The 100 People Who Are Changing America

WHAT SHE'S CHANGING: How to fight global warming. The 27-year-old executive director of Energy Action, a coalition of mostly campus-based environmental groups, Tolkan gets a lot of respect these days. In March, 12,000 people blasted into Washington, D.C., for PowerShift 2009, sponsored by Energy Action, which called it "the largest training and lobby day for climate change solutions in the history of the United States."

KEY QUOTE: "We have new leadership, but we expect them to implement that leadership. We expect and demand that climate legislation gets passed in 2009."

Photo: Fritz Myer

WHAT THEY'RE CHANGING: The record biz. By inventing Guitar Hero and Rock Band, these MIT college buddies made a new way to consume music.

FRIENDS SAY: "I'm loving Rock Band," Nirvana's Krist Novoselic blogged. "Instead of file-sharing, people are actually buying music again! HA!!!"

NEXT FIGHT: Their Beatles game, due later this year, may be Harmonix's biggest yet.

CHANCE OF SUCCESS: 90 percent. Harmonix and the Fab Four have perfect track records.

SEE THE CHANGE: Guitar Hero Official Site and Rock Band Official Site

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Photo: Miller/Getty (Rigopulos), Liz Lander (Egozy)

WHAT SHE'S CHANGING: Randall may have solved one of the most imposing puzzles in physics: why the Earth's gravity appears to be so weak compared with other elementary forces like electromagnetism. Her theory is that gravity may be concentrated in a hidden dimension beyond our normal three — in a warped, parallel universe with totally different chemistry.

NEXT MOVE: Seeking evidence via Europe's Large Hadron Collider, which will create subatomic particles that potentially have momentum in extra dimensions when it starts up again in September.

SEE THE CHANGE: Lisa Randall's Official Site

Photo: Shinji Yamada/ Harvard University

WHAT HE'S CHANGING:Eno finds rock music utterly boring — which is why he's able to help that genre's biggest artists reinvent their sound and make their freshest music. From Talking Heads to U2, he has blurred the line between art for art's sake and pop hitmaking — and last year, he even produced a Coldplay album that (mostly) silenced the haters.

WANNA-BE: Bloom, his music-making iPhone app, lets everyone be Eno for a day.

FRIENDS SAY: "Brian is such a stimulating intellect," says U2 bassist Adam Clayton. "He's always bringing in strange things and strange sounds and different energy."

Photo: Harvey/WireImage

WHAT HE'S CHANGING: He gave the left their balls back. Moore's killer Bush-era run of documentaries — Bowling for Columbine, Fahrenheit 9/11, Sicko — sparked a deep, righteously angry part of progressive brains, making it impossible to sit back and drink another latte.

NEXT MOVE: Think you're pissed about the banking crisis now? Wait until you see his upcoming Wall Street movie.

BAD CALL: His support for Nader in 2000.

KEY QUOTE: "Thank you, Republican Party. You helped us elect one of the most liberal senators to the presidency. We couldn't have done it without you."

SEE THE CHANGE: Michael Moore's Official Site

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Photo: Micelotta/WireImage