I like that short article on time travel at the same site you gave above.
Israeli researcher discovers theoretical model for time travel
By ISRAEL21c staff August 07, 2007
Fantasized about traveling through time ever since you saw the movie Back to the Future or read H.G. Wells? Well, one Israeli scientist has brought this science fiction fantasy just a tiny bit closer to reality.
Professor Amos Ori of the Technion - Israel Institute of Technology has developed a theoretical model of a time machine that could enable future generations to travel in the past. In his article published in the latest issue of Physical Review, Ori provides solutions to a number of difficulties that has long vexed researchers.
But don't make plans just yet to go back in time. According to Ori, very specific conditions are needed to allow for time travel. In a 2004 paper, Ori described a set of conditions needed to create a time loop. A donut shaped vacuum, the loop would curve back onto itself, so that a person traveling could go further back in time with each loop. Ori's theory is a set of mathematical equations that describe hypothetical conditions. If the hypothetical conditions are met, the formation of a closed time loop would create the possibility of time travel.
"If we were to create an area with a warp like this in space that would enable time lines to close on themselves, it might enable future generations to return to visit our time," he conjured. "We, however, could not return to previous ages because our predecessors did not create this infrastructure for us."
Stephen Hawking has described time travel as "an important subject for research" but has also challenged the concept. While the idea of time travel has never been eliminated, scientists have identified the physical challenges required, including the need for exotic matter with negative density.
Ori's latest work has eliminated the need for the exotic matter, as well as non-exotic but unidentified matter that he proposed in the 2004 paper. His new calculations show that the envelope can in fact be filled with dust, a simple modeling of which is used regularly in theoretical physics, while still allowing for the evolution of a time machine. His research, conducted with Technion Ph.D. student Dana Levanony, suggest that the creation of a time machine can only be achieved under a very narrow range of conditions.
"If the proper initial conditions were achieved, the time machine would evolve on its own without any further intervention," explained Ori. "It can be likened to shooting a ship with a cannon. Once the cannon is aimed properly and fired, the cannonball hits the ship on its own, driven solely by the laws of physics."
Read entire Article: here