Global ETD Search

51	The derivation and quasinormal mode spectrum of acoustic anti-de sitter black hole analogues Babb, James Patrick 08 March 2013 (has links) Dumb holes (also known as acoustic black holes) are fluid flows which include an "acoustic horizon:" a surface, analogous to a gravitational horizon, beyond which sound may pass but never classically return. Soundwaves in these flows will therefore experience "effective geometries" which are identical to black hole spacetimes up to a conformal factor. By adjusting the parameters of the fluid flow, it is possible to create an effective geometry which is conformal to the Anti-de Sitter black hole spacetime- a geometry which has recieved a great deal of attention in recent years due to its conjectured holographic duality to Conformal Field Theories. While we would not expect an acoustic analogue of the AdS-CFT correspondence to exist, this dumb hole provides a means, at least in principle, of experimentally testing the theoretical properties of the AdS spacetime. In particular, I have calculated the quasinormal mode spectrum of this acoustic geometry. / Graduate / 0986 / 0753 / jpbabb@yahoo.ca Quasinormal Modes Wave Equations Acoustic Black Holes Acoustics AdS-CFT analogue gravity Anti-de Sitter Sound String Theory Fluid Mechanics Frobenius Method General Relativity Hawking Radiation Hill Determinant Einstein field equations curvature Conformal Spacetimes Black Hole Perturbation Theory
52	Simple cosmological models and their descriptions of the universe Gustafsson, Emil January 2018 (has links) Cosmology is the study of the universe as a whole, and attempts to describe the behaviour of the universe mathematically. The simplest relativistic cosmological models are derived from Einstein's field equations with the assumptions of isotropy and homogeneity. In this thesis, a few simple cosmological models will be derived and evaluated with respect to their description of our universe i.e., how well they match observational data from e.g., the cosmic background radiation and redshift from distant supernovae. The models are derived from Einstein's field equations, which is why a large portion of the thesis will lay the ground work for the field equations by introducing and explaining the language of tensors. / Kosmologi är läran om universum i stort samt dess matematiska beskrivning. De enklaste relativistiska kosmologiska modellerna kan härledas från Einsteins fältekvationer med hjälp av antaganden om isotropi och homogenitet. I denna rapport kommer ett par av de enklaste modellerna att härledas, samt evalueras baserat på hur väl de beskriver vårt universum, det vill säga hur bra de passar de observationer som gjorts på exempelvis den kosmiska bakgrundsstrålningen och rödskifte från avlägsna supernovor. Modellerna härleds utifrån Einsteins fältekvationer, varför en stor del av rapporten består av en introduktion till tensoranalys. Tensors General relativity Einstein's field equations Cosmology Friedmann's equation FLRW-spacetimes Tensorer Allmän relativitetsteori Einsteins fältekvationer Kosmologi Friedmanns ekvation FLRW-rumtider Astronomy, Astrophysics and Cosmology Astronomi, astrofysik och kosmologi Natural Sciences Naturvetenskap

Search results

The derivation and quasinormal mode spectrum of acoustic anti-de sitter black hole analogues

Simple cosmological models and their descriptions of the universe