The locally rotationally symmetric tilted perfect fluid Bianchi type V cosmological model provides examples of future geodesically complete spacetimes that admit a `kinematic singularity' at which the fluid congruence is inextendible but all frame components of the Weyl and Ricci tensors remain bounded. We show that for any positive integer n there are examples of Bianchi type V spacetimes admitting a kinematic singularity such that the covariant derivatives of the Weyl and Ricci tensors up to the n-th order also stay bounded. We briefly discuss singularities in classical spacetimes.
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在对“吸积盘的性质能在观测上区分黑洞和裸奇点吗？“，Bertrand Chauvineau，Phys. Rev. D { \bf 98}，088501（2018），作者确实表明Z. Kovács和T. Harko，Phys. Rev. D { \bf 82}，124047（2010），并且最初在K. D. Krori和D. R. Bhattacharjee，J. Math. Phys. \textbf{23}，637（1982）和K. K. Nandi，P. M.阿尔辛，J.C. Evans和T. B. Nayak，Phys. Rev. \textbf{63}，084027（2001），不满足具有最小耦合标量场的爱因斯坦引力场方程。在我们的回复中，我们想指出的是，这个结果实际上并不是新的，但它已经在文献中发表了。此外，一个旋转的解决方案，推广了克尔度规的非最小耦合标量场确实存在。本文简要地讨论了广义度规的奇点性质，指出它可以作为区分黑洞和裸奇点的一个试验场。我们还提到文献中存在的其他一些打字或技术错误。
