Weekly Papers on Quantum Foundations (9)

Determining the difference between local acceleration and local gravity: applications of the equivalence principle to relativistic trajectories 

from gr-qc by Steven A. BalbusFri Mar 08 2024 12:30:03 (22 hours)# 1.

arXiv:2403.03965v1 Announce Type: new Abstract: We show by direct calculation that the common Equivalence Principle explanation for why gravity must deflect light is quantitatively incorrect by a factor of three in Schwarzschild geometry. It is therefore possible, at least as a matter of principle, to tell the difference between local acceleration and a true gravitational field by measuring the local deflection of light. We calculate as well the deflection of test particles of arbitrary energy, and construct a leading-order coordinate transformation from Schwarzschild to local inertial coordinates, which shows explicitly how the effects of spatial curvature manifest locally for relativistic trajectories of both finite and vanishing rest mass particles.

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Relational Quantum Mechanics, Quantum Relativism, and the Iteration of Relativity 

from physics.hist-ph by Timotheus RiedelFri Mar 08 2024 12:30:03 (22 hours)# 2.

arXiv:2403.04069v1 Announce Type: new Abstract: The idea that the dynamical properties of quantum systems are invariably relative to other systems has recently regained currency. Using Relational Quantum Mechanics (RQM) for a case study, this paper calls attention to a question that has been underappreciated in the debate about quantum relativism: the question of whether relativity iterates. Are there absolute facts about the properties one system possesses relative to a specified reference, or is this again a relative matter, and so on? It is argued that RQM (in its best-known form) is committed to what I call the Unrestricted Iteration Principle (UIP), and thus to an infinite regress of relativisations. This principle plays a crucial role in ensuring the communicability and coherence of interaction outcomes across observers. It is, however, shown to be incompatible with the widespread, conservative reading of RQM in terms of relations, instead necessitating the adoption of the more unorthodox notion of perspectival facts. I conclude with some reflections on the current state of play in perspectivist versions of RQM and quantum relativism more generally, underscoring both the need for further conceptual development and the importance of the iteration principle for an accurate cost-benefit analysis of such interpretations.

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Promising Stabs in the Dark: Theory Virtues and Pursuit-Worthiness in the Dark Energy Problem 

from physics.hist-ph by William J. Wolf, Patrick M. DuerrFri Mar 08 2024 12:30:02 (22 hours)# 3.

arXiv:2403.04364v1 Announce Type: new Abstract: The paper argues that we ought to conceive of the Dark Energy problem — the question of how to account for observational data, naturally interpreted as accelerated expansion of the universe — as a crisis of underdetermined pursuit-worthiness. Not only are the various approaches to the Dark Energy problem evidentially underdetermined; at present, no compelling reasons single out any of them as more likely to be true than the other. More vexingly for working scientists, none of the approaches stands out as uncontroversially preferable over its rivals in terms of its rationally warranted promise, i.e. the reasons to further work on, explore and develop it. We demonstrate this claim by applying a Peircean economic model of pursuit-worthiness in terms of a cognitive cost/benefit estimate — with the instantiation of theory virtues as key indicators of cognitive gains — to the four main Dark Energy proposals (the cosmological constant approach, modified gravity, quintessence, and inhomogeneous cosmologies). Our analysis yields that these approaches do not admit of an unambiguous, or uncontroversial, ranking with respect to which ansatz deserves distinguished attention and research efforts. The overall methodological counsel that our analysis underwrites recommends a pragmatic double research strategy forward: to encourage and foster theory pluralism and the search for tests — with the goal of enhancing the testability of the $\Lambda$CDM model and “testing it to destruction”.

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Conformal Symmetry in Quantum Gravity 

from gr-qc by Ichiro OdaFri Mar 08 2024 12:29:54 (22 hours)# 4.

arXiv:2403.04056v1 Announce Type: cross Abstract: We study the problem of how to derive conformal symmetry in the framework of quantum gravity. We start with a generic gravitational theory which is invariant under both the general coordinate transformation (GCT) and Weyl transformation (or equivalently, local scale transformation), and then construct its BRST formalism by fixing the gauge symmetries by the extended de Donder gauge and scalar gauge conditions. These gauge-fixing conditions are invariant under global $GL(4)$ and global scale transformations. The gauge-fixed and BRST invariant quantum action possesses a huge Poincar\’e-like $IOSp(10|10)$ global symmetry, from which we can construct an extended conformal symmetry in a flat Minkowski background in the sense that the Lorentz symmetry is replaced with the $GL(4)$ symmetry. Moreover, we construct the conventional conformal symmetry out of this extended symmetry. With a flat Minkowski background $\langle g_{\mu\nu} \rangle = \eta_{\mu\nu}$ and a non-zero scalar field $\langle \phi \rangle \neq 0$, the $GL(4)$ and global scale symmetries are spontaneously broken to the Lorentz symmetry, thereby proving that the graviton and the dilaton are respectively the corresponding Nambu-Goldstone bosons, and therefore they must be exactly massless at nonperturbative level. One of remarkable aspects in our findings is that in quantum gravity, a derivation of conformal symmetry does not depend on a classical action, and its generators are built from only the gauge-fixing and the FP ghost actions. Finally, we address a generalized Zumino theorem in quantum gravity.

