Thesis (Ph. D.)--University of Chicago, Dept. of Physics, June 1999. / Includes bibliographical references. Also available on the Internet.

No / This paper examines how such fundamental notions as causality and determinism have undergone changes as a direct result of empirical discoveries. Although such notions are often regarded as metaphysical or a priori concepts, experimental discoveries at the beginning of this century¿radioactive decay, blackbody radiation and spontaneous emission-led to a direct questioning of the notions of causality and determinism. Experimental evidence suggests that these two notions must be separated. Causality and indeterminism are compatible with the behavior of quantum-mechanical systems. The argument also sheds some light on the Duhem-Quine thesis, since experimental results at the periphery of the conceptual scheme directly affect conceptions at the very core.

We first consider four-dimensional gauge theory on twistor space, taking as a case study maximally supersymmetric Yang-Mills theory. Using a twistor action functional, we show that gauge theory scattering amplitudes are naturally computed on twistor space in a manner that is much more efficient than traditional space-time Lagrangian techniques at tree-level and beyond. In particular, by rigorously studying the Feynman rules of a gauge-fixed version of the twistor action, we arrive at the MHV formalism. This provides evidence for the naturality of computing scattering amplitudes in twistor space as well as an alternative proof of the MHV formalism itself. Next, we study other gauge theory observables in twistor space including gauge invariant local operators and Wilson loops, and discuss how to compute their expectation values with the twistor action. This enables us to provide proofs for the supersymmetric correlation function / Wilson loop correspondence as well as conjectures on mixed Wilson loop - local operator correlators at the level of the loop integrand. Furthermore, the twistorial formulation of such observables is naturally algebro-geometric; this leads to novel recursion relations for computing mixed correlators by performing BCFW-like deformations of the observables in twistor space. Finally, we apply these twistor actions to gravity. Using the on-shell equivalence between Einstein and conformal gravity in de Sitter space, we argue that the twistor action for conformal gravity should encode the tree-level graviton scattering amplitudes of Einstein's theory. We prove this in terms of generating functionals, and derive the flat space MHV amplitude as well as a recursive version of the MHV amplitude with cosmological constant. We also include some discussion of super-connections and Coulomb branch regularization on twistor space.

It has been shown that the cosmic censorship conjecture holds for polarized Gowdy spacetimes. In the more general, unpolarized case, however, the question remains open. It is known that cylindrically symmetric dust can collapse to form a naked singularity. Since Gowdy universes comprise gravitational waves that are locally cylindrically symmetric, perhaps these waves can collapse onto a symmetry axis and create a naked singularity. It is known that in the case of cylindrical symmetry, event horizons will not form under gravitational collapse, so the formation of a singularity on the symmetry axis would be a violation of the cosmic censorship conjecture.To search for cosmic censorship violation in Gowdy spacetimes, we must have a better understanding of their singularities. It is known that far from the symmetry axes, the spacetimes are asymptotically velocity term dominated, but this property is not known to hold near the axes. In this thesis, we take the first steps toward understanding on and near axis behavior of Gowdy spacetimes with space-sections that have the topology of the three-sphere. Null geodesic behavior on the symmetry axes is studied, and it is found that in some cases, a photon will wrap around the universe infinitely many times on its way back toward the initial singularity.

