FAUST Seminars Spring 2012

(Wed 9:00 AM in SE 311)

Titles link to the abstracts.

Date Speaker Title
Feb 1
Group Meeting  
Feb 8
Atousa Shirazi (FAU)
Feb 15
Group Meeting  
Feb 22
Petr Tsatsin (FAU)
Feb 29
Xuping Wang (FAU)
Mar 14
Shawn Wilder (FAU)
Mar 21
Group Meeting  
Mar 28
George Reifenberger (FAU)
Apr 4
Group Meeting  
Apr 11
Chun-Yen Lin (UC Davis)
Apr 18
M.E. Hogan (FAU)
Apr 25
Shannon Ray (FAU)

Seminar Abstracts

Asymptotic Analysis of the Euclidean EPRL 4-simplex Amplitude

Atousa Shirazi (FAU), February 8

The semiclassical limit for euclidean EPRL (Engle-Pereira-Rovelli-Livine) spin foam model in 4D will be considered. The main focus is on geometric interpretation of this analysis. For this aim using coherent states play a crucial role. These coherent states will be defined and used for the asymptotic analysis. The talk mainly represents the results of E. Livine and S. Speziale, "New spin foam vertex for quantum gravity" Phys. Rev. D 76, 084028 (2007) and J. Barrett et al., "Asymptotic analysis of the EPRL four-simplex amplitude", J. Math. Phys. 50, 112504 (2009).

Ricci Flow Simulations on Models Made of Triangular Frustum Blocks

Xuping Wang (FAU), February 29

During this talk I will present the latest results of the Ricci flow simulations on the discrete 3-sphere made of frustum blocks.

Explorations of a Quasilocal Definition of Angular Momentum

Shawn Wilder (FAU), March 14

A precise definition of the angular momentum of a black hole in general relativity is possible only when its horizon possesses an axial symmetry. However, most manifolds have no such symmetry. Nonetheless, it is possible to pose an eigenvalue problem on a 2-sphere with lowest eigenmodes corresponding to geometric symmetries. This eigenvalue problem can also be introduced in a more general sense to define how much a manifold is asymmetric. This approximation is used to define the angular momentum of an arbitrary black hole. The presentation will be a summary of the investigation of how sensitive this definition of angular momentum is to perturbations.

On the Question of Cosmic Recall in Quantum Cosmology

M.E. Hogan (FAU), April 18

In loop quantum gravity, spacetime is proven to be discrete, rather than continuous, and this leads to the phenomenon of singularity resolution, where the singularities of classical general relativity are removed via quantum effects. As aresult, space and time extend before the Big Bang, and the initial 'singularity' of the Universe, now of finite size (as part of what is termed the Big Bounce), connects us to a previous universe (and possibly infinitely many others). The question then arises as to whether any of the properties of the previous universe, such as its entropy, information, and physical laws, are erased and forgotten during the Bounce, or whether they are preserved and recalled. Examining the equations of loop quantum cosmology, there is indeed the potential for an erasure, and only very limited cosmic recall. Other related issues, such as the decoherence of quantum states, and the 'Arrow of Time', as well as considerations from other contemporary theories of quantum gravity, are also discussed.