Let (M, g) be a time-oriented Lorentzian manifold and d the Lorentzian distance on M . The function τ(q) := supp<q d(p, q) is the cosmological time function of M , where as usual p < q means that p is in the causal past of q. This function is called regular iff τ(q) <∞ for all q and also τ → 0 along every past inextendible causal curve. If the cosmological time function τ of a spacetime (M, g) ...