When director Alfonso Cuarón co-wrote Gravity with his son Jonás, he knew that he had a thrilling story on his hands: A medical engineer (Sandra Bullock) fights for survival after a freak accident that strands her in the depths of outer space, far from her ship and mission commander (George Clooney). What Cuarón didn't know was how he could possibly film it. ''We realized that it was impossible to do because everyone is in zero-G throughout the movie,'' he says. ''So we had to invent the technology.'' That meant developing a groundbreaking system of LED panels, computer-controlled cameras, and complicated wirework and then digitally erasing it all in the final film to provide a believable, invisible framework for Bullock's performance, much of which she delivered while strapped to a rig in the middle of a box of computerized lights. ''If you're acting to no one and seeing nothing, you think, as an actor, I don't know what part of my body I'm going to pull this out of,'' says the actress. Judging by the roar of Oscar buzz around her performance, Bullock managed just fine and here's a glimpse at how she and the Gravity team did it.