Mr. Cuaron ultimately switched to a 3-meter-by-4-meter box equipped with special lights and placed on a darkened soundstage. Ms. Bullock was "clamped" inside a "gruesome" harness, he said, and placed inside, where she remained for hours. A camera mounted on a robotic arm pivoted and circled, making it look as if Ms. Bullock were floating through the darkness of space.

"I was literally acting off of nothing for up to 10 hours a day, with headphones my only connection to Alfonso," she said. "We made a catalog of music clips - whale sounds, Radiohead, weird screeching of metal - and I memorized them. I would say, 'O.K., give me number four. That's not working. Try number two. That's better, that's getting me to the emotion I need.'"

For one sequence, Ms. Bullock had to stay still while a camera rushed toward her at 40 kilometers per hour, stopping centimeters from her face. Other scenes required her to be strung up by wires while puppeteers maneuvered her through choreographed movements.

Of the film, Ms. Bullock said: "It's about rebirth. How do you let go in the worst possible situation so you can have some kind of release and peace?" She added: "Life is not going to stop coming at you. In the end, you just have to say, 'I have no control.' Your time is precious. Are you really going to waste it worrying about this stuff?"

She was confronting those questions in her personal life in 2010, when Mr. Cuaron flew to Texas and tried to talk her into "Gravity." She had retreated there following the public revelation that her husband, Jesse James, a motorcycle customizer and reality TV celebrity, had been serially unfaithful.

She divorced him, went forward with the adoption of a baby and made it clear that she had no interest in acting anytime soon.

Now, unlike some female Hollywood stars, Ms. Bullock continues to take on challenging work.

"What roles that are available will always be a factor," said Octavia Spencer, an Oscar winner for "The Help" and a friend of Ms. Bullock's since 1996. "But Sandy has been very successful at not letting anyone put her in a box, and that will continue.

"She has done it by continually taking risks - showing us these other colors, hello 'Gravity' - and working her guts out, and not fixating on how she looks in every scene. Those are things that not a lot of other actresses of her echelon do."

The New York Times

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