Theses/Dissertations - Physics
Permanent URI for this collectionhttps://hdl.handle.net/2104/4793
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Browsing Theses/Dissertations - Physics by Author "Cleaver, Gerald B."
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Item Curvature invariants for wormholes and warped spacetimes.(2020-05-01) Mattingly, Brandon John, 1989-; Cleaver, Gerald B.The Carminati and McLenaghan (CM) curvature invariants are powerful tools for probing spacetimes. Henry et al. formulated a method of plotting the CM curvature invariants to study black holes. The CM curvature invariants are scalar functions of the underlying spacetime. Consequently, they are independent of the chosen coordinates and characterize the spacetime. For Class B1 spacetimes, there are four independent CM curvature invariants: R, r1, r2, and w2. Lorentzian traversable wormholes and warp drives are two theoretical solutions to Einstein’s field equations, which allow faster-than-light (FTL) transport. The CM curvature invariants are plotted and analyzed for these specific FTL spacetimes: (i) the Thin-Shell Flat-Face wormhole, (ii) the Morris-Thorne wormhole, (iii) the Thin-Shell Schwarzschild wormhole, (iv) the exponential metric, (v) the Alcubierre metric at constant velocity, (vi) the Natário metric at constant velocity, and (vii) the Natário metric at an accelerating velocity. Plots of the wormhole CM invariants confirm their traversability and show how to distinguish the wormholes. The warp drive CM invariants reveal key features such as a flat harbor in the center of each warp bubble, a dynamic wake for each warp bubble, and rich internal structure(s) of each warp bubble.Item Encrypting the universe.(2017-08-02) Vestal, Lesley, 1991-; Cleaver, Gerald B.Layer one N = 4 SUSY Weakly Coupled Free Fermionic Heterotic String (WCFFHS) Models that include string-scale massive gauge sectors are statistically investigated for even orders through 12 for uniqueness and gauge content. A focus is given to models containing the standard model or gauge group content with the embedded standard model. Results are compared with those of prior searches of N = 4 models without explicit string-scale massive gauge sectors. This search revealed models with standard model gauge content at the string scale, which were not observed in prior searches. Additionally, research regarding an image encryption algorithm is presented. The RGB values of each pixel in an image are encrypted using three intertwined Mandelbrot summations. Runtimes for decryption depend primarily on the size of the image. Modifications to increase complexity and runtime are explored. Advantages include adaptability, reasonable runtime on a typical personal computer and that it is novel, enhancing its security.Item Extremal conditions in early universe cosmology.(2021-10-22) Lee, Jeff S., 1964-; Cleaver, Gerald B.Some aspects of Special Relativity have remained largely unresolved and unexplored even after more than a century since its formulation; this is particularly true in the case of relativistic thermodynamics. Attempts to derive a relativistic temperature transformation have met with limited success, particularly when trying to transform a scalar temperature. Much more credible results have emerged when the inverse temperature (a van-Kampen Israel future-directed timelike 4-vector) was invoked. In this dissertation, the first self-consistent formulations of the relativistic Wien’s Displacement Law and the relativistic Stefan-Boltzmann Law are presented. Also examined is the use of occupation number and the inverse temperature 4-vector to justify temperature inflation of the Cosmic Microwave Background for any relativistic observer. The interaction of the Hawking spectrum of a 1 attometer (10-18 m) primordial black hole with an incoming composite particle reveals that when a primordial black hole reaches the Planck scale, its absorptivity and emissivity cause it to effectively become a white hole for the final instant of its existence.Item Initial systematic investigations of the weakly coupled free fermionic heterotic string landscape statistics.