THE THEORY OF UNIVERSAL GRAVITATION

Author: PAREJA GARCÍA M. JESÚS.
Year: 2003.
University: COMPLUTENSE DE MADRID [www.ucm.es].
Place of defense: FACULTAD DE CIENCIAS FÍSICAS.
Place of preparation: FACULTAD DE CIENCIAS FÍSICA.

Summary: In the first part of this thesis, resulting fundamental properties of relativistic stellar equilibrium models (stationary axisimétricos asintóticamente drawings and free convection) with differential rotation, in particular, it is shown that for a large class of laws rotation (compatible with the field equations and physically relevant) distribution of angular velocity of the fluid is a sign, and in addition, the drive speed and density of rotational angular momentum have the same sign. In the limit of slow rotation, where the field equations yet restricting perifl rotation (through a given rotation Act), deriving sufficient conditions guaranteeing the positivity of the density of angular momentum. In addition, the "average" (with regard to an intrinsic density) of the drive speed is shown that the average value of the angular velocity of the fluid (regardless of the law of rotation, completely in general), this leads to inequality positivity and an upper to the total energy of rotation of the star. The second part discusses various properties (geometric kinematic and dynamic) Two exact solutions interiors given by Wahlquist and Kramer, of the Einstein field equations representing the gravitational field due to an internal body fluid perfect axisimétrico and autogravitante rotating and stationary rigid. Despite the features apparently no-newtonianas the surface of the fluid edge of the settlement of Krames, it is demonstrated through a detailed analysis of the geodesic 3-dimensionales space (indoors), which gives it the properties newtonianas of convexity. Different procedures illustrate the effects "anti-intuitivos" (From a Newtonian) of the dynamics of circular motion in these solutions. The dynamic properties on the edge surface of the fluid and elipticidad "inside" of this area are analyzed varying the rotation speed of the source.

Author: OLMO ALBA GONZALO.
Year: 2004.
University: VALENCIA [www.uv.es].
Place of defense: FACULTAD DE FISICA (UNIVERSIDAD DE VALENCIA).
Place of preparation: FACULTAD DE FÍSICA, UNIVERSIDAD DE VALENCIA.

Summary: In this thesis discusses two of the key predictions of the theory of gravitation Einstein: black holes and the cosmological expansion. On the one hand, it introduces a new formulation to analyze quantum radiation processes in curved spaces and applied to the study of Hawking radiation responsible for the evaporation of black holes. The new design is an alternative to formalism standard ratios Bogolubov and is based on the use of correlation functions of the fields in the area. This method is advantageous compared to the standard technique in many interesting applications. In particular, it clarifies an apparent tension between the production of the emission of particles and energy flows caused by the technical difficulties of formalism ratios Bogolubov. On the other hand, he examines a family of theories of gravity alternatives considered as a possible justification for the phenomenon of cosmic expansion accelerated. This phenomenon is apparent from recent observations of the brightness of supernovae of type "1-a". Those theories include changes to the Lagrangian of Hilbert-Einstein, which generalizes to a function nojlineal of the scalar curvature. It discusses the potential of these two formulations theories, formalism and metric formalism of Palatini, from a standpoint of theories escalar-tensor and observational investigations of ligatures on the Lagrangian imposed by laboratory experiments and observations in the solar system. The analysis concludes that the potential terms of the non-linear curve are bounded by a plinomio quadratic in the scalar curvature. This finding rules out possible terms that grow at low bends are bounded by a quadratic polynomial in the scalar curvature. This finding rules out possible terms that grow at low bends and contests, thus certain models proposed in the literature to justify com cosmic acceleration due to correction of the gravitational dynamics at low cosmic bends.