Look at http://en.wikipedia.org/wiki/Closed_timelike_curve http://en.wikipedia.org/wiki/Closed_timelike_curve I.e., "Closed timelike curves". I'm not expert in

Look at http://en.wikipedia.org/wiki/Closed_timelike_curve http://en.wikipedia.org/wiki/Closed_timelike_curve I.e., "Closed timelike curves". I'm not expert in this matter, but it's a conceptual possibility that fits into general relativity.