They've burst into applause on the mezzanine of New York's Grand Hyatt, whirled like dervishes on San Francisco streets, and jerked robotically in the Mall of America. Now they're milling through the aisles of the Harvard Coop bookstore in Cambridge. "Oh my God, they're doing that thing in our store," says a cashier, "that swarming thing."
The "flash mob" phenomenon is part sanctioned insanity, part Seinfeld on the loose, part nonsensical wanderings through city streets en masse.
As Harvard Coop employees watched and security guards scrambled, a few hundred people crowded into the greeting-card section, holding detailed instructions on what to say and how to act, and raising cameras high above their heads to capture the scene. They were looking for a card for their friend Bill, they told anyone brave enough to ask. He lives in New York.
Ten minutes later, the mob broke into applause, then dispersed. Mobbers, pleased to have joined the fad, went home. Bewildered shoppers moved on. "I think it's nuts," said Reggie De Leon. "What's going on here? I don't watch TV.... I'm here for a pen."
"Bill from New York" is credited with starting flash mobs, which formed just this summer. The gatherings are coordinated through websites and chain e-mails, with the point of being, well, pointless.
Maybe. But the mobs, with their abbreviated, nonsensical performances, are also a mix of fun, rebellion, collective action, and art. Experts say they're a symptom of an increasingly alienated, increasingly wired, society. And although today's mobs strive to stay silly, some say they're a glimpse of future crowds - which could be more purposeful, and more powerful.
"If the pattern [of mobs] catches on, it's plainly going to be adopted by both pranksters and political activists," says Clay Shirky, adjunct professor in the interactive telecommunications program at New York University.
The crowd at the Coop was a diverse one - 30-somethings, college kids, goths and punks - and their reasons for attending were equally varied.
"I really like spontaneous and artistic things," said Bryant Durrell, his glasses fogged over due to the rising room temperature. "It's the appeal of the unknown: rolling the dice at the Vegas table."
Suzie Sims-Fletcher, a Bostonian who also participated in the New York mob at the Grand Hyatt this summer, called the events "joyous fun." "It breaks down everybody's routine," she said. "And there's a certain weird camaraderie."
The mobs are a "cross between streaking and being in a marching band," says Mr. Shirky, who's interested in the cultural and economic effects of Internet technologies. He compares them to moments in which strangers on a subway are briefly united by laughter at a driver's joke - only to reenter their private worlds the next instant. "So far those moments have been serendipitous," he says. "Flash mobs are a way to sort of stage those," reaching out "however temporarily and tenuously."
Those moments of unity are important, say flash mob enthusiasts - especially for isolated urbanites. But because most mobbers still hold fast to privacy, caring little to meet strangers, many come and leave with friends. "Flash mob is a group event," Shirky says, "but it's not necessarily a social event."
Although the Internet has been around for years, it's only now becoming ubiquitous enough to make flash mobs possible. And it's not just the bohemian-but-wired Cambridge crowd that's catching on, says Howard Rheingold, author of the new book, "Smart Mobs: The Next Social Revolution." Internet and cellphone technologies have swayed a presidential election in Korea, rallied people at Seattle's anti-WTO protests, and helped topple Joseph Estrada in the Philippines. More recently, presidential hopeful Howard Dean made headlines - and millions - using his online fan base to beat other Democrats in last quarter's fundraising totals.
As they exist today, flash mobs are primarily for fun, Rheingold says. But they "are early signs of something that's going to grow much bigger."
"The threshold for collective action has been lowered by the Internet and mobile telephones," he continues. "We're talking about political events ... social stuff ... new markets appearing."
And what is, for now, a "raw capability" as Shirky describes it, could easily become a political tool: "All of the organizers of public action who are looking at this stuff now, from the Moral Majority to the Sierra Club, are thinking, 'OK, is this something I can use to accomplish my goal X?'"
Did 28-year-old Bill ever consider all this when he started that first mob in New York? Not really. Nor did he expect mobs to sprout up worldwide.
"The whole thing just started on a lark," says Bill, who does not offer his last name because he doesn't want to be viewed as claiming ownership of the flash mob idea. "It was sort of an experiment to see what would happen."
He says he likes the idea of people not only realizing the power of collective action, but also using it for more serious purposes. Yet for Bill, it's all about those dynamic moments when everyone chirps like a bird, as they did recently in Central Park.
"There's an aesthetic value to them," he says. "I really like ... seeing the space transformed."