Pop goes the music: The move from sound to substance.(Knight Ridder Newspapers)

Byline: Brian McCollum

Right now, we think of it as the insipid diversion that either annoyed or titillated us for a few days. But history may have a different use for the 2004 Super Bowl debacle, making it a convenient benchmark, a handy line of demarcation, in the bigger pop culture story.

When Justin Timberlake ripped the red lace from Janet Jackson's outfit during halftime, he didn't just expose her cleavage. He revealed a bigger kind of chasm _ one that we may someday designate as the moment when American culture of the early 21st century officially split along two different paths.

It may seem a long leap from Jackson's breast to Josh Groban. But that's the point. When the classically trained pop vocalist performs, he brings with him not just one of the country's hottest-selling records, but an entire cultural phenomenon.

Groban is part of an explosive resurgence of grown-up pop, new sounds that sound like old sounds _ ones that are luring many adults back into music stores for the first time in years. As his album "Closer" closes in on 3 million copies sold _ just three months after its release _ Groban is the latest flag-bearer for a trend that's been building steam for several years.

The Billboard pop ...