Bulletin of the American Physical Society
2023 APS April Meeting
Volume 68, Number 6
Minneapolis, Minnesota (Apr 1518)
Virtual (Apr 2426); Time Zone: Central Time
Session AAA02: V: Alternative Theories of Gravity 
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Sponsoring Units: DGRAV Chair: Midhat Farooq, APS Room: Virtual Room 2 
Wednesday, April 26, 2023 1:00PM  1:12PM 
AAA02.00001: Spacetimes between Einstein and KaluzaKlein Chris Vuille Extended general relativity is the extension of general relativity from the tensor algebra to its own universal covering algebra. The universal covering algebra involves all direct sums of tensors of different rank, elements called tensor multinomials. Focusing on a subalgebra consisting of direct sums of scalar, vector, and second rank tensor fields only, results in geometric objects as spacious as those in fivedimensional KaluzaKlein spacetimes while remaining defined over only four spacetime dimensions, hence may be thought of as being between the theories of Einstein and Kaluza and Klein. It is possible to deduce the equivalent of Christoffel symbols from the equivalent geodesic equation, and from the Christoffel symbols, the extended Ricci curvature. The extended Ricci curvature yields the Ricci tensor of general relativity, Maxwell's electromagnetism, and a KaluzaKlein scalar field equation as components of a single secondrank tensor multinomial equation. The scalar field couples naturally to the square of the electric charge, leading to a new force that may be significant only in collapsed matter or in a cosmological setting. There are numerous possible new Lagrangians unique to this formalism, and rich new ways of introducing scalar fields and accelerated cosmological expansion. In one of many such solutions, a scalar field source that falls off with expanding volume forces a dark energy equation of state. 
Wednesday, April 26, 2023 1:12PM  1:24PM 
AAA02.00002: On the Emission of the Gravitational Radiation by Light via Gravitational Redshift Mehmet B Ökten

Wednesday, April 26, 2023 1:24PM  1:36PM 
AAA02.00003: Compensator fields in dimensional reduction and compactification without truncation — Part III: Einstein Gravity Michael B Schulz In dimensionally reduced theories with gauge or diffeomorphism invariance, consistency of the KaluzaKlein ansatz requires the introduction of compensator fields. The compensator fields project gaugevariant field fluctuations to their physical horizontal components, which in turn determine the gaugeinvariant moduli space metric that appears in kinetic terms of the lower dimensional theory. The compensator fields must be introduced "by hand" in dimensional reduction (i.e., compactification truncated to zero modes), but arise automatically in the full untruncated theory. Warming up with gauge theory, and then focusing on pure Einstein gravity compactified on an arbitrary compact manifold, we reexpress the full untruncated parent theory in lower dimensional language, and identify the compensator fields. One of their known geometric interpretations features prominently. The moduli space of metrics on the compact manifold can be regarded as a fiber bundle whose fiber is the space of diffeomorphisms. The compensator fields arise as a repackaging of the connection on this bundle. 
Wednesday, April 26, 2023 1:36PM  1:48PM 
AAA02.00004: Violation of the Equivalence Principle for some Macroscopic Quantum Bodies Andrei G Lebed We consider macroscopic ensembles of the hydrogen atoms in a weak postNewtonian gravitation field in the presence of quantum effects. We show that for the most ensembles the Einstein’s Equivalence Principle is valid in the above mentioned quantum case. On the other hand, it is shown to be broken for some special macroscopic ensembles [1] – the coherent quantum superpositions of the stationary quantum states. We discuss how such ensembles (which we call “Gravitational demons”) can be created using laser technique in the Earth’s laboratories and how the violation of the Equivalence Principle can be observed. 
Wednesday, April 26, 2023 1:48PM  2:00PM 
AAA02.00005: Concept of quantum spacetime structure Initial stage (Basic framework) Aman Yadav This paper's aim is to showcase a possible fundamental structure of spacetime, which is done by using the basic concepts of quantum time crystal i.e. discrete time transitional symmetry. I am able to comprehend the structural description of spacetime in a way that elucidates the origin of gravity and may describe the working of quantum gravity. This paper provides an alternate framework to understand gravity in a more thorough way, to get one step closer to completing the "Theory of Everything". 
Wednesday, April 26, 2023 2:00PM  2:12PM 
AAA02.00006: Gravitational wave energymomentum tensor and radiated power in a strongly curved background Diana Vaman, Yuchen Du Allowing for the possibility of extra dimensions, there are two paradigms: either the extra dimensions are hidden from observations by being compact and small as in KaluzaKlein scenarios, or the extra dimensions are large/noncompact and undetectable due to a large warping as in the RandallSundrum scenario. In the latter case, the fivedimensional background has a large curvature, and Isaacson's construction of the gravitational energymomentum tensor, which relies on the assumption that the wavelength of the metric fluctuations is much smaller than the curvature length of the background spacetime, cannot be used. In this work, we construct the gravitational energymomentum tensor in a strongly curved background such as RandallSundrum. We perform a scalarvectortensor decomposition of the metric fluctuations with respect to the $SO(1,3)$ background isometry and construct the covariantlyconserved gravitational energymomentum tensor out of the gaugeinvariant metric fluctuations. We also give a formula for the radiated power. 
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