上午2:57 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Shech, Elay (2022) Scientific Understanding in the Aharonov-Bohm Effect. [Preprint]

Nature abhors redundancies: A no-go result for density matrix realism

上午2:55 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2022) Nature abhors redundancies: A no-go result for density matrix realism. [Preprint]

2022年5月28日 星期六 上午9:20 | | | Marco Bellini, Hyukjoon Kwon, Nicola Biagi, Saverio Francesconi, Alessandro Zavatta, M. S. Kim | | | quant-ph updates on arXiv.org |

The principle of microscopic reversibility lies at the core of fluctuation theorems, which have extended our understanding of the second law of thermodynamics to the statistical level. In the quantum regime, however, this elementary principle should be amended as the system energy cannot be sharply determined at a given quantum phase space point. In this work, we propose and experimentally test a quantum generalization of the microscopic reversibility when a quantum system interacts with a heat bath through energy-preserving unitary dynamics. Quantum effects can be identified by noting that the backward process is less likely to happen in the existence of quantum coherence between the system’s energy eigenstates. The experimental demonstration has been realized by mixing coherent and thermal states in a beam-splitter, followed by heterodyne detection in an optical setup. We verify that the quantum modification for the principle of microscopic reversibility is critical in the low-temperature limit, while the quantum-to-classical transition is observed as the temperature of the thermal field gets higher.

2022年5月28日 星期六 上午9:20 | | | Prateek Chawla, U. Shrikant, C. M. Chandrashekar | | | quant-ph updates on arXiv.org |

We set the criteria for a quantum walk to exhibit nontrivial dynamics when placed in an indefinite causal order and study two-period quantum walks when the evolution operators are arranged in a causally ordered sequence and in an indefinite causal order using quantum switch. When either forward or backward causal sequence is implemented, one observes a causal asymmetry in the dynamics, in the sense that the reduced dynamics of the coin state is more non-Markovian for one particular temporal order of operations than that of the other. When the dynamics is defined using evolution operators in a superposition of causal orders, the reduced dynamics of the coin space exhibit higher non-Markovian behavior than either of the definite causal orders. This effect can be interpreted as a Parrondo-like effect in non-Markovianity of the reduced state dynamics of the coin. We further generalize the qualitative description of our results pertaining to the dynamics when the walk has a higher number of periods.

2022年5月28日 星期六 上午9:20 | | | T. Zalialiutdinov, D. Solovyev, D. Chubukov, S. Chekhovskoi, L. Labzowsky | | | quant-ph updates on arXiv.org |

It is well-known that the 4-rotation in the 4-dimensional space-time is equivalent to the CPT-transformation (C is the charge conjugation, P is the space inversion and T is the time-reversal). The standard definition of the T-reversal includes the change of the sign of time variable and replacement of the initial state of the particle (system of particles) by the final state and vice versa. Since the time-reversal operation changes the state of a particle, the particle’s wave function cannot be the eigenfunction of the corresponding operator with a certain eigenvalue, as in the case of space parity. Unlike the CPT-transformation, the separate P, T, or C transformations cannot be reduced to any 4-rotation. The extended Lorentz group incorporates all the separate C, P, or T transformations which do not bring the time axis out of the corresponding light cone. The latter restriction is included in the standard definition of the time-reversal. In the present communication, we ignore this restriction.

This allows to introduce the “time arrow” operator and characterize every particle by the new quantum number – “time arrow” value. The wave functions of all particles are eigenfunctions of this operator with eigenvalues equal to “time arrow” values. The particles with the “time arrow” values opposite to the “time arrow” value in our universe form another universe (anti-universe). The existence of anti-universe can be confirmed, in principle, by laboratory (atomic) experiments. The anti-universe may be also considered as a candidate to the role of dark matter.

Galileo and a forgotten poem on the 1604 supernova. (arXiv:2204.04001v3 [physics.hist-ph] UPDATED)

2022年5月28日 星期六 上午9:20 | | | physics.hist-ph updates on arXiv.org |

Authors: Alessandro De Angelis

In October 1604, when SN1604, the last naked-eye visible supernova in our Galaxy, exploded, Galileo Galilei was the professor of mathematics and astronomy at the University of Padua, teaching the mechanics of planets. He was therefore the figure of reference to whom all the doubts and questions that such an apparition brought with it were addressed. The University of Padua asked Galilei to outline the situation by exposing in three public conferences his point of view in order to answer the many questions that raged among the academic community and the common people. Three conferences that Galilei held almost immediately between November and December in the Aula Magna of the Bo, the central building of the University. A month after Galilei’s lectures a treatise on the supernova appeared in Padua. The unknown Antonio Lorenzini, behind whose name it is easy to see the inspiration of Cesare Cremonini, an Aristotelian professor of natural philosophy in Padua, published a booklet entitled Discourse about the new star which debunked the conclusions of Galilei. One month after was published in Padua by the same editor the Dialogo de Cecco di Ronchitti da Bruzene in perpuosito de la stella nuova, a booklet in Paduan dialect replying to Lorenzini. The Dialogo appears in the national edition of Galilei’s works and is attributed to Galileo himself with the help of the monk Girolamo Spinelli; it does not appear instead a poem in octaves, by an unknown author (presumably Galilei), published as an appendix to the first edition of 1605, and immediately replaced in the second edition. We publish it here, with a comment.

A precision test of averaging in AdS/CFT. (arXiv:2205.12968v1 [hep-th])

2022年5月28日 星期六 上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Jordan Cotler, Kristan Jensen

We reconsider the role of wormholes in the AdS/CFT correspondence. We focus on Euclidean wormholes that connect two asymptotically AdS or hyperbolic regions with $\mathbb{S}^1\times \mathbb{S}^{d-1}$ boundary. There is no solution to Einstein’s equations of this sort, as the wormholes possess a modulus that runs to infinity. To find on-shell wormholes we must stabilize this modulus, which we can do by fixing the total energy on the two boundaries. Such a wormhole gives the saddle point approximation to a non-standard problem in quantum gravity, where we fix two asymptotic boundaries and constrain the common energy. Crucially the dual quantity does not factorize even when the bulk is dual to a single CFT, on account of the fixed energy constraint. From this quantity we extract the microcanonical spectral form factor. For a chaotic theory this quantity is self-averaging, i.e. well-approximated by averaging over energy windows, or over coupling constants.

We go on to give a precision test involving the microcanonical spectral form factor where the two replicas have slightly different coupling constants. In chaotic theories this form factor is known to smoothly decay at a rate universally predicted in terms of one replica physics, provided that there is an average either over a window or over couplings. We compute the expected decay rate for holographic theories, and the form factor from a wormhole, and the two exactly agree for a wide range of two-derivative effective field theories in AdS. This gives a precision test of averaging in AdS/CFT.

Our results interpret a number of confusing facts about wormholes and factorization in AdS and suggest that we should regard gravitational effective field theory as a mesoscopic description, analogous to semiclassical mesoscopic descriptions of quantum chaotic systems.

Black holes and cryptocurrencies. (arXiv:2205.12995v1 [hep-th])

2022年5月28日 星期六 上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Alexey Milekhin

It has been proposed in the literature that the volume of Einstein-Rosen bridge is equal to complexity of state preparation (“Complexity=Volume” conjecture). Taking this statement outside the horizon, one might be tempted to propose “Complexity=Time” correspondence. In this Essay we argue that in a blockchain protocol, which is the foundation of all modern cryptocurrencies, time is emergent and it is defined according to a version of “Complexity=Time”.

Probing the Information-Probabilistic Description. (arXiv:2105.05034v2 [gr-qc] UPDATED)

2022年5月28日 星期六 上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Merab Gogberashvili, Beka Modrekiladze

The information conservation principle is probed for classically isolated systems, like the Hubble sphere and black holes, for which the rise of entanglement entropy across their horizons is expected. We accept the analogy of Landauer’s principle that entanglement information should introduce some negative potential energy, which corresponds to the positive energy of measurements that destroy this quantum behavior. We estimated these dark-energy-like contributions and found that they can explain the dark energy of the Universe and also are able to resolve the observed superluminal motion and redshift controversies for black holes.

Non-universality of free fall in quantum theory. (arXiv:2204.03279v2 [gr-qc] UPDATED)

2022年5月28日 星期六 上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Viacheslav A. Emelyanov

We show by embodying the Einstein equivalence principle and general covariance in quantum theory that wave-function spreading rules out universality of free fall, and vice versa. Assuming the former is more fundamental than the latter, we gain a quantitative estimate of the free-fall non-universality, which turns out to be empirically testable in atom interferometry.

2022年5月28日 星期六 上午8:00 | | | Latest Results for Synthese |

**Abstract**

Over the last century, there have been considerable variations in the frequency of use and types of diagrams used in mathematical publications. In order to track these changes, we developed a method enabling large-scale quantitative analysis of mathematical publications to investigate the number and types of diagrams published in three leading mathematical journals in the period from 1885 to 2015. The results show that diagrams were relatively common at the beginning of the period under investigation. However, beginning in 1910, they were almost completely unused for about four decades before reappearing in the 1950s. The diagrams from the 1950s, however, were of a different type than those used earlier in the century. We see this change in publication practice as a clear indication that the formalist ideology has influenced mathematicians’ choice of representations. Although this could be seen as a minor stylistic aspect of mathematics, we argue that mathematicians’ representational practice is deeply connected to their cognitive practice and to the contentual development of the discipline. These changes in publication style therefore indicate more fundamental changes in the period under consideration.

Philosophical Issues raised by Quantum Theory and its Interpretations

2022年5月26日 星期四 下午2:13 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Myrvold, Wayne C. (2022) Philosophical Issues raised by Quantum Theory and its Interpretations. The Oxford Handbook of the History of Quantum Interpretations. pp. 53-75.

Temporal Becoming in a Relativistic Universe: Causal Diamonds and Gödel’s Philosophy of Time

2022年5月26日 星期四 下午2:11 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Aames, Jimmy (2022) Temporal Becoming in a Relativistic Universe: Causal Diamonds and Gödel’s Philosophy of Time. [Preprint]

Non-classical mechanical states guided in a phononic waveguide

2022年5月23日 星期一 上午8:00 | | | Simon Gröblacher | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 23 May 2022; doi:10.1038/s41567-022-01612-0

Non-classical vibrations are generated and transmitted along a mechanical waveguide, providing a platform for distributing quantum information and realizing hybrid quantum devices using phonons in a solid-state system.

Grothendieck’s theory of schemes and the algebra–geometry duality

2022年5月23日 星期一 上午8:00 | | | Latest Results for Synthese |

**Abstract**

We shall address from a conceptual perspective the duality between *algebra* and *geometry* in the framework of the refoundation of algebraic geometry associated to Grothendieck’s theory of schemes. To do so, we shall revisit scheme theory from the standpoint provided by the problem of recovering a mathematical structure *A* from its representations \(A \rightarrow B\) into other similar structures *B*. This vantage point will allow us to analyze the relationship between the *algebra-geometry duality* and (what we shall call) the *structure-semiotics duality* (of which the *syntax-semantics duality* for propositional and predicate logic are particular cases). Whereas in classical algebraic geometry a certain kind of rings can be recovered by considering their representations with respect to a unique codomain *B*, Grothendieck’s theory of schemes permits to reconstruct general (commutative) rings by considering representations with respect to a category of codomains. The strategy to reconstruct the object from its representations remains the same in both frameworks: the elements of the ring *A* can be realized—by means of what we shall generally call *Gelfand transform*—as quantities on a topological space that parameterizes the relevant representations of *A*. As we shall argue, important dualities in different areas of mathematics (e.g. Stone duality, Gelfand duality, Pontryagin duality, Galois-Grothendieck duality, etc.) can be understood as particular cases of this general pattern. In the wake of Majid’s analysis of the Pontryagin duality, we shall propose a Kantian-oriented interpretation of this pattern. We shall use this conceptual framework to argue that Grothendieck’s notion of *functor of points* can be understood as a “relativization of the *a priori*” (Friedman) that generalizes the relativization already conveyed by the notion of *domain extension* to more general variations of the corresponding (co)domains.

2022年5月21日 星期六 下午3:50 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Grimmer, Daniel (2022) A Discrete Analog of General Covariance — Part 2: Despite what you’ve heard, a perfectly Lorentzian lattice theory. [Preprint]

Spacetime Emergence: Collapsing the Distinction Between Content and Context?

2022年5月21日 星期六 下午3:49 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Crowther, Karen (2022) Spacetime Emergence: Collapsing the Distinction Between Content and Context? [Preprint]

Quantum gravity in a laboratory?

2022年5月21日 星期六 下午3:48 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Huggett, Nick and Linnemann, Niels and Schneider, Mike D. (2022) Quantum gravity in a laboratory? [Preprint]

]]>2022年5月19日 星期四 上午1:29 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2022) A no-go result for Bohmian mechanics. [Preprint]

From Unobservable to Observable: Scientific Realism and the Discovery of Radium

2022年5月19日 星期四 上午1:28 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Allzén, Simon (2022) From Unobservable to Observable: Scientific Realism and the Discovery of Radium. Journal for General Philosophy of Science. ISSN 0925-4560

2022年5月19日 星期四 上午1:27 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Grimmer, Daniel (2022) A Discrete Analog of General Covariance — Part 2: Despite what you’ve heard, a perfectly Lorentzian lattice theory. [Preprint]

THE MIND’S EYE: DE-MYSTIFYING CONSCIOUSNESS

2022年5月19日 星期四 上午1:26 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Shkliarevsky, Gennady (2022) THE MIND’S EYE: DE-MYSTIFYING CONSCIOUSNESS. [Preprint]

A Discrete Analog of General Covariance — Part 1: Could the world be fundamentally set on a lattice?

