Seeing “Gravity” is the closest most of us will ever come to knowing what it’s like to be in outer space. In fact, after seeing “Gravity,” I hope I never do experience space firsthand. That place is terrifying. There’s no air! Or gravity! You break free from your tether while space-walking, and guess what? You float away forever. NO THANK YOU.

This and other lessons are taught in Alfonso Cuarón’s breathtakingly tense sci-fi thriller, a dazzling special-effects showcase that uses state-of-the-art technology to put us right in the spacesuits with Sandra Bullock and George Clooney. They play astronauts — Clooney’s the veteran mission commander; Bullock’s a biomedical engineer in space for the first time — who find themselves in perilous circumstances when their space shuttle is hit by debris. Bullock and Clooney are essentially the only people in the movie, and they’re both utterly convincing as they struggle with a diminishing oxygen supply and other crises.

Cuarón (“Children of Men,” “Harry Potter and the Prisoner of Azkaban”) wrote the screenplay with his son Jonas — but truth be told, there wasn’t a lot of writing to be done. The story is uncomplicated, and the dialogue and characterization are no more than serviceable.

What makes “Gravity” worth seeing — and seeing in 3D, on the biggest screen you can find — is its totally immersive style. Long, unbroken takes shot by a smoothly floating camera simulate the sensation of being in space, and Cuarón eerily conveys the appropriate feelings of isolation and helplessness. I’m not sure I exhaled more than five or six times the whole 90 minutes.

B+ (1 hr., 30 min.; PG-13, a little profanity, a lot of intense perilous situations and some violent images.)