Time travel would have to be more of a jump than a change of direction, I guess.
You mean like applying time dilation between the two ends of a wormhole?
Incidentally, I had an interesting idea regarding this: suppose you had two ends of a wormhole,
A and
B, with a time difference of
t between them -
B being the one farther into the future, so that you go from
A to
B to move forward through time and vice versa. Now, if we place wormhole
A inside wormhole
B, it will come out of wormhole
A at some point in time
t before it was placed into wormhole
B. That is to say, we can double the time difference between a pair of temporally separated wormhole portals by placing one inside the other.
More generally, we can increase the time difference between two temporally separated wormhole portals
t1 apart by passing one of them through another pair of temporally separated portals
t2 apart. If we pass
both of them through this gate in opposite directions, we can achieve a temporal separation of
t1 + 2t2. So, we could obtain a time machine with years in between the two portals by simply flying one portal around the Earth and then effecting repeated applications of this technique, as opposed to the conventional "wait seventy years for a rocket to fly to some faraway place and back at near light speed".
Now all we need to do is invent a wormhole.
