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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

Cosmological models of the early universe

Mimoso, Jose Pedro January 1993 (has links)
No description available.
2

Alternative Realities/The Multiverse: A Metaphysical Conundrum

Wynn, Freda A. 02 February 2006 (has links)
Films of every era reflect the concerns and fears of Western society. The acceleration of technology, the loss of a concrete world, the uneasy relationship with humans and ever increasing complex machines are inducing a fear of losing the ability to discern reality. The reality of ideas from science and the world around are woven into the narratives that we use to explain life.The films we watch reflect our hopes and fears and as the fears increase so do films with a shared theme of alternative realities. To know reality and search for the true Self is the job of the hero and the protagonist in recent alternative reality films.
3

Pattern recognition in astrophysics and the anthropic principle

Darg, Daniel W. January 2012 (has links)
The role of the Anthropic Principle in astrophysics and cosmology is examined in two principal parts. The first (minor) part takes a chiefly philosophical perspective and examines the manner in which human cognition features into discussions on cosmic origins. It is shown that the philosophical questions raised by the Anthropic Principle and ‘fine-tuning of life’ bear resemblances to problems within the philosophy of mind and we seek a common origin for this surprising parallel. A form of ‘epistemic structural realism’ is defended and used to critique the physicalist identity thesis. It is argued that equating ‘reality’ with mathematical structures, which is the basis of the identity thesis, leads to incoherent conclusions. Similar reasoning is used to critique infinite Multiverse theories. In the second (major) part, we gradually transition into mainstream astrophysics, first presenting a new line of research to explore counterfactual universes using semi-analytic models (SAMs) and offering a preliminary study wherein the cosmological constant is varied and the effects on ‘advanced civilisations’ are examined. The importance of galaxy mergers is highlighted and leads to their study. We first try solving the pattern-recognition problem of locating mergers using the Galaxy Zoo database and produce the largest homogenous merger catalogue to date. We examine their properties and compare them with the SAMs of the Millennium Simulation finding good general agreement. We develop the Galaxy Zoo approach with a new visual-interface design and double the size of the merger catalogue of SDSS mergers in the local Universe.
4

Paradoxes of human will in the time travel film

Elder, Ricki 09 February 2010
This study discusses how the literary device of time travel can limit or empower protagonists. The main focus is on H.G. Wells The Time Machine and the two films of the same name inspired by the novel. The popularity of time travel in film springs from the myriad storytelling possibilities the device provides, and the writers agenda determines what place, if any, logic and causality have in the story. Some narratives endorse the theory of eternalism, where time is fixed and the time travellers actions are fated to be consistent with the history the traveller knows. But many films rely on theories of multiple timelines and many worlds, giving the traveller a much greater range of agency. Paradoxes of causality can inhibit the travellers actions as well. This essay discusses the broad spectrum in time travel narrative, where at one end travellers are imprisoned in history, and at the other they enjoy a great deal of freedom.
5

Paradoxes of human will in the time travel film

Elder, Ricki 09 February 2010 (has links)
This study discusses how the literary device of time travel can limit or empower protagonists. The main focus is on H.G. Wells The Time Machine and the two films of the same name inspired by the novel. The popularity of time travel in film springs from the myriad storytelling possibilities the device provides, and the writers agenda determines what place, if any, logic and causality have in the story. Some narratives endorse the theory of eternalism, where time is fixed and the time travellers actions are fated to be consistent with the history the traveller knows. But many films rely on theories of multiple timelines and many worlds, giving the traveller a much greater range of agency. Paradoxes of causality can inhibit the travellers actions as well. This essay discusses the broad spectrum in time travel narrative, where at one end travellers are imprisoned in history, and at the other they enjoy a great deal of freedom.
6

Study of cohomogeneity one three dimensional Einstein universe / Etudes des espaces d'Einstein tridimensionnels de cohomogénéité un

Hassani, Masoud 04 July 2018 (has links)
Dans cette thèse des actions conformes de cohomogénéité un sur l'univers d'Einstein tridimensionel sont classifiées. Notre stratégie est d'établir dans un premier temps quel peut être le groupe de transformations conformes impliqué, à conjugaison près. Nous décrivons aussi la topologie et la nature causale des orbites d'une telle action. / In this thesis, the conformal actions of cohomogeneity one on the three-dimensional Einstein universe are classified. Our strategy in this study is to determine the representation of the acting group in the group of conformal transformations of Einstein universe up to conjugacy. Also, we describe the topology and the causal character of the orbits induced by cohomogeneity one actions in Einstein universe.
7

Une Application Des N-Univers A L'argument De L'apocalypse Et Au Paradoxe De Goodman

