TT23,
Yes, in theory, time travel is possible.
But we have two daunting problems that have to be over come before we can move forward.
General Relativity is a theory of gravity. It is valid, has been proven to be true at every turn of events...but it can't in its present form be combined successfully with quantum mechanics.
Quantum mechanics is a theory of probability in physical events at the tiniest scales. It is valid, has been proven to be true at every turn of events...but it cannot explain gravity and cannot be combined with General Relativity in its present form. If you add gravity into quantum mechanics the formulas (and the universe) "blow up."
If we are to understand the true nature of time and how the universe "really" works we have to develop a new theory of relativity that combines GTR and QM. From that new theory GTR and QM should "pop" out of the solution just like Newtonian Mechanics "pops' out of GTR as a limiting case.
Once we do that we will have a concise answer to the time travel question.
That will probably be the (relatively) easy part of the problem. Having a valid theory of time travel that is firmly based on the theoretical physics that evolves won't get us into the past. The real problem will then fall to the future Rainman's sector...engineering.
A host of very competent scientist-engineers will then have to look at the science, take the puzzle to the drawing boards and find a way to translate theory into practice. Whole new schools of engineering will have to be developed. It will be very expensive but there will be spin-off technologies that can assist with the funding. I'd love to be around to see the spin-off PC technology from that venture. /ttiforum/images/graemlins/smile.gif