Juliusz Doboszewski (University of Bonn)
Title: Kerr black holes and time machines
Abstract: Spinning black holes are a fairly well-established feature of our universe, but maximally extended Kerr spacetime has chronology violating regions. How likely is it, then, that our universe contains chronology violating regions? At the moment this is primarily a conceptual problem. In this context, I will (i) review some of the precise notions of time machines, (ii) discuss whether and under what additional conditions extensions of Kerr spacetime can be viewed as viable candidates for time machines, and (iii) criticize recent claim that time machines (and other forms of time travel to the past in general relativity) are incompatible with the second law of thermodynamics.