2022年5月19日 星期四 上午1:19 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Grimmer, Daniel (2022) A Discrete Analog of General Covariance — Part 1: Could the world be fundamentally set on a lattice? [Preprint]

Beyond semiclassical time. (arXiv:2205.09147v1 [gr-qc])

上午11:02 | | | Leonardo Chataignier | | | quant-ph updates on arXiv.org |

We show that the usual Born-Oppenheimer type of approximation used in quantum gravity, in which a semiclassical time parameter emerges from a weak-coupling expansion of the Wheeler-DeWitt constraint, leads to a unitary theory at least up to the next-to-leading order in minisuperspace models. As there are no unitarity-violating terms, this settles the issue of unitarity at this order, which has been much debated in the literature. Furthermore, we also show that the conserved inner product is gauge-fixed in the sense that the measure is related to the Faddeev-Popov determinant associated with the choice of semiclassical time as a reparametrization gauge. This implies that the Born-Oppenheimer approach to the problem of time is, in fact, an instance of a relational quantum theory, in which transition amplitudes can be related to conditional probabilities.

上午11:02 | | | Francisco M. Fernández | | | quant-ph updates on arXiv.org |

We apply the Frobenius (power-series) method to some simple exactly-solvable and conditionally-solvable quantum-mechanical models with supposed physical interest. We show that the supposedly exact solutions to radial eigenvalue equations derived in recent papers are not correct because they do not satisfy some well-known theorems. We also discuss the origin of the mistake by means of the approach indicated above.

上午11:02 | | | physics.hist-ph updates on arXiv.org |

Authors: Daniel Grimmer

Despite quantum theory’s remarkable success at predicting the (statistical) results of experiments, many philosophers worry that it nonetheless lacks some crucial connection between theory and experiment. Such worries are at the root of the Quantum Measurement Problem. We can identify two kinds of worries: 1) pragmatic: it’s unclear how to model our experiments to extract theoretical predictions, and 2) realist: there is no realist narrative for the experiment underlying these theoretical predictions. While both worries deserve attention, the pragmatic worries have far worse consequences if left unanswered. Moreover, as I will argue, upon reflection, a satisfactory explanation of almost all of quantum theory’s experimental successes unavoidably involves modeling quantum fields at some point. Thus, without a pragmatic theory-to-experiment link for QFT, we are at risk of losing any right to claim evidential support for large parts of quantum theory. Hence, I focus on the Pragmatic QFT Measurement Problem.

But, what makes modeling measurements in QFT so hard? As I will discuss, attempts to naively transplant our non-relativistic quantum measurement theory into QFT are deeply unphysical and unsatisfying. Thus we need a new (or at least refined) measurement theory for QFT. However, as I will argue, aiming too directly at a new measurement theory is an incautious way to proceed and is apt to lead us astray. This paper proposes an alternate way forward: We ought to first better understand how our non-relativistic quantum measurement theory is rooted in notions of measurement chains and Heisenberg cuts. Then we ought to generalize these notions and transplant them into QFT. Such a transplant is carried out in this paper. My analysis suggests the need for a pragmatic QFT-cut analogous to the need for a pragmatic Heisenberg cut in non-relativistic contexts.

上午11:02 | | | physics.hist-ph updates on arXiv.org |

Authors: Yiming Pan, Eliahu Cohen, Ebrahim Karimi, Avraham Gover, Norbert Schonenberger, Tomas Chlouba, Kangpeng Wang, Saar Nehemia, Peter Hommelhoff, Ido Kaminer, Yakir Aharonov

How does the quantum-to-classical transition of measurement occur? This question is vital for both foundations and applications of quantum mechanics. Here, we develop a new measurement-based framework for characterizing the classical and quantum free electron-photon interactions and then experimentally test it. We first analyze the transition from projective to weak measurement in generic light-matter interactions and show that any classical electron-laser-beam interaction can be represented as an outcome of a weak measurement. In particular, the appearance of classical point-particle acceleration is an example of an amplified weak value resulting from weak measurement. A universal factor quantifies the measurement regimes and their transition from quantum to classical, where Gamma corresponds to the ratio between the electron wavepacket size and the optical wavelength. This measurement-based formulation is experimentally verified in both limits of photon-induced near-field electron microscopy and the classical acceleration regime using a dielectric laser accelerator. Our results shed new light on the transition from quantum to classical electrodynamics, enabling to employ the essence of wave-particle duality of both light and electrons in quantum measurement for exploring and applying many quantum and classical light-matter interactions.

Way down in the hole… and up again. (arXiv:2205.09610v1 [gr-qc])

上午11:02 | | | gr-qc updates on arXiv.org |

Authors: Valentin Boyanov

I argue that an approach which uses an appropriate admixture of both classical and semiclassical effects is essential for understanding the ultimate fate of gravitational collapse and the nature of black holes. I provide an example of a problem which pushes the boundaries of what is known in both the classical and semiclassical approaches: the evolution of the inner horizon of a black hole. I show that solving this problem requires considering perturbations of both classical and semiclassical origin. In fact, it has been found that classical mass inflation might be counteracted by a semiclassical tendency for the inner horizon to inflate outward.

Energy and entropy in the Geometrical Trinity of gravity. (arXiv:2205.09716v1 [gr-qc])

上午11:02 | | | gr-qc updates on arXiv.org |

Authors: Débora Aguiar Gomes, Jose Beltrán Jiménez, Tomi S. Koivisto

All energy is gravitational energy. That is the consequence of the equivalence principle, according to which gravity is the universal interaction. The physical charges of this interaction have remained undisclosed, but the Adventof the Geometrical Trinity opened a new approach to this foundational problem. Here it is shown to provide a background-independent unification of the previous, non-covariant approaches of Bergmann-Thomson, Cooperstock, Einstein, von Freud, Landau-Lifshitz, Papapetrou and Weinberg. First, the Noether currents are derived for a generic Palatini theory of gravity coupled with generic matter fields, and then the canonical i.e. the unique charges are robustly derived and analysed, particularly in the metric teleparallel and the symmetric teleparallel versions of General Relativity. These results, and their application to black holes and gravitational waves, are new.

Time delay interferometry without clock synchronisation. (arXiv:2202.01124v3 [gr-qc] UPDATED)

上午11:02 | | | gr-qc updates on arXiv.org |

Authors: Olaf Hartwig, Jean-Baptiste Bayle, Martin Staab, Aurélien Hees, Marc Lilley, Peter Wolf

Time-delay interferometry (TDI) is a data processing technique for LISA designed to suppress the otherwise overwhelming laser noise by several orders of magnitude. It is widely believed that TDI can only be applied once all phase or frequency measurements from each spacecraft have been synchronized to a common time frame. We demonstrate analytically, using as an example the commonly-used Michelson combination X, that TDI can be computed using the raw, unsynchronized data, thereby avoiding the need for an initial synchronization processing step and significantly simplifying the initial noise reduction pipeline. Furthermore, the raw data is free of any potential artifacts introduced by clock synchronization and reference frame transformation algorithms, which allows to operate directly on the MHz beatnotes. As a consequence, in-band clock noise is directly suppressed as part of TDI, in contrast to the approach previously proposed in the literature (in which large trends in the beatnotes are removed before the main laser-noise reduction step, and clock noise is suppressed in an extra processing step). We validate our algorithm with full-scale numerical simulations that use LISA Instrument and PyTDI and show that we reach the same performance levels as the previously proposed methods, ultimately limited by the clock sideband stability.

]]>Koberinski, Adam and Smeenk, Chris (2022) *Lambda and the limits of effective field theory.* [Preprint]

Dorato, Mauro and Morganti, Matteo (2022) *What Ontology for Relational Quantum Mechanics?* [Preprint]

Giovanelli, Marco (2020) *Like Thermodynamics before Boltzmann. On the Emergence of Einstein’s Distinction between Constructive and Principle Theories.* Studies In History and Philosophy of Science Part B: Studies In History and Philosophy of Modern Physics, 71. pp. 118-157. ISSN 13552198Giovanelli, Marco (2022) *Geometrization vs. Unification. The Reichenbach-Einstein Quarrel about the Fernparallelismus Field Theory.* Synthese, 213. ISSN 1573-0964Laudisa, Federico (2022) *When Did Locality Become ‘Local Realism’? A Historical and Critical Analysis (1963-1978).* [Preprint]

Gao, Shan (2022) *A no-go result for wave function realism.* [Preprint]

Dark matter or strong gravity?. (arXiv:2205.07153v1 [gr-qc])

下午6:38 | | | Saurya Das, Sourav Sur | | | quant-ph updates on arXiv.org |

We show that Newton’s gravitational potential, augmented by a logarithmic term, partly or wholly mitigates the need for dark matter. As a bonus, it also explains why MOND seems to work at galactic scales. We speculate on the origin of such a potential.

下午6:38 | | | Chenwei Lv, Qi Zhou | | | quant-ph updates on arXiv.org |

We show that quantum dynamics of any systems with $SU(1,1)$ symmetry give rise to emergent Anti-de Sitter spacetimes in 2+1 dimensions (AdS$_{2+1}$). Using the continuous circuit depth, a quantum evolution is mapped to a trajectory in AdS$_{2+1}$. Whereas the time measured in laboratories becomes either the proper time or the proper distance, quench dynamics follow geodesics of AdS$_{2+1}$. Such a geometric approach provides a unified interpretation of a wide range of prototypical phenomena that appear disconnected. For instance, the light cone of AdS$_{2+1}$ underlies expansions of unitary fermions released from harmonic traps, the onsite of parametric amplifications, and the exceptional points that represent the $PT$ symmetry breaking in non-Hermitian systems. Our work provides a transparent means to optimize quantum controls by exploiting shortest paths in the emergent spacetimes. It also allows experimentalists to engineer emergent spacetimes and induce tunnelings between different AdS$_{2+1}$.

下午6:38 | | | Flaminia Giacomini, Časlav Brukner | | | quant-ph updates on arXiv.org |

The Principle of Equivalence, stating that all laws of physics take their special-relativistic form in any local inertial frame, lies at the core of General Relativity. Because of its fundamental status, this principle could be a very powerful guide in formulating physical laws at regimes where both gravitational and quantum effects are relevant. However, its formulation implicitly presupposes that reference frames are abstracted from classical systems (rods and clocks) and that the spacetime background is well defined. It is unclear if it continues to hold when quantum systems, which can be in a quantum relationship with other physical systems, are taken as reference frames, and in a superposition of classical spacetime structures. Here, we tackle both questions by introducing a relational formalism to describe quantum systems in a superposition of curved spacetimes. We build a unitary transformation to the quantum reference frame (QRF) of a quantum system in curved spacetime, and in a superposition thereof. In both cases, a QRF can be found such that the metric looks locally minkowskian. Hence, one cannot distinguish, with a local measurement, if the spacetime is flat or curved, or in a superposition of such spacetimes. This transformation identifies a Quantum Local Inertial Frame. We also find a spacetime path-integral encoding the dynamics of a quantum particle in spacetime and show that the state of a freely falling particle can be expressed as an infinite sum of all possible classical geodesics. We then build the QRF transformation to the Fermi normal coordinates of such freely falling quantum particle and show that the metric is locally minkowskian. These results extend the Principle of Equivalence to QRFs in a superposition of gravitational fields. Verifying this principle may pave a fruitful path to establishing solid conceptual grounds for a future theory of quantum gravity.

下午6:38 | | | Walter F. Wreszinski | | | quant-ph updates on arXiv.org |

We review our approach to the second law of thermodynamics, viewed as a theorem asserting the growth of the mean (Gibbs-von Neumann) entropy of quantum spin systems undergoing automorphic (unitary) adiabatic transformations. Non-automorphic interactions with the environment, although known to produce on the average a strict reduction of the entropy of systems with finite number of degrees of freedom, are proved to conserve the mean entropy on the average. The results depend crucially on two properties of the mean entropy, proved by Robinson and Ruelle for classical systems, and Lanford and Robinson for quantum lattice systems: upper semicontinuity and affinity.

下午6:38 | | | physics.hist-ph updates on arXiv.org |

Authors: Verity Allan

A discussion of the history of scientific computing for Radio Astronomy in the Cavendish Laboratory of the University of Cambridge in the decades after the Second World War. This covers the development of the aperture synthesis technique for Radio Astronomy and how that required using the new computing technology developed by the University’s Mathematical Laboratory: the EDSAC, EDSAC 2 and TITAN computers. It looks at the scientific advances made by the Radio Astronomy group, particularly the assembling of evidence which contradicted the Steady State Hypothesis. It also examines the software advances that allowed bigger telescopes to be built: the Fast Fourier Transform (FFT) and the degridding algorithm. Throughout, the contribution of women is uncovered, from the diagrams they drew for scientific publications, through programming and operating computers, to writing scientific papers.

下午6:38 | | | physics.hist-ph updates on arXiv.org |

Authors: Daniel Grimmer

A crucial step in the history of General Relativity was Einstein’s adoption of the principle of general covariance which demands a coordinate independent formulation for our spacetime theories. General covariance helps us to disentangle a theory’s substantive content from its merely representational artifacts. It is an indispensable tool for a modern understanding of spacetime theories. Motivated by quantum gravity, one may wish to extend these notions to quantum spacetime theories (whatever those are). Relatedly, one might want to extend these notions to discrete spacetime theories (i.e., lattice theories). This paper delivers such an extension with surprising consequences, extending Part 1 (arXiv:2204.02276) to a Lorentzian setting.

This discrete analog of general covariance reveals that lattice structure is rather less like a fixed background structure and rather more like a coordinate system, i.e., merely a representational artifact. This discrete analog is built upon a rich analogy between the lattice structures appearing in our discrete spacetime theories and the coordinate systems appearing in our continuum spacetime theories. I argue that properly understood there are no such things as lattice-fundamental theories, rather there are only lattice-representable theories. It is well-noted by the causal set theory community that no theory on a fixed spacetime lattice is Lorentz invariant, however as I will discuss this is ultimately a problem of representational capacity, not of physics. There is no need for the symmetries of our representational tools to latch onto the symmetries of the thing being represented. Nothing prevents us from using Cartesian coordinates to describe rotationally invariant states/dynamics. As this paper shows, the same is true of lattices in a Lorentzian setting: nothing prevents us from defining a perfectly Lorentzian lattice(-representable) theory.

