Are loop quantum cosmos never singular?
Are loop quantum cosmos never singular?
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DOI：
10.1088/0264-9381/26/12/125005
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发表时间：
2009-01
影响因子：
3.5
通讯作者：
Parampreet Singh
中科院分区：
文献类型：
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作者：
Parampreet Singh
在圈量子宇宙学（LQC）框架下，给出了平坦、各向同性和均匀时空中所有已知类型奇点的统一处理方法。这些包括刘海，紧缩和所有未来的奇点。使用有效的时空描述，我们进行了一个模型无关的曲率，测地线的行为和奇异性的强度的性质的一般分析。为了说明的目的，还进行了基于现象学模型的分析。我们表明，所有的标度因子的值，在一个强的奇异性可能会发生被排除在有效的圈量子时空。此外，如果演化导致标度因子消失或发散，则圈量子宇宙在该区域中是渐近地deSitter的。我们还表明，存在一类突发极值事件，其中包括最近讨论的可能性，曲率或其衍生物将始终发散。然而，这样的事件原来是无害的弱曲率奇点，测地线可以扩展。我们的研究结果指向一个通用的解决方案，在LQC的物理奇点。
A unified treatment of all known types of singularities for flat, isotropic and homogeneous spacetimes in the framework of loop quantum cosmology (LQC) is presented. These include bangs, crunches and all future singularities. Using effective spacetime description we perform a model-independent general analysis of the properties of curvature, behavior of geodesics and strength of singularities. For illustration purposes a phenomenological model based analysis is also performed. We show that all values of the scale factor at which a strong singularity may occur are excluded from the effective loop quantum spacetime. Further, if the evolution leads to either a vanishing or divergent scale factor then the loop quantum universe is asymptotically deSitter in that regime. We also show that there exists a class of sudden extremal events, which includes a recently discussed possibility, for which the curvature or its derivatives will always diverge. Such events however turn out to be harmless weak curvature singularities beyond which geodesics can be extended. Our results point toward a generic resolution of physical singularities in LQC.