe and the biosphere on Earth are getting more diverse and complex with time. This formulation utilizes a quantitative definition of the complexity of organized matters, organized complexity (OC) [6]. We then apply this law to the coincidence (or fine-tuning) problem about the fundamental physical constants. We introduce a new principle, the principle of increasing complexity, on the law of increasing complexity and explain the coincidence with this new principle without using the anthropic principle. The principle implies that an (approximate) reduction of this macro law to fundamental physical laws would lead to a concrete analysis of the coincidence problem of fundamental physical constants.

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Wed Feb 15 2023 09:46:51 (3 days)

# 11.

A standard line in the contemporary philosophical literature has it that physical theories are equivalent only when they agree on their empirical content, where this empirical content is often understood as being encoded in the equations of motion of those theories. In this article, we question whether it is indeed the case that the empirical content of a theory is exhausted by its equations of motion, showing that (for example) considerations of boundary conditions play a key role in the empirical equivalence (or otherwise) of theories. Having argued for this, we show that philosophical claims made by \cite{Knox2011-KNONTA} that general relativity is equivalent to teleparallel gravity, and by \cite{Weatherall2016-WEAANG} that electromagnetism in the Faraday tensor formalism is equivalent to electromagnetism in the vector potential formalism, can both be called into question. We then show that properly considering the role of boundary conditions in theory structure can potentially restore these claims of equivalence and close with some remarks on the pragmatics of adjudications on theory identity.

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Wed Feb 15 2023 03:38:13 (3 days)

# 12.

Gao, Shan (2023) Does Bohmian mechanics solve the measurement problem? Maybe not yet. [Preprint]

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Mon Feb 13 2023 04:01:11 (5 days)

# 13.

Gao, Shan (2023) A quantum observer cannot report her observation; otherwise superluminal signaling is possible. [Preprint]