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Jonte R Hance, John Rarity, James Ladyman
Fri Sep 15 2023 13:00:24 (20 hours)
# 1.
We here reply to a recent comment by Vaidman on our paper, “Weak values and the past of a quantum particle”, which we published in Physical Review Research. In his Comment, he first admits that he is just defining (assuming) the weak trace gives the presence of a particle — however, in this case, he should use a term other than presence, as this already has a separate, intuitive meaning other than “where a weak trace is”. Despite this admission, Vaidman then goes on to argue for this definition by appeal to ideas around an objectively-existing idea of presence. We show these appeals are flawed, and rely on their own conclusion — that there is always a matter of fact about the location of a quantum particle.
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T. Banks (NHETC and Dept. of Physics and Astronomy, Rutgers University)
Fri Sep 15 2023 13:00:23 (20 hours)
# 2.
We argue that no theoretical model of quantum gravity in a causal diamond whose boundary has finite maximal area, can be verified with arbitrary precision by experiments done in that diamond. This shows in particular that if our own universe remains in an asymptotically future de Sitter state for a time long enough for our local group of galaxies to collapse into a black hole, then no information processing system with which we can communicate could ever distinguish between many competing models of the AsdS universe. This article is written in an attempt to be accessible to a wide audience, so certain elementary facts about quantum mechanics are reviewed, briefly.
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Matthew Edmonds, Antonino Flachi, Marco Pasini
Fri Sep 15 2023 13:00:11 (20 hours)
# 3.
Nonlinearities in the dispersion relations associated with different interactions designs, boundary conditions and the existence of a physical cut-off scale can alter the quantum vacuum energy of a nonrelativistic system nontrivially. As a material realization of this, we consider a 1D-periodic rotating, interacting non-relativistic setup. The quantum vacuum energy of such a system is expected to comprise two contributions: a fluctuation-induced quantum contribution and a repulsive centrifugal-like term. We analyze the problem in detail within a complex Schoedinger quantum field theory with a quartic interaction potential and perform the calculations non-perturbatively in the interaction strength by exploiting the nonlinear structure of the associated nonlinear Schroedinger equation. Calculations are done in both zeta-regularization, as well as by introducing a cut-off scale. We find a generic, regularization-independent behavior, where the competition between the interaction and rotation can be balanced at some critical ring-size, where the quantum vacuum energy has a maxima and the force changes sign. The inclusion of a cut-off smoothes out the vacuum energy at small distance but leaves unaltered the long distance behavior. We discuss how this behavior can be tested with ultracold-atoms.
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Patrick Hayden, Jinzhao Wang
Fri Sep 15 2023 13:00:11 (20 hours)
# 4.
The Bekenstein bound posits a maximum entropy for matter with finite energy confined to a spacetime region. It is often interpreted as a fundamental limit on the information that can be stored by physical objects. In this work, we test this interpretation by asking whether the Bekenstein bound imposes constraints on a channel’s communication capacity, a context in which information can be given a mathematically rigorous and operationally meaningful definition. We first derive a bound on the accessible information and demonstrate that the Bekenstein bound constrains the decoding instead of the encoding. Then we study specifically the Unruh channel that describes a stationary Alice exciting different species of free scalar fields to send information to an accelerating Bob, who is therefore confined to a Rindler wedge and exposed to the noise of Unruh radiation. We show that the classical and quantum capacities of the Unruh channel obey the Bekenstein bound. In contrast, the entanglement-assisted capacity is as large as the input size even at arbitrarily high Unruh temperatures. This reflects that the Bekenstein bound can be violated if we do not properly constrain the decoding operation in accordance with the bound. We further find that the Unruh channel can transmit a significant number of zero-bits, which are communication resources that can be used as minimal substitutes for the classical/quantum bits needed for many primitive information processing protocols, such as dense coding and teleportation. We show that the Unruh channel has a large zero-bit capacity even at high temperatures, which underpins the capacity boost with entanglement assistance and allows Alice and Bob to perform quantum identification. Therefore, unlike classical bits and qubits, zero-bits and their associated information processing capability are not constrained by the Bekenstein bound.
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Fri Sep 15 2023 07:47:27 (1 day)
# 5.
Kelley, Mikayla (2023) A Contextual Accuracy Dominance Argument for Probabilism. [Preprint]
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Fri Sep 15 2023 07:37:15 (1 day)
# 6.
March, Eleanor and Wolf, William J. and Read, James (2023) On the geometric trinity of gravity, non-relativistic limits, and Maxwell gravitation. [Preprint]
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Ryan Wilkinson
Wed Sep 13 2023 18:00:00 (2 days)
# 7.
Author(s): Ryan Wilkinson
A mathematical model shows how increased intricacy of cognitive tasks can break the mirror symmetry of the brain’s neural network.
[Physics 16, s133] Published Wed Sep 13, 2023
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Robert S. Eisenberg
Wed Sep 13 2023 09:26:35 (2 days)
# 8.
Maxwell defined a ‘true’ or ‘total’ current that is quite different from the definition of current used by most scientists today. He said that “… true electric current … is not the same thing as the current of conduction but that the time variation of the electric displacement must be taken into account in estimating the total movement of electricity”. We reconcile these views and show that true current are a universal property of electrodynamics independent of properties of matter, without the approximation of a dielectric constant. The resulting Maxwell Current Law is a generalization ofKirchhoff Law of Conduction Current used in circuit analysis, but true currents need not be confined to circuits. The universal Maxwell Current Law can be applied to complex circuits as they work in our computers on nanosecond time scales. It also can be applied to the signaling systems and to mitochondria of living systems. The Maxwell Current Law clarifies flows of electrons, protons, and ions in mitochondria that generate ATP, the molecule used to store chemical energy throughout life. This approach reinterprets the classical chemiosmotic hypothesis of ATP production. The conduction current of protons in mitochondria is driven by the protonmotive force including its component electrical potential, just as in the classical chemiosmotic hypothesis. The conduction current is, however, just part of the true current of Maxwell. Maxwell’s current does not accumulate, in contrast to conduction current of protons which does accumulate. Details of accumulation do not have to be considered in analyses of true current. The treatment here allows the chemiosmotic hypothesis to take advantage of the knowledge of current flow in the physical and engineering sciences, particularly its Kirchhoff and Maxwell Current Laws. Knowing the current means knowing an important part of the mechanism of ATP synthesis.
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Wed Sep 13 2023 08:43:12 (3 days)
# 9.
Gasco, Enrico (2022) The model of thin shell in General Relativity. Proceedings of the SISFA 42nd Annual Conference. pp. 183-189.
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Wed Sep 13 2023 08:00:21 (3 days)
# 10.
Chen, Lu and Read, James (2023) Is the metric signature really electromagnetic in origin? [Preprint]
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Mark Buchanan
Mon Sep 11 2023 08:00:00 (5 days)
# 11.
Nature Physics, Published online: 11 September 2023; doi:10.1038/s41567-023-02193-2
A post-particle future
