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Resumen:
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Thanks to the quality and variety of recent observations, we are now capable of measuring cosmological parameters with a 1% precision. For a decade, we can talk about a precision cosmological science. However, even if we have a good control over the universe evolution from nucleosynthesis, the fundamental nature of its energetic content still remains elusive. On the one side, the cause of the current accelerated expansion is still unknown, this is the so-called “Dark Energy” problem. The most conservative proposal assumes the domination of a cosmological constant, with two contributions: a geometric term that arises naturally in Einstein equations and a vacuum energy of quantum origin. This explanation has theoretical difficulties; however, other models capable of generating such an acceleration are speculative and it is not clear that they do not suffer from similar problems. On the other hand, we also ignore the fundamental nature of the major part of the matter content. The measurements of the astrophysical objects mass from their luminosity underestimate systematically their total mass. This is known as the “Dark Matter” problem. The most popular explanation postulates the existence of a cold non-barionic component that does not (or weakly) interact with photons. It is finally worth mentioning the necessity of including an extra element to the cosmological standard model. On the one hand, initial conditions inferred from observations are very specific, for instance an universe with flat spatial sections is unstable as a solution of the Einstein equations. On the other hand, regions that would have not been in causal contact at decoupling have the same thermal spectrum. Moreover, the spectrum of inhomogeneities seems to be almost scale invariant. In order to solve these problems, the cosmological model is usually supplemented with a primordial period of accelerated expansion known as “inflation”...
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