NOTHING DEFINES man's lonely place in the universe so crisply as the shot of the untethered astronaut drifting helplessly through space.

Few motion-picture images are as fearful, or as powerful. More gripping, in their ground-control-to-Major-Tom way, than, say, the monster popping out John Hurt's stomach in "Alien."

Stanley Kubrick used the lost-in-space astronaut memorably in "2001" - a man slowly receding into a doomed speck against the backdrop of space, icy and remorseless. And that's the spacewalk template: We're all hanging by a thread, suspended in a vast and pitiless universe.

Or are we?

The images take on new meaning in the stunning "Gravity," another man-in-space movie that ponders the essence of life in the inky blackness.

Whoa, you say - that sounds super boring.

Well, it's not.

For one thing it's a woman-in-space movie, often featuring Sandra Bullock in her underwear, proving that Alfonso Cuaron learned something from Ridley Scott.

And the whole thing kicks off with a crackerjack, technically marvelous action sequence that's way better than anything you saw this summer.

"Gravity" commences with spacewalking shuttle astronauts repairing a space station when a hail of debris tears their ship and station, and chances of living, to shreds. (This scene will win every Oscar for sound and visual effects.)

"Gravity" then splits into separate, and separately engrossing, movies. One is a rousing, Spielbergian serial cliff-hanger about an astronaut's pell-mell bid for survival, hopscotching among U.S., Russian and Chinese space equipment in a long-shot bid to find an escape pod back to Earth.

The other looks at the spiritual dimension of survival, along the lines of "Cast Away," or "Life of Pi," or "127 Hours," and is built around the character of Astronaut Ryan (Bullock).

If Ryan is to endure, she must first decide that she wants to - she's a medical technician who volunteered for this space mission in part because Earth holds nothing for her, the residue of personal tragedy.

The foil to her ambiguity is a classic, can-do, "Right Stuff" astrodude named Matt (George Clooney) who, at the movie's outset, cracks jokes and cavorts in space while mopey Ryan installs scientific equipment.

His macho space-jock cool kicks in when the disaster strikes - and again, let's say what a brilliant sequence this is. Watching it, you see again what the new digital cinema was made for - the blank blue screen as its own limitless universe of possibility.

It's like watching James Cameron play with some new 3-D spatial puzzle, only "Gravity" has the thematic fingerprints of Cuaron, whose worldview ("Children of Men") makes his work unique.

Certainly his POV stands out next to Scott or Kubrick, for whom space is the place wherein no one can hear your scream, and probably wouldn't care if they could.

Cuaron's a different cat altogether. He's a warm and sometimes sentimental humanist, and there are few shots of his pinwheeling humans that do not also feature our planet - home - glowing blue in the background.

There is talk of Mother Earth, images of umbilical attachment, and a woman whose own connection to life is thoughts of those she's loved and lost.

At one point, Ryan's grief becomes a tear as blue and wet as Earth itself, quivering in the empty chill of a careening space module.

This small thing, this single drop of water, is also what digital cinema was born for.

Cuaron goes big in the movie's final moments, conjuring an image amid the pseudo-religious noodling that seems like a nod to the hard-core Darwinists in the audience, linking both in a spirit of renewal and possibility.

I like his optimism. Even if it's sometimes a bit cockeyed. The implied we're-all-in-this-together lessons of international cooperation (Russian and Chinese and American equipment) would play better if the Chinese and Russians were not currently backing Syrian President Bashar al Assad.

But I like the movie's hopefulness, so against the grain of the end-of-everything scowling that we find in every other movie and TV show these days.

Next to that kind of superficial, fashionable pessimism, Cuaron's vision has real gravity.

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