COT3 - Nonsingular Cosmology |
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Speaker |
Nogueira Araújo, Aline |
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Co-autors |
M. Novello, J. M. Salim |
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Talk Title |
Cyclic Magnetic Universe |
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Abstract |
Recent works have shown the important role that Nonlinear Electrodynamics (NLED) can have in two crucial questions of Cosmology, concerning particular moments of its evolution for very large and for low-curvature regimes, that is for very condensed phase and at the period of acceleration. It is presented here a toy model of a complete cosmological scenario in which the main factor responsible for the geometry is a nonlinear magnetic field that produces a FRW homogeneous and isotropic geometry. In this scenario one distinguishes four different phases: a bouncing period, a radiation era, an acceleration era and a re-bouncing. It has already been shown that in NLED a strong magnetic field can overcome the inevitability of a singular region typical of linear Maxwell theory; on the other extreme situation, that is for very weak magnetic field it can accelerate the expansion. The present model goes one step further: after the acceleration phase the universe re-bounces and enter in a collapse era. This behavior is a manifestation of the invariance under the dual map of the scale factor $ a(t) \rightarrow 1/ a(t),$ a consequence of the corresponding inverse symmetry of the electromagnetic field ($ F \rightarrow 1/ F,$ where $F \equiv F^{\mu\nu}F_{\mu\nu}$) of the NLED theory presented here. Such sequence collapse-bouncing-expansion-acceleration-re-bouncing-collapse constitutes a basic unitary element for the structure of the universe that can be repeated indefinitely yielding what is called here a Cyclic Magnetic Universe. |
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