New evidence against cosmic censorship in five dimensions was announced today in the arxiv. The evidence is numerical, but it is done by a very good group of people working on numerical general relativity: Luis Lehner and Frans Pretorius. They argue that in the black string Gregory Laflamme instability the system develops `singularities in finite time’ as seen from the outside. This is due to the way the system evolves ins a self-similar way.
This is important because for these systems one can not ignore quantum gravity effects for a ‘generic’ set of initial conditions. For a long time the system of the black string Gregory-Laflamme instability was believed to provide a counterexample for cosmic censorship, but various technical results made it hard to prove and showed that the problem was rather difficult to approach.
Once again, higher dimensions show that they are very different from four dimensions when it comes to the study of Einstein’s equations. The first statement that went out was the ‘no hair’ theorem when people found all kinds of super-tubes, black rings, etc where one could have many stationary solutions to Einstein’s equations (with some matter) with the same quantum numbers and with black objects involved in their description.