下午6:38 | | | physics.hist-ph updates on arXiv.org |

Authors: Dalton A R Sakthivadivel

In a recent technical critique of the free energy principle (FEP) due to Aguilera-Millidge-Tschantz-Buckley, it is argued that there are a number of instances where the FEP\textemdash as conventionally written, in terms of densities over states\textemdash is uninformative about the dynamics of many physical systems, and by extension, many `things.’ In this informal comment on their critique, I highlight two points of interest where their derivations are largely correct, but where their arguments are not fatal to the FEP. I go on to conjecture that a path-based formulation of the FEP has key features which restore its explanatory power in broad physical regimes. Correspondingly, this piece takes the position that the application of a state-based formulation of the FEP is inappropriate for certain simple systems, but, that the FEP can be expected to hold regardless.

Coarse-grained modelling out of equilibrium

下午6:38 | | | ScienceDirect Publication: Physics ReportsScienceDirect RSShttps://www.sciencedirect.com/journal/physics-reportsRSS for NodeTue, 23 Jul 2019 10:02:48 GMTCopyright © 2019 Elsevier B.V. All rights reservedRapid solidification as non-ergodic phenomenonPublication date: 20 July 2019Source: Physics Reports, Volume 818Author(s): P.K. Galenko, D. JouAbstractRapid solidification is a relevant physical phenomenon in material sciences, whose theoretical analysis requires going beyond the limits of local equilibrium statistical physics and thermodynamics and, in particular, taking account of ergodicity breaking and of generalized formulation of thermodynamics. The ergodicity breaking is related to the time symmetry breaking and to the presence of some kinds of fluxes and gradient flows making that an average of microscopic variables along time is different than an average over some chosen statistical ensemble. In fast processes, this is due, for instance, to the fact that the system has no time enough to explore the who |

Publication date: 19 August 2022

**Source:** Physics Reports, Volume 972

Author(s): Tanja Schilling

Effective field theory from Relativistic Generalized Uncertainty. (arXiv:2205.06878v1 [gr-qc])

下午6:38 | | | gr-qc updates on arXiv.org |

Authors: Vasil Todorinov, Saurya Das, Pasquale Bosso

Theories of Quantum Gravity predict a minimum measurable length and a corresponding modification of the Heisenberg Uncertainty Principle to the so-called Generalized Uncertainty Principle (GUP). However, this modification is usually formulated in non-relativistic language, making it unclear whether the minimum length is Lorentz invariant. We have formulated a Relativistic Generalized Uncertainty Principle, resulting in a Lorentz invariant minimum measurable length and the resolution of the composition law problem. This proved to be an important step in the formulation of Quantum Field Theory with minimum length. We derived the Lagrangians consistent with the existence of minimal length and describing the behaviour of scalar, spinor, and U(1) gauge fields. We calculated the Feynman rules (propagators and vertices) associated with these Lagrangians. Furthermore, we calculated the Quantum Gravity corrected scattering cross-sections for a lepton-lepton scattering. Finally, we compared our results with current experiments, which allowed us to improve the bounds on the scale at which quantum gravity phenomena will become relevant.

Causal completions as Lorentzian pre-length spaces. (arXiv:2205.07148v1 [gr-qc])

下午6:38 | | | gr-qc updates on arXiv.org |

Authors: L. Ake Hau, Saul Burgos, Didier A. Solis

In this work we revisit the notion of the (future) causal completion of a globally hyperbolic spacetime and endow it with the structure of a Lorentzian pre-length space. We further carry out this construction for a certain class of generalized Robertson-Walker spacetimes.

Entanglement between two evaporating black holes. (arXiv:2111.11688v2 [hep-th] UPDATED)

下午6:38 | | | gr-qc updates on arXiv.org |

Authors: Akihiro Miyata, Tomonori Ugajin

We study a thermo-field double type entangle state on two disjoint gravitating universes, say A and B, with an eternal black hole on each. As was shown previously, its entanglement entropy of the universe A is computed by the generalized entropy on a new spacetime constructed by suitably gluing the black holes on A and B. We study such spacetime gluings when universes are asymptotically flat and AdS cases, especially when the masses of these black holes are different. We also clarify the rule to construct such a glued spacetime in more general settings from the gravitational path integral view point.

Unruh-DeWitt detectors in cosmological spacetimes. (arXiv:2204.00359v2 [gr-qc] UPDATED)

下午6:38 | | | gr-qc updates on arXiv.org |

Authors: Aindriú Conroy

We analyse the response and thermal behaviour of an Unruh-DeWitt detector as it travels through cosmological spacetimes, with special reference to the question of how to define surface gravity and temperature in dynamical spacetimes. Working within the quantum field theory on curved spacetime approximation, we consider a detector as it travels along geodesic and accelerated Kodama trajectories in de Sitter and asymptotically de Sitter FLRW spacetimes. By modelling the temperature of the detector using the detailed-balance form of the Kubo–Martin–Schwinger (KMS) conditions as it thermalises, we can better understand the thermal behaviour of the detector as it interacts with the quantum field, and use this to compare competing definitions of surface gravity and temperature that persist in the literature. These include the approaches of Hayward-Kodama, Ashtekar et al., Fodor et al., and Nielsen-Visser. While these are most often examined within the context of a dynamical black hole, here we shift focus to surface gravity on the evolving cosmological horizon.

The fate of causal structure under time reversal

2022年5月15日 星期日 下午3:50 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Williams, Porter (2022) The fate of causal structure under time reversal. THEORIA. An International Journal for Theory, History and Foundations of Science, 37 (1). pp. 87-102. ISSN 0495-4548

Bi-directionality and time in causal relationships

2022年5月15日 星期日 下午3:50 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Samaniego, Fernanda (2022) Bi-directionality and time in causal relationships. THEORIA. An International Journal for Theory, History and Foundations of Science, 37 (1). pp. 103-109. ISSN 0495-4548

2022年5月13日 星期五 上午8:00 | | | Stefanie Reichert | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 13 May 2022; doi:10.1038/s41567-022-01617-9

Watch out for the W

2022年5月9日 星期一 上午8:00 | | | Latest Results for Synthese |

**Abstract**

This study reconstructs the 1928–1929 correspondence between Reichenbach and Einstein about the latter’s latest distant parallelism-unified field theory, which attracted considerable public attention at the end of the 1920s. Reichenbach, who had recently become a Professor in Berlin, had the opportunity to discuss the theory with Einstein and therefore sent him a manuscript with some comments for feedback. The document has been preserved among Einstein’s papers. However, the subsequent correspondence took an unpleasant turn after Reichenbach published a popular article on distant parallelism in a newspaper. Einstein directly wrote to the Editorial Board complaining about Reichenbach’s unfair use of off-the-record information. While Reichenbach’s reply demonstrates a sense of personal betrayal at Einstein’s behavior, his published writings of that period point to a sense of intellectual betrayal of their shared philosophical ideals. In his attempts to unify both electricity and gravitation, Einstein had abandoned the physical heuristic that guided him to the relativity theory, to embrace a more speculative, mathematical heuristic that he and Reichenbach had both previously condemned. A decade-long personal and intellectual friendship grew fainter and then never recovered. This study, relying on archival material, aims to revisit the Reichenbach–Einstein relationship in the late 1920s in light of Reichenbach’s neglected contributions to the epistemology of the unified field theory program. Thereby, it hopes to provide a richer account of Reichenbach’s philosophy of space and time.

Schrödinger’s Equation as a Consequence of the Central Limit Theorem Without Assuming Prior Physical Laws [Foundations of Physics volume 52, Article number: 50 (2022)]

P. M. Grinwald

The central limit theorem has been found to apply to random vectors in complex Hilbert space. This amounts to sufficient reason to study the complex–valued Gaussian, looking for relevance to quantum mechanics. Here we show that the Gaussian, with all terms fully complex, acting as a propagator, leads to Schrödinger’s non-relativistic equation including scalar and vector potentials, assuming only that the norm is conserved. No physical laws need to be postulated a priori. It thereby presents as a process of irregular motion analogous to the real random walk but executed under the rules of the complex number system. There is a standard view that Schrödinger’s equation is deterministic, whereas wavefunction “collapse” is probabilistic (by Born’s rule)—we have now a demonstrated linkage to the central limit theorem, indicating a stochastic picture at the foundation of Schrödinger’s equation itself. It may be an example of Wheeler’s “It from bit” with “No underlying law”. Reasons for the primary role of C are open to discussion. The present derivation is compared with recent reconstructions of the quantum formalism, which have the aim of rationalizing its obscurities.

Discretised Hilbert Space and Superdeterminism [arXiv:2204.05763 (quant-ph)]

T.N. Palmer

In computational physics it is standard to approximate continuum systems with discretised representations. Here we consider a specific discretisation of the continuum complex Hilbert space of quantum mechanics – a discretisation where squared amplitudes and complex phases are rational numbers. The fineness of this discretisation is determined by a finite (prime-number) parameter p. As p→∞, unlike standard discretised representations in computational physics, this model does not tend smoothly to the continuum limit. Instead, the state space of quantum mechanics is a singular limit of the discretised model at p=∞. Using number theoretic properties of trigonometric functions, it is shown that for large enough values of p, discretised Hilbert space accurately describes ensemble representations of quantum systems within an inherently superdeterministic framework, one where the Statistical Independence assumption in Bell’s theorem is formally violated. In this sense, the discretised model can explain the violation of Bell inequalities without appealing to nonlocality or indefinite reality. It is shown that this discretised framework is not fine tuned (and hence not conspiratorial) with respect to its natural state-space p-adic metric. As described by Michael Berry, old theories of physics are typically the singular limits of new theories as a parameter of the new theory is set equal to zero or infinity. Using this, we can answer the challenge posed by Scott Aaronson, critic of superderminism: to explain when a great theory in physics (here quantum mechanics) has ever been `grudgingly accommodated' rather than`

gloriously explained’ by its candidate successor theory (here a superdeterministic theory of quantum physics based on discretised Hilbert space).

上午9:34 | | | physics.hist-ph updates on arXiv.org |

Authors: Cormac O’Raifeartaigh

Einstein’s blackboard is a well-known exhibit at the History of Science Museum at Oxford University. However, it is much less well known that the writing on the board provides a neat summary of a work of historic importance, Einstein’s 1931 model of the expanding universe. As a visual representation of one of the earliest models of the universe to be proposed in the wake of Hubble’s observations of the nebulae, the blackboard provides an intriguing snapshot of a key moment in modern astronomy and cosmology. In addition, one line on the blackboard that is not in Einstein’s 1931 paper casts useful light on some anomalies in the calculations of that paper.

Quantum computers as an amplifier for existential risk. (arXiv:2205.02761v1 [physics.soc-ph])

上午9:34 | | | physics.hist-ph updates on arXiv.org |

Authors: Benjamin F. Schiffer

Quantum computing is expected to have a profound impact on society. In this work we discuss the potential consequences on existential risk for humanity. Even with the timeline for large-scale fault-tolerant quantum computing still unclear, it is highly likely that quantum computers will eventually realize an exponential speedup for certain practical applications. We identify quantum simulation as the most relevant application in this regard and we qualitatively outline different risk trajectories. Both amplifying and mitigating effects of quantum computing for existential risk are anticipated. In order to prevent quantum computing from being an amplifier of existential risk, we call for increased efforts by the scientific community towards reducing potential future quantum risk. This viewpoint seeks to add a new perspective to the discussion on technological risk of quantum computing.

An analogue of the Riemann Hypothesis via quantum walks. (arXiv:2204.00765v2 [quant-ph] UPDATED)

上午9:34 | | | Norio Konno | | | quant-ph updates on arXiv.org |

We consider an analogue of the well-known Riemann Hypothesis based on quantum walks on graphs with the help of the Konno-Sato theorem. Furthermore, we give some examples for complete, cycle, and star graphs.

When does a particle arrive?. (arXiv:2205.02219v2 [quant-ph] UPDATED)

上午9:34 | | | Simone Roncallo, Krzysztof Sacha, Lorenzo Maccone | | | quant-ph updates on arXiv.org |

We compare the different proposals that have appeared in the literature to describe a measurement of the time of arrival of a quantum particle at a detector. We show that there are multiple regimes where different proposals give inequivalent, experimentally discriminable, predictions. This analysis paves the way for future experimental tests.

Extreme events in dynamical systems and random walkers: A review

上午9:34 | | | ScienceDirect Publication: Physics ReportsScienceDirect RSShttps://www.sciencedirect.com/journal/physics-reportsRSS for NodeTue, 23 Jul 2019 10:02:48 GMTCopyright © 2019 Elsevier B.V. All rights reservedRapid solidification as non-ergodic phenomenonPublication date: 20 July 2019Source: Physics Reports, Volume 818Author(s): P.K. Galenko, D. JouAbstractRapid solidification is a relevant physical phenomenon in material sciences, whose theoretical analysis requires going beyond the limits of local equilibrium statistical physics and thermodynamics and, in particular, taking account of ergodicity breaking and of generalized formulation of thermodynamics. The ergodicity breaking is related to the time symmetry breaking and to the presence of some kinds of fluxes and gradient flows making that an average of microscopic variables along time is different than an average over some chosen statistical ensemble. In fast processes, this is due, for instance, to the fact that the system has no time enough to explore the who |

Publication date: 5 July 2022

**Source:** Physics Reports, Volume 966

Author(s): Sayantan Nag Chowdhury, Arnob Ray, Syamal K. Dana, Dibakar Ghosh

上午9:34 | | | gr-qc updates on arXiv.org |

Authors: Daniel Sobral-Blanco, Camille Bonvin

To test the theory of gravity one needs to test, on one hand, how space and time are distorted by matter and, on the other hand, how matter moves in a distorted space-time. Current observations provide tight constraints on the motion of matter, through the so-called redshift-space distortions, but they only provide a measurement of the sum of the spatial and temporal distortions, via gravitational lensing. In this Letter, we develop a method to measure the time distortion on its own. We show that the coming generation of galaxy surveys, like the Square Kilometer Array, will allow us to measure the distortion of time with an accuracy of 10-30\%. Such a measurement will be essential to test deviations from General Relativity in a fully model-independent way. In particular, it can be used to compare the spatial and temporal distortions of space-time, that are predicted to be the same in $\Lambda$CDM but generically differ in modified theories of gravity.

