A mass of hyper tweens swarms a small auditorium in London’s Science  Museum. They have been waiting outside on a cold January night for an  hour and are extremely eager for things to start. In miniskirts, lace  tights, and sparkly headbands, with bracelets piled high and cell-phone  cameras at the ready, close to 200 girls shuffle in, giddy with  anticipation and oblivious to the occasional boy in the crowd. The fans  of Justin Bieber have only one boy on their minds: JUSTIN is boldly  written on one girl’s forehead; another has J.B. scrawled on her left  cheek. Some hold up handmade signs with devotional love letters. Many  are furiously text-messaging, no doubt flaunting their imminent dream  come true to less fortunate friends doing Sunday-night homework. When  will he be here? “Justin! Justin! Justin!” they are chanting. And it is  deafening.
A fresh-faced former hockey player from  Stratford, Ontario, Canada, Justin Bieber, 16, has emerged as the pop  prince of the Twitter generation, able to fill Madison Square Garden  with squealing pubescents, as he did for a show this past December.  Unlike Miley Cyrus or the Jonas Brothers, Bieber is not a Disney  creation but a self-styled Internet sensation, a YouTube meteor who was  discovered in 2007 after he posted dulcet covers of songs by Stevie  Wonder, Ne-Yo, and Usher. That tender moxie caught the eye of his  current manager, hip-hop executive Scooter Braun, who signed Bieber at  age 13—and then attracted the attention of Usher and Justin Timberlake,  who engaged in a bidding war for the budding superstar. Usher won, and  Bieber’s debut EP, My World (RBMG/Island Def Jam), released in  November 2009, broke Billboard records and went platinum within  two months. Even the president wants a piece of him. “It’s the only  time I’ve ever been nervous to perform,” Bieber says of playing for the  Obamas during the holidays in Washington, D.C.
 This London show is an intimate one for Bieber, marking the U.K.  release of 
My World. Wearing a black leather jacket and skinny  gray jeans, Bieber slinks onstage, conscious of but not overly cocky  about his 
Tiger Beat prettiness and ultrasmooth moves (he  actually has a “swagger coach”). Girls go wild, hugging one another with  an excitement verging on evangelical fervor. A bodyguard steps in to  keep the hormonal advances at bay, but Bieber flirts with the worship,  stepping out into the audience and causing one fan to weep merely by  touching her hand. Bieber seems unfazed, poised, proud.
 
Backstage, sitting around a table with  various handlers, who take turns keeping him entertained, Bieber says he  likes closely interacting with his fans but admits that the hysteria  can at times be over the top. For example, last November he was forced  to cancel an appearance at Long Island’s Roosevelt Field mall because  the throngs got out of control. Teenage girls are obviously . . .  “Crazy!” Bieber pipes in. His hit songs like “One Less Lonely Girl” and  “Love Me” fuel obsessively tweeted adolescent fantasies, and his looks  don’t help ease the madness—those big brown eyes, that mop of perfectly  swept hair! “I don’t style it. I just blow-dry it and”—he pauses and  tousles his hair—“kind of shake it,” he says with a charming Southern  twang, acquired since moving to Atlanta to propel his career as a  recording artist. He has a house there, a step up from his childhood  bedroom, where the walls were plastered with posters of Beyoncé. “I’ve  been totally in love with her since I was seven. She kinda broke my  heart when she married Jay-Z,” he says with an adorably wry smile.
 Bieber is prone to self-reflective pronouncements that toy with  maturity: “I haven’t been in love yet. I’ve definitely loved girls. But  it’s kinda like puppy love. It’s not the real thing, but that’s what you  think at the time.” He is still very much a kid, however, restlessly  shredding a napkin and throwing the scraps at his manager, excitedly  cracking jokes about Chuck -Norris, and breaking into spontaneous  dances. “I leave the hip thrusts to Michael Jackson,” he teases. He  picks up his Gibson guitar and starts playing to his entourage,  including his stylist, his musical director, and his father, Jeremy  Bieber.
 (Justin normally travels with his mother, but this week he’s sent her  to a spa and his dad is -stepping in.) “Down, down—let me teach you  something,” he instructs his father, who is -accompanying him on another  guitar. They rehearse a song from Bieber’s new album, 
My World 2.0,  which is out this month and features contributions by Ludacris,  Christopher “Tricky” Stewart, and The Dream. The songs will  be—shock!—“mostly about girls, again,” the boy wonder says. “I want them  to hear my music and wanna play it again because it made their hearts  feel good.”
 So what exactly is Bieber’s ideal world? “I want my world to be fun.  No parents, no rules, no nothing. Like, no one can stop me,” he says,  and then repeats it. “No one can stop me.”