This thread gave me an idea. What if a method of "FTL" travel, similar to wormhole would consist of a tunnel that had a physical distance "inside" that any signal would have to traverse, and that distance being equal to the time dilation between the mouths of the tunnel since its/their creation expressed in distance (time * c)? So that if one mouth was (instantly) accelerated to 0.9c, then after one year the length of the inside of the tunnel would be 1-(1/γ))ct which gives 0.564 light-years. Could such a system be used to create a paradox? I'm thinking that any attempt at time-travel by putting a mouth at a high relative velocity would just elongate the tunnel, which might prevent paradoxes, but I don't know enough about space-time diagrams to see if it would actually "elongate" fast enough. Can anyone shed light on this?