Two Novel Observational Tests of General Relativity. (arXiv:2205.02746v1 [gr-qc])

上午9:34 | | | gr-qc updates on arXiv.org |

Authors: Abraham Loeb (Harvard)

We propose two novel observational tests of general relativistic predictions: (i) Detecting the memory effect from a massive black hole merger at the Galactic Center through Lunar Ranging; and (ii) Violation of a limiting flux versus redshift as a flag of new physics. First, I show that a gravitational wave pulse from a major merger of massive black holes at the Galactic center induces a permanent increase in the Earth-Moon separation. For black holes of millions of solar masses, the shift in the local gravitational potential is comparable to the Earth-Moon potential, leading to the Moon being perturbed relative to the Earth during the passage of the pulse. The permanent increase in the Earth-Moon separation is a fraction of a millimeter, measurable by lunar ranging for future merger events. Second, I show that General Relativity sets an absolute upper limit on the energy flux observed from a cosmological source as a function of its redshift. Detecting a brighter source in gravitational waves, neutrinos or light, would flag new physics. The derived flux limit can also be used to determine the maximum redshift possible for any source with an unknown origin.

Alcubierre Warp Drive in Bohmian Quantum Gravity. (arXiv:2205.02780v1 [physics.gen-ph])

上午9:34 | | | gr-qc updates on arXiv.org |

Authors: Sijo K. Joseph

Alcubierre warp drive metric is coupled to quantum mechanical scalar matter field. The requirement of the exotic matter for the warp drive is mapped into a conformal wave equation. This result into a fourth order partial differential equation in terms of the quantum mechanical density. Finding a proper quantum mechanical density obeying the proposed partial differential equation will be a resolution to the exotic matter problem of Alcubierre warp drive in Bohmian Quantum Gravity context.

The Penrose Property with a Cosmological Constant. (arXiv:2106.02536v2 [gr-qc] UPDATED)

上午9:34 | | | gr-qc updates on arXiv.org |

Authors: Peter Cameron

A spacetime satisfies the non-timelike boundary version of the Penrose property if the timelike future of any point on $\mathcal{I}^-$ contains the whole of $\mathcal{I}^+$. This property was first discussed for asymptotically flat spacetimes by Penrose, along with an equivalent definition (the finite version). In this paper we consider the Penrose property in greater generality. In particular we consider spacetimes with a non-zero cosmological constant and we note that the two versions of the property are no longer equivalent. In asymptotically AdS spacetimes it is necessary to re-state the property in a way which is more suited to spacetimes with a timelike boundary. We arrive at a property previously considered by Gao and Wald. Curiously, this property was shown to fail in spacetimes which focus null geodesics. This is in contrast to our findings in asymptotically flat and asymptotically de Sitter spacetimes. We then move on to consider some further example spacetimes (with zero cosmological constant) which highlight features of the Penrose property not previously considered. We discuss spacetimes which are the product of a Lorentzian and a compact Riemannian manifold. Perhaps surprisingly, we find that both versions of the Penrose property are satisfied in this product spacetime if and only if they are satisfied in the Lorentzian spacetime only. We also discuss the Ellis-Bronnikov wormhole (an example of a spacetime with more than one asymptotically flat end) and the Hayward metric (an example of a non-singular black hole spacetime).

Quantum evolution of the Hawking state for black holes. (arXiv:2204.13126v1 [hep-th] CROSS LISTED)

上午9:34 | | | gr-qc updates on arXiv.org |

Authors: Steven B. Giddings, Julie Perkins

We give a general description of the evolving quantum state of a Schwarzschild black hole, in the quantum field theory approximation. Such a time-dependent description is based on introducing a choice of time slices. We in particular consider slices that smoothly cross the horizon, and introduction of “stationary” such slices simplifies the analysis. This analysis goes beyond standard derivations of Hawking radiation that focus on asymptotic excitations, and in particular gives an evolving state that is regular at the horizon, with no explicit transplanckian dependence, and that can in principle be generalized to incorporate interacting fields. It is also expected to be useful in connecting to information-theoretic investigation of black hole evolution. The description of the evolving state depends on the choice of slices as well as coordinates on the slices and mode bases; these choices give different “pictures” analogous to that of Schr\”odinger. Evolution does have a simpler appearance in an energy eigenbasis, but such a basis is also singular at the horizon; evolution of regular modes has a more complicated appearance, whose properties may be inferred by comparing with the energy eigenbasis. In a regular description, Hawking quanta are produced in a black hole atmosphere, at scales comparable to the horizon size. This approach is also argued to extend to more general asymptotics, such as that of anti de Sitter space. In the latter context, this analysis provides a description of the hamiltonian and evolution of a black hole that may be compared to the large-$N$ dynamics of the proposed dual CFT.

Reassessing the Notion of a Kuhnian Revolution What Happened in Twentieth-Century Chemistry

上午3:58 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Scerri, Eric (2021) Reassessing the Notion of a Kuhnian Revolution What Happened in Twentieth-Century Chemistry. B. Wray (ed.), Interpreting Kuhn,. pp. 124-141.

A (strictly) contemporary perspective on trans-Planckian censorship

上午3:56 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Schneider, Mike D. (2022) A (strictly) contemporary perspective on trans-Planckian censorship. [Preprint]

Idealisations and the No-Miracle Argument

上午3:54 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Ruyant, Quentin (2022) Idealisations and the No-Miracle Argument. [Preprint]

The introduction of topology into analytic philosophy: two movements and a coda

2022年5月5日 星期四 上午8:00 | | | Latest Results for Synthese |

**Abstract**

Both early analytic philosophy and the branch of mathematics now known as topology were gestated and born in the early part of the 20th century. It is not well recognized that there was early interaction between the communities practicing and developing these fields. We trace the history of how topological ideas entered into analytic philosophy through two migrations, an earlier one conceiving of topology geometrically and a later one conceiving of topology algebraically. This allows us to reassess the influence and significance of topological methods for philosophy, including the possible fruitfulness of a third conception of topology as a structure determining *similarity*.

The Inaccessibility of the Past is not Statistical

2022年5月3日 星期二 下午4:34 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Emily, Adlam (2022) The Inaccessibility of the Past is not Statistical. [Preprint]

The sky is blue, and other reasons quantum mechanics is not underdetermined by evidence

2022年5月3日 星期二 下午4:31 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Wallace, David (2022) The sky is blue, and other reasons quantum mechanics is not underdetermined by evidence. [Preprint]

Understanding Time Reversal in Quantum Mechanics: A Full Derivation

2022年5月3日 星期二 下午4:30 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2022) Understanding Time Reversal in Quantum Mechanics: A Full Derivation. [Preprint]

Variable relativity of causation is good

2022年5月3日 星期二 上午8:00 | | | Latest Results for Synthese |

**Abstract**

Interventionism is a theory of causation with a pragmatic goal: to define causal concepts that are useful for reasoning about how things could, in principle, be purposely manipulated. In its original presentation, Woodward’s (2003) interventionist definition of causation is relativized to an analyzed variable set. In Woodward (2008), Woodward changes the definition of the most general interventionist notion of cause, contributing cause, so that it is no longer relativized to a variable set. This derelativization of interventionism has not gathered much attention, presumably because it is seen as an unproblematic way to save the intuition that causal relations are objective features of the world. This paper first argues that this move has problematic consequences. Derelativization entails two concepts of unmediated causal relation that are not coextensional, but which nonetheless do not entail different conclusions about manipulability relations within any given variable set. This is in conflict with the pragmatic orientation at the core of interventionism. The paper then considers various approaches for resolving this tension but finds them all wanting. It is concluded that interventionist causation should not be derelativized in the first place. Various considerations are offered rendering that conclusion acceptable.

Not so distinctively mathematical explanations: topology and dynamical systems

2022年5月3日 星期二 上午8:00 | | | Latest Results for Synthese |

**Abstract**

So-called ‘distinctively mathematical explanations’ (DMEs) are said to explain physical phenomena, not in terms of contingent causal laws, but rather in terms of mathematical necessities that constrain the physical system in question. Lange argues that the existence of four or more equilibrium positions of any double pendulum has a DME. Here we refute both Lange’s claim itself and a strengthened and extended version of the claim that would pertain to any *n*-tuple pendulum system on the ground that such explanations are actually causal explanations in disguise and their associated modal conditionals are not general enough to explain the said features of such dynamical systems. We argue and show that if circumscribing the antecedent for a necessarily true conditional in such explanations involves making a causal analysis of the problem, then the resulting explanation is not distinctively mathematical or non-causal. Our argument generalises to other dynamical systems that may have purported DMEs analogous to the one proposed by Lange, and even to some other counterfactual accounts of non-causal explanation given by Reutlinger and Rice.

Dystopian or Utopian? Two Images of Alan Turing

2022年5月2日 星期一 上午4:36 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gonçalves, Bernardo (2020) Dystopian or Utopian? Two Images of Alan Turing. [Preprint]

]]>下午4:28 | | | physics.hist-ph updates on arXiv.org |

Authors: Maxwell J D Ramstead, Dalton A R Sakthivadivel

We comment on a technical critique of the free energy principle in linear systems by Aguilera, Millidge, Tschantz, and Buckley, entitled “How Particular is the Physics of the Free Energy Principle?” Aguilera and colleagues identify an ambiguity in the flow of the mode of a system, and we discuss the context for this ambiguity in earlier papers, and their proposal of a more adequate interpretation of these equations. Following that, we discuss a misinterpretation in their treatment of surprisal and variational free energy, especially with respect to their gradients and their minima. In sum, we argue that the results in the target paper are accurate and stand up to rigorous scrutiny; we also highlight that they, nonetheless, do not undermine the FEP.

下午4:28 | | | physics.hist-ph updates on arXiv.org |

Authors: Marina Cortês, Stuart A. Kauffman, Andrew R. Liddle, Lee Smolin

The Universe contains everything that exists, including life. And all that exists, including life, obeys universal physical laws. Do those laws then give adequate foundations for a complete explanation of biological phenomena? We discuss whether and how cosmology and physics must be modified to be able to address certain questions which arise at their intersection with biology. We show that a universe that contains life, in the form it has on Earth, is in a certain sense radically non-ergodic, in that the vast majority of possible organisms will never be realized. We argue from this that complete explanations in cosmology require a mixture of reductionist and functional explanations.

下午4:28 | | | Jonte R. Hance, John Rarity, James Ladyman | | | quant-ph updates on arXiv.org |

In discussion of the interpretation of quantum mechanics the terms `ontic’ and `epistemic’ are often used in the sense of pertaining to what exists, and pertaining to cognition or knowledge respectively. The terms are also often associated with the formal definitions given by Harrigan and Spekkens for the wavefunction in quantum mechanics to be $\psi$-ontic or $\psi$-epistemic in the context of the ontological models framework. The formal definitions are contradictories, so that the wavefunction can be either $\psi$-epistemic or $\psi$-ontic but not both. However, we argue, nothing about the informal ideas of epistemic and ontic interpretations rules out wavefunctions representing both reality and knowledge. The implications of the Pusey-Barrett-Rudolph theorem and many other issues may be rethought in the light of our analysis.

A Quantum-Mechanical Mechanism for Reducing the Cosmological Constant. (arXiv:2204.13124v1 [hep-th])

下午4:28 | | | gr-qc updates on arXiv.org |

Authors: Nemanja Kaloper, Alexander Westphal

We exhibit a mechanism which dynamically adjusts cosmological constant toward $0^+$. The adjustment is quantum-mechanical, discharging cosmological constant in random discrete steps. It renders de Sitter space unstable, and triggers its decay toward Minkowski. Since the instability dynamically stops at $\Lambda = 0$, the evolution favors the terminal Minkowski space without a need for anthropics. The mechanism works for any QFT coupled to gravity.

Tests of gravity theories with pulsar timing. (arXiv:2204.13468v1 [gr-qc])

下午4:28 | | | gr-qc updates on arXiv.org |

Authors: Paulo C. C. Freire

Over the last few years, a set of new results from pulsar timing has introduced much tighter constraints on violations of the strong equivalence principle (SEP), either via a direct verification of the universality of free fall for a pulsar in a triple star system, or from tests of the nature of gravitational waves, in particular a search for dipolar gravitational wave emission in a variety of binary pulsars with different masses. No deviations from the SEP have been detected in our experiments. These results introduce some of the most stringent constraints on several classes of alternative theories of gravity and complement recent results from the ground-based gravitational wave detectors.

Local Dynamical Effects of Scale Invariance: the Lunar Recession. (arXiv:2204.13560v1 [astro-ph.EP])

下午4:28 | | | gr-qc updates on arXiv.org |

Authors: Andre Maeder, Vesselin Gueorguiev

Scale invariance is expected in empty Universe models, while the presence of matter tends to suppress it. As shown recently, scale invariance is certainly absent in cosmological models with densities equal to or above the critical value $\varrho_{\mathrm{c}} =3H^2_0/(8 \pi G)$. For models with densities below $\varrho_{\mathrm{c}}$, the possibility of limited effects remains open. If present, scale invariance would be a global cosmological property. Some traces could be observable locally. For the Earth-Moon two-body system, the predicted additional lunar recession would be increased by 0.92 cm/yr, while the tidal interaction would also be slightly increased.

