TORONTO - It's one thing to make a science fiction film. It's another to feel like you're living in one.

You would think that for Alfonso Cuarón - director of the verite road pic Y Tu Mamá También, the giant Hogwarts installment Harry Potter and the Prisoner of Azkaban, and the dystopian thriller Children of Men - a nice, simple stranded-in-space saga would be a cakewalk. Or at least a space walk.

You would think wrong.

"Here's the thing," says the filmmaker, on the couch in a swanky hotel on the morning after the Toronto International Film Festival premiere of his Sandra Bullock/George Clooney survival thriller. "It is unlike any other movie set that you have seen. You would go to Shepperton Studio, where we were shooting, and you would enter and it didn't look like a set at all. It looked like a weird giant science experiment - because at the end of the stage you would see this cube, 9 feet by 9 feet, an empty cube, in which all the walls inside were LED lights. And the cube was elevated six feet high and there was a long track leading up to to the cube, with one robot, like the robots that they use for car manufacturing, carrying a camera . . . that would go in and out of the cube all the time.

"And in both wings of the stage, it was just rows and rows and rows and rows of geeks on computers. . . .

"It was an amazing experience, but it's not what I consider 'moviemaking.' "

The reason for all the geeks and gizmos was that for much of Gravity, its two characters - NASA astronauts played by Bullock and Clooney - are floating in orbit around Earth. Zero gravity inside their space craft - and outside the craft, spinning and cartwheeling in the vast, empty, silent void.

In order to create the effect of weightlessness, all sorts of rigs - nest-like rigs, bicycle seat-like rigs, rigs designed and manipulated by the puppeteers behind the stage production of War Horse - were deployed. And while the actors were in their rigging, CG animation sequences, produced over the two years leading up to the live shoot, were projected in that cube, or onto it, or something like that.

Even Cuarón finds it hard to explain.

"The technologies involved robotics and LED lights and integration of CG with live action," he says. "I doubt, at the end, that my explanation would really clarify much, but I can tell you this: Everything was preprogrammed, so the actors were limited in terms of what they could do, or couldn't do . . . . Once we started shooting, there was no room to change timings, or positions, or cues. They could change the language they performed, as long as it fit the frame of time and the position. But this was not about improv."

Which is the reason Robert Downey Jr., who Cuarón had been talking to about the project, opted out. (Over its many years in development, Natalie Portman, Marion Cotillard, and Scarlett Johansson were all reportedly considered for the role Bullock finally landed.)

"It took so long, this project," the director says. "We had conversations with actors, and then, you know, 'OK, well, I'm going to do this movie,' 'OK, well, I'll catch up with you,' and then you end up not catching up. . . . And it was not until we were really ready to go that we got serious and said, 'OK, we can make offers to actors now.' We could not make offers to actors when we didn't know when we were going to shoot."

And Downey?

"Once we defined the technology, it became clear that how we were going to make it and what Robert does were not compatible. How can you tell Robert to stick to the timing? The thing with Robert is that he improvises all the time, and tries different things, so it was not going to be something in which he would really expand what he's great at."

But as sorry as he was to see Downey go - and the other stars he'd been meeting with - Cuarón is hardly unhappy now.

"I ended up maybe in the best place," he says, speaking of his A-list duo. "And I have to say in my experience that happens quite a lot. All of these journeys and obstacles just bring everything to the right place. I was very lucky."

Gravity, certain to be an awards contender, opens Friday. 

Robert Reich's glass is half full. Despite the sobering numbers and grim case studies in the must-see documentary Inequality for All, Robert Reich, former U.S. Secretary of Labor and current University of California, Berkeley, professor, isn't all gloom and doom about our prospects. In the film, directed by Jacob Kornbluth and adapted from Reich's book, Aftershock: The Next Economy and America's Future, the charismatic, self-deprecating economist takes a look at the ever-widening income gap in America - its causes and its consequences, as more wealth is concentrated in fewer hands.

"As I say in the start of the film, not only are we the most unequal of all the developed countries, but we're surging towards greater inequality faster," says Reich, on the phone from New York the other day.

Still, by the end of the picture, Reich is practically beaming rays of sunshine as he impels the students in a giant lecture hall to go out and do good.

"I'm not a cockeyed optimist," Reich cautions. "But there are reasons for optimism. One is that the economy can't continue in the direction it's going without risking more deep recessions, booms and busts and chronically high unemployment.

"The rich would do better with a smaller share of a rapidly growing economy than they are doing now with a large share of an economy that's barely growing because the majority of Americans don't have the purchasing power to keep it going. And I like to think that the wealthy are rational and know that it's in the best interest of everyone to reverse the trends . . . .

"It's not a zero-sum game in which the only way that the middle class and the poor do better is if the wealthy do worse. In fact, our history is very much of a positive-sum game. The rising tide lifts all boats.

"And this is the other thing that makes me optimistic: that there have been at least three times in the past century where we made major adjustments and reduced inequality, increased equal opportunity, spread the prosperity to a much greater extent and saved capitalism from its own excesses."

Yes! Inequality for All opened Friday at the Ritz Five.