Weekly Papers on Quantum Foundations (15)

On separable states in relativistic quantum field theory. (arXiv:2304.03120v1 [gr-qc]) 

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gr-qc updates on arXiv.org

 by 

Ko Sanders

Fri Apr 07 2023 09:03:53 (23 hours)

# 1.

We initiate an investigation into separable, but physically reasonable, states in relativistic quantum field theory. In particular we will consider the minimum amount of energy density needed to ensure the existence of separable states between given spacelike separated regions. This is a first step towards improving our understanding of the balance between entanglement entropy and energy (density), which is of great physical interest in its own right and also in the context of black hole thermodynamics. We will focus concretely on a linear scalar quantum field in a topologically trivial, four-dimensional globally hyperbolic spacetime. For rather general spacelike separated regions $A$ and $B$ we prove the existence of a separable quasi-free Hadamard state. In Minkowski spacetime we provide a tighter construction for massive free scalar fields: given any $R>0$ we construct a quasi-free Hadamard state which is stationary, homogeneous, spatially isotropic and separable between any two regions in an inertial time slice $t=\mathrm{const.}$ all of whose points have a distance $>R$. We also show that the normal ordered energy density of these states can be made $\le 10^{21}\frac{m^4}{(mR)^8}e^{-\frac14mR}$ (in Planck units). To achieve these results we use a rather explicit construction of test-functions $f$ of positive type for which we can get sufficient control on lower bounds on $\hat{f}$.

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The Next Generation Event Horizon Telescope Collaboration: History, Philosophy, and Culture. (arXiv:2304.02463v1 [physics.hist-ph]) 

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physics.hist-ph updates on arXiv.org

 by 

Peter Galison, Juliusz Doboszewski, Jamee Elder, Niels C. M. Martens, Abhay Ashtekar, Jonas Enander, Marie Gueguen, Elizabeth A. Kessler, Roberto Lalli, Martin Lesourd, Alexandru Marcoci, Sebastián Murgueitio Ramírez, Priyamvada Natarajan, James Nguyen, Luis Reyes-Galindo, Sophie Ritson, Mike D. Schneider, Emilie Skulberg, Helene Sorgner, Matthew Stanley, Ann C. Thresher, Jeroen Van Dongen, James Owen Weatherall, Jingyi Wu, Adrian Wüthrich

Thu Apr 06 2023 09:15:36 (1 day)

# 2.

This white paper outlines the plans of the History Philosophy Culture Working Group of the Next Generation Event Horizon Telescope Collaboration.

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Necessitating Spacetime. (arXiv:2304.02467v1 [physics.hist-ph]) 

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physics.hist-ph updates on arXiv.org

 by 

Kyle Singh, Jenna Van Dyke

Thu Apr 06 2023 09:15:35 (1 day)

# 3.

We investigate structure that describes physical data in gravitational systems that is, to one degree or another, independent of the metric and affine structure. We dub such structure surplus structure and seek to incorporate it into our ontological commitments. An emphasis is placed on those structures which are required to constrain our models motivated by physical data. We look at the fall-offs of the gauge fields in asymptotically flat spacetimes, the computation of entanglement entropies in the AdS/CFT correspondence, and the addition of arbitrary parameters which modify the causal structure of spacetime in Kruskal coordinates. We also present a historical overview of the understanding of singularities in classical gravitation. Primary sources are turned to here. A toy cosmological model is also explored in which global topology is determined by an additional function which we prescribe as a dynamical $\Lambda$. Such surplus structure is classified using the language of intermediaries and positioned within the system of a shifting-scale ontology as introduced in prior work.

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Is quantum mechanics creationism, and not science?. (arXiv:1802.00227v7 [physics.hist-ph] UPDATED) 

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physics.hist-ph updates on arXiv.org

 by 

Werner A Hofer

Wed Apr 05 2023 08:54:21 (3 days)

# 4.

I revisit the reply of Bohr to Einstein. Bohr’s assertion that there are no causes in atomic scale systems is, as a closer analysis reveals, not in line with the Copenhagen interpretation since it would contain a statement about reality. What Bohr should have written is that there are no causes in mathematics, which is universally acknowledged. The law of causality requires physical effects to be due to physical causes. For this reason any theoretical model which replaces physical causes by mathematical objects is creationism, that is, it creates physical objects out of mathematical elements. I show that this is the case for most of quantum mechanics.

