Fri - 03/11/22

A New Guest in the Third Quantized Multiverse

  • Authors: Samuel Barroso Bellido, Fabian Wagner
  • Subjects: General Relativity and Quantum Cosmology (gr-qc)
  • Arxiv link: https://arxiv.org/abs/2203.05387
  • Abstract In the present article we point out a conceptual issue of the Third Quantization formalism for Canonical Quantum Gravity. Based on earlier results on interuniversal entanglement, the theory and with it the picture of noninteracting universe-antiuniverse pairs is incomplete. In particular, the variation of the entanglement entropy with the scale factor, understood as a measure of time, implies either an interaction between pairs of universes or universes with a heat bath. We propose a simple solution to the problem by adding a new quantum field to the formalism. Correspondingly, particles of this field mediate interactions between universes – depending on the model at tree level or one loop – and may further provide a heat bath in the background.

PQM and the GUP: Implications of Lattice Dynamics and Minimal Uncertainties in Quantum Mechanics and Cosmology

  • Authors: Gabriele Barca, Eleonora Giovannetti, Giovanni Montani
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)
  • Arxiv link: https://arxiv.org/abs/2203.05398
  • Abstract We compare two alternative representations of quantum mechanics: Polymer Quantum Mechanics (PQM), which presents features similar to Loop Quantum Gravity and Loop Quantum Cosmology, and the Generalized Uncertainty Principle (GUP) representation, that through a modified Algebra yields an alternative uncertainty principle similar to those derived in String Theories and Brane Cosmology. These formalisms can be recast to apparently look similar, but while the GUP yields an absolute minimal uncertainty on position, PQM implements some kind of ultraviolet cut-off through a lattice and does not have a minimal uncertainty. Then we implement them on the anisotropic Bianchi I model in Misner-like variables on a semiclassical level: PQM always implies a removal of the singularities, while the GUP fails to do so, highlighting once again how the two representations are fundamentally incompatible.

There is no new related paper today

  1. [2203.05475] - Surprises in Lorentzian path-integral of Gauss-Bonnet gravity - Gaurav Narain

  2. [2203.04968] - Projective measurement of black holes - Beni Yoshida

  3. [2203.04973] - The Spacetime Geometry of Fixed-Area States in Gravitational Systems - Xi Dong, Donald Marolf, Pratik Rath, Amirhossein Tajdini, Zhencheng Wang

  4. [2203.04981] - Snowmass White Paper: Micro- and Macro-Structure of Black Holes - Iosif Bena, Emil J. Martinec, Samir D. Mathur, Nicholas P. Warner

  5. [2203.05023] - AdS black brane coupled to non-abelian logarithmic gauge theory and color DC conductivity - Mehdi Sadeghi

  6. [2203.05491] - Balanced Partial Entanglement in Flat Holography - Debarshi Basu

  7. [2203.05559] - Weak gravity versus scale separation - Niccolò Cribiori, Gianguido Dall’Agata

Thu - 03/10/22

There is no new related paper today

There is no new related paper today

  1. [2203.04918] - Bouncing Cosmology in Fourth-Order Gravity - Marcello Miranda, Daniele Vernieri, Salvatore Capozziello, Francisco S. N. Lobo

  2. [2203.04817] - BV quantization of dynamical fuzzy spectral triples - James Gaunt, Hans Nguyen, Alexander Schenkel

Wed - 03/09/22

On the fate of quantum black holes

  • Authors: Viqar Husain, Jarod George Kelly, Robert Santacruz, Edward Wilson-Ewing
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2203.04238
  • Abstract We study the quantum dynamics of the Lema\^itre-Tolman-Bondi space-times using a polymer quantization prescription based on loop quantum cosmology that incorporates fundamental discreteness. By solving an effective equation derived from this quantization, we find analytical solutions for the Oppenheimer-Snyder and thin-shell collapse models, and numerical solutions for a variety of asymptotically flat collapsing dust profiles. Our study (i) tracks the formation, evolution and disappearance of dynamical horizons, (ii) shows that matter undergoes a non-singular bounce that results in an outgoing shock wave, (iii) determines black hole lifetime to be proportional to the square its mass, and (iv) provides a conformal diagram that substantially modifies the standard “information loss” picture by resolving the singularity and replacing the event horizon by transient apparent horizons.

