上午9:49 | | | physics.hist-ph updates on arXiv.org |

Authors: Søren Toxvaerd

In 1687 Isaac Newton published PHILOSOPHI\AE \ NATURALIS PRINCIPIA MATHEMATICA, where the classical analytic dynamics was formulated. But Newton also formulated a discrete dynamics, which is the central difference algorithm, known as the Verlet algorithm. In fact Newton used the central difference to derive his second law. The central difference algorithm is used in computer simulations,where almost all Molecular Dynamics simulations are performed with the Verlet algorithm or other reformulations of the central difference algorithm. Here we show, that the discrete dynamics obtained by Newtons algorithm for Kepler’s equation has the same solutions as the analytic dynamics. The discrete positions of a celestial body are located on an ellipse, which is the exact solution for a shadow Hamiltonian nearby the Hamiltonian for the analytic solution.

上午9:48 | | | Julian Huber, Peter Kirton, Stefan Rotter, Peter Rabl | | | quant-ph updates on arXiv.org |

The effect of PT-symmetry breaking in coupled systems with balanced gain and loss has recently attracted considerable attention and has been demonstrated in various photonic, electrical and mechanical systems in the classical regime. Here we generalize the definition of PT symmetry to finite-dimensional open quantum systems, which are described by a Markovian master equation. Specifically, we show that the invariance of this master equation under a certain symmetry transformation implies the existence of stationary states with preserved and broken parity symmetry. As the dimension of the Hilbert space grows, the transition between these two limiting phases becomes increasingly sharp and the classically expected PT-symmetry breaking transition is recovered. This quantum-to-classical correspondence allows us to establish a common theoretical framework to identify and accurately describe PT-symmetry breaking effects in a large variety of physical systems, operated both in the classical and quantum regimes.

上午9:48 | | | T. N. Palmer | | | quant-ph updates on arXiv.org |

An arbitrarily dense discretisation of the Bloch sphere of complex Hilbert states is constructed, where points correspond to bit strings of fixed finite length. Number-theoretic properties of trigonometric functions (not part of the quantum-theoretic canon) are used to show that this constructive discretised representation incorporates many of the defining characteristics of quantum systems: completementarity, uncertainty relationships and (with a simple Cartesian product of discretised spheres) entanglement. Unlike Meyer’s earlier discretisation of the Bloch Sphere, there are no orthonormal triples, hence the Kocken-Specker theorem is not nullified. A physical interpretation of points on the discretised Bloch sphere is given in terms of ensembles of trajectories on a dynamically invariant fractal set in state space, where states of physical reality correspond to points on the invariant set. This deterministic construction provides a new way to understand the violation of the Bell inequality without violating statistical independence or factorisation, where these conditions are defined solely from states on the invariant set. In this finite representation there is an upper limit to the number of qubits that can be entangled, a property with potential experimental consequences.

上午9:48 | | | ScienceDirect Publication: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern PhysicsScienceDirect RSShttps://www.sciencedirect.com/journal/studies-in-history-and-philosophy-of-science-part-b-studies-in-history-and-philosophy-of-modern-physicsRSS for NodeWed, 24 Jul 2019 09:46:42 GMTCopyright © 2019 Elsevier Ltd. All rights reservedImprints of the underlying structure of physical theoriesPublication date: Available online 12 July 2019Source: Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern PhysicsAuthor(s): Jorge ManeroAbstractIn the context of scientific realism, this paper intends to provide a formal and accurate description of the structural-based ontology posited by classical mechanics, quantum mechanics and special relativity, which is preserved across the empirical domains of these theories and explain their successful predictions. Along the lines of ontic structural realism, such a description is undertaken by |

Publication date: Available online 6 March 2020

**Source:** Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics

Author(s): Mordehai Milgrom

上午9:48 | | | gr-qc updates on arXiv.org |

Authors: Boris Latosh

Review of the most basic issues appearing in the most conservative approaches to quantum theory of gravity is given. The most part of the review is devoted to issues of perturbative quantization based on functional integral technique. Discussion of canonical quantization program in context of quantum gravity is given. Discussion of effective field theory methods Implementation for quantum gravity is given.

上午9:48 | | | gr-qc updates on arXiv.org |

Authors: Vipin Chandra Dubey, Umesh Kumar Sharma

In this work, we use the statefinder parameter diagnostic to the Holographic principle inspired dark energy models, taking into consideration, the Tsallis Holographic dark energy (THDE) model, the standard Holographic dark energy (HDE) model, and the R$\acute{e}$nyi holographic dark energy (RHDE) model. The evolutionary behaviour of first statefinder $r(z)$, second statefinder parameter $s(z)$, the statefinder parameter pairs $(r, s)$ and $(r, q)$ as well as the deceleration parameter $q(z)$ are plotted for comparison for the various parameter values of the respective dark energy models. In the low redshift region, it is observed from these plots that the Tsallis holographic dark energy (THDE) model and R$\acute{e}$nyi holographic dark energy (RHDE) model approach to the $\Lambda$CDM model. While for the HDE model, the evolutionary behaviour can be differentiated from the $\Lambda$CDM model in the low-redshift region. For all three dark energy models, a direct comparison in $q(z)$, $r(z)$, $s(z)$, $(r, s)$ and $(r, q)$ plane have also been done, in which the discrimination between these three models with the $\Lambda$CDM model) may be easily seen.

