I'm not sure, I do agree, though, that "Worm-holes" would be our only option at this point and time, and that's even pushing it...Way I see it, a worm-hole is in fact just a tunnel in a sense, we could never actually go the speed of light, which is why the theory of worm-holes came along, it's pretty much what it is, a shortcut, your not actually time-traveling, just breaking space in order to get somewhere in less time, when a wormhole appears, take space, lets say a planet is 4 light years away, well with a wormhole you can get there in less time. Put it this way, your on a highway, you can either continue going around, or take a tunnel that leads to the same road anyways...its nothing more than a shortcut in my opinion, i don't believe you actually travel through time, as in going into the future or into the past.
*EDIT* --- Guess we'll never know 'til it's done I suppose.
The only possible form of time travel is going into your own future, if you consider time is just a perspective or a scale for aging. The method would be manipulating the light years, of hyper speed, in space. You could force yourself to age simply by unraveling your DNA, in all scientific theory. There's actually a lot of scientific theory, related, to how God shortened people's life spans in Biblical times.
Maybe there are laws and guidelines, or maybe they can't come back and alter the past with the chance of wiping out the future, maybe they can only be observers. Maybe they just blend in as influential members of society, and everything just fits along like it never happened.
perhaps but just like criminals there are people there breaking the law. suicide bombers break the law while killing people and themselves for what they believe in. it only takes one person like that to ruin time