Some observations on cosmological time functions
Some observations on cosmological time functions
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DOI：
10.1063/1.4807429
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发表时间：
2013-05
影响因子：
1.3
通讯作者：
N. Ebrahimi
中科院分区：
文献类型：
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作者：
N. Ebrahimi
给出了全局双曲性的一个新的刻画。宇宙学时间函数的概念和它的规律性是由安德森等人[“宇宙学时间函数，”类。量子重力15，309（1998）]10.1088/0264-9381/15/2/006，证明了如果（M，g）的宇宙学时间函数是正则的，那么它是全局双曲的。本文证明了：若（M，g）是整体双曲的，则存在一个光滑函数Ω > 0，使得（M，Ωg）的宇宙时间函数是正则的.证明了Friedman-Robertson-步行者时空（（a，B）× fH，− dt 2 + fh），a，B < ∞的宇宙学时间函数是正则的，并且这种时空的宇宙学时间函数的正则性在Lor（M）中是稳定的.
A new characterization for global hyperbolicity is given. The concept of cosmological time function and its regularity was considered by Anderson et al. [“The cosmological time function,” Class. Quantum Grav. 15, 309 (1998)]10.1088/0264-9381/15/2/006 and it was proved that if the cosmological time function of (M, g) is regular then it is globally hyperbolic. In this paper it is proved that if (M, g) is globally hyperbolic then there is a smooth function Ω > 0 such that the cosmological time function of (M, Ωg) is regular. It is also proved that the cosmological time function of Friedman-Robertson-Walker spacetime ((a, b) × f H, −dt2 + f h), a, b < ∞, is regular and in addition the regularity of cosmological time function for this kind of spacetimes is stable in Lor (M).