arXiv 0802.18752008-02-13astro-ph

循环磁宇宙

Cyclic Magnetic Universe

M. Novello, Aline N. Araujo, J. M. Salim

发表信息：: Int.J.Mod.Phys.A24:5639-5658,2009
DOI：: 10.1142/S0217751X09046321

摘要：

最近的工作表明，非线性电动力学（NLED）在宇宙学的两个关键问题中可以发挥重要作用，这两个问题涉及到非常大和低曲率区域的演化的特定时刻，即非常凝聚的阶段和目前的加速阶段。我们在这里提出了一个玩具模型的一个完整的宇宙学的情况下，负责的几何形状的主要因素是一个非线性磁场，产生FRW均匀和各向同性的几何形状。在这种情况下，我们区分四个不同的阶段：反弹期，辐射期，加速期和反弹期。已经表明，在NLED中，强磁场可以克服线性麦克斯韦理论典型的奇异区域的不可避免性;在另一种极端情况下，即对于非常弱的磁场，它可以加速膨胀。目前的模型更进了一步：在加速阶段之后，宇宙反弹并进入坍缩时代。这种行为是在比例因子$ a(t) \to 1/ a(t),$的对偶映射下的不变性的表现，这是这里提出的NLED理论的电磁场（$ F \to 1/ F,$，其中$F \equiv F^{μν}F_{μν}$）的相应逆对称性的结果。这样的序列往复-弹跳-膨胀-加速-再弹跳-坍缩构成了宇宙结构的基本酉元素，它可以无限重复，产生我们所说的循环磁宇宙。

英文摘要：

Recent works have shown the important role 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 present period of acceleration. We present here a toy model of a complete cosmological scenario in which the main factor responsible for the geometry is a nonlinear magnetic field which produces a FRW homogeneous and isotropic geometry. In this scenario we distinguish four distinct 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) \to 1/ a(t),$ a consequence of the corresponding inverse symmetry of the electromagnetic field ($ F \to 1/ F,$ where $F \equiv F^{μν}F_{μν}$) 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 we call a Cyclic Magnetic Universe.

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