"At 600 km. above the Earth," we're told in the new film "Gravity," "There is nothing to carry sound. No air pressure. No oxygen. Life in space is impossible." And yet, there we are.

The evocation of Ridley Scott's 1979 "Alien" ("In space, no one can hear you scream") is apt: "Gravity" is a bit like "Alien" without the alien, replacing it with existential despair that's just as likely to take a fatal bite out of the heroine. Here the heroine is Dr. Ryan Stone (Sandra Bullock), a medical engineer sent via space shuttle to assist in repairs to the Hubble Space Telescope.

In the film's first sequence -- a bravura 12-minute segment crafted to appear as a single camera shot with no cuts -- satellite debris shoots at the shuttle and the telescope, causing a fatal accident that threatens to strand and thereby kill Stone and shuttle commander Matt Kowalski (George Clooney). Dwindling oxygen and thruster power threaten their survival, as does Stone's natural panic due to the circumstances and her inexperience.

And then there's the thornier question of just how much Stone even wants to live, given the loss of her 4-year-old daughter. Though she deadpans at one point, "I hate space," Stone has little love for the "gravity" of life on Earth, which she has gladly escaped to be in the remote void ("the silence -- I could get used to it"). With long stretches of time alone with her thoughts, Stone goes to some dark places.

In a way, "Gravity" is a cinematic stunt, carried off with impeccable narrative formalism and filmic techniques, including 3-D that amplifies the effect of zero-G fire and tears. Taking the baton from George Lucas' virtual "Star Wars" sets, director Alfonso Cuaron advances the art with astonishing precision of wall-to-wall special effects that convincingly place the movie stars into outer-space environments -- sometimes in a spectacular action-adventure mode, and sometimes in a lyrical vein taking after "2001: A Space Odyssey" (artful poses that turn a space capsule into a womb).

Look past the phenomenal eye candy and "Gravity" is pretty corny at its base, co-scripted by Cuaron and his son Jonas. But it's also potentially stirring as a call-to-action allegory about those tempted to disconnect depressively from society. And "Gravity" moves us closer to an art-house/blockbuster-hybrid paradigm that could be Hollywood's salvation (Cuaron's "Harry Potter and the Prisoner of Azkaban" was a good warm-up).

All audiences will be able to agree that "Gravity" is thrilling, with its relentless pace and near-unbearable tension as a survivalist adventure that captures the primal terror of present death while exploring the will or won't to live. As Clooney's character puts it, life is "one hell of a ride." So is "Gravity."