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Sat Nov 18 2023 05:57:12 (4 hours)
# 1.
Stamenkovic, Philippe (2023) On the (lack of) usefulness of professional philosophy of science. [Preprint]
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Michael Schirber
Fri Nov 17 2023 18:00:00 (16 hours)
# 2.
Author(s): Michael Schirber
An early-Universe spike in dark energy could resolve a disagreement between two cosmic-expansion-rate measurements, but such a spike may conflict with observations of quasar spectra.
[Physics 16, s164] Published Fri Nov 17, 2023
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| The number of fundamental constants from a spacetime-based perspective. (arXiv:2311.09249v1 [gr-qc]) |
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George E. A. Matsas, Vicente Pleitez, Alberto Saa, Daniel A. T. Vanzella
Fri Nov 17 2023 13:41:31 (20 hours)
# 3.
We revisit Duff, Okun, and Veneziano’s divergent views on the number of fundamental constants and argue that the issue can be set to rest by having spacetime as the starting point. This procedure disentangles the resolution in what depends on the assumed spacetime (whether relativistic or not) from the theories built over it. By defining that the number of fundamental constants equals the minimal number of independent standards necessary to express all observables, as assumed by Duff, Okun, and Veneziano, it is shown that the same units fixed by the apparatuses used to construct the spacetimes are enough to express all observables of the physical laws defined over them. As a result, the number of fundamental constants equals two in Galilei spacetime and one in relativistic spacetimes.
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Stefano Lepri, Roberto Livi, Stefano Ruffo
Fri Nov 17 2023 13:41:30 (20 hours)
# 4.
The year 1953 is pivotal for computational physics: the first application of the Monte-Carlo method is published and calculations of the so-called Fermi-Pasta-Ulam-Tsingou experiment are started. It is the beginning of the massive use in the physical sciences of numerical methods implemented on electronic computers and a decisive step in the development of modern nonlinear dynamics. This will lead to an unpredictable development during the following 70 years. We briefly review the unfolding of these events and present some recent results that show how the issues raised are still relevant today
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Tomi Koivisto
Fri Nov 17 2023 13:41:29 (20 hours)
# 5.
The more precise definition and the more fundamental understanding of the concepts of time, energy, entropy and information are building upon the new, relativistic foundation of gravity. This lecture is an attempt to explain the basic principles that underpin this progress, by focusing on the simple but subtle universal definition of energy. The principles are unearthed from Einstein’s theory and Noether’s theorems, beneath a century of misconceptions.
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Daniel Harlow, Tokiro Numasawa
Fri Nov 17 2023 13:41:18 (20 hours)
# 6.
Spacetime inversion symmetries such as parity and time reversal play a central role in physics, but they are usually treated as global symmetries. In quantum gravity there are no global symmetries, so any spacetime inversion symmetries must be gauge symmetries. In particular this includes $\mathcal{CRT}$ symmetry (in even dimensions usually combined with a rotation to become $\mathcal{CPT}$), which in quantum field theory is always a symmetry and seems likely to be a symmetry of quantum gravity as well. In this article we discuss what it means to gauge a spacetime inversion symmetry, and we explain some of the more unusual consequences of doing this. In particular we argue that the gauging of $\mathcal{CRT}$ is automatically implemented by the sum over topologies in the Euclidean gravity path integral, that in a closed universe the Hilbert space of quantum gravity must be a real vector space, and that in Lorentzian signature manifolds which are not time-orientable must be included as valid configurations of the theory. In particular we give an example of an asymptotically-AdS time-unorientable geometry which must be included to reproduce computable results in the dual CFT.
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Giorgio Torrieri
Fri Nov 17 2023 13:41:11 (20 hours)
# 7.
This work is divided into two parts. The first examines recent proposals for “witnessing” quantum gravity via entanglement from the point of view of Bronstein’s original objection to a quantization of gravity. Using techniques from open quantum systems we sketch how unavoidable decoherence from both inertial and gravitational backreaction between probe and detector could spoil the experimental detection of the quantization of gravity. We argue that this “failure” is actually an inherent feature of any quantum description that attempts to incorporate the equivalence principle exactly within quantum dynamics. In the second part, we speculate on how an exact realization of the equivalence principle might be implemented in an effective quantum field theory via the general covariance of correlators. While we are far from giving an explicit construction of such a theory we point out some features and consequences of such a program.
