90 minutes may feel like 90 days in this slow and sometimes painfully boring post-apocalyptic movie from director M. Night Shyamalan, the perpetrator of such terrible films as “Lady in the Water”, “The Happening” and (oh dear Lord) “The Last Airbender”. In “After Earth”, Will Smith plays Cypher, the leader of Nova Prime, the planet where humans live after they destroyed nature’s balance 1000 years ago. The man is so serious, even his son Kitai (Jaden Smith) can’t get close to him. The solution? A spaceship crash that strands Cypher and Kitai on Earth. Cypher breaks both his legs (of course). So it’s up to sonny boy to go out and recover a beacon that will save their lives and bring them together. Or something like that. Meanwhile, daddy Smith sits around and stares at computer screens while his son does all the work. Look, “After Earth” has its moments and isn’t as bad as you might think, but overall it is burdened with paper thin characters and a sorry lack of thrills, flair or coherence. And if you’re going to spend 90 minutes with just a handful of characters, they might as well be played by charismatic actors. Unfortunately, Jaden Smith’s performance is almost laughable. Director M. Night Shyamalan is working here from a novel by Scientology founder L. Ron Hubbard. The film’s faults certainly don’t lie in its impressive physical production. But science-fiction, as much as any genre depends on a great idea at its core, and this one simply isn’t original enough. Worse, it wants you to believe that it can rival the best sci-fi flicks of all time. Talk about being delusional.