Note on cosmic censorship

A number of recent theorems by Krolak and Newman purport to prove cosmic censorship by showing that “strong curvature” singularities must be hidden behind horizons. I prove that Newman's “null, strong curvature” condition, which he imposes on certain classes of null geodesics to restrict curvature growth in the space-time, does not hold in many physically realistic space-times: it is not satisfied by any null geodesic in the relevant class in any open Friedmann cosmological model, nor does it hold for any null geodesic in the relevant class in maximal Schwarzschild space. More generally, I argue that the singularity predicted by the Penrose singularity theorem is unlikely to be of the type eliminated by Newman. Thus the Newman theorems are probably without physical significance. The Krolak theorems, although based on a physically significant definition of strong curvature singularity, are mathematically invalid, and his approach cannot be used to obtain a cosmic censorship theorem.