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Spiros Cotsakis, Jose P. Mimoso, John Miritzis

Wed Apr 26 2023 08:57:12 (2 days)

# 7.

We discuss cosmological implications of the frame principle which states that physics is independent of frames. We show that there are frame-independent solutions that are globally stable, suggesting that they represent physically relevant solutions. This result highlights the importance of further investigation into the implications of the cosmological frame principle for cosmological properties that depend on a use of conformal frames.

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Wed Apr 26 2023 00:27:28 (3 days)

# 8.

Smeenk, Chris and Weatherall, James Owen (2023) Dark Energy or Modified Gravity? [Preprint]

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Jonte R. Hance, John Rarity, James Ladyman

Tue Apr 25 2023 13:30:06 (3 days)

# 9.

We investigate four key issues with using a nonzero weak value of the spatial projection operator to infer the past path of an individual quantum particle. First, we note that weak measurements disturb a system, so any approach relying on such a perturbation to determine the location of a quantum particle describes the state of a disturbed system, not that of a hypothetical undisturbed system. Secondly, even assuming no disturbance, there is no reason to associate the non-zero weak value of an operator containing the spatial projection operator with the classical idea of `particle presence’. Thirdly, weak values are only measurable over ensembles, and so to infer properties of individual particles from values of them is problematic. Finally, weak value approaches to the path of a particle do not provide information beyond standard quantum mechanics (and the classical modes supporting the experiment). We know of no experiment with testable consequences that demonstrates a connection between particle presence and weak values.

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Xabier Oianguren-Asua, Carlos F. Destefani, Matteo Villani, David K. Ferry, Xavier Oriols

Tue Apr 25 2023 13:30:05 (3 days)

# 10.

In this chapter, we will take a trip around several hot-spots where Bohmian mechanics and its capacity to describe the microscopic reality, even in the absence of measurements, can be harnessed as computational tools, in order to help in the prediction of phenomenologically accessible information (also useful for the followers of the Copenhagen theory). As a first example, we will see how a Stochastic Schr\”odinger Equation, when used to compute the reduced density matrix of a non-Markovian open quantum system, necessarily seems to employ the Bohmian concept of a conditional wavefunction. We will see that by dressing these conditional wavefunctions with an interpretation, the Bohmian theory can prove to be a useful tool to build general quantum frameworks, like a high-frequency electron transport model. As a second example, we will introduce how a Copenhagen “observable operator” can be derived from numerical properties of the Bohmian trajectories, which within Bohmian mechanics, are well-defined even for an “unmeasured” system. Most importantly in practice, even if these numbers are given no ontological meaning, not only we will be able to simulate (thus, predict and talk about) them, but we will see that they can be operationally determined in a weak value experiment. Therefore, they will be practical numbers to characterize a quantum system irrespective of the followed quantum theory.

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Tue Apr 25 2023 00:37:55 (4 days)

# 11.

Alemañ-Berenguer, Rafael-Andrés (2023) The ontological burden of mathematics and scientific realism. [Preprint]

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Penha Maria Cardozo Dias

Mon Apr 24 2023 10:33:38 (4 days)

# 12.

The association of information with entropy has been argued on plausibility arguments involving the operation of imaginary engines and beings, and it is not a universal theorem. In this paper, a theorem by Charles Bennett on reversible computation is recognized as the much needed theorem. It is proposed a real, non thermal engine, operated by humans. Its operation has stages analogous to the stages in Bennett’s reversible three-tape computer. The engine makes possible to prove two results: (1) the engine operates on two laws, similar to the laws of thermodynamics, which are conditions on the possibility of resetting the engine; (2) entropy is the measure of erased information, and is measured in physical units, which complies with Landauer’s principle. A prototype at work is shown in video.

