(Agencies)
Updated: 2007-08-21 15:46

"The machine is space-time itself," Ori said. "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."

Ori emphasized one significant limitation of this time machine - "it can't be used to travel to a time before the time machine was constructed." His findings are detailed in the August 3 issue of the journal Physical Review D.

A number of obstacles remain, however. The gravitational fields required to make such a closed time-like curve would have to be very strong, "on the order of what you might find close to a black hole," Ori told LiveScience. "We don't have any way of creating such strong gravitational fields today, and we certainly have no way of manipulating any such gravitational fields."

Even if time machines were technically feasible, the gravitational fields involved need to be manipulated in very specific, accurate ways, and Ori said his calculations suggest any time machine could be very unstable, meaning "the tiniest deviations might keep one from working. We need to explore the problem of stability of time machines further."

Theoretical physicist Ken Olum of Tufts University in Medford, Mass., who did not participate in this study, was skeptical concerning how this new model claimed to sidestep prior theoretical objections to time travel.

Still, Olum noted, "It's important if it's right - that there really is some kind of loophole. So this should be scrutinized very closely." The point of such work, he added, was to "expand the bounds of what's possible, what kind of things we can have and what kinds of things we cannot have."

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