Franceschi, Paul 11 1900 (has links)
Several philosophical problems are based on an analogy between a real situation and a probabilistic model. Such problems are based on urn analogies. The present dissertation aims to describe and implement a methodology oriented towards the resolution of philosophical problems based on an urn analogy. This methodology is based on the use of the n-universes. To this end, I describe first the n-universes in a detailed way. I also discuss the difficulties of the theory of n-universes related to the demultiplication of the criteria and to the relation one/many between the objects and a given criterion.On the one hand, I present an application of the framework of n-universes to the Doomsday argument and to the problems recently appeared in the literature in keeping with the Doomsday argument. My concern is also with showing how the application of the framework of n-universes to several problems and thought experiments related to the Doomsday argument helps clarifying the problem data and making disappear the associated ambiguity. I present then an analysis of the following problems related to the Doomsday argument: the two urn case, God's Coin Toss, the Sleeping Beauty Problem, the Presumptuous Philosopher, Lazy Adam, and the Shooting-Room Paradox. I present lastly a solution to the Doomsday argument, based on a third route, by contrast to two types of solutions classically described.On the other hand, I present an application of the framework of n-universes to Goodman's paradox. I replace first Goodman's statement in the framework of n-universes. I propose then a solution to the paradox, based on a distinction between two different modelizations of Goodman's statement in two structurally different n-universes.
8

Um sistema de Gentzen para Cálculos com Identidade Parcial e Universos Abertos / A Gentzen System for Calculations Partial identity and Open Universes

Mazak, Rene Pierre Maximilian Eduard 22 June 2010 (has links)
Os sistemas Q1 e Q2, desenvolvidos por Andréa Lopari?, perfazem três principais modificações na semântica clássica: primeiramente, o universo do discurso pode não estar limitado aos objetos que pertencem ao domínio de uma dada estrutura; em segundo lugar, a relação de identidade é determinada como a diagonal desse domínio (assim, tal relação pode não ser aplicável a todas as coisas sobre as quais a linguagem possa falar); em terceiro lugar, o quantificador existencial, em Q1, bem como o universal, em Q2, podem alcançar valores que estejam fora do domínio da estrutura. Como consequência, embora definida classicamente, a negação apresenta alguns comportamentos não clássicos - a negação de um predicado numa fórmula atômica, por exemplo, pode caracterizar algo maior que, e não tão bem definido quanto, o complemento da extensão desse predicado relativamente ao domínio. [...]. / The systems Q1 and Q2, developed by Andréa Lopari?, make up three main changes in classical semantics: first, the universe of discourse can be not limited by the objects that belongs to the domain of a given structure; second, the relation of identity is fixed as a diagonal of this domain (so, it may be not applicable to all things about what the language can speak); third, the existential quantifier in Q1, as well as the universal in Q2, may capture values out of the domain of the structure. As a consequence, although classically defined, the negation presents some non-classical behavior - a negated predicate in an atomic formula, for instance, may characterize something larger and not as well defined as the complement of the extension of this predicate relatively to the domain. [...].
9

Pelos olhos das crianças : uma etnografia da favela do Gonzaga

Begnami, Patricia dos Santos 12 March 2008 (has links)
Made available in DSpace on 2016-06-02T19:00:20Z (GMT). No. of bitstreams: 1 2436.pdf: 415459 bytes, checksum: f3ac7d64da545327ef95198f75249eb2 (MD5) Previous issue date: 2008-03-12 / Financiadora de Estudos e Projetos / This research had the objective to enlarge and to deepen the suburb analysis, using as an object the Gonzaga shantytown, located in São Carlos, in the countryside of the state of São Paulo, and a neighborhood spotted by the population of the city as a troubled one, and the home of most of the criminals operating in the city, since it s one of the neighborhoods where most inhabitants have low incomes. Through the ethnography focused on the study of a case, the Gonzaga shantytown, I have revised the co-extensive relation between two generation universes: the adult and the infantile, investigating the sociability in the neighborhood, using as objects, the street, the relationships among the children, and also the relationships between the children, their parents and their relatives. In sum, I have investigated through the field research, the participating observation, the ethnography as the children are committed with the configuration, and the net of social activities in the neighborhood and how all that is represented and portrayed in the children s behavior and sociability, as much as in their ludic activities. In this research, the main role is played by the children, therfore the text was built from the children s point of view; they are interlocutors. Thus, the children were treated as subjects, capable of representing and signifying their own experiences, as actors and social agents that signify, and not merely re-signify their social environment, and that perceive the world and represent it in their own way. At last, this research shows how the Gonzaga shantytown s children represent and signify the neighborhood where they live in, and, because of the children, we are able to know the life experience of those who live in the suburbs or in shantytowns, which is different than the one presented by the tv channels and the newspapers, medias that do not realize the diversity of inhabitants in these neighborhoods. / Essa pesquisa teve por objetivo ampliar e a aprofundar a análise sobre periferia, tomando como objeto de estudos a favela do Gonzaga, localizada na cidade de São Carlos, interior do estado de São Paulo, bairro estigmatizado pela população sãocarlense, que o vê como um bairro problema , local em que reside a maioria dos criminosos que atuam na cidade, pois é um dos bairros que abriga a população de baixa renda. Através da etnografia focalizada num estudo de caso, a favela do Gonzaga, problematizei a relação co-extensiva entre dois universos geracionais: o adulto e o infantil, investigando a sociabilidade no bairro, tomando como objetos de análise, a rua, a relação entre as crianças, a relação das crianças com os pais e com a parentela. Em suma, investiguei através da pesquisa de campo, da observação participante, da etnografia como as crianças estão comprometidas com a configuração e a rede de práticas sociais no bairro e como isso está representado e reproduzido no comportamento e na sociabilidade infantil e nas suas práticas lúdicas. Nesse trabalho de pesquisa as crianças ocuparam lugar central, por isso o texto é a partir do ponto de vista das crianças, elas são interlocutoras da pesquisa. Dessa forma, as crianças foram tratadas como sujeitos capazes de representar e significar suas experiências, como atores e agentes sociais que significam e não apenas resignificam seu mundo social, que apreendem o mundo e o representam a sua maneira. Enfim, essa pesquisa mostra como as crianças da favela do Gonzaga representam e significam o bairro em que vivem e, através das crianças conhecemos a experiência de vida daquelas pessoas que moram em periferias ou em favelas que é diferente daquela veiculada por meio da mídia ou de jornais, que não percebem a multiplicidade de sujeitos que moram nesses bairros.
10

