No time machines in classical general relativity

@article{Krasnikov2002NoTM,
  title={No time machines in classical general relativity},
  author={S. Krasnikov},
  journal={Classical and Quantum Gravity},
  year={2002},
  volume={19},
  pages={4109-4129}
}
  • S. Krasnikov
  • Published 17 November 2001
  • Philosophy
  • Classical and Quantum Gravity
Irrespective of local conditions imposed on the metric, any extendible spacetime U has a maximal extension containing no closed causal curves outside the chronological past of U. We prove this fact and interpret it as impossibility (in classical general relativity) of the time machines insofar as the latter are defined to be causality-violating regions created by human beings (as opposed to those appearing spontaneously). 

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