La cosmologie est actuellement à un tournant de l'histoire de son développement. L'abondance de données observationnelles diverses et précises a permis de développer et de confirmer un modèle standard de concordance pour décrire les grandes échelles de l'Univers. Fort de ce succès, il devient crucial d'interroger les fondements de ce modèle standard, afin, notamment, d'éclaircir l'origine d'environ 90 % du contenu énergétique de l'Univers, qualifié de matière et d'énergie sombres.<br />En lien avec le problème de l'énergie sombre, cette thèse se propose d'explorer, à travers les propriétés dynamiques de champs scalaires, deux principes qui se trouvent au coeur de la cosmologie: les principes d'équivalence et cosmologique.<br />Le principe d'équivalence est abordé à travers les théories scalaire-tenseur de la gravité, permettant d'intégrer la Relativité Générale dans un cadre large de théories respectant la version faible du principe d'équivalence tout en permettant de tester sa version forte. Dans cette perspective, les propriétés dynamiques et les conséquences cosmologiques de ces théories sont discutées.<br />Le principe cosmologique quant à lui est reformulé; ses contours sont redéfinis, menant à la formulation de modèles cosmologiques différents du modèle standard, par le biais des cosmologies inhomogènes moyennées. Ces modèles permettent de prendre en compte de façon consistante la structuration à petites échelles de l'Univers et son homogénéité aux grandes échelles, ouvrant ainsi la possibilité d'expliquer l'énergie sombre par la formation des structures; il est également possible de les mettre en correspondance avec l'apparition de champs scalaires dans le cadre du modèle standard.

As observações astronômicas dos últimos 15 anos revelaram que o universo atualmente está expandindo aceleradamente. No contexto da relatividade geral se acredita que a energia escura, cujo melhor candidato é a densidade do vácuo ($\\Lambda/8\\pi G$), é o agente responsável por este estado acelerado. No entanto, o termo $\\Lambda$ tem duas sérias dificuldades: o problema da constante cosmológica e o problema da coincidência. Com o objetivo de aliviar o problema da constante cosmológica, muitos modelos adotam um termo $\\Lambda$ dinâmico, permitindo seu decrescimento ao longo de toda a história cósmica. Neste tipo de modelo, a equação de conservação do tensor momento energia total exige uma troca de energia entre a densidade do vácuo e as outras componentes energéticas do universo; o que também alivia o problema da coincidência. Neste trabalho discutimos diferentes consequências de um vácuo dinâmico no âmbito cosmológico e no processo de colapso gravitacional. Em particular, analisamos o caso em que a densidade do vácuo possui uma dinâmica não trivial com a escala de energia típica do universo, que depende monotonamente do parâmetro de Hubble, decrescendo ao longo de toda a história cósmica. Nos referiremos a este modelo como modelo deflacionário. Nesse contexto, utilizando os primeiros termos da expansão para a densidade do vácuo, sugerida pela teoria do grupo de renormalização em espaço-tempos curvos, propomos um novo cenário cosmológico baseado numa densidade do vácuo dinâmica. O cenário proposto é completo no sentido de que o mesmo vácuo é responsável pelas duas fases aceleradas do universo, conectadas por uma fase de radiação e um estágio de domínio da matéria. Neste cenário o universo plano é não singular, iniciando sua evolução a partir de um estágio do tipo de Sitter e, portanto, toda a história cósmica ocorre entre duas fases de Sitter limites. Este modelo não apresenta o problema de horizonte, e nele a nucleossíntese cosmológica ocorre como no modelo de Friedmann, e embora este modelo seja muito próximo do modelo $\\Lambda$CDM, o grande acúmulo de observações no estágio recente do universo permitirão que este poda ser testado. Adicionalmente, mostraremos que generalizações do modelo deflacionário incluindo curvatura espacial apresentam propriedades e vantagens similares. Usando observações de $H(z)$, da luminosidade de supernovas tipo Ia, da função de crescimento linear das perturbações escalares, e da posição do pico das oscilações acústicas de bárions conseguimos vincular um dos parâmetros do modelo. Por outro lado, analisando a física do universo primordial, assumindo um vácuo não perturbado, conseguimos limitar um segundo parâmetro fazendo uso do índice espectral das perturbações escalares. Com o objetivo de fazer uma análise mais completa do modelo no âmbito cosmológico, analisamos também as possíveis restrições oriundas da validade da segunda lei da termodinâmica em sua forma generalizada (GSLT). Para isto investigamos a evolução tanto da entropia associada ao horizonte aparente do universo, que é um horizonte atrapante devido a que o escalar de Ricci é positivo, como do seu conteúdo material. Motivados pela forma como a singularidade primordial do universo é evitada devido aos efeitos do decaimento do vácuo, incluímos no presente trabalho outra linha de desenvolvimento: a análise dos estágios finais do processo de colapso gravitacional em presença de uma densidade do vácuo dinâmica. Centraremos