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R. E. Kastner

Mon Apr 24 2023 10:33:37 (4 days)

# 13.

The traditional, standard approach to quantum theory is to assume that the theory “really” contains only unitary physical dynamics–i.e., that the only physically quantifiable evolution is that given by the time-dependent Schrodinger equation. This leads to two distinct classes of interpretations for the standard theory in its orthodox form: (i) an Everettian-type approach assuming that all mutually exclusive outcomes occur in different “branches” of the universe; or (ii) single-outcome approaches that assume a “projection postulate” (PP) with no accompanying physical account within quantum theory. A contrasting, unorthodox approach is to suggest forms of quantum theory that involve physical non-unitarity; these are called “objective collapse models.” Among these are Penrose’s theory of gravitation-induced collapse and the Transactional Interpretation. The primary focus of this paper is an example demonstrating that standard quantum theory (with or without the projection postulate) can in-principle yield empirically consequential inconsistencies. Thus, it appears that for quantum theory to be viable in a realist sense (as opposed to being an instrumentalist protocol in which inconsistencies are evaded by changing the protocol), it must possess genuine, physical non-unitarity yielding well-defined single outcomes. This leads to the conclusion that objective collapse models should be more seriously considered.

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Iulian D. Toader

Mon Apr 24 2023 10:33:36 (4 days)

# 14.

The paper offers an argument against an intuitive reading of the Stone-von Neumann theorem as a categoricity result, thereby pointing out that, against what is usually taken to be the case, this theorem does not entail any model-theoretical difference between the theories that validate it and those that don’t.

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Volodymyr Ihnatovych

Mon Apr 24 2023 10:33:35 (4 days)

# 15.

The article reveals the error, that in classical thermodynamics leads to the Gibbs paradox. The essence of the error lies in the fact that the entropy of an ideal gas is attributed to additive quantities, but it is not correct. The value of an additive quantity for a whole object is equal to the sum of its values for the parts of the object in any division of the object into parts. The entropy of an ideal gas in classical thermodynamics is expressed by the equation that contains the term Rnln(V/n), where n is the number of moles of gas, V is the volume of gas, R is the universal gas constant, or by equations equivalent to it. As a result, the entropy of an ideal gas is equal to the sum of the entropies of its parts only if the parts of the gas are in different places (separated by an impermeable partition). If the parts of the gas form a mixture, then the sum of the entropies of the parts is not equal to the entropy of the gas. Despite this, the entropy of an ideal gas is considered to be an additive quantity. This gives rise to a series of inexplicable conclusions known as different formulations of the Gibbs paradox.

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Andrea Cavagna; Luca Di Carlo; Irene Giardina; Tomás S. Grigera; Stefania Melillo; Leonardo Parisi; Giulia Pisegna; Mattia Scandolo

Mon Apr 24 2023 08:00:00 (5 days)

# 16.

Nature Physics, Published online: 24 April 2023; doi:10.1038/s41567-023-02028-0

Tests of the predictions of the renormalization group in biological experiments have not yet been decisive. Now, a study on the collective dynamics of insect swarms provides a long-sought match between experiment and theory.

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Mohammadamin Tajik; Ivan Kukuljan; Spyros Sotiriadis; Bernhard Rauer; Thomas Schweigler; Federica Cataldini; João Sabino; Frederik Møller; Philipp Schüttelkopf; Si-Cong Ji; Dries Sels; Eugene Demler; Jörg Schmiedmayer

Mon Apr 24 2023 08:00:00 (5 days)

# 17.

Nature Physics, Published online: 24 April 2023; doi:10.1038/s41567-023-02027-1

The scaling of entanglement entropy and mutual information is key for the understanding of correlated states of matter. An experiment now reports the measurement of von Neumann entropy and mutual information in a quantum field simulator.

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Mon Apr 24 2023 04:39:54 (5 days)

# 18.

Held, Carsten (2023) A Presupposition of Bell’s Theorem. [Preprint]

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Sun Apr 23 2023 00:31:06 (6 days)

# 19.

Meskhidze, Helen and Weatherall, James Owen (2023) Torsion in the Classical Spacetime Context. [Preprint]

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Sun Apr 23 2023 00:28:18 (6 days)

# 20.

Elber-Dorozko, Lotem and Loewenstein, Yonatan (2023) Do retinal neurons also represent somatosensory inputs? On why neuronal responses are not sufficient to determine what neurons do. Cognitive Science.