Scalar Resonances in Axially Symmetric Spacetimes

We study properties of resonant solutions to the scalar wave equation in several axially symmetric spacetimes. We prove that non-axial resonant modes do not exist neither in the Lanczos dust cylinder, the $(2+1)$ extreme BTZ spacetime nor in a class of simple rotating wormhole solutions. Moreover, we find unstable solutions to the wave equation in the Lanczos dust cylinder and in the $r^2 <0$ region of the extreme $(2+1)$ BTZ spacetime, two solutions that possess closed timelike curves. Similarities with previous results obtained for the Kerr spacetime are explored.Comment: International Journal of Modern Physics D, in pres

Constraining the fundamental interactions and couplings with Eötvös experiments

Upper bounds for the violation of the Weak Equivalence Principle (WEP) by the fundamental interactions have been given before. We now recompute the limits on the parameters measuring the strength of the violation with the whole set of high accuracy Eötvös experiments. Besides, limits on spatial variation of the fundamental constants α, sin 2θ W and v, the vacuum expectation value of the Higgs field, are found in a model independent way. Limits on other parameters in the gauge sector are also found from the structure of the Standard Model.Facultad de Ciencias Astronómicas y Geofísica

Constraining the fundamental interactions and couplings with Eötvös experiments

Upper bounds for the violation of the Weak Equivalence Principle (WEP) by the fundamental interactions have been given before. We now recompute the limits on the parameters measuring the strength of the violation with the whole set of high accuracy Eötvös experiments. Besides, limits on spatial variation of the fundamental constants α, sin 2θ W and v, the vacuum expectation value of the Higgs field, are found in a model independent way. Limits on other parameters in the gauge sector are also found from the structure of the Standard Model.Facultad de Ciencias Astronómicas y Geofísica

Brane-world cosmology and varying G

We consider a brane-world cosmological model coupled to a bulk scalar field. Since the brane tension turns out to be proportional to Newton’s coupling G, in such a model a time variation of G naturally occurs. By resorting to available bounds on the variation of G, the parameters of the model are constrained. The constraints coming from nucleosynthesis and CMB result to be the severest ones.Facultad de Ciencias Astronómicas y Geofísica

Literatura y astronomía : Dos aspectos complementarios del conocimiento humano

Se analizan tres ejemplos de textos literarios con referencias astronómicas, para ejemplificar las conexiones entre ciencia y arte.Three literary texis with astronómical references are analyzed as examples of the comiections between art and Science.Facultad de Humanidades y Ciencias de la Educació

Exact Philosophy of Space-Time : In honour of Mario Castagnino

Starting from Bunge's (1977) scientific ontology, we expose a materialistic relational theory of space-time, that carries out the program initiated by Leibniz, and provides a protophysical basis consistent with any rigorous formulation of General Relativity. Space-time is constructed from general concepts which are common to any consistent scientific theory and they are interpreted as emergent properties of the greatest assembly of things, namely, the world.Facultad de Ciencias Astronómicas y Geofísica

El modelo cosmológico actual

El modelo cosmológico standard depende de un pequeño número de parâmetros que deben determinarse a través de la observación. En los últimos años se han realizado importantes progresos en su determinación y, por consiguiente, en la contrastación de teoria con experimento. Discutimos brevemente algunos de los principales resultados obtenidos en los últimos años