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Wed Nov 15 2023 14:52:21 (2 days)
# 8.
Del Santo, Flavio and Gisin, Nicolas (2023) Potentiality realism: A realistic and indeterministic physics based on propensities. [Preprint]
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Wed Nov 15 2023 14:50:00 (2 days)
# 9.
Stoica, Ovidiu Cristinel (2023) Asking physics about physicalism, zombies, and consciousness. [Preprint]
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Wed Nov 15 2023 14:25:50 (2 days)
# 10.
Asenjo, Felipe and Hojman, Sergio and Linnemann, Niels and Read, James (2023) Abnormal light propagation and the underdetermination of theory by evidence in astrophysics. [Preprint]
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A. E. S. Hartmann
Wed Nov 15 2023 10:32:57 (2 days)
# 11.
An integral translation of Paolo Gulmanelli’s seminar notes “Su una teoria dello spin isotopico” (Casa Editrice, Milano, 1957) is presented. This is the only exposition that contains all elements of Pauli’s attempt at a non-Abelian Kaluza-Klein theory in 1953.
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Estelle Asmodelle
Wed Nov 15 2023 10:32:56 (2 days)
# 12.
This is a contemporary review of the involvement of Mileva Maric, Albert Einsteins first wife, in his theoretical work between the period of 1900 to 1905. Separate biographies are outlined for both Mileva and Einstein, prior to their attendance at the Swiss Federal Polytechnic in Zurich in 1896. Then, a combined journal is described, detailing significant events. In additional to a biographical sketch, comments by various authors are compared and contrasted concerning two narratives: firstly, the sequence of events that happened and the couples relationship at particular times. Secondly, the contents of letters from both Einstein and Mileva. Some interpretations of the usage of pronouns in those letters during 1899 and 1905 are re-examined, and a different hypothesis regarding the usage of those pronouns is introduced. Various papers are examined and the content of each subsequent paper is compared to the work that Mileva was performing. With a different take, this treatment further suggests that the couple continued to work together much longer than other authors have indicated. We also evaluate critics and supporters of the hypothesis that Mileva was involved in Einsteins work, and refocus this within a historical context, in terms of women in science in the late 19th century. Finally, the definition of, collaboration (co-authorship, specifically) is outlined. As a result, recommendations are stated, the first of which is that Mileva should be seriously considered as an honorary co-author of one, possibly two, papers, and secondly, of which it is recommended that a serious inquiry should be made, concerning the extent of Mileva Mari\’cs involvement in Albert Einsteins published works between 1902 and 1905.
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R. E. Kastner, Andreas Schlatter
Wed Nov 15 2023 10:32:55 (2 days)
# 13.
A restricted form of Landauer’s Principle, independent of computational considerations, is shown to hold for thermal systems by reference to the joint entropy associated with conjugate observables. It is shown that the source of the compensating entropy for irreversible physical processes is due to the ontological uncertainty attending values of such mutually incompatible observables, rather than due to epistemic uncertainty as traditionally assumed in the information-theoretic approach. In particular, it is explicitly shown that erasure of logical (epistemic) information via reset operations is not equivalent to erasure of thermodynamic entropy, so that the traditional, information-theoretic form of Landauer’s Principle is not supported by the physics. A further implication of the analysis is that there is no Maxwell’s Demon in the real world.
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Martin Plávala and Matthias Kleinmann
Tue Nov 14 2023 18:00:00 (3 days)
# 14.
Author(s): Martin Plávala and Matthias Kleinmann
We show that the phase-space formulation of general probabilistic theories can be extended to include a generalized time evolution and that it can describe a nonquantum hydrogenlike system which is stable, has discrete energy levels, and includes the Zeeman effect. This allows us to study dynamical …