Este trabalho é a narrativa de uma experiência didática de aplicação de um módulo que abordou um tópico de Física Moderna e Contemporânea, a Teoria da Relatividade Restrita, no Ensino Médio. A proposta foi aplicada em uma escola particular situada no município de Arroio do Meio, RS, em uma turma de terceira série do nível médio regular, sob o referencial teórico da teoria cognitiva de Jean William Fritz Piaget (1896-1980) e sob o referencial epistemológico de Thomas Samuel Kuhn (1922-1996). Descreve-se o planejamento das aulas, a implementação da proposta e os resultados obtidos com sua aplicação em sala de aula na modalidade de um curso extraclasse. A forma como o módulo foi pensado e o nível de profundidade que foi possível alcançar aparecem ao longo do texto, que também oferece uma revisão da literatura em que a relevância da inclusão da Física Moderna e Contemporânea no currículo do Ensino Médio é discutida. Os resultados indicam que é possível trabalhar tópicos de Física Moderna e Contemporânea no ensino regular, que os alunos apreciaram e mostraram disposição para aprender assuntos atuais e que o esforço para introduzir pequenas atualizações curriculares é válido e precisa ser incentivado como uma das possíveis alternativas para se alcançar a melhoria de qualidade de ensino na Educação Básica. Ao final, um produto educacional em formato de texto de apoio, orientação e motivação aos professores de Física é apresentado. / This work is the narrative of a didactic experience of application of a module that addressed a topic of Modern and Contemporary Physics, the Special Theory of Relativity, in High School. The proposal was applied in a private school located in the county of Arroio do Meio, RS, for one group of third grade of regular secondary level, under the theoretical framework of cognitive theory of Jean William Fritz Piaget (1896-1980) and under the epistemological framework of Thomas Samuel Kuhn (1922-1996). It describes the planning of classes, the implementation of the proposal and the results obtained from its application in the classroom in the form of an extracurricular course. The way the module has been designed and the level of depth that was achieved is discussed throughout the text, which also provide a review of the literature in which importance of inclusion of Modern and Contemporary Physics in High School curriculum is discussed. The results indicate that it is possible teach subjects of Modern and Contemporary Physics in regular education. The results also indicated that students enjoyed and showed willingness to learn current issues and the effort to introduce small curriculum updates is valid and needs to be encouraged as one of the possible alternatives to achieve the improvement of teaching quality in basic education. At the end, an educational product in form of text, guidance and motivation to physics teachers is presented.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2016-04-15T12:30:25Z No. of bitstreams: 1 PDF - Alessandra Uchôa.pdf: 1564895 bytes, checksum: 61bc9f483c207af02ed046e81c22e85d (MD5) / Approved for entry into archive by Secta BC (secta.csu.bc@uepb.edu.br) on 2016-07-22T20:20:29Z (GMT) No. of bitstreams: 1 PDF - Alessandra Uchôa.pdf: 1564895 bytes, checksum: 61bc9f483c207af02ed046e81c22e85d (MD5) / Approved for entry into archive by Secta BC (secta.csu.bc@uepb.edu.br) on 2016-07-22T20:20:37Z (GMT) No. of bitstreams: 1 PDF - Alessandra Uchôa.pdf: 1564895 bytes, checksum: 61bc9f483c207af02ed046e81c22e85d (MD5) / Made available in DSpace on 2016-07-22T20:20:37Z (GMT). No. of bitstreams: 1 PDF - Alessandra Uchôa.pdf: 1564895 bytes, checksum: 61bc9f483c207af02ed046e81c22e85d (MD5) Previous issue date: 2013-11-05 / The relevance of teaching about science has been an important issue for educational researches over the last decades. In this new approach, the use of history and philosophy of science is a promising pedagogical strategy to introduce them to treat about development of scientific knowledge in the context of education. To support our research, we in Martins (1990, 2006), Matthews (1995), El-Hani (2006), elements to understand the purpose of the study of the History of Science and justify its use in teaching science. In view of the insertion of the history of modern physics course in teacher training, was drafted six texts to be applied for future physics teachers. The student’s texts include major historical events from Aristotle to Einstein. With this material we intend to demystify the current view that the claims of the theory of special relativity is attributed only to Albert Einstein, without considering, or even decrease, the contribution of Poincaré, Lorentz and others that were of fundamental importance. / A relevância de ensinar conteúdos sobre as ciências tem se intensificado nas pesquisas educacionais das últimas décadas. Nesse sentido, a história e filosofia da ciência podem ser configuradas como sendo um interessante recurso pedagógico para tratar sobre a construção do conhecimento científico no ensino. Para subsidiar a nossa pesquisa, buscamos em Martins (1990; 2006), Matthews (1995), El-Hani (2006), elementos para entender o propósito dos estudos da História da Ciência, bem como justificar o seu uso no ensino da mesma. Na perspectiva da inserção da história da física moderna e contemporânea no curso de formação de professores, foi elaborado seis textos para ser aplicados para futuros professores de física. Os textos dos alunos contemplam os principais fatos históricos desde Aristóteles até Albert Einstein. Com este material pretendemos desmistificar a visão atual em que os créditos da teoria da relatividade especial são atribuídos somente a Albert Einstein, sem considerar, ou até mesmo diminuir, a contribuição de Poincaré, Lorentz e outros que foram de fundamental importância.

