Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session T15: Classical Gravity: Mathematical FormalismRecordings Available

Hide Abstracts 
Sponsoring Units: DGRAV Chair: David Lowe, Brown University Room: Marquis C 
Monday, April 11, 2022 3:45PM  3:57PM 
T15.00001: The DiracBergmann algorithm: Singular Lagrangians, Constrained Hamiltonian Systems and Gauge Invariance J D Brown

Monday, April 11, 2022 3:57PM  4:09PM 
T15.00002: An Invariant Characterization of the LeviCivita Spacetimes Cooper K Watson, William Julius, Matthew Gorban, David D McNutt, Eric W Davis, Gerald B Cleaver In the years 1917–1919 Tullio LeviCivita published a number of papers presenting new exact solutions to Einstein’s equations. These works, while partially translated, remains largely inaccessible to English speaking researchers. Furthermore, the age and structures of these papers have often resulted in more contemporary works citing these papers in confusing or incorrect ways. It is not uncommon to find the series of LeviCivita's papers cited by the general heading of the entire series or by referencing to only the first article in the series. Here, we clarify the structure of LeviCivita's works on exact solutions that are of current interest. We review and characterize these solutions and their properties. We present them in a modern readable manner as well as show a new additional alternative form to one solution. 
Monday, April 11, 2022 4:09PM  4:21PM 
T15.00003: Analysis of LeviCivita Spacetimes using the CartanKarlhede Algorithm William Julius, Cooper K Watson, Matthew Gorban, David D McNutt, Eric W Davis, Gerald B Cleaver Here, a brief introduction to the CartanKarlhede algorithm is given. This algorithm allows for the (local) characterization of spacetimes and is applied to several of the LeviCivita spacetimes. This method allows for the identification of the limits of several distinct spacetimes as a single solution, as well as uniquely characterize these solutions as a reference for future work. 
Monday, April 11, 2022 4:21PM  4:33PM 
T15.00004: Local and covariant flow relations for OPE coefficients in Lorentzian spacetimes Mark G Klehfoth, Robert M Wald As their spacetime points approach coincidence, the npoint functions of local quantum field theories can be approximated to arbitrary precision by their operator product expansions (OPEs). The coefficients of OPEs are cnumber distributions which contain important information about both the quantum fields and the physical states. Under variations of the interaction parameters, Hollands et al. have shown the OPE coefficients of renormalizable Euclidean QFTs satisfy "flow equations". These Euclidean flow equations have been proven to hold orderbyorder in perturbation theory, but remain mathematically well defined under very general assumptions for any value of the interaction parameters. The flow equations, therefore, potentially provide a nonperturbative approach to obtaining OPE coefficients. However, there exist serious obstacles to deriving flow relations for OPE coefficients on Lorentzian spacetimes in a manner compatible with locality and covariance. In this talk, I describe these issues and our resolutions to them for a solvable toy model: KleinGordon theory with the mass viewed as an "interaction parameter". Our approach to obtaining local and covariant flow relations for the KleinGordon OPE coefficients on Lorentzian spacetimes generalizes to interacting QFTs. 
Monday, April 11, 2022 4:33PM  4:45PM 
T15.00005: Boundary conditions and proof of the scalar, vector, tensor decomposition theorem in cosmological perturbation theory Asanka Amarasinghe, Matthew M Phelps, Tianye Liu, Daniel A Norman, Philip D Mannheim Cosmological perturbations play a vital role in the study of the anisotropy of the cosmic microwave background radiation and in largescale structure formation. The standard procedure for treating these perturbations is to decompose them into scalar (S), vector (V) and tensor (T) components, and assume that the three sectors independently satisfy the fluctuation equations. Ordinarily, this procedure is carried out in a convenient gauge in a background geometry with vanishing spatial 3curvature. We have carried out a general SVT decomposition in a cosmology with an arbitrary spatial 3curvature and expansion radius in a completely gauge invariant way that involves no choice of gauge at all. We have been able to prove the decomposition theorem in this general case, by first manipulating the fluctuation equations so that the various sectors separate out at a higher derivative level; and then finding appropriate boundary conditions under which the solving of these equations leads to the form that is required of the decomposition theorem. With these boundary conditions we thus justify the use of the decomposition theorem in the standard Einstein gravity based cosmology. In addition we establish the decomposition theorem in the alternate conformal gravity theory. 
Monday, April 11, 2022 4:45PM  4:57PM 
T15.00006: The geometry of field sheet foliations of spacetime in forcefree electrodynamics Govind Menon In this talk, I will present the geometry of foliations of a spacetime whose distributions are kernels of a forcefree electromagnetic field. Forcefree electrodynamics (FFE) in curved spacetime is the natural setting for black hole magnetospheres. In particular, the BlandfordZnajek mechanism is an example of FFE. I will conclude the talk by presenting strategies for obtaining exact solutions for FFE. 
Monday, April 11, 2022 4:57PM  5:09PM 
T15.00007: Quantum Corrections to Classical Time Dilation Alexander R Smith, Mehdi Ahmadi, Piotr grochowski, Kacper Debski, Andrzej Dragan At the intersection of quantum mechanics and relativity lies the possibility for a clock to move along a superposition of two distinct classical trajectories — perhaps these trajectories correspond to different speeds or locations in a gravitational field of the clock. It is then natural to ask: what time dilation would such a quantum clock observe? Using covariant time observables, I will introduce a formulation of relational quantum dynamics that allows for a probabilistic formulation of relativistic time dilation. This framework will then be used to describe quantum time dilation effects that occur when a clock moves in a superposition of different relativistic momenta and is at rest in a spatial superposition of an external gravitational field. I will argue that these time dilation effects may be observable with presentday technology and offer a new test of fundamental physics in the regime where quantum coherence and relativistic effects play an important role. 
Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2023 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700