Reading the scholarly theories on going back in time—which, by the way, might be possible

TriStar / Alliance; D. Reidel

TO THE NAKED EYE, IT MAY APPEAR THAT: Looper, the Bruce Willis-Joseph Gordon-Levitt vehicle that opened last weekend, is a pretty nifty film with an impossible, imaginary premise: It's possible to travel back in time and change the past.

BUT ACCORDING TO SOME EXPERTS WHO THOUGHT VERY HARD ABOUT THIS: Looper is definitely unrealistic, but not for the reason we might think. Time travel, as it turns out, may not be impossible at all—it's the alteration of the course of history that's the dubious part.

Yes, activate suspension of disbelief now. But the maybe-viability of time travel has kept logicians, physicists, philosophers, and other academics squabbling among themselves for decades. Several modern theories of time travel are built on Albert Einstein's vision of the universe: a model that imagines a four-dimensional spacetime continuum with a curving shape. Einstein's model, according to University of Connecticut theoretical physicist and aspiring time-machine builder Ron Mallett, allows for the possibility of warps, twists, and manipulations of space and time, which would bend the continuum into a closed loop that would enable time travel. Dr. Mallett explained some of his theories to CNN in 2007:

Mallett's lifelong dream has been to build a time machine in order to go backward in time and tell his father, who died of a heart attack when Mallett was 10, not to smoke. As Mallett points out, though, science is still a long way away from sending an actual person—or even an object or piece of data—to a different point in the future or the past. The discussion of time travel's feasibility rests squarely on the theoretical possibility at this point.