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arXiv 1202.1397gr-qcastro-ph.CO
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DGP膜世界中的振荡宇宙

Oscillating universe in the DGP braneworld

Kaituo Zhang, Puxun Wu, Hongwei Yu

摘要:

用一种方法,其中的弗里德曼方程被写在一种形式,使演化的标度因子可以被视为一个粒子的“潜力”,我们分类所有可能的宇宙演化的DGP braneworld方案与暗辐射项保留。通过假设能量分量分别为无压物质、辐射或真空能,我们发现在物质或真空能占主导地位的情况下,标度因子有一个最小值$a_0$。在物质支配的情况下,大爆炸奇点在某些特殊情况下是可以避免的,可能存在振荡宇宙或弹跳宇宙。如果宇宙尺度因子在初始时处于振荡区域,宇宙可能会经历振荡。在多次振荡之后,它可能通过量子隧穿演化到反弹点,然后膨胀。然而,如果宇宙最初从无限尺度收缩,它可以转身,然后永远膨胀。在真空能量占优的情况下,存在一个稳定的爱因斯坦静态,以避免大爆炸奇点。然而,在某些情况下,在物质或真空能量占主导地位的情况下,一种新的奇异性可能会出现在$a_0$作为不连续的标度因子的结果。在辐射主导的情况下,宇宙可能起源于大爆炸奇点,但避免这个奇点的反弹宇宙也是可能的。

英文摘要:

With a method in which the Friedmann equation is written in a form such that evolution of the scale factor can be treated as that of a particle in a "potential", we classify all possible cosmic evolutions in the DGP braneworld scenario with the dark radiation term retained. By assuming that the energy component is pressureless matter, radiation or vacuum energy, respectively, we find that in the matter or vacuum energy dominated case, the scale factor has a minimum value $a_0$. In the matter dominated case, the big bang singularity can be avoided in some special circumstances, and there may exist an oscillating universe or a bouncing one. If the cosmic scale factor is in the oscillating region initially, the universe may undergo an oscillation. After a number of oscillations, it may evolve to the bounce point through quantum tunneling and then expand. However, if the universe contracts initially from an infinite scale, it can turn around and then expand forever. In the vacuum energy dominated case, there exists a stable Einstein static state to avoid the big bang singularity. However, in certain circumstances in the matter or vacuum energy dominated case, a new kind of singularity may occur at $a_0$ as a result of the discontinuity of the scale factor. In the radiation dominated case, the universe may originate from the big bang singularity, but a bouncing universe which avoids this singularity is also possible.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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