Dark energy and the return of the phoenix universe
Dark energy and the return of the phoenix universe
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DOI：
10.1103/physrevd.79.063503
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发表时间：
2008-12
影响因子：
5
通讯作者：
J. Lehners;P. Steinhardt
中科院分区：
文献类型：
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作者：
J. Lehners;P. Steinhardt
在基于单一标量场的循环宇宙模型中(例如M理论中决定膜间距的辐射子)，实际上整个宇宙都经历了热化平滑和扁平阶段，反弹，并进入了一个新的膨胀和冷却时代。然而，如果尺度不变的曲率微扰是由熵机制产生的，那么这种稳定的演化是不可能发生的，因为它需要两个标量场(例如，辐射子和Calabi-Yau伸缩子)沿着不稳定的经典轨迹演化。事实上，我们在这里展示了宇宙的压倒性部分未能通过发热期；然而，只要周期的暗能量阶段持续足够长的时间，大约一万亿年，足够的体积仍然存在，循环永远继续。两个后果是暗能量的新角色和宇宙的全球结构从根本上不同于永恒的膨胀。
In cyclic universe models based on a single scalar field (e.g., the radion determining the distance between branes in M theory), virtually the entire Universe makes it through the ekpyrotic smoothing and flattening phase, bounces, and enters a new epoch of expansion and cooling. This stable evolution cannot occur, however, if scale-invariant curvature perturbations are produced by the entropic mechanism because it requires two scalar fields (e.g., the radion and the Calabi-Yau dilaton) evolving along an unstable classical trajectory. In fact, we show here that an overwhelming fraction of the Universe fails to make it through the ekpyrotic phase; nevertheless, a sufficient volume survives and cycling continues forever provided the dark energy phase of the cycle lasts long enough, of order a trillion years. Two consequences are a new role for dark energy and a global structure of the Universe radically different from that of eternal inflation.