The Earth-Moon distance is the most systematically measured distance in the Solar System, thanks to the Lunar Laser Ranging (LLR) experiment active since 1970. The observed lunar recession from LLR amounts to 3.83 ($\pm 0.009$) cm/yr; implying a tidal change of the length-of-the-day (LOD) by 2.395 ms/cy. However, the observed change of the LOD since the Babylonian Antiquity is only 1.78 ms/cy, a result supported by paleontological data, and implying a lunar recession of 2.85 cm/yr. The significant difference of (3.83-2.85) cm/yr = 0.98 cm/yr, already pointed out by several authors over the last two decades, corresponds well to the predictions of the scale-invariant theory, which is also supported by several other astrophysical tests.

Quantum magnonics: When magnon spintronics meets quantum information science

下午4:27 | | | ScienceDirect Publication: Physics ReportsScienceDirect RSShttps://www.sciencedirect.com/journal/physics-reportsRSS for NodeTue, 23 Jul 2019 10:02:48 GMTCopyright © 2019 Elsevier B.V. All rights reservedRapid solidification as non-ergodic phenomenonPublication date: 20 July 2019Source: Physics Reports, Volume 818Author(s): P.K. Galenko, D. JouAbstractRapid solidification is a relevant physical phenomenon in material sciences, whose theoretical analysis requires going beyond the limits of local equilibrium statistical physics and thermodynamics and, in particular, taking account of ergodicity breaking and of generalized formulation of thermodynamics. The ergodicity breaking is related to the time symmetry breaking and to the presence of some kinds of fluxes and gradient flows making that an average of microscopic variables along time is different than an average over some chosen statistical ensemble. In fast processes, this is due, for instance, to the fact that the system has no time enough to explore the who |

Publication date: 26 June 2022

**Source:** Physics Reports, Volume 965

Author(s): H.Y. Yuan, Yunshan Cao, Akashdeep Kamra, Rembert A. Duine, Peng Yan

Objective description in physics

2022年4月29日 星期五 下午3:47 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Halvorson, Hans (2022) Objective description in physics. [Preprint]

A simple proof that the global phase is real

2022年4月29日 星期五 下午3:46 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2022) A simple proof that the global phase is real. [Preprint]

Reassessing the strength of a class of Wigner’s friend no-go theorems

2022年4月29日 星期五 下午3:45 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Okon, Elias (2022) Reassessing the strength of a class of Wigner’s friend no-go theorems. [Preprint]

2022年4月28日 星期四 上午8:00 | | | Carl A. Miller | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 28 April 2022; doi:10.1038/s41567-022-01597-w

A theoretical analysis shows how a person’s location in space could be verified by the transmission of single photons. A vital application of quantum networks may be within reach.

Quantum Relativity of Subsystems

2022年4月27日 星期三 下午6:00 | | | Shadi Ali Ahmad, Thomas D. Galley, Philipp A. Höhn, Maximilian P. E. Lock, and Alexander R. H. Smith | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Shadi Ali Ahmad, Thomas D. Galley, Philipp A. Höhn, Maximilian P. E. Lock, and Alexander R. H. Smith

One of the most basic notions in physics is the partitioning of a system into subsystems and the study of correlations among its parts. In this Letter, we explore this notion in the context of quantum reference frame (QRF) covariance, in which this partitioning is subject to a symmetry constraint. W…

[Phys. Rev. Lett. 128, 170401] Published Wed Apr 27, 2022

Structuralism, indiscernibility, and physical computation

2022年4月27日 星期三 上午8:00 | | | Latest Results for Synthese |

**Abstract**

Structuralism about mathematical objects and structuralist accounts of physical computation both face indeterminacy objections. For the former, the problem arises for cases such as the complex roots *i* and \(-i\) , for which a (non-trivial) automorphism can be defined, thus establishing the structural identity of these importantly distinct mathematical objects (see e.g. Keränen in Philos Math 3:308–330, 2001). In the case of the latter, the problem arises for logical duals such as AND and OR, which have invertible structural profiles (see e.g. Shagrir in Mind 110(438):369–400, 2001). This makes their physical implementations indeterminate, in the sense that their structural profiles alone cannot establish whether a given physical component is an AND-gate or an OR-gate. Doherty (PhilPapers, https://philpapers.org/rec/DOHCI-3, 2021) has recently shown both problems to be analogous, and has argued that computational structuralism is threatened with the absurd conclusion that computational *digits* might be indiscernible, such that, if structural properties are all that we have to go on, the binary digit 0 must be treated as identical to the binary digit 1 (rendering pure structuralism absurd). However, we think that a solution to the indiscernibility problem for mathematical structuralists, drawing on the work of David Hilbert, can be adapted for the analogous problem in the computational case, thereby rescuing the structuralist approach to physical computation.

Nonclassical probability, convex hulls, and Dutch Books

2022年4月27日 星期三 上午3:15 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gil Sanchez, Michał and Gyenis, Zalán and Wronski, Leszek (2022) Nonclassical probability, convex hulls, and Dutch Books. [Preprint]

On Automorphism Criteria for Comparing Amounts of Mathematical Structure

2022年4月27日 星期三 上午3:15 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Barrett, Thomas William and Manchak, JB and Weatherall, James Owen (2022) On Automorphism Criteria for Comparing Amounts of Mathematical Structure. [Preprint]

The Lorentz transformation in a fishbowl: a comment on Cheng and Read’s “Why not a sound postulate?”

2022年4月25日 星期一 上午6:15 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Shanahan, Daniel The Lorentz transformation in a fishbowl: a comment on Cheng and Read’s “Why not a sound postulate?”. UNSPECIFIED.

2022年4月25日 星期一 上午6:11 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Halpin, John F. (2022) Fine-tuning and Humean Laws: Fine-tuning as argument for a non-governing account of laws rather than for God or multiverse. [Preprint]

]]>Williams, Porter (2022) *Entanglement, Complexity, and Causal Asymmetry in Quantum Theories.* Foundations of Physics.

Williams, Porter (2022) *The fate of causal structure under time reversal.* [Preprint]

Wallace, David (2022) *On the reality of the global phase.* [Preprint]

Ciepielewski, Gerardo Sanjuan and Okon, Elias (2022) *From locality to factorizability: a novel escape from Bell’s theorem.* [Preprint]

上午8:43 | | | Anandamay Das Bhowmik, Preeti Parashar | | | quant-ph updates on arXiv.org |

Despite being the most fundamental object in quantum theory, physicists are yet to reach a consensus on the interpretation of a quantum wavefunction. In the broad class of realist approaches, quantum states are viewed as Liouville-like probability distributions over some space of physical variables where indistinguishabity of non-orthogonal states is attributed to overlaps between these distributions. Here we argue that such an interpretation of quantum indistinguishability is wrong. In particular, we show that quantum mechanical prediction of maximal violation of Mermin inequality in certain thought experiment is incompatible with all ontological interpretations for quantum theory where indistinguishability of non-orthonal quantum states is explained, even partially, in terms of overlap of their Liouville distributions.

Decoherence: From Interpretation to Experiment. (arXiv:2204.09755v1 [quant-ph])

上午8:43 | | | Maximilian Schlosshauer | | | quant-ph updates on arXiv.org |

I offer a few selected reflections on the decoherence program, with an emphasis on Zeh’s role and views. First, I discuss Zeh’s commitment to a realistic interpretation of the quantum state, which he saw as necessary for a consistent understanding of the decoherence process. I suggest that this commitment has been more fundamental than, and prior to, his support of an Everett-style interpretation of quantum mechanics. Seen through this lens, both his defense of Everett and the genesis of his ideas on decoherence emerge as consequences of his realistic view of the quantum state. Second, I give an overview of experiments on decoherence and describe, using the study of collisional decoherence as an example, the close interplay between experimental advances and theoretical modeling in decoherence research.

Temperature uncertainty relation in non-equilibrium thermodynamics. (arXiv:2204.10044v1 [quant-ph])

上午8:43 | | | Ning Zhang, Si-Yuan Bai, Chong Chen | | | quant-ph updates on arXiv.org |

Temperature uncertainty of a system in canonical ensemble is inversely determined by its energy fluctuation, which is known as the temperature-energy uncertainty relation. No such uncertainty relation was discovered for a non-equilibrium open quantum system. In this article, we derive a universal temperature uncertainty relation for general non-equilibrium processes. We find that it is the fluctuation of heat absorbed from the thermal bath, more specifically the sum of trajectory heat and correlation heat defined from sequential bath energy measurements, determines the temperature uncertainty. Detail analyses show that correlations between system and bath’s process function and state function are the resources for decreasing the temperature uncertainty. In addition to reveal a fundamental uncertainty relation, our results are conductive to design ultrahigh sensitive quantum thermometer.

上午8:43 | | | Elisabeth Wagner, Ramil Nigmatullin, Alexei Gilchrist, Gavin K. Brennen | | | quant-ph updates on arXiv.org |

The information flow in a quantum system is a fundamental feature of its dynamics. An important class of dynamics are quantum cellular automata (QCA), systems with discrete updates invariant in time and space, for which an index theory has been proposed for the quantification of the net flow of quantum information across a boundary. While the index is rigid in the sense of begin invariant under finite-depth local circuits, it is not defined when the system is coupled to an environment, i.e. for non-unitary time evolution of open quantum systems. We propose a new measure of information flow for non-unitary QCA denoted the information current which is not rigid, but can be computed locally based on the matrix-product operator representation of the map.

Life and death in the tails of the GRW wave function. (arXiv:1407.4746v2 [quant-ph] UPDATED)

上午8:43 | | | David Wallace | | | quant-ph updates on arXiv.org |

It is often assumed that the only effect of the Ghirardi-Rimini-Weber (`GRW’) dynamical collapse mechanism on the `tails’ of the wavefunction (that is, the components of superpositions on which the collapse is \emph{not} centred) is to reduce their weight. In consequence the tails are often thought to behave exactly as do the various branches in the Everett interpretation except for their much lower weight.

These assumptions are demonstrably inaccurate: the collapse mechanism has substantial and detectable effects within the tails. The relevance of this misconception for the dynamical-collapse theories is debatable, though.

Does acceleration assist entanglement harvesting?. (arXiv:2111.04392v2 [quant-ph] UPDATED)

上午8:43 | | | Zhihong Liu, Jialin Zhang, Robert B. Mann, Hongwei Yu | | | quant-ph updates on arXiv.org |

We explore whether acceleration assists entanglement harvesting for a pair of uniformly accelerated detectors in three different acceleration scenarios, i.e., parallel, anti-parallel and mutually perpendicular acceleration, both in the sense of the entanglement harvested and harvesting-achievable separation between the two detectors. Within the framework of entanglement harvesting protocols and the Unruh-DeWitt model of detectors locally interacting with massless scalar fields via a Gaussian switching function with an interaction duration parameter, we find that, in the sense of the entanglement harvested, acceleration is a mixed blessing insofar as it increases the harvested entanglement for a large detector energy gap relative to the interaction duration parameter, whilst inhibiting the entanglement harvested for a small energy gap. Regarding the harvesting-achievable separation range between the detectors, we further find that for very small acceleration and large energy gap, both relative to the duration parameter, acceleration-assisted enhancement can happen in all three acceleration scenarios. This is in sharp contrast to what was argued previously: that the harvesting-achievable range can be enhanced only for anti-parallel acceleration. However, for a not too small acceleration relative to the duration parameter and an energy gap larger than the acceleration, we find that only detectors in parallel acceleration possess a harvesting-achievable range larger than those at rest.

Ehrenfest theorem in relativistic quantum theory. (arXiv:2111.10798v2 [quant-ph] UPDATED)

上午8:43 | | | Iwo Bialynicki-Birula, Zofia Bialynicka-Birula | | | quant-ph updates on arXiv.org |

Ehrenfest theorem is proven in relativistic quantum theory of charged particles, moving under the influence of an external electromagnetic field. In order to extend the classic Ehrenfest result to the relativistic domain we bypassed the problems with the relativistic position operator by deriving directly Newton’s second law. Our approach is characterized by its universality. The detailed form of the wave equation is not needed. All that is required is the existence of the conserved electric four-current built from the particle wave function. The derivation is based on the conservation laws for the energy and momentum.

上午8:43 | | | Hing-Tong Cho, Jen-Tsung Hsiang, Bei-Lok Hu | | | quant-ph updates on arXiv.org |

An important yet perplexing result from work in the 90s and 00s is the near-unity value of the ratio of fluctuations in the vacuum energy density of quantum fields to the mean in a collection of generic spacetimes. This was done by way of calculating the noise kernels which are the correlators of the stress-energy tensor of quantum fields. In this paper we revisit this issue via a quantum thermodynamics approach, by calculating two quintessential thermodynamic quantities: the heat capacity and the quantum compressibility of some model geometries filled with a quantum field at high and low temperatures. This is because heat capacity at constant volume gives a measure of the fluctuations of the energy density to the mean. When this ratio approaches or exceeds unity, the validity of the canonical distribution is called into question. Likewise, a system’s compressibility at constant pressure is a criterion for the validity of grand canonical ensemble. We derive the free energy density and, from it, obtain the expressions for these two thermodynamic quantities for thermal and quantum fields in 2d Casimir space, 2d Einstein cylinder and 4d ($S^1 \times S^3$ ) Einstein universe. To examine the dependence on the dimensionality of space, for completeness, we have also derived these thermodynamic quantities for the Einstein universes with even-spatial dimensions: $S^1 \times S^2$ and $S^1 \times S^4$. With this array of spacetimes we can investigate the thermodynamic stability of quantum matter fields in them and make some qualitative observations on the compatibility condition for the co-existence between quantum fields and spacetimes, a fundamental issue in the quantum and gravitation conundrum.

On energy for accelerating observers in black hole spacetimes. (arXiv:2203.00085v2 [gr-qc] UPDATED)

上午8:43 | | | gr-qc updates on arXiv.org |

Authors: Seth A. Major

Quasi-local energies for constantly accelerating observers in Ba\~nados, Teitelboim, and Zanelli (BTZ), Schwarzschild and Schwarzschild-de Sitter spacetimes are derived. The energies are expressed in terms of acceleration, cosmological constant, and area, quantities measurable by the observers. Based on results from quantum fields in curved spacetime for the redshifted Hawking temperature, entropy and thermodynamic-like laws are briefly explored in the three spacetimes.

