Richard Linklater started making his new movie in 2002. That it took a dozen years to finish might imply some familiar horror story about the difficulty of modern filmmaking, but actually it was the point all along. In Boyhood, a Texas schoolkid, played by Ellar Coltrane, grows up right before our eyes. He’s 18 when the movie ends, and where did the time go? Maybe only Linklater could do a radical narrative experiment that’s also just another low-key slice of life. Obviously the movie required rigorous control, but never does it give off a sense of the filmmaker clutching it too tightly. The boy’s sister is played by the director’s daughter Lorelei, and their parents are played by Patricia Arquette and Ethan Hawke, whose complete on-boardness with Linklater’s project manifests in some of the best work they’ve ever done. It could easily have been too densely packed, with all those years brusquely clipped and crammed into just a few hours, but the real coup is that it’s filled with open space. Linklater always has understood the poetic possibility of cinematic ellipses. So Boyhood has a lifelike metabolism: You blink and suddenly someone’s gone, long gone. There are periods when aging is less apparent, at least on the older characters, but what does stand out is how their personal circumstances change. Some patches seem more polished than others, but that unevenness only fortifies the movie’s credibility. Inevitably it’s a reminder that you were a kid once, and maybe you had a kid once, or more than once, and now you know all too well the feeling that the speed of life, once presumed constant, does accelerate. Here, the long-game drama always defaults to something profoundly ordinary. It’s beautiful, and what cinema was made for.