There's no such thing as time travel without plot holes. As characters jump backward and forward in a timeline, technical complexities multiply. Laws of physics are broken. The more you consider how it doesn't make sense, the more the premise crumbles.
Looper knows this. Writer-director Rian Johnson's slick, charming thriller doesn't explain time travel or provide phony science to explain how someone can meet his younger self. Instead, it brushes aside the temporal issues with a single line: ''I don't want to talk about time-travel shit. If we start, we're gonna be here all day making diagrams with straws.'' Simple as that.
That simplicity is on display, for better and for worse, throughout Looper. Johnson eschews technical mumbo-jumbo again and again, smartly mining the broader implications of time travel to build intimate portraits of his characters. Joe (Joseph Gordon-Levitt), narrating his own story, explains that he lives in the year 2044. Time travel hasn't been invented yet, but it will be in 30 years. Almost immediately, the technology will be made illegal -- but criminal gangs will use it to zap victims into the past to be killed by ''loopers'' like Joe. Unbeknownst to Joe, an impossibly powerful figure in the future is sending retired loopers back in time to be killed by their younger selves. (This is called ''closing the loop.'') Young Joe panics when he realizes that his next target is, in fact, Old Joe (Bruce Willis), setting off a cat-and-mouse chase that's almost as silly and thrilling as it sounds.
Of course, Looper is not without flaws. Johnson abruptly shifts gears midway through the movie, shifting attention to a farmhouse where Young Joe meets a shotgun-toting woman (Emily Blunt) and her ominously creepy son, Cid (Pierce Gagnon). Gordon-Levitt's face, which was bizarrely enhanced to mimic a young Willis, is a distracting example of the uncanny valley. And yes, there are plot holes. Nonetheless, Looper is a fine example of a tight, satisfying sci-fi movie. It may not be able to explain time travel, but it's got a whole lot of heart.