Bulletin of the American Physical Society
2014 Annual Meeting of the Mid-Atlantic Section of the APS
Volume 59, Number 9
Friday–Sunday, October 3–5, 2014; University Park, Pennsylvania
Session E5: Gravitation and Cosmology II |
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Chair: Marc Geiller, Pennsylvania State University Room: Life Sciences Building 009 |
Saturday, October 4, 2014 3:30PM - 3:42PM |
E5.00001: Covariant Loop Quantum Gravity Wolfgang Wieland This talk gives a brief overview over recent developments in covariant loop quantum gravity. I will report on the semi-classical limit of the theory, and comment on the prominent role that spinors have for the theory. [Preview Abstract] |
Saturday, October 4, 2014 3:42PM - 3:54PM |
E5.00002: Canonical Effective Methods for Quantum Systems Suddhasattwa Brahma, Martin Bojowald Canonical effective equations are a powerful method of describing quantum systems. Using this formulation, we not only recover the results known from standard field theory, but also extend them, for instance, by allowing for a non-gaussian state as the expansion basis (useful for cosmology), and accommodating a deformed version of general covariance. Several interesting applications of these methods (like Coleman-Weinberg type potentials and higher derivative corrections) shall be discussed in this talk. [Preview Abstract] |
Saturday, October 4, 2014 3:54PM - 4:06PM |
E5.00003: Entanglement entropy production in gravitational collapse Eugenio Bianchi After 40 years of active research the question of the fate of information that falls into a black hole is still open. In this talk I discuss recent results that allow us to compute the entanglement entropy production in gravitational collapse. For a solvable model of black hole formation I show that the entanglement entropy of the radiation emitted by the black hole reproduces all the standard thermodynamic results on Hawking radiation. In the second part of the talk I apply these new methods to models of gravitational collapse in which quantum gravity effect avoid the formation of a singularity. In these black hole models there is a trapping horizon but no event horizon: the radiation coming out from the black hole at late times is expected to purify the early radiation so that no information is lost. I discuss some unexpected features of this ``purifying'' radiation and put new bounds on the time need for the recovery of information that fell into the black hole. [Preview Abstract] |
Saturday, October 4, 2014 4:06PM - 4:18PM |
E5.00004: Black hole fireworks: quantum-gravity effects outside the horizon spark black to white hole tunneling Hal Haggard, Carlo Rovelli We show that there is a classical metric satisfying the Einstein equations outside a finite spacetime region where matter collapses into a black hole and then emerges from a white hole. We compute this metric explicitly. We show how quantum theory determines the (long) time for the process to happen. A black hole can thus quantum-tunnel into a white hole. For this to happen, quantum gravity should affect the metric also in a small region outside the horizon: we show that contrary to what is commonly assumed, this is not forbidden by causality or by the semiclassical approximation, because quantum effects can pile up over a long time. This scenario alters radically the discussion on the black hole information puzzle. [Preview Abstract] |
Saturday, October 4, 2014 4:18PM - 4:30PM |
E5.00005: Numerical aspects of loop quantum cosmology Brajesh Gupt A key feature of the singularity resolution in loop quantum cosmology (LQC) is the occurrence of the quantum bounce when the spacetime curvature becomes comparable to the Planck scale. The presence of quantum bounce greatly modifies the dynamics of the early universe and can have important implications for the observational signatures. Although the quantum bounce has been previously studied via numerical methods for initial conditions that correspond to large macroscopic universes at late times, a detailed study of the robustness of the quantum bounce for a generic class of initial condition has so far been missing due to severe computational challenges. I will talk about the numerical scheme, Chimera, which we have developed to tackle these computational challenges and some important results pertaining to the observable consequences of the loop quantum geometry. [Preview Abstract] |
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