esta análise na determinação de modelos que possam ou não evitar a formação de um buraco negro. Mostraremos que modelos com um termo de vácuo proporcional à densidade de energia total do sistema, não podem evitar a formação de uma singularidade no estágio final do processo de colapso. Adicionalmente obteremos correções para a massa colapsada, para o tempo de formação do horizonte e para o tempo de colapso como função dos parâmetros do modelo e da curvatura espacial. Por último analisaremos a influência de uma densidade do vácuo capaz de dominar sobre as outras componentes no regime de altas energias, mostrando que este tipo de dinâmica na densidade do vácuo evita a formação de um estado final singular. / The astronomical observations of the last 15 years revealed that the universe is currently undergoing an expanding accelerating phase. In the general relativity context is believed that dark energy, whose best candidate is the vacuum energy density $ho_v \\equiv \\Lambda/8\\pi G$, is the fuel responsible for the present accelerating stage. However, the so-called $\\Lambda$-term has two serious drawnbacks, namely: the cosmological constant problem and the coincidence problem. In order to alleviate the cosmological constant problem, many models adopt a dynamical $\\Lambda$ term, thereby allowing its decreasing throughout the cosmic history. In this kind of model, the total energy conservation law defined in terms of the energy momentum tensor requires an energy exchange between the vacuum and the material components of the universe, which also contributes to alleviate the coincidence problem. In the present thesis we discuss different consequences of an interacting vacuum component both in the cosmological scenario as well as in the process of gravitational collapse. In particular, in the cosmological domain, we examine the case where the vacuum has a nontrivial dynamics dependent on a typical energy scale, the Hubble parameter, that decreases in the course of the cosmic history. We will refer to this model as deflationary model. In this context, by using a truncated expansion for the vacuum energy density, as suggested by the renormalization group theory in curved space-time, we propose a new cosmological scenario based on a dynamical $\\Lambda$-term. The proposed scenario is complete in the sense that the same vacuum is responsible for both accelerating phases of the universe, which are linked by two subsequent periods of radiation and non-relativistic matter domination. In this scenario the flat universe is nonsingular and starts its evolution from an asymptotic de Sitter stage, so that the cosmic story takes place between two extreme de Sitter phases. The model is free of the horizon problem as well as of the \"graceful exit\" problem plaguing many inflationary variants. In addition, the cosmological nucleosynthesis occurs as in the Friedmann model and the observations in the latest stages of the universe can potentially differentiate between the deflationary and the standard $\\Lambda$CDM model. The generalizations including spatial curvature are aslo discussed in detail. On the other hand, by using the late time tests like type Ia supernovae, the redshift dependence of the Hubble parameter, $H(z)$, the linear growth function of scalar perturbations, and the peak position of baryon acoustic oscillations we have constrained the basic parameters of the model. Conversely, analyzing the physics of the primordial universe and assuming that the vacuum is a smooth component, we have also constrained the spectral index of scalar density perturbations. In order to establish a more complete analysis of our cosmological scenario, we also discuss the possible constraints arising from the validity of the generalized second law of thermodynamics, that is, by including the horizon thermodynamics. Since the apparent horizon of the universe behaves like a trapped horizon because the Ricci scalar is positive, we investigate the evolution of both the entropy of the material components and the entropy associated to the horizon. Motivated by the avoidance of the Big-Bang singularity due to the decaying vacuum effects, we have explored another line of development: the analysis of the final stages of gravitational collapse process in the presence of a dynamic vacuum. This analysis focused on the determination of models able to prevent or not the formation of a black hole. In this connection, we shown that the presence of an interacting vacuum proportional to the total energy density of the system does not prevent the formation of a singularity in the final stages of the collapsing process. In addition, we obtain corrections for the collapsed mass, the horizon time formation and the collapsing time as a function of the free parameters and the spatial curvature of the models. Finally, we have also analyzed the influence of a vacuum contribution which dominates the other components into the high energy limit (due to the presence of higher orders terms in the contraction rate), and shown that for this kind of models the growth of the vacuum energy density prevents the formation of the singularity.

