Possible existence of time machines in a five-dimensional spacetime

Abstract: The idea of constructing a time machine is not new and even received a boost thanks to the realization that a traversable wormhole could be converted to a time machine. It was shown in a paper that the time-travel paradoxes can be avoided by assuming the existence of two or more histories or parallel timelines. Accordingly, we start with a physically acceptable model, a spacetime that is anti-de Sitter due to an extra time-like dimension. This model allows the existence of closed time-like curves, as well as two different histories, thereby suggesting a possible avoidance of the time-travel paradoxes. By assuming that the extra dimension is independent of the radial coordinate, the wormhole retains its basic geometric properties regardless of its location.