Teorias modificadas da gravitação e a violação de causalidade

Silva, Paulo José Ferreira Porfírio da 22 February 2017 (has links)
Submitted by Vasti Diniz (vastijpa@hotmail.com) on 2017-09-13T14:26:30Z No. of bitstreams: 1 arquivototal.pdf: 2274734 bytes, checksum: 20f744b4f2279525b9a574a0a0de7838 (MD5) / Made available in DSpace on 2017-09-13T14:26:30Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2274734 bytes, checksum: 20f744b4f2279525b9a574a0a0de7838 (MD5) Previous issue date: 2017-02-22 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / In this thesis we deal with G odel-type Universes in the context of modi ed gravity, in particular, Chern-Simons modi ed gravity and Brans-Dicke theory with cosmological constant (BD- ). The G odel-type metrics have been intensively discussed in the General Relativity (GR) over years. It is known that such a metrics present Closed Time-like Curves (CTC's), in other words, the G odel-type metrics are themselves an example of the causality violation. Our goal is verify the consistency of the G odel-type metrics within the Chern-Simons modi ed gravity in both: non-dynamical and dynamical formulations. In the non-dynamical framework, we show that is possible a vacuum solution in contrast to GR. Another essentially new result that we get is the presence of causal solutions for a well-motivated matter source, in general, the solutions have no analogue in GR. Moreover, the vacuum solution represents the limiting case separating the completely causal and non-causal regions, such a property re ects the topological features of the Chern-Simons theory. The primordial distinguishing feature between the Chern-Simons modi ed gravity and GR solutions is the presence of the breaking Lorentz symmetry. It turns out this breaking opens up a range of new solutions. We show that the non-trivial Chern-Simons solutions in the non-dynamical framework is accompanied by rst-order corrections of the Lorentz-violating parameter. Furthermore, in the dynamical framework the geometric parameters are also a ected by second-order corrections of the Lorentzviolating parameter. We also investigated the G odel-type metrics in BD- model. We obtain a vacuum solution which is completely causal, m2 = 4!2, where for ~! ! 1 one recovers the GR with a scalar eld and cosmological constant. It is worth calling attention to the role of the cosmological constant that is fundamental in this context. / Nesta tese tratamos os Universos tipo Code' no contexto da gravidade modificada, em particular, na gravidade modificada de Chern-Simons e na teoria de Brans-Dicke com constante cosmolOgica (BD-A). As metricas tipo Code' vem sendo intensamente discuti­das na Relatividade Geral (RG) ao longo dos anon. Sabe-se que tail metricas apresentam Curvas tipo Tempo Fechadas (CTC's), ou seja, as prOprias metricas tipo Code' sao um exemplo da violagao de causalidade. Nosso objetivo é verificar a consistencia das metricas do tipo Code' dentro da gravidade modificada de Chern-Simons em ambas as formula-goes: nao dinamica e dinamica. Na formulagao nao-dinamica, mostramos que é possivel uma solugao de vacuo diferentemente da RG. Outro resultado essencialmente novo que obtemos é a presenga de solugoes causais para uma fonte de materia bem motivada, em geral, as solugoes nao tem analog° na RG. Alem disso, a solugao de vacuo representa o caso limite que separa as regioes completamente causal e nao causal, tal propriedade re­flete as caracteristicas topolOgicas da teoria de Chern-Simons. A caracteristica que difere fundamentalmente as solugoes da gravidade modificada de Chern-Simons e as da RG é a presenga da quebra da simetria de Lorentz. Acontece que essa quebra abre um leque de novas solugoes. Mostramos que as solugoes nao triviais de Chern-Simons na formulagao nao dinamica sao acompanhadas por corregoes de primeira ordem do parametro de viola­gao de Lorentz. Alem disso, na formulagao dinamica os parametros geometricos tambem sao afetados por corregoes de segunda ordem do parametro de violagao de Lorentz. Investigamos tambem as metricas tipo Code' no modelo BD-A. Obtemos uma solugao de vacuo completamente causal, m2 = 4w2, onde para cD -+ oo recupera-se a GR com um campo escalar e constante cosmolOgica. Vale a pena chamar a atengao para o papel da constante cosmolOgica que é fundamental neste contexto.

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