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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Topics in gravity

Kashani-Poor, Amir-Kian 27 April 2011 (has links)
Not available / text
2

Topics in gravity

Kashani-Poor, Amir-Kian. January 2002 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.
3

LOOP QUANTUM GRAVITY DYNAMICS: MODELS AND APPLICATIONS

Unknown Date (has links)
In this dissertation we study the dynamics of loop quantum gravity and its applications. We propose a tunneling phenomenon of a black hole-white hole transition and derive an amplitude for such transition using the spinfoam framework. We investigate a special class of kinematical states for loop quantum gravity - Bell spin networks - and show that their entanglement entropy obeys the area law. We develop a new spinfoam vertex amplitude that has the correct semi-classical limit. We then apply this new amplitude to calculate the graviton propagator and a cosmological transition amplitude. The results of these calculations show feasibility of computations with the new amplitude and its viability as a spinfoam model. Finally, we use physical principles to radically constrain ambiguities in the cosmological dynamics and derive unique Hamiltonian dynamics for Friedmann-Robertson-Walker and Bianchi I cosmologies. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2019. / FAU Electronic Theses and Dissertations Collection
4

Space and Particles at the Planck Scale

Konopka, Tomasz January 2007 (has links)
The aim of this thesis is to summarize some results in two approaches to studying how quantum gravity may be relevant for experiments. The first approach starts off by stating that one of the questions a theory of quantum gravity might address is how a large-scale universe can be constructed from discrete Planck-size elements. Starting from a discussion of the role of causal and foliation structure in causal dynamical triangulations, this approach leads to a formulation of a model based on graphs whose purpose is to uncover what kind organizational principle or structure might be responsible for endowing spacetime with manifold-like properties. Thus in this approach, experimental input used to constrain models for quantum gravity are observations of glaring large-scale properties of the universe such as the dimensionality or total size. The second approach considers the possible effects of quantum gravity on the propagation of particles. In particular, the focus is on understanding the physics of deformed special relativity when this novel symmetry is seen as a residual effect due to a gauge fixing from a higher dimensional system. Thus here the hope is to connect a proposal for quantum gravity phenomenology with precision experiments of particle properties. A synthesis of such complementary approaches would represent a consistent model for quantum gravity phenomenology and is the background goal for the work in this thesis. The extent to which such a synthesis can be described today is presented.
5

Topology in Fundamental Physics

Hackett, Jonathan January 2011 (has links)
In this thesis I present a mathematical tool for understanding the spin networks that arise from the study of the loop states of quantum gravity. The spin networks that arise in quantum gravity possess more information than the original spin networks of Penrose: they are embedded within a manifold and thus possess topological information. There are limited tools available for the study of this information. To remedy this I introduce a slightly modi ed mathematical object - Braided Ribbon Networks - and demonstrate that they can be related to spin networks in a consistent manner which preserves the di eomorphism invariant character of the loop states of quantum gravity. Given a consistent de nition of Braided Ribbon Networks I then relate them back to previous trinion based versions of Braided Ribbon Networks. Next, I introduce a consistent evolution for these networks based upon the duality of these networks to simplicial complexes. From here I demonstrate that there exists an invariant of this evolution and smooth deformations of the networks, which captures some of the topological information of the networks. The principle result of this program is presented next: that the invariants of the Braided Ribbon Networks can be transferred over to the original spin network states of loop quantum gravity. From here we represent other advances in the study of braided ribbon networks, accompanied by comments of their context given the consistent framework developed earlier including: the meaning of isolatable substructures, the particular structure of the capped three braids in trivalent braided ribbon networks and their application towards emergent particle physics, and the implications of the existence of microlocal topological structures in spin networks. Lastly we describe the current state of research in braided ribbon networks, the implications of this study on quantum gravity as a whole and future directions of research in the area.
6

Aspects of cosmology and quantum gravity in an accelerating universe

Krishnan, Chethan, 1978- 28 August 2008 (has links)
Not available / text
7

In search of quantum de Sitter space: generalizing the Kodama state

Randono, Andrew Culp 28 August 2008 (has links)
The Kodama state is unique in being an exact solution to all the constraints of quantum gravity that also has a well defined semi-classical interpretation as the quantum version of a classical spacetime, namely de Sitter or anti-de sitter space. Despite this, the state fails to pass some of the key tests of a physically realistic quantum state. In an attempt to resolve this problem, we track down the root of the problem to a choice for a particular parameter: the Immirzi parameter. The Kodama state takes this parameter to be complex, whereas modern formulations of canonical quantum gravity require that the parameter is real. We generalize the Kodama state to real values of the Immirzi parameter, and find that the generalization opens up a large Hilbert space of states, one of which can be directly interpreted as particular slicing of de Sitter space. We then show that these states resolve, or are expected to resolve many of the problems associated with the original version of Kodama state. In order to resolve the interpretation of the multitude of states, we develop a new model of covariant classical and quantum gravity where the full Lorentz group is retained as a local symmetry group, and the canonical evolution generated by the constraints has a close relation to a larger group: that de Sitter group. This formalism gives strong evidence that the multitude of generalized Kodama states can be unified into a single quantum state that is quantum de Sitter space. / text
8

Relativistic spin networks

Steele, Christopher Mark January 2003 (has links)
No description available.
9

Superstring inspired phenomenology

Blair, G. A. January 1986 (has links)
No description available.
10

Space and Particles at the Planck Scale

Konopka, Tomasz January 2007 (has links)
The aim of this thesis is to summarize some results in two approaches to studying how quantum gravity may be relevant for experiments. The first approach starts off by stating that one of the questions a theory of quantum gravity might address is how a large-scale universe can be constructed from discrete Planck-size elements. Starting from a discussion of the role of causal and foliation structure in causal dynamical triangulations, this approach leads to a formulation of a model based on graphs whose purpose is to uncover what kind organizational principle or structure might be responsible for endowing spacetime with manifold-like properties. Thus in this approach, experimental input used to constrain models for quantum gravity are observations of glaring large-scale properties of the universe such as the dimensionality or total size. The second approach considers the possible effects of quantum gravity on the propagation of particles. In particular, the focus is on understanding the physics of deformed special relativity when this novel symmetry is seen as a residual effect due to a gauge fixing from a higher dimensional system. Thus here the hope is to connect a proposal for quantum gravity phenomenology with precision experiments of particle properties. A synthesis of such complementary approaches would represent a consistent model for quantum gravity phenomenology and is the background goal for the work in this thesis. The extent to which such a synthesis can be described today is presented.

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