The ability to travel back in time, though entirely hypothetical, isn't explicitly forbidden by our current understanding of space and time, embodied in the general theory of relativity. Time travel tends to play havoc with other laws of physics, however, and researchers showed that data encryption systems relying on quantum principles can be broken by allowing the data stream to interact with a quantum state that travels back in time.
by
stargaming
2009-06-21 07:28
physics