Este trabalho pretende discutir como as relações com a alteridade operam politicamente entre os Guarani Mbya; de que maneira os seus movimentos, como a esquiva, conformam modos políticos de conduzir a incorporação do exterior, transformando posições e relações de poder. Tomado primeiramente a partir da dança do xondaro, personagem que remete a diferentes funções e a uma forma de relação, o movimento da esquiva irá além para ajudar a pensar as dinâmicas entre corpos, coletivos e mundos, contribuindo para suspender oposições exclusivas entre resistência e fuga. A esquiva (jeavy uka fazer errar) surge como um movimento nem exclusivamente positivo, nem negativo. Em termos políticos: não submete e tampouco deixa se submeter. A análise aborda também a prática da enganação conforme ela aparece em narrativas mitológicas guarani, cuja operação revela um mecanismo de crítica política na mitologia. Ao final, após revisitarmos oprocesso histórico da resistência guarani, chegamos ao contexto contemporâneoda luta indígena pelas demarcações, na qual desdobram-se atualizações de figuras-chaves da política ameríndia, como o xamã e o guerreiro. Assim, seja no passadoou no presente, busco demonstrar como a esquiva guarani é um movimentocapaz de produzir, de forma concomitante, possibilidades de resistência opostas einterdependentes. / This work intends to discuss how the relations with the alterity operate politically among the Guarani Mbya; in which manners their movements, such as the dodge, conform political ways to conduct the incorporation of the exterior, transforming power positions and relations. Taking into account, primarily, the dance of the xondaro, a figure that alludes to different functions and to a form of relation, the movement of the dodge goes beyond to help reflect about the dynamics of bodies, collectives and worlds, contributing to a suspension of exclusive oppositions between resistance and escape. The dodge (jeavy uka make mistake) appears as a movement, not exclusively positive, nor negative. In political terms: it does not submit nor submits oneself. The analysis addresses as well the practice of deceit, according to how it appears in the mythological guarani narratives, whose operation in the mythology reveals a mechanism of political critique. At the end, after revisiting the historical process of resistance of the guarani, one reaches to a contemporary context of indigenous struggle for land demarcation, in which are unfolded updates of key figures of the Amerindian politics, such as the xamã and the warrior. Thus, be it in the past or the present, the work here presented seeks to demonstrate how the guarani dodge is a movement capable of generate, in a concomitant manner, opposed and interdependent possibilities of resistance.

This dissertation on negating, resisting or affirming cosmological principle towards an African humanism leadership theory and model has evolved through an embryonic process that arose from the research ‘itch’ as regards the way in which post-colonial African leadership has been critiqued. This research ‘itch’ also focused on how the postcolonial leadership in Africa, were trail blazers in formulating liberation philosophies and ideologies that did not, unfortunately, translate into sustainable peace and development. Thus, this dissertation has been a journey of immersion into the public and macro-level discourse contained in pre-colonial, colonial and postcolonial African leadership case studies. This enriching journey revealed a postcolonial African leadership which had focused on ideologies and philosophies and had deviated from the spirituality embedded in indigenous cosmologies and knowledge systems. Hence, this dissertation examines relevant cosmological principles embedded in indigenous cosmologies and knowledge systems for analysing African leadership; for the embryonic process that begins with the universal humanism perspective of African leadership, cognitive justice and transformation by enlargement, and basic African humanism perspectives. Thus, this study examines cognitive justice as the enabler of indigenous cosmologies and transformation by enlargement as the enabler of indigenous knowledge systems, both of which provide relevant cosmological principles for analysing African leadership. In addition, the dissertation analyses indigenous cosmologies and knowledge systems from the African continent in an effort to distinguish between the various forms of leadership found in Africa and to generate an African humanism leadership theory and model. The indigenous cosmologies and knowledge systems in this dissertation are from four regions in Africa, namely, North Africa (Egypt); West Africa (Ghana-Akan); the Horn of Africa (Ethiopia) and Southern Africa (Bantu). The methodologies used in the study include Afrikology and critical discourse analysis and enabled the research study to ascertain whether cosmological principles embedded in indigenous cosmologies and knowledge systems are relevant for analysing African leadership. Critical discourse analysis enabled the geographic triangulation of African leadership and the indigenous cosmologies and knowledge systems, thus resulting in the development of the African humanism leadership theory and model of individual dualism leadership. / Educational Studies / M. Ed. (Philosophy of Education)