Can the graviton have a large mass near black holes?. (arXiv:1709.07503v2 [gr-qc] UPDATED)

上午8:43 | | | gr-qc updates on arXiv.org |

Authors: Jun Zhang, Shuang-Yong Zhou

The mass of the graviton, if nonzero, is usually considered to be very small, e.g. of the Hubble scale, from several observational constraints. In this paper, we propose a gravity model where the graviton mass is very small in the usual weak gravity environments, below all the current graviton mass bounds, but becomes much larger in the strong gravity regime such as a black hole’s vicinity. For black holes in this model, significant deviations from general relativity emerge very close to the black hole horizon and alter the black hole quasi-normal modes, which can be extracted from the ringdown waveform of black hole binary mergers. Also, the enhancement of the graviton mass near the horizon can result in echoes in the late time ringdown, which can be verified in the upcoming gravitational wave observations of higher sensitivity.

Entanglement and Superposition Are Equivalent Concepts in Any Physical Theory

2022年4月22日 星期五 下午6:00 | | | Guillaume Aubrun, Ludovico Lami, Carlos Palazuelos, and Martin Plávala | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Guillaume Aubrun, Ludovico Lami, Carlos Palazuelos, and Martin Plávala

In general probabilistic theories, superposition, in the form of what the authors define as strong incompatibility, is equivalent to entanglement.

[Phys. Rev. Lett. 128, 160402] Published Fri Apr 22, 2022

The Introduction of Topology into Analytic Philosophy: Two Movements and a Coda

2022年4月22日 星期五 上午4:19 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Fletcher, Samuel C. and Lackey, Nathan (2022) The Introduction of Topology into Analytic Philosophy: Two Movements and a Coda. [Preprint]

Justifying the use of purely formal analogies in physics

2022年4月22日 星期五 上午4:19 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Fraser, Doreen (2022) Justifying the use of purely formal analogies in physics. In: UNSPECIFIED.

The Naturalistic Case for Free Will

2022年4月21日 星期四 下午4:12 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

List, Christian (2022) The Naturalistic Case for Free Will. [Preprint]

A Bayesian analysis of self-undermining arguments in physics

2022年4月21日 星期四 下午4:10 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Wallace, David (2022) A Bayesian analysis of self-undermining arguments in physics. [Preprint]

Understanding Time Reversal in Quantum Mechanics: A Full Derivation

2022年4月21日 星期四 下午4:09 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2022) Understanding Time Reversal in Quantum Mechanics: A Full Derivation. [Preprint]

Naturalism, Functionalism and Chance: Not a Best Fit for the Humean

2022年4月21日 星期四 下午4:06 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Fernandes, Alison (2022) Naturalism, Functionalism and Chance: Not a Best Fit for the Humean. [Preprint]

Conceptualizing paradigms: on reading Kuhn’s history of the quantum

2022年4月21日 星期四 下午4:05 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Potters, Jan (2022) Conceptualizing paradigms: on reading Kuhn’s history of the quantum. Annals of Science.

Information is Physical: Cross-Perspective Links in Relational Quantum Mechanics

2022年4月21日 星期四 下午4:04 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Adlam, Emily and ROVELLI, Carlo (2022) Information is Physical: Cross-Perspective Links in Relational Quantum Mechanics. [Preprint]

Econometric methods and Reichenbach’s principle

2022年4月21日 星期四 上午8:00 | | | Latest Results for Synthese |

**Abstract**

Reichenbach’s ‘principle of the common cause’ is a foundational assumption of some important recent contributions to quantitative social science methodology but no similar principle appears in econometrics. Angrist et al. (Rubin J Am Stat Assoc 91:444–455, 1996) has argued that the principle is necessary for instrumental variables methods in econometrics, and Angrist Krueger (Quarterly Journal of Economics 106:976–1014, 1991) builds a framework using it that he proposes as a means of resolving an important methodological dispute among econometricians. Through analysis of instrumental variables methods and the issue of multicollinearity, we aim to show that the relationship of the principle to econometric methods is more nuanced than implied by previous work but nevertheless may make a valuable contribution to the coherence and validity of existing methods.

Discretised Hilbert Space and Superdeterminism [arXiv:2204.05763]

In computational physics it is standard to approximate continuum systems with discretised representations. Here we consider a specific discretisation of the continuum complex Hilbert space of quantum mechanics – a discretisation where squared amplitudes and complex phases are rational numbers. The fineness of this discretisation is determined by a finite (prime-number) parameter p. As p→∞, unlike standard discretised representations in computational physics, this model does not tend smoothly to the continuum limit. Instead, the state space of quantum mechanics is a singular limit of the discretised model at p=∞. Using number theoretic properties of trigonometric functions, it is shown that for large enough values of p, discretised Hilbert space accurately describes ensemble representations of quantum systems within an inherently superdeterministic framework, one where the Statistical Independence assumption in Bell’s theorem is formally violated. In this sense, the discretised model can explain the violation of Bell inequalities without appealing to nonlocality or indefinite reality. It is shown that this discretised framework is not fine tuned (and hence not conspiratorial) with respect to its natural state-space p-adic metric. As described by Michael Berry, old theories of physics are typically the singular limits of new theories as a parameter of the new theory is set equal to zero or infinity. Using this, we can answer the challenge posed by Scott Aaronson, critic of superderminism: to explain when a great theory in physics (here quantum mechanics) has ever been `grudgingly accommodated' rather than`

gloriously explained’ by its candidate successor theory (here a superdeterministic theory of quantum physics based on discretised Hilbert space).

上午8:51 | | | Porter Williams | | | quant-ph updates on arXiv.org |

It is often claimed that one cannot locate a notion of causation in fundamental physical theories. The reason most commonly given is that the dynamics of those theories do not support any distinction between the past and the future, and this vitiates any attempt to locate a notion of causal asymmetry — and thus of causation — in fundamental physical theories. I argue that this is incorrect: the ubiquitous generation of entanglement between quantum systems grounds a relevant asymmetry in the dynamical evolution of quantum systems. I show that by exploiting a connection between the amount of entanglement in a quantum state and the algorithmic complexity of that state, one can use recently developed tools for causal inference to identify a causal asymmetry — and a notion of causation — in the dynamical evolution of quantum systems. https://doi.org/10.1007/s10701-022-00562-0

Sign of the Feynman Propagator and Irreversibility. (arXiv:2204.06928v1 [quant-ph])

上午8:51 | | | Allan Tameshtit | | | quant-ph updates on arXiv.org |

For the interacting Feynman propagator $ \Delta_{F,int}(x,y) $ of scalar electrodynamics, we show that the sign property, $ \operatorname{Re} i\Delta_{F,int} \geq 0 $, hinges on the reversibility of time evolution. In contrast, $ \operatorname{Im} i\Delta_{F,int} $ is indeterminate. When we switch to reduced dynamics under the weak coupling approximation, the positive semidefinite sign of $ \operatorname{Re} i\Delta_{F,int} $ is generally lost, unless we impose severe restrictions on the Kraus operators that govern time evolution. With another approximation, the rotating wave approximation, we may recover the sign by restricting the test functions to exponentials under certain conditions.

Geometric model for the electron spin correlation. (arXiv:2108.07869v3 [quant-ph] UPDATED)

上午8:51 | | | Ana María Cetto | | | quant-ph updates on arXiv.org |

The quantum formula for the spin correlation of the bipartite singlet spin state, $C_{Q}(\boldsymbol{a},\boldsymbol{b})$, is derived on the basis of a probability distribution $\rho(\phi)$ that is generic, i. e., independent of $(\boldsymbol{a},\boldsymbol{b})$. In line with a previous result obtained within the framework of the quantum formalism, the probability space is partitioned according to the sign of the product $A=\alpha\beta$ of the individual spin projections $\alpha$ and $\beta$ onto $\boldsymbol{a}$ and $\boldsymbol{b}$; this precludes the transfer of $\alpha$ or $\beta$ from $C_{Q}(\boldsymbol{a},\boldsymbol{b})$ to $C_{Q}(\boldsymbol{a},\boldsymbol{b’})$, for $\boldsymbol{b’}\neq\boldsymbol{b}.$ A specific physical model that reproduces the quantum spin correlation serves to validate our approach.

上午8:51 | | | Emily Adlam, Carlo Rovelli | | | quant-ph updates on arXiv.org |

Relational quantum mechanics (RQM) is an interpretation of quantum mechanics based on the idea that quantum states describe not an absolute property of a system but rather a relationship between systems. In this article, we observe that there is a tension between RQM’s naturalistic emphasis on the physicality of information and the inaccessibility of certain sorts of information in current formulations of RQM. Therefore we propose a new postulate for RQM which requires that all of the information possessed by a certain observer is stored in physical variables of that observer and thus accessible by measurement to other observers, so observers can reach intersubjective agreement about quantum events which have occurred in the past. Based on this postulate, we suggest an ontology for RQM which upholds the principle that quantum states are always relational, but which also postulates a set of quantum events which are not strictly relational. We show that the new postulate helps address some existing objections to RQM and finally we address the Frauchiger-Renner experiment in the context of RQM.

The Fate of Causal Structure under Time Reversal. (arXiv:2204.06740v1 [physics.hist-ph])

上午8:51 | | | physics.hist-ph updates on arXiv.org |

Authors: Porter Williams

What happens to the causal structure of a world when time is reversed? At first glance it seems there are two possible answers: the causal relations are reversed, or they are not. I argue that neither of these answers is correct: we should either deny that time-reversed worlds have causal relations at all, or deny that causal concepts developed in the actual world are reliable guides to the causal structure of time-reversed worlds. The first option is motivated by the instability under intervention of time-reversed dynamical evolutions. The second option is motivated by a recognition of how contingent structural features of the actual world shape, and license the application of, our causal concepts and reasoning strategies.

上午8:51 | | | physics.hist-ph updates on arXiv.org |

Authors: Porter Williams

It is often claimed that one cannot locate a notion of causation in fundamental physical theories. The reason most commonly given is that the dynamics of those theories do not support any distinction between the past and the future, and this vitiates any attempt to locate a notion of causal asymmetry — and thus of causation — in fundamental physical theories. I argue that this is incorrect: the ubiquitous generation of entanglement between quantum systems grounds a relevant asymmetry in the dynamical evolution of quantum systems. I show that by exploiting a connection between the amount of entanglement in a quantum state and the algorithmic complexity of that state, one can use recently developed tools for causal inference to identify a causal asymmetry — and a notion of causation — in the dynamical evolution of quantum systems. https://doi.org/10.1007/s10701-022-00562-0

Moir\’e Gravity and Cosmology. (arXiv:2204.06574v1 [hep-th])

上午8:50 | | | gr-qc updates on arXiv.org |

Authors: Alireza Parhizkar, Victor Galitski

The vacuum catastrophe is a fundamental puzzle, where the observed scales of the cosmological constant are many orders of magnitude smaller than the natural scales expected in the theory. This work proposes a new “bi-world” construction that may offer an insight into the cosmological constant problem. The model includes a (3+1)-dimensional manifold with two different geometries and matter fields residing on them. The diffeomorphism invariance and causality highly constrain the two metrics to be conformally related, $\eta_{\mu \nu} = \phi^2 g_{\mu \nu}$. This reduces the theory to a standard single-world description, but introduces a new inherently geometrical “moir\’e field,” $\phi$. Interestingly, the moir\’e field has the character of both a dilaton and Higgs field familiar in the conventional theory. Integrating out the moir\’e field naturally gives rise to the Starobinsky action and inflationary dynamics. In the framework of the Friedmann-Lemaitre-Robertson-Walker solution, we reduce an effective action for the moir\’e field to that of a particle moving in a Mexican hat potential. The equations of motion are then solved numerically and the moir\’e field is shown to approach a Mexican-hat minimum in an oscillatory fashion, which is accompanied by the decay of the Hubble parameter. Under additional reasonable assumptions, the vacuum energy asymptotically approaches zero in the end of inflationary evolution. The physics presented here shares similarities with the moir\’e phenomena in condensed matter and elsewhere, where two similar structures superimposed upon give rise to a superstructure with low emergent energy scales compared to the native theories.

上午8:50 | | | gr-qc updates on arXiv.org |

Authors: Souvik Pramanik

We have developed a proper path integral formalism consistent with the deformed version of the quantum mechanics which contains a maximum observable length scale at the order of the Cosmological particle horizon, existing in cosmology. First, we have presented the modifications to the classical mechanics which shows non-minimal effects on the equation of motion of a particle. Next, we have provided representation of the deformed quantum mechanical algebra. With this algebra in hand, we have calculated the general form of the path integral propagator in this deformed background. Finally, as a most simple case, we have built up the explicit form of the free particle propagator. The modifications to the free particle propagator shows some non-trivial effects in this case, which can have some important significance.

Gravitational wave memory and its tail in cosmology. (arXiv:2204.06981v1 [gr-qc])

上午8:50 | | | gr-qc updates on arXiv.org |

Authors: Niko Jokela, K. Kajantie, Miika Sarkkinen

We study gravitational wave memory effect in the FRW cosmological model with matter and cosmological constant. Since the background is curved, gravitational radiation develops a tail part arriving after the main signal that travels along the past light cone of the observer. First we discuss first order gravitational wave sourced by a binary system, and find that the tail only gives a negligible memory, in accord with previous results. Then we study the nonlinear memory effect coming from induced gravitational radiation sourced by first order gravitational radiation propagating over cosmological distances. In the light cone part of the induced gravitational wave we find a novel term missed in previous studies of the cosmological memory effect. Furthermore, we show that the induced gravitational wave has a tail part that slowly accumulates after the light cone part has passed and grows to a sizeable magnitude over a cosmological timescale. This tail part of the memory effect will be a new component in the stochastic gravitational wave background.

