What’s so special about 3-D?
By adding a dimension, it makes movies look more like the “real” world, and pulls the audience “inside’’ the film in a visceral way. Human vision is stereoscopic, meaning that when we focus on something, our eyes absorb visual information from two slightly different vantage points. The brain then resolves the two perspectives into a single view that has depth as well as height and width. Three-dimensional movies, with the help of special glasses, replicate that process, so that the floating mountains in Avatar seem to hover over the theater seats, and the creatures in the Na’vis’ jungle appear to fly or slither into moviegoers’ laps. Movie studios are now banking on the astonishing realism of 3-D to lure people away from their home theaters and game consoles, and back into cinemas. “It shatters the idea of going to a movie as a passive experience,” says director Gil Kenan. “It becomes something more akin to a thrill ride.”

How long has 3-D been around?
For a surprisingly long time. Early filmmakers experimented with 3-D as far back as 1890, and the first commercially released 3-D movie was the 1922 film The Power of Love. For that movie, synchronized projectors simultaneously ran two separate strips of film, which audiences viewed wearing two-toned, cardboard-framed glasses. But the effect was underwhelming, and the film wasn’t widely released. Since then, while the technology has steadily improved, 3-D has gone in and out of vogue, enjoying a brief resurgence in the 1950s, when audiences flocked to see Vincent Price in House of Wax, and again in the 1970s, when producers of cheesy action movies like The Magnificent Bodyguards and even cheesier porno films like Supersonic Supergirls embraced the technology. The current resurgence of 3-D began in 2004, when the animated feature Polar Express grossed $305 million.

Are special glasses still required?
Unfortunately, yes. Although the cardboard-framed models of yesteryear have been replaced with reusable, plastic-framed eyewear, today’s glasses haven’t completely eliminated the problems that have plagued them from the start. They fit awkwardly, at best, over conventional glasses. And some people complain that the glasses make them dizzy, while others find that the lenses darken screen images so much that they’re hard to see.

Why is 3-D back in fashion?
In a word, money. DVD revenues are falling off due to inexpensive rental services such as Netflix, and the studios are hungry for new sources of income. Theater owners also are struggling to compete with the movies people can now watch on big-screen, high-definition TVs. “Both exhibitors and studios are looking for ways to say, ‘This is really different from the DVD. This is worth getting in your car and driving 20 miles for,’” says Richard Gelfond, co-chairman of IMAX. And exhibitors can charge more for 3-D tickets—$14 per adult at a typical first-run theater, versus $11 for a conventional movie.

Is 3-D drawing crowds as predicted?
Much better than predicted, actually. Pixar studios’ Up sold $723 million in tickets worldwide and won the 2010 Oscar for Best Animated Feature. Avatar is the most financially successful movie of all time, selling more than $2.6 billion in tickets worldwide so far. Alice in Wonderland took in a record-breaking $116 million in its opening weekend—a total that might have been even higher if Fox Film Studios hadn’t convinced theater owners to keep showing its film Avatar rather than make room for Disney’s Alice. That jostling for screen space is likely to intensify.

Aren’t there enough 3-D theaters to meet demand?
Not nearly enough. The U.S. has only about 4,000 3-D screens in operation—not many for a country of 300 million people. Until the runaway successes of Avatar and Alice, exhibitors were reluctant to invest the $150,000 needed to upgrade a projection system to digital 3-D. Now they’re racing to install 150 3-D systems a month. “We are expanding as fast as we can,” says John Fithian of the National Association of Theatre Owners, “but we are not ready to handle the number of pictures coming out in the next few months in 3-D.”

Will 3-D eventually replace 2-D completely?
Moviemakers say yes. “It’s a little bit like when films first got sound,” says producer Mike Devlin. “Once people start to get used to it, it’s going to pretty much take over the industry, like when televisions got color.” Both DreamWorks and Disney/Pixar are going 3-D for all their animated films, and Warner Bros. has committed to an ambitious slate of 3-D films. But not everyone is thrilled. If 3-D becomes the norm, some critics warn, viewers will demand even flashier thrills. “3-D will ravish our senses and take us on rides that no drug can match,” says The New Yorker’s Anthony Lane, “but my guess is that, like so many blessings, it won’t make us happy. It will make us want more.”

3-D comes to the living room
In an episode of 1950s TV show The Honeymooners, Ralph Kramden explains to his wife why he refuses to buy a new television: “I’m waiting for 3-D.” His wait is over. Sony, LG, and Samsung all unveiled 3-D sets at this year’s consumer electronics show in Las Vegas, and ESPN and Discovery Communications both plan to launch channels that will show exclusively 3-D content. It remains to be seen, though, whether consumers will clamor for the new sets, which start at $2,000, especially after millions have recently upgraded to HD. (And yes, you’ll need special glasses for home viewing, too.) Riddhi Patel of market researcher iSuppli thinks the question might stir some domestic discord. “I think 90 percent of the males in this country would be dying to watch the Super Bowl” in 3-D, she tells The New York Times. But their spouses might not be in such a hurry. “You don’t necessarily want the ladies of The View sitting around you when you watch them.”