In this thesis we study a deformation of a black-hole spacetime due to another strong sources of gravity. Keeping within static and axially symmetric metrics, we consider a binary of Schwarzschild black holes held apart from each other by a repulsive effect of an Appell ring. After verifying that such a system can rest in static equilibrium (without any supporting struts), we compute its several basic geometric characteristics and we plot simple invariants determined by the metric functions (especially lapse, or, equivalently, potential) and by their first and second derivatives (gravitational acceleration and Kretschmann scalar). Then we extend the analysis below the black-hole horizon and inspect the behaviour of the scalars inside. The geometry turns out to be deformed in a non-trivial way, we even find regions of negative Kretschmann scalar in some cases. In the second part, we present a summary of the perturbative solution describing a slowly rotating system of a black hole surrounded by a thin finite circular disc, and an analysis of equatorial circular geodesics in such a spacetime. 1

<p>In this thesis we study multipole moments of axisymmetric spacetimes. Using the recursive definition of the multipole moments of Geroch and Hansen we develop a method for computing all multipole moments of a stationary axisymmetric spacetime without the use of a recursion. This is a generalisation of a method developed by Herberthson for the static case.</p><p>Using Herberthson’s method we also develop a method for finding a static axisymmetric spacetime with arbitrary prescribed multipole moments, subject to a specified convergence criteria. This method has, in general, a step where one has to find an explicit expression for an implicitly defined function. However, if the number of multipole moments are finite we give an explicit expression in terms of power series.</p> / Note: The two articles are also available in the pdf-file. Report code: LiU-TEK-LIC-2006:4.

This is a thesis on general relativity. It analyzes dynamical properties of Einstein's field equations in cosmology and in the vicinity of spacetime singularities in a number of different situations. Different techniques are used depending on the particular problem under study; dynamical systems methods are applied to cosmological models with spatial homogeneity; Hamiltonian methods are used in connection with dynamical systems to find global monotone quantities determining the asymptotic states; Fuchsian methods are used to quantify the structure of singularities in spacetimes without symmetries. All these separate methods of analysis provide insights about different facets of the structure of the equations, while at the same time they show the relationships between those facets when the different methods are used to analyze overlapping areas. The thesis consists of two parts. Part I reviews the areas of mathematics and cosmology necessary to understand the material in part II, which consists of five papers. The first two of those papers uses dynamical systems methods to analyze the simplest possible homogeneous model with two tilted perfect fluids with a linear equation of state. The third paper investigates the past asymptotic dynamics of barotropic multi-fluid models that approach a `silent and local' space-like singularity to the past. The fourth paper uses Hamiltonian methods to derive new monotone functions for the tilted Bianchi type II model that can be used to completely characterize the future asymptotic states globally. The last paper proves that there exists a full set of solutions to Einstein's field equations coupled to an ultra-stiff perfect fluid that has an initial singularity that is very much like the singularity in Friedman models in a precisely defined way. / <p>Status of the paper "Perfect Fluids and Generic Spacelike Singularities" has changed from manuscript to published since the thesis defense.</p>

RODRIGUES, Joyce Mota. Entre telescópios e potes de barro: O eclipse solar e as expedições científicas em 1919/Sobral-CE. 2012. 133f. – Dissertação (Mestrado) – Universidade Federal do Ceará, Programa de Pós-graduação em História, Fortaleza (CE), 2012. / Submitted by Márcia Araújo (marcia_m_bezerra@yahoo.com.br) on 2013-10-11T11:19:45Z No. of bitstreams: 1 2012-DIS-JMRODRIGUES.pdf: 2543894 bytes, checksum: a2a82ca5560d8cf6847c270518012867 (MD5) / Approved for entry into archive by Márcia Araújo(marcia_m_bezerra@yahoo.com.br) on 2013-10-11T13:12:05Z (GMT) No. of bitstreams: 1 2012-DIS-JMRODRIGUES.pdf: 2543894 bytes, checksum: a2a82ca5560d8cf6847c270518012867 (MD5) / Made available in DSpace on 2013-10-11T13:12:05Z (GMT). No. of bitstreams: 1 2012-DIS-JMRODRIGUES.pdf: 2543894 bytes, checksum: a2a82ca5560d8cf6847c270518012867 (MD5) Previous issue date: 2012 / This research seeks to understand the daily routine of British, American and Brazilian Expeditions, in 1919, in the city of Sobral, in an attempt to confirm the Theory of Relativity by Albert Einstein. The relationships developed between scientists, local authorities and the media expose the discourses and scientific practices of modernity and backwardness local. / Esta pesquisa procura entender o cotidiano das Expedições Britânica, Americana e Brasileira, no ano de 1919, na cidade de Sobral, na tentativa de confirmar a Teoria da Relatividade de Albert Einstein. As relações travadas entre cientistas, autoridades locais e imprensa explicitam os discursos e as práticas científicas contrastantes de modernidade universal e atraso local.