| Resumo : |
The already established and successful standard model of Cosmology, the Lambda CDM, (an acronym for Lambda Cold Dark Matter Model), whose field equations are derived from General Relativity, describes very well the universe as being isotropic and homogeneous in its distribution of matter and energy. Some solid physical explanations, however, seem to be far from being explained by this model alone, such as the 96\% of energy and matter that fills the universe (Dark Matter and Dark Energy). Einstein's General Relativity has also proved adequate on small scales in explaining the advance of the perihelion of Mercury's orbit around the Sun as well as the bending of light, and the Relative Astrophysics in describing neutron stars and predicting the existence of black holes. In this thesis, we are going to explore extensions of the theory of General Relativity: the Induced Matter Model - or STM Model (Space-Time-Matter Model), and the f(R,T) conserved theory of gravity, where R is Ricci's scalar of curvature and T the trace of the energy-momentum tensor. We applied the STM model to Cosmology and obtained a unique equation of state for the three eras of the universe (radiation, matter, and dark energy). This model presents our universe, 4-dimensional, and all the matter in it, as a geometric manifestation on the surface of a 5-dimensional space-time vacuum, with the energy associated with that vacuum. All cosmological parameters were analyzed and compared with observational data from the $\Lambda CDM$ model. We also analyzed traversable wormholes. This study was carried out in the light of the conserved f(R, T) theory, that is, imposing the conservation of the energy-momentum tensor in the theory. In this second work, we analyze parameters that satisfied energy conditions inside the wormhole without the need to be filled with exotic matter, as occurs as a condition for them to be traversable in the solutions obtained from General Relativity. |