Gauge Theories of Gravitation. (arXiv:1210.3775v4 [gr-qc] UPDATED)

上午8:50 | | | gr-qc updates on arXiv.org |

Authors: Milutin Blagojević, Friedrich W. Hehl

During the last five decades, gravity, as one of the fundamental forces of nature, has been formulated as a gauge theory of the Weyl-Cartan-Yang-Mills type. The present text offers commentaries on the articles from the most prominent proponents of the theory. In the early 1960s, the gauge idea was successfully applied to the Poincar\’e group of spacetime symmetries and to the related conserved energy-momentum and angular momentum currents. The resulting theory, the Poincar\’e gauge theory, encompasses Einstein’s general relativity as well as the teleparallel theory of gravity as subcases. The spacetime structure is enriched by Cartan’s torsion, and the new theory can accommodate fermionic matter and its spin in a perfectly natural way. This guided tour starts from special relativity and leads, in its first part, to general relativity and its gauge type extensions \`a la Weyl and Cartan. Subsequent stopping points are the theories of Yang-Mills and Utiyama and, as a particular vantage point, the theory of Sciama and Kibble. Later, the Poincar\’e gauge theory and its generalizations are explored and special topics, such as its Hamiltonian formulation and exact solutions, are studied. This guide to the literature on classical gauge theories of gravity is intended to be a stimulating introduction to the subject.

Emergence and Breaking of Duality Symmetry in Generalized Fundamental Thermodynamic Relations

2022年4月15日 星期五 下午6:00 | | | Zhiyue Lu and Hong Qian | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Zhiyue Lu and Hong Qian

Thermodynamics as limiting behaviors of statistics is generalized to arbitrary systems with probability *a priori* where the thermodynamic infinite-size limit is replaced by a multiple-measurement limit. A duality symmetry between Massieu’s and Gibbs’s entropy arises in the limit of infinitely repeate…

[Phys. Rev. Lett. 128, 150603] Published Fri Apr 15, 2022

Thermal superconducting quantum interference proximity transistor

2022年4月14日 星期四 上午8:00 | | | Francesco Giazotto | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 14 April 2022; doi:10.1038/s41567-022-01578-z

Heat transport in electronic systems is influenced by nearby superconductors due to the so-called proximity effect. Combining this with the manipulation of superconductivity using magnetic fields enables the control of nanoscale thermal transport.

Arithmetic logical Irreversibility and the Turing’s Halt Problem

2022年4月13日 星期三 上午4:19 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Lapin, Yair (2021) Arithmetic logical Irreversibility and the Turing’s Halt Problem. [Preprint]

Maximal Speed for Macroscopic Particle Transport in the Bose-Hubbard Model

2022年4月12日 星期二 下午6:00 | | | Jérémy Faupin, Marius Lemm, and Israel Michael Sigal | | | PRL: General Physics: Statistical and Quantum Mechanics, Quantum Information, etc. |

Author(s): Jérémy Faupin, Marius Lemm, and Israel Michael Sigal

The Lieb-Robinson bound asserts the existence of a maximal propagation speed for the quantum dynamics of lattice spin systems. Such general bounds are not available for most bosonic lattice gases due to their unbounded local interactions. Here we establish for the first time a general ballistic uppe…

[Phys. Rev. Lett. 128, 150602] Published Tue Apr 12, 2022

No free lunch for Schrödinger’s cat

2022年4月12日 星期二 上午8:00 | | | Richard Brierley | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 12 April 2022; doi:10.1038/s41567-022-01593-0

No free lunch for Schrödinger’s cat

On the indispensability of theoretical terms and entities

2022年4月12日 星期二 上午8:00 | | | Latest Results for Synthese |

**Abstract**

Some realists claim that theoretical entities like numbers and electrons are indispensable for describing the empirical world. Motivated by the meta-ontology of Quine, I take this claim to imply that, for some first-order theory *T* and formula \(\delta (x)\) such that \(T \vdash \exists x \delta \wedge \exists x \lnot \delta \) , where \(\delta (x)\) is intended to apply to all and only empirical entities, there is no first-order theory \(T’\) such that (a) *T* and \(T’\) describe the \(\delta \) :s in the same way, (b) \(T’ \vdash \forall x \delta \) , and (c) \(T’\) is at least as attractive as *T* in terms of other theoretical virtues. In an attempt to refute the realist claim, I try to solve the general problem of *nominalizing* *T* (with respect to \(\delta \) ), namely to find a theory \(T’\) satisfying conditions (a)–(c) under various precisifications thereof. In particular, I note that condition (a) can be understood either in terms of syntactic or semantic equivalence, where the latter is strictly stronger than the former. The results are somewhat mixed. On the positive side, even under the stronger precisification of (a), I establish that (1) if the vocabulary of *T* is finite, a nominalizing theory can always be found that is recursive if *T* is, and (2) if *T* postulates infinitely many \(\delta \) :s, a nominalizing theory can always be found that is no more computationally complex than *T*. On the negative side, even under the weaker precisification of (a), I establish that (3) certain finite theories cannot be nominalized by a finite theory.

The a-theory of time, temporal passage, and comprehensiveness

2022年4月11日 星期一 上午8:00 | | | Latest Results for Synthese |

**Abstract**

It has been argued recently that one major difficulty facing the A-theory of time consists in the view’s failure to provide a satisfactory account of the passage of time. Critics have objected that this particular charge is premised on an unduly strong conception of temporal passage, and that the argument does not go through on alternative, less demanding conceptions of passage. The resulting dialectical stalemate threatens to prove intractable, given the notorious elusiveness of the notion of temporal passage. Here I argue that there is progress to be made in this regard. The argument from passage takes issue with a certain feature of the standard versions of the A-theory that is in fact problematic independently of worries about temporal passage. To illustrate this, I present a new argument, the argument from comprehensiveness, which demonstrates that the standard A-theoretic account of temporal reality is inadequate, even if it is granted that it can accommodate passage.

Where Does General Relativity Break Down?

2022年4月11日 星期一 上午6:39 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Weatherall, James Owen (2022) Where Does General Relativity Break Down? [Preprint]

A Conjecture on the Origin of Superselection Rules – with a Comment on “The Global Phase Is Real”

2022年4月11日 星期一 上午6:38 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2022) A Conjecture on the Origin of Superselection Rules – with a Comment on “The Global Phase Is Real”. [Preprint]

Two Approaches to Reduction: A Case Study from Statistical Mechanics

2022年4月11日 星期一 上午6:36 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Guo, Bixin (2020) Two Approaches to Reduction: A Case Study from Statistical Mechanics. [Preprint]

Quantum spatial superpositions and the possibility of superluminal signaling

2022年4月11日 星期一 上午6:33 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Ávila, Partricio and Okon, Elias and Sudarsky, Daniel and Wiedemann, Martín (2022) Quantum spatial superpositions and the possibility of superluminal signaling. [Preprint]

]]>上午9:17 | | | Michael te Vrugt, Tobias Frohoff-Hülsmann, Eyal Heifetz, Uwe Thiele, Raphael Wittkowski | | | quant-ph updates on arXiv.org |

Field theories for the one-body density of an active fluid, such as the paradigmatic active model B+, are simple yet very powerful tools for describing phenomena such as motility-induced phase separation. No comparable theory has been derived yet for the underdamped case. In this work, we introduce active model I+, an extension of active model B+ to particles with inertia. The governing equations of active model I+ are systematically derived from the microscopic Langevin equations. We show that, for underdamped active particles, thermodynamic and mechanical definitions of the velocity field no longer coincide and that the density-dependent swimming speed plays the role of an effective viscosity. Moreover, active model I+ contains the Schr\”odinger equation in Madelung form as a limiting case, allowing to find analoga of the quantum-mechanical tunnel effect and of fuzzy dark matter in the active fluid. We investigate the active tunnel effect analytically and via numerical continuation.

New Directions in the Search for Dark Matter. (arXiv:2204.03085v1 [hep-ph])

上午9:17 | | | Surjeet Rajendran | | | quant-ph updates on arXiv.org |

The identification of the nature of dark matter is one of the most important problems confronting particle physics. Current observational constraints permit the mass of the dark matter to range from $10^{-22}$ eV – $10^{48}$ GeV. Given the weak nature of these bounds and the ease with which dark matter models can be constructed, it is clear that the problem can only be solved experimentally. In these lectures, I discuss methods to experimentally probe a wide range of dark matter candidates.

Non-universality of free fall in quantum theory. (arXiv:2204.03279v1 [gr-qc])

上午9:17 | | | Viacheslav A. Emelyanov | | | quant-ph updates on arXiv.org |

We show by respecting the Einstein equivalence principle and general covariance in quantum theory that wave-function spreading rules out universality of free fall, and vice versa. Assuming the former is more fundamental than the latter, we gain a quantitative estimate of the free-fall non-universality, which turns out to be empirically testable in atom interferometry.

Is the dynamical quantum Cheshire cat detectable?. (arXiv:2204.03374v1 [quant-ph])

上午9:17 | | | Jonte R. Hance, James Ladyman, John Rarity | | | quant-ph updates on arXiv.org |

We explore how one might detect the dynamical quantum Cheshire cat proposed by Aharonov et al. We show that, in practice, we need to bias the initial state by adding/subtracting a small probability amplitude (`field’) of the orthogonal state, which travels with the disembodied property, to make the effect detectable (i.e. if our initial state is $|\uparrow_z\rangle$, we need to bias this with some small amount $\delta$ of state $|\downarrow_z\rangle$). This biasing, which can be done either directly or via weakly entangling the state with a pointer, effectively provides a phase reference with which we can measure the evolution of the state. The outcome can then be measured as a small probability difference in detections in a mutually unbiased basis, proportional to this biasing $\delta$. We show this is different from counterfactual communication, which provably does not require any probe field to travel between sender Bob and receiver Alice for communication. We further suggest an optical polarisation experiment where these phenomena might be demonstrated in a laboratory.

Is the dynamical quantum Cheshire cat detectable?. (arXiv:2204.03374v1 [quant-ph])

上午9:17 | | | physics.hist-ph updates on arXiv.org |

Authors: Jonte R. Hance, James Ladyman, John Rarity

We explore how one might detect the dynamical quantum Cheshire cat proposed by Aharonov et al. We show that, in practice, we need to bias the initial state by adding/subtracting a small probability amplitude (`field’) of the orthogonal state, which travels with the disembodied property, to make the effect detectable (i.e. if our initial state is $|\uparrow_z\rangle$, we need to bias this with some small amount $\delta$ of state $|\downarrow_z\rangle$). This biasing, which can be done either directly or via weakly entangling the state with a pointer, effectively provides a phase reference with which we can measure the evolution of the state. The outcome can then be measured as a small probability difference in detections in a mutually unbiased basis, proportional to this biasing $\delta$. We show this is different from counterfactual communication, which provably does not require any probe field to travel between sender Bob and receiver Alice for communication. We further suggest an optical polarisation experiment where these phenomena might be demonstrated in a laboratory.

上午9:17 | | | physics.hist-ph updates on arXiv.org |

Authors: Johannes Falk, Edwin Eichler, Katja Windt, Marc-Thorsten Hütt

The rich body of physical theories defines the foundation of our understanding of the world. Its mathematical formulation is based on classical Aristotelian (binary) logic. In the philosophy of science the ambiguities, paradoxes, and the possibility of subjective interpretations of facts have challenged binary logic, leading, among other developments, to Gotthard G\”unther’s theory of polycontexturality (often also termed ‘transclassical logic’). G\”unther’s theory explains how observers with subjective perception can become aware of their own subjectivity and provides means to describe contradicting or even paradox observations in a logically sound formalism. Here we summarize the formalism behind G\”unther’s theory and apply it to two well-known examples from physics where different observers operate in distinct and only locally valid logical systems. Using polycontextural logic we show how the emerging awareness of these limitations of logical systems entails the design of mathematical transformations, which then become an integral part of the theory. In our view, this approach offers a novel perspective on the structure of physical theories and, at the same time, emphasizes the relevance of the theory of polycontexturality in modern sciences.

Time Evolution in Quantum Cosmology. (arXiv:2204.03043v1 [gr-qc])

上午9:17 | | | gr-qc updates on arXiv.org |

Authors: Anne-Katherine Burns, David E. Kaplan, Tom Melia, Surjeet Rajendran

The quantum description of time evolution in non-linear gravitational systems such as cosmological space-times is not well understood. We show, in the simplified setting of mini-superspace, that time evolution of this system can be obtained using a gauge fixed path integral, as long as one does not integrate over proper time. Using this gauge fixed action we can construct a Hamiltonian in the coherent – or classical – state basis. We show that by construction the coherent states satisfy the classical dynamical equations of General Relativity. They do not satisfy the Hamiltonian constraint. A consequence of this is that the Wheeler-DeWitt equation should not be satisfied in quantum gravity. Classical states have a natural non-trivial time evolution since they are not eigenstates of the Hamiltonian. A general feature of the unconstrained quantum theory of gravity is the prediction of a pressureless dark matter component of either sign energy density in the classical universe which may lead to novel phenomenology.

The Structuralist Approach to Underdetermination

2022年4月8日 星期五 上午4:06 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Lee, Chanwoo (2022) The Structuralist Approach to Underdetermination. [Preprint]

What is it like to be a chimpanzee?

2022年4月6日 星期三 上午8:00 | | | Latest Results for Synthese |

**Abstract**

Chimpanzees and humans are close evolutionary relatives who behave in many of the same ways based on a similar type of agentive organization. To what degree do they experience the world in similar ways as well? Using contemporary research in evolutionarily biology and animal cognition, I explicitly compare the kinds of experience the two species of capable of having. I conclude that chimpanzees’ experience of the world, their experiential niche as I call it, is: (i) intentional in basically the same way as humans’; (ii) rational in the sense that it is self-critical and operates with logically structured causal and intentional inferences; but (iii) not normative at all in that it does not operate with “objective” evaluative standards. Scientific data do not answer philosophical questions, but they provide rich raw material for scientists and philosophers alike to reflect on and clarify fundamental psychological concepts.

