Supertube domain walls and elimination of closed timelike curves in string theory

We show that some novel physics of supertubes removes closed timelike curves from many supersymmetric spaces which naively suffer from this problem. The main claim is that supertubes naturally form domain walls, so while analytical continuation of the metric would lead to closed timelike curves, across the domain wall the metric is nondifferentiable, and the closed timelike curves are eliminated. In the examples we study, the metric inside the domain wall is always of the Godel type, while outside the shell it looks like a localized rotating object, often a rotating black hole. Thus this mechanism prevents the appearance of closed timelike curves behind the horizons of certain rotating black holes.