This dissertation on negating, resisting or affirming cosmological principle towards an African humanism leadership theory and model has evolved through an embryonic process that arose from the research ‘itch’ as regards the way in which post-colonial African leadership has been critiqued. This research ‘itch’ also focused on how the postcolonial leadership in Africa, were trail blazers in formulating liberation philosophies and ideologies that did not, unfortunately, translate into sustainable peace and development. Thus, this dissertation has been a journey of immersion into the public and macro-level discourse contained in pre-colonial, colonial and postcolonial African leadership case studies. This enriching journey revealed a postcolonial African leadership which had focused on ideologies and philosophies and had deviated from the spirituality embedded in indigenous cosmologies and knowledge systems. Hence, this dissertation examines relevant cosmological principles embedded in indigenous cosmologies and knowledge systems for analysing African leadership; for the embryonic process that begins with the universal humanism perspective of African leadership, cognitive justice and transformation by enlargement, and basic African humanism perspectives. Thus, this study examines cognitive justice as the enabler of indigenous cosmologies and transformation by enlargement as the enabler of indigenous knowledge systems, both of which provide relevant cosmological principles for analysing African leadership. In addition, the dissertation analyses indigenous cosmologies and knowledge systems from the African continent in an effort to distinguish between the various forms of leadership found in Africa and to generate an African humanism leadership theory and model. The indigenous cosmologies and knowledge systems in this dissertation are from four regions in Africa, namely, North Africa (Egypt); West Africa (Ghana-Akan); the Horn of Africa (Ethiopia) and Southern Africa (Bantu). The methodologies used in the study include Afrikology and critical discourse analysis and enabled the research study to ascertain whether cosmological principles embedded in indigenous cosmologies and knowledge systems are relevant for analysing African leadership. Critical discourse analysis enabled the geographic triangulation of African leadership and the indigenous cosmologies and knowledge systems, thus resulting in the development of the African humanism leadership theory and model of individual dualism leadership. / Educational Studies / M. Ed. (Philosophy of Education)

La existencia o no de ancestros en la Amazonía indígena ha sidoobjeto de importantes debates. Sin embargo, los líderes de la región no dudan en llamar ‘ancestrales’ sus saberes, normas o territorios,en un sentido que, desde un punto de vista académico, puede parecer enigmático. «Ancestrales, pero… ¿con o sin ancestros?», preguntaría entonces, confuso, el antropólogo. En este artículo propongo aportar elementos de respuesta a estapregunta a través del caso peruano. Primero analizo cómo los líderes indígenas amazónicos, conectándose al circuito del derecho internacional, adoptan la noción jurídica de ‘posesión ancestral’ del territorio para adaptarla al ámbito político. Este planteamiento rinde cuenta de la generalización y uniformización reciente del vocablo ‘ancestral’ pero deja pendiente el problema de su eventual articulación con las cosmologías indígenas que pretende reflejar. Por eso, en la segunda parte, intento sondear sobre la pertinenciade la categoría de ‘ancestro’ en la Amazonía indígena, recordando brevemente el debate académico para ir definiendo en qué medida esta categoría puede cobrar sentido. A partir del testimonio de un experimentado líder awajún, la tercera parte permite, entonces, volver más explícitos los diferentes sentidos y planos referenciales que despliega la referencia a lo ancestral, mostrando cómo los indígenas amazónicos no solo adoptan elementos conceptuales y discursivos externos, sino que al mismo tiempo los transforman a partir de sus propias singularidades cosmológicas y perspectivas políticas. / The existence —or not— of the concept of ancestors in the indigenous Amazon has been the subject of much debate. However, regional leaders do not hesitate to call upon ‘ancestral’ knowledge, customs, or territories in the sense that, from an academic point of view, could appear enigmatic. «Ancestral, but… with or without ancestors?» is the question a confused anthropologist might ask. In this article, I propose to offer elements of a response to this question,based on a case study in Peru. First I analyze how Amazonian indigenous leaders, following international law, have adopted the legal notion of ‘ancestral possession’ of their territory to adapt it to the political sphere. This approach accounts for the recent generalization and uniformization of the term ‘ancestral’, but poses the problem of how it articulates with the indigenous cosmologies that it supposes to reflect. For this reason, I explore in the second section the pertinence of the category of ‘ancestor’ in the indigenous Amazon, briefly drawing upon the academic debate in order to define inwhat way this category takes on meaning. Based on testimony from an experienced Awajún leader, we thus return in the third section more explicitly to the different meanings and planes of reference that unfold when one uses the term ‘ancestral’, showing how Amazonian indigenous people not only adopt external conceptual elements and arguments, but also transform them based on their own cosmological singularities and political perspectives.

