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Bruno Arderucio Costa, Yuri Bonder
Fri Sep 22 2023 09:55:02 (23 hours)
# 1.
We study the physical effects of torsion as predicted by the Einstein-Cartan theory in the test particle approximation and the non-relativist limit. We first present the corresponding non-relativistic Hamiltonian for a 2-spinor. Then, we solve an idealized reflection and transmission problem for a non-relativistic spin-$\frac{1}{2}$ beam travelling across a spin-polarized target. We identify deviations in the spin polarizations of the reflected and transmitted as observables capable of distinguishing Einstein-Cartan from standard general relativity. If measured, this effect would constitute compelling evidence for the presence of spacetime torsion.
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Hansol Noh, Paul M. Alsing, Warner A. Miller, Doyeol Ahn
Fri Sep 22 2023 09:54:48 (23 hours)
# 2.
The fundamental theories of general relativity and quantum mechanics are incompatible, presenting a significant theoretical challenge. General relativity offers an effective description of gravity and large-scale dynamics, while quantum mechanics describes phenomena for atomic- to Planck-scale. The Wigner rotation angle (WRA) of a photon induced by gravity, where relativistic effects become observable in its quantum spin state, is a significant point of interest as a promising candidate for direct observation near Earth by considering its small but measurable order. In this paper, we reveal that the momentum-dependent WRA displays a non-reciprocal characteristic. This distinct behavior leads to a measurable relative WRA difference between two paths of an interferometer within the Earth’s gravitational field, while the WRA of a photon has conventionally been viewed as having a trivial value on a closed loop. Building on this finding, we propose an experiment that can be used to test the theoretical framework of the WRA induced in curved spacetime through the use of the Hong-Ou-Mandel (HOM) quantum interference effect for photons in near-Earth orbits. We show that in our proposed experiment the coincident photon counting rate depends on the difference of the momentum-dependent WRA in the two arms of an interferometer.
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Jens Chluba, Luke Hart
Fri Sep 22 2023 09:54:47 (23 hours)
# 3.
Fundamental physical constants need not be constant, neither spatially nor temporally. — This seeming simple statement has profound implications for a wide range of physical processes and interactions, and can be probed through a number of observations. In this chapter, we highlight how CMB measurements can constrain variations of the fine-structure constant and the electron rest mass during the cosmological recombination era. The sensitivity of the CMB anisotropies to these constants arises because they directly affect the cosmic ionization history and Thomson scattering rate, with a number of subtle atomic physics effects coming together. Recent studies have revealed that variations of the electron rest mass can indeed alleviate the Hubble tension, as we explain here. Future opportunities through measurements of the cosmological recombination radiation are briefly mentioned, highlighting how these could provide an exciting avenue towards uncovering the physical origin of the Hubble tension experimentally.
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Wed Sep 20 2023 23:35:28 (2 days)
# 4.
Weinstein, Galina (2023) Reframing the Event Horizon: The Harlow-Hayden Computational Approach to the Firewall Paradox. [Preprint]
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Wed Sep 20 2023 23:28:46 (2 days)
# 5.
Andersen, Holly (2023) Every View is a View From Somewhere: Pragmatist Laws and Possibility. [Preprint]
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Katherine Wright
Wed Sep 20 2023 18:00:00 (2 days)
# 6.
Author(s): Katherine Wright
The concurrent analysis of two measurements of a biochemical signaling network can provide more information than two separate probes of the datasets.
[Physics 16, s138] Published Wed Sep 20, 2023
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Tue Sep 19 2023 04:42:30 (4 days)
# 7.
Fay, Jonathan (2023) Mach’s Principle and Mach’s Hypotheses. [Preprint]
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Tue Sep 19 2023 04:38:11 (4 days)
# 8.
Van Strien, Marij (2023) Why Bohm was never a determinist. [Preprint]
