Ray, Shannon

Relationships
Member of: Graduate College
Person Preferred Name
Ray, Shannon
Model
Digital Document
Publisher
Florida Atlantic University
Description
One of the most fundamental problems in classical general relativity is the
measure of e↵ective mass of a pure gravitational field. The principle of equivalence
prohibits a purely local measure of this mass. This thesis critically examines the most
recent quasi-local measure by Wang and Yau for a maximally rotating black hole
spacetime. In particular, it examines a family of spacelike 2-surfaces with constant
radii in Boyer-Lindquist coordinates. There exists a critical radius r* below which, the
Wang and Yau quasi-local energy has yet to be explored. In this region, the results of
this thesis indicate that the Wang and Yau quasi-local energy yields complex values
and is essentially equivalent to the previously defined Brown and York quasi-local
energy. However, an application of their quasi-local mass is suggested in a dynamical
setting, which can potentially give new and meaningful measures. In supporting this
thesis, the development of a novel adiabatic isometric mapping algorithm is included.
Its purpose is to provide the isometric embedding of convex 2-surfaces with spherical
topology into Euclidean 3-space necessary for completing the calculation of quasilocal
energy in numerical relativity codes. The innovation of this algorithm is the
guided adiabatic pull- back routine. This uses Ricci flow and Newtons method to give isometric embeddings of piecewise simplicial 2-manifolds, which allows the algorithm
to provide accuracy of the edge lengths up to a user set tolerance.
Model
Digital Document
Publisher
Florida Atlantic University Digital Library
Description
Alexandrov proved that any simplicial complex homeomorphic to a sphere with strictly positive Gaussian curvature at each vertex could be isometrically embedded in three-dimensional Euclidean space as a convex polyhedron. Due to the nonconstructive nature of his proof, there have yet to be any algorithms that realize the Alexandrov Embedding in polynomial time. Following his proof, we produced the adiabatic isometric mapping AIM algorithm. The AIM algorithm is approximately quadratic in time and reproduces edge lengths up to arbitrary accuracy.