Isn't time cause and effect? I mean Einstein theory wouldn't work unless time was cause and effect. The whole point is the curved geometry under gravity and under motion is the increased length between two points. So things like the future and the past aren't real dimensions. Without something happening there is no time, why time can be altered by other means other than just motion or gravity. If you freeze someone or something for instance you've slowed reactions (cause and effect) which is time. I think a lot of people view time as a flow or even a dimension, why there are notions of time travel. No matter how much mathematics you use to prove GR allows time travel the error is the improper use of time as a spatial dimension. Remember time is a reaction, cause and effect, not a line where by one can travel along like a dimension.
Oh and I did see the PBS special with all the physics big wigs. The big problem using the wormhole, in GR at least, is the time dilation happens at the mouth of the hole and not to anything outside of the mouth. When the hole returns, it returns to the frame it had left! If you travel through the hole you would end up exactly where the hole is currently in time on earth.
ET