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Mesoscopic Schwinger effect 

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Nature Physics

 by 

Roshan Krishna Kumar

Wed Apr 05 2023 08:00:00 (3 days)

# 5.

Nature Physics, Published online: 05 April 2023; doi:10.1038/s41567-023-02019-1

The production of particle–antiparticle pairs in a vacuum — the Schwinger effect — requires extreme conditions that are out of reach of tabletop experiments. A mesoscopic simulation of this phenomenon has now been carried out in graphene devices.

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Explanatory Depth in Primordial Cosmology: A Comparative Study of Inflationary and Bouncing Paradigms 

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Wed Apr 05 2023 06:35:43 (3 days)

# 6.

Wolf, William J. and Thebault, Karim P Y (2023) Explanatory Depth in Primordial Cosmology: A Comparative Study of Inflationary and Bouncing Paradigms.

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Brains as Quantum Mechanical Systems – A New Model 

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Wed Apr 05 2023 06:27:48 (3 days)

# 7.

Broka, Chris A. (2023) Brains as Quantum Mechanical Systems – A New Model. [Preprint]

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Absorbing the Arrow of Electromagnetic Radiation. (arXiv:2205.14233v2 [physics.hist-ph] UPDATED) 

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physics.hist-ph updates on arXiv.org

 by 

Mario Hubert, Charles T. Sebens

Tue Apr 04 2023 12:31:51 (3 days)

# 8.

We argue that the asymmetry between diverging and converging electromagnetic waves is just one of many asymmetries in observed phenomena that can be explained by a past hypothesis and statistical postulate (together assigning probabilities to different states of matter and field in the early universe). The arrow of electromagnetic radiation is thus absorbed into a broader account of temporal asymmetries in nature. We give an accessible introduction to the problem of explaining the arrow of radiation and compare our preferred strategy for explaining the arrow to three alternatives: (i) modifying the laws of electromagnetism by adding a radiation condition requiring that electromagnetic fields always be attributable to past sources, (ii) removing electromagnetic fields and having particles interact directly with one another through retarded action-at-a-distance, (iii) adopting the Wheeler-Feynman approach and having particles interact directly through half-retarded half-advanced action-at-a-distance. In addition to the asymmetry between diverging and converging waves, we also consider the related asymmetry of radiation reaction.

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Quantum Haecceity. (arXiv:2301.00502v4 [quant-ph] UPDATED) 

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physics.hist-ph updates on arXiv.org

 by 

Ruth E. Kastner

Tue Apr 04 2023 12:31:50 (3 days)

# 9.

There is an extensive philosophical literature on the interrelated issues of identity, individuality, and distinguishability in quantum systems. A key consideration is whether quantum systems are subject to a strong form of individuality termed “haecceity” (from the Latin for “this-ness”). I argue that the traditional, strong form of haecceity does not apply at the quantum level, but that in order to properly account for the need for symmetrization in quantum systems, a weaker kind of haecceity must be involved, which I call “quantum haecceity.” In the process, I also question some generally accepted tenets of the current debate, such as the idea that symmetrization of states for identical quanta must be postulated and reflects permutation invariance. Instead, I note that a perturbative Hamiltonian is required for exchange effects, which suggests that the need for symmetrization arises from specific physical conditions.

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Beyond relationalism in quantum theory 

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Tue Apr 04 2023 02:06:38 (4 days)

# 10.

Pipa, Francisco (2023) Beyond relationalism in quantum theory. [Preprint]

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Double-slit time diffraction at optical frequencies 

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Nature Physics

 by 

Romain Tirole; Stefano Vezzoli; Emanuele Galiffi; Iain Robertson; Dries Maurice; Benjamin Tilmann; Stefan A. Maier; John B. Pendry; Riccardo Sapienza

Mon Apr 03 2023 08:00:00 (5 days)

# 11.

Nature Physics, Published online: 03 April 2023; doi:10.1038/s41567-023-01993-w

A temporal version of Young’s double-slit experiment shows characteristic interference in the frequency domain when light interacts with time slits produced by ultrafast changes in the refractive index of an epsilon-near-zero material.

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Scope of the action principle 

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PhilSci-Archive: No conditions. Results ordered -Date Deposited.

Sun Apr 02 2023 10:04:39 (5 days)

# 12.

Struyve, Ward (2023) Scope of the action principle. [Preprint]

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