A serious Brad Pitt captivates as a father of three boys in 1950s Texas, but he’s one of the few good things in this confusing (if gorgeous) art film. The drama shifts jarringly from Pitt’s suburban family saga to — huh? — a history of the Earth from the Big Bang to the age of dinosaurs and up to the present. The movie’s muddled point? To explore and understand the roots of creation. But it is extremely pretentious — and at 138 minutes, it unspools as slowly as tree growth.