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Nonrelativistic spatiotemporal quantum reference frames 

from PRA – fundamentalconcepts by Michael Suleymanov, Ismael L. Paiva, and Eliahu CohenThu Mar 07 2024 05:00:00 (2 days)# 5.

Author(s): Michael Suleymanov, Ismael L. Paiva, and Eliahu Cohen

Quantum reference frames have attracted renewed interest recently, as their exploration is relevant and instructive in many areas of quantum theory. Among the different types, position and time reference frames have captivated special attention. Here, we introduce and analyze a nonrelativistic frame…

[Phys. Rev. A 109, 032205] Published Thu Mar 07, 2024

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The local validity of special relativity from a scale-relative perspective 

from philsciThu Mar 07 2024 03:11:00 (2 days)# 6.

Linnemann, Niels and Read, James and Teh, Nicholas (2024) The local validity of special relativity from a scale-relative perspective. [Preprint]

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The Causal Axioms of Algebraic Quantum Field Theory: A Diagnostic 

from physics.hist-ph by Francisco Calder\’onWed Mar 06 2024 10:37:27 (2 days)# 7.

arXiv:2401.06504v2 Announce Type: replace-cross Abstract: Algebraic quantum field theory (AQFT) puts forward three “causal axioms” that aim to characterize the theory as one that implements relativistic causation: the spectrum condition, microcausality, and primitive causality. In this paper, I aim to show, in a minimally technical way, that none of them fully explains the notion of causation appropriate for AQFT because they only capture some of the desiderata for relativistic causation I state or because it is often unclear how each axiom implements its respective desideratum. After this diagnostic, I will show that a fourth condition, local primitive causality (LPC), fully characterizes relativistic causation in the sense of fulfilling all the relevant desiderata. However, it only encompasses the virtues of the other axioms because it is implied by them, as I will show from a construction by Haag and Schroer (1962). Since the conjunction of the three causal axioms implies LPC and other important results in QFT that LPC does not imply, and since LPC helps clarify some of the shortcomings of the three axioms, I advocate for a holistic interpretation of how the axioms characterize the causal structure of AQFT against the strategy in the literature to rivalize the axioms and privilege one among them.

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On the Time Orientation of Probability 

from physics.hist-ph by Andrea Di Biagio, Carlo RovelliTue Mar 05 2024 16:54:39 (3 days)# 8.

arXiv:2403.01062v1 Announce Type: new Abstract: An influential theorem by Satosi Wantabe convinced many that there can be no genuinely probabilistic theory with both non-trivial forward and backward transition probabilities. We show that this conclusion does not follow from the theorem. We point out the flaw in the argument, and we showcase examples of theories with well-defined backward and forward transition probabilities.

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Special theory of regularity 

from physics.hist-ph by Juliano C. S. NevesTue Mar 05 2024 16:54:38 (3 days)# 9.

arXiv:2204.08413v2 Announce Type: replace Abstract: The theory of regularity is a philosophical perspective in which laws of nature are just descriptions, that is to say, laws of nature do not govern the world. Moreover, according to the theory of regularity, the number of laws of nature might be infinite, thus any attempt towards the theory of everything is doomed. Here I propose a special or restricted theory of regularity. The main difference as to the well-known version of that theory is both the range of validity and the scale of the laws of nature. Laws of nature ought to be considered just inside the observable universe and within certain energy and length scales. Even so I apply the theory of regularity to the multiverse scenario. As a consequence, the special theory of regularity supports only two types of multiverses by comparison with our world: those ones with a different sequence of unique events and different laws of nature and those ones with the same sequence of unique events and the same laws of nature instanced by the unique events. The latter case is some sort of eternal recurrence or a parallel eternal recurrence.

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The Unruh Effect and Theory Interpretation in an Effective Framework 

from philsciSat Mar 02 2024 21:50:08 (6 days)# 10.

Maggiani, Marco (2024) The Unruh Effect and Theory Interpretation in an Effective Framework. [Preprint]

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