上午9:48 | | | gr-qc updates on arXiv.org |

Authors: Wan Mohamad Husni Wan Mokhtar

It is well known that a receding mirror in Minkowski spacetime can model the formation of a black hole, producing Hawking-like radiation at late times. We ask what an observer would need to do to discern whether the radiation is fermionic or bosonic. Specialising to massless fields in 1+1 dimensions, we find that an Unruh-DeWitt detector accomplishes this: the late time transition rate of a detector coupled linearly to the scalar density of a spinor field is proportional to the Helmholtz free energy density of a fermionic thermal bath, hence showing a clear sign of Fermi-Dirac statistics, with no counterpart in the response of a detector coupled linearly to a scalar field or its derivative. By contrast, an observer examining just the stress-energy tensor sees no difference between a fermion and a boson, neither at late times nor early.

2020年3月6日 星期五 下午5:34 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

2020年3月6日 星期五 上午8:00 | | | Latest Results for Synthese |

### Abstract

Integration information theories posit that the integration of information is necessary and/or sufficient for consciousness. In this paper, we focus on three of the most prominent information integration theories: Information Integration Theory (IIT), Global Workspace Theory (GWT), and Attended Intermediate-Level Theory (AIR). We begin by explicating each theory and key concepts they utilize (e.g., information, integration, etc.). We then argue that the current evidence indicates that the integration of information (as specified by each of the theories) is neither necessary nor sufficient for consciousness. Unlike GWT and AIR, IIT maintains that conscious experience is both necessary and sufficient for consciousness. We present empirical evidence indicating that simple features are experienced in the absence of feature integration and argue that it challenges IIT’s necessity claim. In addition, we challenge IIT’s sufficiency claim by presenting evidence from hemineglect cases and amodal completion indicating that contents may be integrated and yet fail to give rise to subjective experience. Moreover, we present empirical evidence from subjects with frontal lesions who are unable to carry out simple instructions (despite appearing to understand their meaning) and argue that they are irreconcilable with GWT. Lastly, we argue that empirical evidence indicating that patients with visual agnosia fail to identify objects they report being conscious of present a challenge to AIR’s necessity claim.

2020年3月6日 星期五 上午8:00 | | | Nina Meinzer | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 06 March 2020; doi:10.1038/s41567-020-0850-8

To see a quantum bird

2020年3月5日 星期四 下午2:36 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

2020年3月5日 星期四 下午2:16 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

2020年3月5日 星期四 上午9:17 | | | physics.hist-ph updates on arXiv.org |

Authors: Flavio Del Santo

Karl Popper published, in 1968, a paper that allegedly found a flaw in a very influential article of Birkhoff and von Neumann, which pioneered the field of “quantum logic”. Nevertheless, nobody rebutted Popper’s criticism in print for several years. This has been called in the historiographical literature an “unsolved historical issue”. Although Popper’s proposal turned out to be merely based on misinterpretations and was eventually abandoned by the author himself, this paper aims at providing a resolution to such historical open issues. I show that (i) Popper’s paper was just the tip of an iceberg of a much vaster campaign conducted by Popper against quantum logic (which encompassed several more unpublished papers that I retrieved); and (ii) that Popper’s paper stimulated a heated debate that remained however confined within private correspondence.

2020年3月4日 星期三 下午4:25 | | | Philsci-Archive: No conditions. Results ordered -Date Deposited. |

2020年3月2日 星期一 上午8:00 | | | J. M. Raimond | | | Nature Physics – Issue – nature.com science feeds |

Nature Physics, Published online: 02 March 2020; doi:10.1038/s41567-020-0812-1

This article puts in perspective the relationship between cavity and circuit quantum electrodynamics, two related approaches for studying the fundamental quantum interaction between light and matter.

2020年3月2日 星期一 上午8:00 | | | Latest Results for Synthese |

2020年3月2日 星期一 上午8:00 | | | Latest Results for Synthese |

### Abstract

According to Humeanism about the laws, the laws of nature are nothing over and above certain kinds of regularities about particular facts (the “Humean mosaic”). Humeanism has often been accused of circularity: according to scientific practice laws often explain their instances, but on the Humean view they also reduce to the mosaic, which includes those instances. In this paper I formulate the circularity problem in a way that avoids a number of controversial assumptions routinely taken for granted in the literature, and against which many extant responses are therefore ineffective. I then propose a solution that denies the alleged Humean commitment that laws are explained by their instances. The solution satisfies three desiderata that other solutions don’t: it provides independent motivation against the idea that Humean laws are explained by their instances; it specifies the sense in which Humean laws are nonetheless “nothing over and above” their instances; and it gives an alternative account of what *does* explain the laws, if not their instances. This solution, I will argue, is not only the simplest but also the oldest one: it appeals only to tools and theses whose first appearance predates the earliest statements of the circularity problem itself.

2020年3月2日 星期一 上午8:00 | | | Latest Results for Foundations of Physics |

### Abstract

We show that the big bang is a coordinate singularity for a large class of \(k = -1\) inflationary FLRW spacetimes which we have dubbed ‘Milne-like.’ By introducing a new set of coordinates, the big bang appears as a past boundary of the universe where the metric is no longer degenerate—a result which has already been investigated in the context of vacuum decay (Coleman and De Luccia in Phys Rev D 21:3305–3315, 1980). We generalize their results and approach the problem from a more mathematical perspective. Similar to how investigating the geometrical properties of the \(r = 2m\) event horizon in Schwarzschild led to a better understanding of black holes, we believe that investigating the geometrical properties of the big bang coordinate singularity for Milne-like spacetimes could lead to a better understanding of cosmology. We show how the mathematics of these spacetimes may help illuminate certain issues associated with dark energy, dark matter, and the universe’s missing antimatter.