Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session C13: Quantum Gravity I |
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Sponsoring Units: GGR Chair: Seth Major, Hamilton College Room: Key 9 |
Saturday, April 11, 2015 1:30PM - 1:42PM |
C13.00001: T-duality off shell in 3D Type II superspace Martin Polacek We give the manifestly T-dual formulation of the massless sector of the classical 3D Type II superstring in off-shell 3D $N\,=\,2$ superspace, including the action. It has a simple relation to the known superspace of 4D $N\,=\,1$ supergravity in 4D M-theory via 5D F-theory. The prepotential appears as part of the vielbein, without derivatives. [Preview Abstract] |
Saturday, April 11, 2015 1:42PM - 1:54PM |
C13.00002: Four-dimensional entropy from three-dimensional gravity Steven Carlip In loop quantum gravity, the boundary term at a black hole horizon is formally equivalent to an action for three-dimensional gravity. I show how to use this equivalence to obtain the four-dimensional Bekenstein-Hawking entropy from well-understood computations of the entropy of the three-dimensional black hole. [Preview Abstract] |
Saturday, April 11, 2015 1:54PM - 2:06PM |
C13.00003: Recursive Generation of Space-Times Dennis Marks Space-times can be generated recursively from a time-like unit basis vector \textbf{T} and a space-like one \textbf{S}. \textbf{T} is unique up to sign, corresponding to particles and antiparticles. \textbf{S} has the form of qubits. Qubits can make quantum transitions, suggesting spontaneous generation of space-time. Recursive generation leads from 2 dimensions to 4, with grades of the resulting algebra corresponding to space-time, spin-area, momentum-energy, and action. Dimensions can be open (like space-time) or closed. A closed time-like dimension has the symmetry of electromagnetism; 3 closed space-like dimensions have the symmetry of the weak force. The 4 open dimensions and the 4 closed dimensions produce an 8-dimensional space with a symmetry that is the product of the Yang regularization of the Heisenberg-Poincar\'{e} group and the GUT regularization of the Standard Model. After 8 dimensions, the pattern of real geometric algebras repeats itself, producing a recursive lattice of spontaneously expanding space-time with the physics of the Standard Model at each point of the lattice, implying conservation laws by Noether's theorem. The laws of nature are not preexistent; rather, they are consequences of the uniformity of space-time. The uniformity of space-time is a consequence of its recursive generation. [Preview Abstract] |
Saturday, April 11, 2015 2:06PM - 2:18PM |
C13.00004: ABSTRACT WITHDRAWN |
Saturday, April 11, 2015 2:18PM - 2:30PM |
C13.00005: Hessian and graviton propagator of the proper vertex Atousa Chaharsough Shirazi, Jonathan Engle, Ilya Vilenskiy The proper spin-foam vertex amplitude was obtained from the EPRL vertex by projecting out all but a single gravitational sector, in order to enable correct semi-classical behavior. In this paper we calculate the gravitational two-point function predicted by the proper spin-foam vertex to lowest order in the vertex expansion. We find the same answer as in the EPRL case, so that the theory is consistent with the predictions of linearized gravity in the regime of small curvature. The method for calculating the two-point function is again to cast it in terms of an action integral and to use stationary phase methods. Thus, the calculation of the Hessian matrix plays a key role. Once the Hessian is calculated, it is used not only to calculate the two-point function, but also to calculate the coefficient appearing in the semi-classical limit of the proper vertex amplitude itself. This coefficient can be thought of as the effective discrete ``measure factor'' encoded in the spin-foam model. [Preview Abstract] |
Saturday, April 11, 2015 2:30PM - 2:42PM |
C13.00006: Quantum Gravity: Have We Been Asking The Right Question? Hontas Farmer To get the correct answer one must ask the correct question. In the field of quantum gravity the question has been how do we quantize General Relativity or derive a quantum theory which becomes General Relativity at low energies. Observing that Quantum Field Theory was the result of making Quantum Mechanics into a relativistic theory, I asked myself why not make QFT obey the principles of GR? I answered this question with a model I call Relativization. In a series of three papers I presented an answer to this alternative question which gives finite results for everything from black holes to particle physics. However, others may answer this question more elegantly than I have. Have we by studying quantum gravity for 50 + years been asking the wrong question, and thus experiencing difficulty, all this time? [Preview Abstract] |
Saturday, April 11, 2015 2:42PM - 2:54PM |
C13.00007: Surface Tension and Negative Pressure Interior of a Non-Singular ``Black Hole'' Emil Mottola, Pawel Mazur The interior Schwarzschild solution for a static, spherically symmetric collapsed star has a pressure divergence that is integrable, and induces a non-isotropic transverse stress with a finite surface energy and surface tension. When compressed to the Schwarzschild radius, the surface is at the same radius and the interior solution has constant negative pressure, thereby describing a gravitational condensate star, a fully collapsed state already inherent in and predicted by classical General Relativity. The redshifted surface tension of the condensate star surface is given by is the difference of surface gravities between the exterior and interior Schwarzschild solutions. The First Law, $dM=dE_v+\tau dA$ is a purely mechanical classical relation at zero temperature and zero entropy, describing the volume energy and surface energy respectively. Since there is no event horizon, the Schwarzschild time of such a non-singular gravitational condensate star is a global time, which is consistent with unitary time evolution in quantum theory. The interior acts as a defocusing lens for light passing through the condensate, leading to imaging characteristics distinguishable from a black hole. The discrete surface modes of oscillation which should be detectable by their GWave signatures [Preview Abstract] |
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