magic of movies genuinely registers as a vibe in Sam Mendes’ “Empire of Light,” a frustratingly uneven and often meandering period drama written by Mendes, loosely drawing remembrances from his own formative years. And he pulls from “a lockdown mindset,” too, as the director put it before his ’80s-set film’s world premiere at the Telluride Film Festival, a melancholic state of being marked by feelings of loneliness and even fear that things we love (like movie theaters) would be lost forever in a post-pandemic world.Perhaps because his inspirations seem to be so extensive here, it often feels like Mendes is searching for a story within a bottomless well of moods and ideas throughout “Empire of Light.” Ironically enough, this undisciplined disposition is the exact opposite of the kind of taut restraint that was at the core of “1917,” his previous, tightly orchestrated and end-to-end choreographed film.“Empire of Light” starts with an admiration towards the enchanted majesty of cinemas, as Hilary (an affecting Olivia Colman, with an impressively wide-ranging emotional scale) preps the beautiful movie palace she works at for its daily opening, her gentle touches aided by Trent Reznor and Atticus Ross’ soothingly nostalgic score.