]]>上午9:20 | | | Sebastian Horvat, Borivoje Dakić | | | quant-ph updates on arXiv.org |

Suppose that Alice stumbles upon a box containing some confidential information and wishes to read out the latter. The problem is that the box is practically unbreakable and the information is so encoded as not to leave any physical trace in the environment, thereby leaving Alice with apparently no means of gathering the information. While the information is per assumption inaccessible classically, we show that it can be read out almost perfectly within quantum mechanics. Interestingly, the task can be accomplished only if Alice employs additional boxes, which need to be identical to the initial one in the quantum-mechanical sense. After formalizing the task we show how its solution relies on an interplay between entanglement and quantum indistinguishability. We also discuss the broader merit of our findings, thereby pointing out their relevance for quantum information processing.

We cannot believe we overlooked these Majorana discoveries. (arXiv:2203.17060v1 [cond-mat.mes-hall])

上午9:20 | | | Sergey Frolov, Vincent Mourik | | | quant-ph updates on arXiv.org |

In 2011-2012 we performed experiments on hybrid superconductor-semiconductor nanowire devices which yielded signatures of Majorana fermions based on zero-bias peaks in tunneling measurements. The research field that grew out of those findings and other contemporary works has advanced significantly, and a lot of new knowledge and insights were gained. However, key smoking gun evidence of Majorana is still lacking. In this paper, we report that while reviewing our old data recently, armed with a decade of knowledge, we realized that back in 2012 our results contained two breakthrough Majorana discoveries. Specifically, we have observed quantized zero-bias peaks, the hallmark of ideal Majorana states. Furthermore, we have observed the closing and re-opening of the induced gap perfectly correlated with the emergence of the zero-bias peak – clear evidence of the topological quantum phase superconducting transition. These insights should pave the way to topological Majorana qubits, and you should also check supplementary information for important disclosures.

上午9:20 | | | Maurice de Gosson | | | quant-ph updates on arXiv.org |

We emphasize in these pedagogical notes the that the theory of the Radon transform and its applications is best understood using the theory of the metaplectic group and the quadratic Fourier transforms generating metaplectic operator.. Doing this we hope that these notes will be useful to a larger audience, including researchers in time-frequency analysis.

On free fall of quantum matter. (arXiv:2110.10056v2 [hep-th] UPDATED)

上午9:20 | | | Viacheslav A. Emelyanov | | | quant-ph updates on arXiv.org |

We propose an approach that allows to systematically take into account gravity in quantum particle physics. It is based on quantum field theory and the general principle of relativity. These are used to build a model for quantum particles in curved spacetime. We compute by its means a deviation from a classical geodesic in the Earth’s gravitational field. This shows that free fall depends on quantum-matter properties. Specifically, we find that the free-fall universality and the wave-packet spreading are mutually exclusive phenomena. We then estimate the E\”{o}tv\”{o}s parameter for a pair of atoms freely falling near the Earth’s surface, provided that the wave-packet spreading is more fundamental than the weak equivalence principle.

上午9:20 | | | Daniel Reiche, Francesco Intravaia, Kurt Busch | | | quant-ph updates on arXiv.org |

When two or more objects move relative to one another in vacuum, they experience a drag force which, at zero temperature, usually goes under the name of quantum friction. This contactless non-conservative interaction is mediated by the fluctuations of the material-modified quantum electrodynamic vacuum and, hence, is purely quantum in nature. Numerous investigations have revealed the richness of the mechanisms at work, thereby stimulating novel theoretical and experimental approaches and identifying challenges as well as opportunities. In this article, we provide an overview of the physics surrounding quantum friction and a perspective on recent developments.

Can quantum mechanics breed negative masses?. (arXiv:2112.08881v2 [gr-qc] CROSS LISTED)

上午9:20 | | | Bruno Arderucio Costa, George E. A. Matsas | | | quant-ph updates on arXiv.org |

The Casimir effect realizes the existence of static negative energy densities in quantum field theory. We establish physically reasonable conditions for the non-negativity of the total mass of a Casimir apparatus held in equilibrium in the Minkowski background, irrespectively of any condensed matter consideration. Specifically, the dynamical equilibrium requires the presence of additional matter to hold the system apart. As long as this extra matter satisfies the dominant energy condition, the mass of the combined system is positive. Thus, the very same reason why energy cannot travel backwards in time could be the underlying mechanism behind the positivity of the mass. We discuss the takeaways from the Casimir setting to more general circumstances.

上午9:20 | | | Marian Kupczynski | | | quant-ph updates on arXiv.org |

Bell inequalities may only be derived, if hidden variables do not depend on the experimental settings. The stochastic independence of hidden and setting variables is called: freedom of choice, free will, measurement independence or no conspiracy. By imbedding the Bell causal structure in a larger causal network the authors correctly prove, that one can explain and quantify possible violation of measurement independence without evoking the super-determinism. They assume the independence of the variables that causally determine the settings and investigate how they might become correlated with hidden variables. Using their extended causal networks they derive a contextual probabilistic model on which their further correct results are based. The authors seem to ignore that contextual probabilistic model may be derived directly using only probabilistic concepts and incorporating correctly setting dependent variables describing measuring instruments. In these contextual probabilistic models experimenters freedom of choice is not compromised and the results of Bell Tests including an apparent violation of Einsteinian nonsignaling may be explained in a locally causal way. Talking about freedom of choice is misleading and is rooted in incorrect understanding of Bayes Theorem. We explain why freedom of choice should be called noncontextuality and why its violation in Bell Tests confirms only the contextual character of quantum observables. Therefore, contextuality and not experimenters freedom of choice are important resources in quantum information.

Distillation of Indistinguishable Photons. (arXiv:2203.15197v2 [quant-ph] UPDATED)

上午9:20 | | | Jeffrey Marshall | | | quant-ph updates on arXiv.org |

A reliable source of identical (indistinguishable) photons is a prerequisite for exploiting interference effects, which is a necessary component for linear optical based quantum computing, and applications thereof such as Boson sampling. Generally speaking, the degree of distinguishability will determine the efficacy of the particular approach, for example by limiting the fidelity of constructed resource states, or reducing the complexity of an optical circuits output distribution. It is therefore of great practical relevance to engineer sources of highly indistinguishable photons. Inspired by magic state distillation, we present a protocol using standard linear optics (such as beamsplitters) which can be used to increase the indistinguishability of a photon source, to arbitrary accuracy. In particular, in the asymptotic limit of small error, we show that using 9 (16) photons one can distill a single purer photon, with error decreasing by 1/3 (1/4) per iteration. We demonstrate the scheme is robust to detection errors (such as dark counts) to second order.

Comparing constellations across cultures. (arXiv:2203.16649v1 [physics.hist-ph])

上午9:20 | | | physics.hist-ph updates on arXiv.org |

Authors: Charles Kemp, Duane W Hamacher, Daniel R Little, Simon J Cropper

Cultural astronomy reveals ways in which perception and culture have shaped the interpretation of the night sky.

Contemplating the fate of modified gravity. (arXiv:2203.16610v1 [gr-qc])

上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Alexey Golovnev, Maria-Jose Guzman

Possible models of modified gravity are being extensively studied now, with most phenomenological motivations coming from puzzles and tensions in cosmology with a natural desire to better fit the known and newly coming data. At the same time, available experimental evidence is limited for testing gravity as a force, beyond the regimes in which the theory of general relativity has proven to be successful. This situation leads researchers to look for “the simplest modification” to general relativity, in a certain class of models, that is enough to solve one or more problems. As a result, we are lost amidst a variety of theories with no deeper guiding principle. In this essay, we openly discuss these problems, and propose some ideas on how to go.

Observable vacuum energy is finite in expanding space. (arXiv:2203.16753v1 [gr-qc])

上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Csaba Balazs

In this work I reason that in expanding space only those quantum modes contribute to the measured vacuum energy that do not transcend the observable volume. Since all quantised field modes have various observable consequences, when a gravitational horizon causally confines an observer to a finite volume quantised modes should be restricted to the observable patch to remain consistent with gravity.

Within the observable patch of Friedmann-Lemaitre-Robertson-Walker (FLRW) space the vacuum expectation value of the energy-momentum tensor can be expressed as a sum over discrete field modes. Friedmann’s first equation provides a straightforward ultraviolet cut-off allowing only a finite number of modes in the sum. The finite volume acts as an infrared regulator and the calculation of the vacuum energy density is tractable without regularisation and renormalisation.

To test the validity of this idea I quantise a scalar field on an FLRW background and calculate its vacuum energy density in the vacuum dominated, conformal, holographic limit. In this limit I show that the quantum vacuum energy density scales with the square of the Hubble parameter, consistently with gravity. In this example quantum vacuum expands space while the horizon of the expanding space limits the energy density of the vacuum to the observed value.

Gravitizing the Quantum. (arXiv:2203.17137v1 [gr-qc])

上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Per Berglund, Tristan Hübsch, David Mattingly, Djordje Minic

We discuss a new approach to the problem of quantum gravity in which the quantum mechanical structures that are traditionally fixed, such as the Fubini-Study metric in the Hilbert space of states, become dynamical and so implement the idea of gravitizing the quantum. In particular, in this formulation of quantum gravity the quantum geometry is still consistent with the principles of unitarity and also captures fundamental aspects of (quantum) gravity, such as topology change. Furthermore, we address specific ways of testing this new approach to quantum gravity by utilizing multi-path interference and optical lattice atomic clocks.

Microscopic black holes as probes for quantum gravity. (arXiv:2203.12332v2 [gr-qc] UPDATED)

上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Samuel Kováčik

One of the main goals of contemporary theoretical physics is to find the quantum theory of gravity. There are various working hypotheses, mostly operating in the regime of high-energy physics well above the reach of particle accelerators. So far, strong experimental or observational evidence to guide the theory is missing. A possible consequence of quantum gravity and quantum spacetime that is often discussed is the vacuum dispersion effect. In this paper, we consider a different line of quantum space phenomenology, the behaviour of microscopic black holes. Even though their exact nature is unknown, some of their features are very model-independent, allowing us to draw conclusions about their role in the current cosmological models.

Singularity resolution in gravitational collapse. (arXiv:2110.07343v3 [gr-qc] UPDATED)

上午9:20 | | | gr-qc updates on arXiv.org |

Authors: Karim Mosani, Dipanjan Dey, Kaushik Bhattacharya, Pankaj S. Joshi

We investigate the unhindered gravitational collapse of a homogeneous scalar field with nonzero potential, a two-dimensional analog of the Mexican hat-shaped Higgs field potential. The collapsing scalar field is surrounded by an exterior retarded (outgoing) generalized Vaidya spacetime. We prove that the density dependence on the scale factor cannot be expressed as an algebraic function in such a scenario. For a certain transcendental expression of the density of such field as a function of scale factor, we then show that the collapse evolves to a singularity at an infinite comoving time, which is equivalent to saying that the singularity is avoided altogether. An ultra high density region of the order of Planck length can, however, be reached in a finite comoving time. The absence of the formation of trapped surfaces makes this ultra high density region globally visible.

One world is (probably) just as good as many

2022年4月1日 星期五 下午4:15 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Steeger, Jer (2022) One world is (probably) just as good as many. [Preprint]

What if there are only particles in Bohmian mechanics?

2022年4月1日 星期五 下午4:15 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Gao, Shan (2022) What if there are only particles in Bohmian mechanics? [Preprint]

2022年4月1日 星期五 下午4:12 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Schroeren, David (2022) The Global Phase Is Real. [Preprint]

Invariance, Intrinsicality, and Perspicuity

2022年4月1日 星期五 下午4:11 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Jacobs, Caspar (2022) Invariance, Intrinsicality, and Perspicuity. [Preprint]

“Reverse Engineering” the de Broglie Wave

2022年4月1日 星期五 下午4:10 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Shanahan, Daniel “Reverse Engineering” the de Broglie Wave. UNSPECIFIED.

History as a Tool for Natural Science: How Ernst Mach Applied Historical Methods to Physics

2022年4月1日 星期五 下午4:10 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

ten Hagen, Sjang L. (2022) History as a Tool for Natural Science: How Ernst Mach Applied Historical Methods to Physics. Historical Studies in the Natural Sciences, 52 (1). pp. 40-79.

A pragmatist challenge to constraint laws

2022年4月1日 星期五 下午4:08 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Andersen, Holly (2018) A pragmatist challenge to constraint laws. Metascience, 27 (1). pp. 19-25. ISSN 0815-0796

Hodgson on the relations between philosophy, science and time

2022年4月1日 星期五 下午4:08 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Andersen, Holly (2022) Hodgson on the relations between philosophy, science and time. British Journal for the History of Philosophy.

2022年4月1日 星期五 下午4:07 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Landsman, Klaas (2022) Reopening the Hole Argument. [Preprint]

One world is (probably) just as good as many

2022年3月31日 星期四 上午8:00 | | | Latest Results for Synthese |

**Abstract**

One of our most sophisticated accounts of objective chance in quantum mechanics involves the Deutsch–Wallace theorem, which uses state-space symmetries to justify agents’ use of the Born rule when the quantum state is known. But Wallace argues that this theorem requires an Everettian approach to measurement. I find that this argument is unsound. I demonstrate a counter-example by applying the Deutsch–Wallace theorem to the de Broglie–Bohm pilot-wave theory.

Quantum Relativity without Relativism

2022年3月29日 星期二 下午4:36 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Healey, Richard (2022) Quantum Relativity without Relativism. [Preprint]

2022年3月29日 星期二 下午4:33 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

Adlam, Emily (2022) Does Science need Intersubjectivity? The Problem of Confirmation in Orthodox Interpretations of Quantum Mechanics. [Preprint]

2022年3月28日 星期一 上午8:00 | | | Igor Mazin | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 28 March 2022; doi:10.1038/s41567-022-01575-2

Scientists have long preferred the simplest possible explanation of their data. More recently, a worrying trend to favour unnecessarily complex interpretations has taken hold.

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