There is no new related paper today

  1. [2203.03633] - Tensors and Algebras: An algebraic spacetime interpretation for tensor models - Dennis Obster

Tue - 03/08/22

There is no new related paper today

From spin foams to area metric dynamics to gravitons

  • Authors: Bianca Dittrich, Athanasios Kogios
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2203.02409
  • Abstract Although spin foams arose as quantizations of the length metric degrees of freedom, the quantum configuration space is rather based on areas as more fundamental variables. This is also highlighted by the semi-classical limit of four-dimensional spin foam models, which is described by the Area Regge action. Despite its central importance to spin foams the dynamics encoded by the Area Regge action is only poorly understood, in particular in the continuum limit. We perform here a systematic investigation of the dynamics defined by the Area Regge action on a regular centrally subdivided hypercubical lattice. This choice of lattice avoids many problems of the non-subdivided hypercubical lattice, for which the Area Regge action is singular. The regularity of the lattice allows to extract the continuum limit and its corrections, order by order in the lattice constant. We show that, contrary to widespread expectations which arose from the so-called flatness problem of spin foams, the continuum limit of the Area Regge action does describe to leading order the same graviton dynamics as general relativity. The next-to-leading order correction to the effective action for the length metric is of second order in the lattice constant, and is given by a quadratic term in the Weyl curvature tensor. This correction can be understood to originate from an underlying dynamics of area metrics. This suggests that the continuum limit of spin foam dynamics does lead to massless gravitons, and that the leading order quantum corrections can be understood to emerge from a generalization of the configuration space from length to area metrics.

  1. [2203.01956] - Complex Saddles and Euclidean Wormholes in the Lorentzian Path Integral - Gregory J. Loges, Gary Shiu, Nidhi Sudhir

  2. [2203.02492] - Gravitating spinning strings in AdS$_3$ - Henry Maxfield, Zhencheng Wang

Mon - 03/07/22

There is no new related paper today

From spin foams to area metric dynamics to gravitons

  • Authors: Bianca Dittrich, Athanasios Kogios
  • Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
  • Arxiv link: https://arxiv.org/abs/2203.02409
  • Abstract Although spin foams arose as quantizations of the length metric degrees of freedom, the quantum configuration space is rather based on areas as more fundamental variables. This is also highlighted by the semi-classical limit of four-dimensional spin foam models, which is described by the Area Regge action. Despite its central importance to spin foams the dynamics encoded by the Area Regge action is only poorly understood, in particular in the continuum limit. We perform here a systematic investigation of the dynamics defined by the Area Regge action on a regular centrally subdivided hypercubical lattice. This choice of lattice avoids many problems of the non-subdivided hypercubical lattice, for which the Area Regge action is singular. The regularity of the lattice allows to extract the continuum limit and its corrections, order by order in the lattice constant. We show that, contrary to widespread expectations which arose from the so-called flatness problem of spin foams, the continuum limit of the Area Regge action does describe to leading order the same graviton dynamics as general relativity. The next-to-leading order correction to the effective action for the length metric is of second order in the lattice constant, and is given by a quadratic term in the Weyl curvature tensor. This correction can be understood to originate from an underlying dynamics of area metrics. This suggests that the continuum limit of spin foam dynamics does lead to massless gravitons, and that the leading order quantum corrections can be understood to emerge from a generalization of the configuration space from length to area metrics.

  1. [2203.01956] - Complex Saddles and Euclidean Wormholes in the Lorentzian Path Integral - Gregory J. Loges, Gary Shiu, Nidhi Sudhir

  2. [2203.02492] - Gravitating spinning strings in AdS$_3$ - Henry Maxfield, Zhencheng Wang

New papers last week