Chicago, ILUSA 60605
April 3, 2013
Assuming we are talking about time travel into the past, the mechanisms that I can think of which would make it consistent precludes both negative and positive consequences. Time travel into the future on the other hand is much simpler. We do it all the time when we travel on an airliner and return to our starting point to compare times. The difference of course is very small. For a more dramatic comparison we'd need a vehicle that can travel at relativistic speeds. A benefit of this sort of time travel is that the exploration of the galaxy becomes possible in a human lifetime. It's not as convenient or interesting as travel using something exotic like wormholes and warp drive spacetimes, but the physics at relativistic velocity is well understood whereas the former is highly speculative.
Into the future: yes. Into the past: possibly. A fancy way to express time travel into the past is a "Closed Timelike Curve", or CTC. If these geodesics are possible, the best bet to explain how they are paradox free is the Many Worlds interpretation of QM. The other is the Novikov Self Consistency Principle. My favorite time travel movie that uses the latter is "The Final Countdown".
I work in IT for the defense & national security industry and have a bachelor's in physics, an associates in engineering and passion for both theoretical and applied physics. My other interests include corpus linguistics for intelligence analysis.