- #76

George Jones

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But this violates the well-known theorem that every compact spacetime contains closed timelike curves. The simple proof of this theorem is independent of energy conditions and of the cosmological constant; see Theorem 3.3.11 of Naber's Spacetime and Singularities: an Introduction or Proposition 6.4.2 of Hawking and Ellis.Take a FRW universe with negative cosmological constant. One topology that is consistent with the metric (though not the only one) is S^4. You do not necessarily get CtCs.