Considéré généralement comme objet de l’art, sujet de la littérature et catégorie de l’esthétique chinoise, shanshui, les « montagnes-eaux », est censé relever d’un sentiment et d’une conception de la nature relativement différente de celle de l’Occident. Or la construction moderne de shanshui au prisme de la nature n’intègre la multiple pratique paysagère historiquement fondée dans la tradition lettrée, inextricablement liée à l’invention des montagnes-eaux : l’érémitisme, la recherche d’immortalité, l’excursion, la réunion littéraire lettrée, la création poétique, picturale et du jardin. Centrée sur l’histoire tri-séculaire après la chute de la Dynastie Han, en exposant les conjonctures particulières, analysant la notion ‘ziran’ dans l’étude du Mystère, rassemblant et traduisant les écrits et poèmes thématiques qui témoignent des mouvements et tendances extra-mondains dans les milieux lettrés sous les Wei-Jin (220-420), cette thèse vise à montrer que shanshui, plutôt que d’être constitué par la dualité nature/art, est inventé comme un paradigme confrontant, dans une bipolarisation de la réalité lettrée à cette époque, l’espace confucéen et l’espace taoïste, le service et la retraite, les affaires mondaines et la recherche de l’idéal par-delà la société. Autour de shanshui se cristallisent les idées-valeurs comme l’authenticité, la dévotion, la vertu, la liberté, le naturalisme, le mysticisme, la créativité et la transcendance immanente, en cela, nous supposons la co-naissance des montagnes-eaux et d’un idéal-type de l’humanisme classique chinois. / Generally regarded as the object of art, the subject of literature and Chinese aesthetic category, Shanshui (mountains-waters) is believed to be relevant to aesthetical feelings as well as the philosophical concept of nature that is different from that of the West. However, the modern construction of Shanshui through the prism of nature does not integrate the multiple landscape practices historically founded in the gentry's tradition, which had contributed to the invention of mountains-waters: eremitism, immortality seeking, excursion, gathering of literary circles, and the creation of poetry, paintings and gardens. Focusing on the history of Wei-Jin (220-420) after the fall of the Han dynasty, exposing the particular contexts, analyzing the notion of 'Ziran' in the Xuanxue school, gathering and translating the writings and thematic poems showing the extra-mundane movements and tendencies in literate milieus under this time, this thesis aims to show that Shanshui, rather than being constituted by the duality of nature and art, has been invented as a cultural paradigm to confront, in a bipolarization of the reality of ruling gentry class, the Confucian space and the Taoist space, service and disengagement, mundane concerns and pursuit of the Ideal beyond society. Around Shanshui the ideas and values such as authenticity, deep affection, virtue, liberty, naturalism, mysticism, creativity and immanent transcendence are crystallized, in this way, we may assume the co-birth of mountains-waters and an ideal type of Chinese classical humanism. / 山水研究以往側重于詩歌，繪畫與哲學分析，并普遍將山水視為自然再現，自然情感與某種不同於西方自然觀的審美表達。然而，“相對不同”的判定卻是建立在自然／文化兩分的現代二元范式的“普世應用”上的。因為僅僅強調山水源於“發現自然”並不能整合與山水緊密相關且貫穿於士傳統中的文化實踐：如隱逸，遊仙，遊覽，雅集，以及對世外理想之境的不懈書寫，描畫與營造。本論文考察了魏晉時期(220-420)的社會，政治與文化背景：名教自然的對立，隱逸遊仙的結合，魏晉風度，衣冠南渡，僑立，宗教興起，道釋義理在文化士族內部經由玄學促生的思想轉向等；通過分析魏晉玄學中的自然概念，整理翻譯相關的歷史文本與詩歌，試圖說明，與其說山水是自然／藝術的二元構建，毋寧說山水是士階層在仕與隱，經世與玄遠，世表與塵外的現實兩極化中所創建的一種文化範式。圍繞山水，凝聚了一系列具有重要文化特徵的理念与價值——保真，養身，自足，逍遙，自然主義，暢神玄覽，內在超越與審美理想。這意味著與山水共生的是一種中國古典人文主義的理想型。