(2011-09-14) Renner, Timothy, 1984-; Cleaver, Gerald B.; Physics.; Baylor University. Dept. of Physics.A C++ framework was constructed with the explicit purpose of systematically generating string models using the Weakly Coupled Free Fermionic Heterotic String (WCFFHS) method. The software, optimized for speed, generality, and ease of use, has been used to conduct preliminary systematic investigations of WCFFHS vacua. Documentation for this framework is provided in the Appendix. After an introduction to theoretical and computational aspects of WCFFHS model build- ing, a study of ten-dimensional WCFFHS models is presented. Degeneracies among equivalent expressions of each of the known models are investigated and classified. A study of more phenomenologically realistic four-dimensional models based on the well known “NAHE” set is then presented, with statistics being reported on gauge content, matter representations, and space-time supersymmetries. The final study is a parallel to the NAHE study in which a variation of the NAHE set is systematically extended and examined statistically. Special attention is paid to models with “mirroring” — identical observable and hidden sector gauge groups and matter representations.Item Investigation into compactifed dimensions: Casimir energies and phenomenological aspects.(2009-01-07T22:13:03Z) Obousy, Richard K.; Cleaver, Gerald B.; Physics.; Baylor University. Dept. of Physics.A central theme in this dissertation is the notion of the quantum vacuum. To a particle physicist, the term 'vacuum' means the ground state of a theory. In general, this ground state must obey Lorentz invariance, at least with regards to 3 spatial dimensions, meaning that the vacuum must look identical to all observers. At all energies probed by experiments to date, the universe is accurately described as a set of quantum fields. If we take the Fourier transform of a free quantum field, each mode of a fixed wavelength behaves like a simple harmonic oscillator. A quantum mechanical property of a simple harmonic oscillator is that the ground state exhibits zero-point fluctuations as a consequence of the Heisenberg Uncertainty Principle. These fluctuations give rise to a number of phenomena; however, two are particularly striking. First, the Casimir Effect, which will be examined in detail in this dissertation is arguably the most salient manifestation of the quantum vacuum. In its most basic form it is realized through the interaction of a pair of neutral parallel conducting plates. The presence of the plates modifies the quantum vacuum, and this modification causes the plates to be pulled toward each other. Second is the prediction of a vacuum energy density, which is an intrinsic feature of space itself. Many attempts have been made to relate this vacuum energy to the cosmological constant Lambda, which is a common feature in modern cosmology; however, calculations are typically plagued either by divergences or by ridiculously high predictions which are far removed from observation. This chapter will first provide a brief historical review of the vacuum and then discuss in detail some of the attempts to explain the vacuum in the language of Quantum Field Theory (QFT).Item Investigation of low Higgs models in Weakly Coupled Free Fermionic Heterotic String Theory.(2010-10-08T16:25:07Z) Pechan, Kristen.; Cleaver, Gerald B.; Physics.; Baylor University. Dept. of Physics.Superstring phenomenology explores classes of vacua which can reproduce the Standard Model at low energy. We consider Weakly Coupled Free Fermionic Heterotic String Theory (WCFFHST) which produces four dimensional Standard-like Models and allows for their SO(10) embedding. In the models herein, we explore the removal of extra Higgs representations via free fermion boundary conditions directly at the string level, rather than in the low energy effective field theory. We focus on the flat direction analysis of four models with reduced number of Higgs, after flat direction analysis of a three generation reduced Higgs model revealed no stringent F- and D-flat solutions to all order in the superpotential. Flat direction analysis of the four models presented herein shows the lack of D- and F-flat solutions to all order is not a general property of low Higgs models, as stringent flat directions appear to all order for three of our four models.Item Reflections on general relativity from perspectives of black hole physics and Hořava-Lifshitz gravity.(2015-07-30) Deng, Yanbin, 1982-; Cleaver, Gerald B.The physical logic of the Theory of General Relativity is summarized employing differential geometry of surfaces in three dimensional Euclidean space as a visual assistance for understanding. The applications of general relativity in fields as cosmology and black hold physics is summarized. Of the unsolved problem such as cosmology of the very early universe, dark matter and dark energy, black hole singularity and quantization of gravity, some are more fundamental, while some are more about the specific application of general relativity to particular situations. As an application of general relativity, the Hawking temperature and tunneling rate for the Fermion tunnelling process was obtained for a regular black hole which has no singularity inside the body. Hořava-Lifshitz theory, proposed by some physicists as an attempt to fix the quantization problem of general relativity, is employed in the study of a holography problem.