The phenomenon happens about once a decade, generally around the midway point, and it goes something like this: A pop star arrives seemingly out of nowhere and either rewrites the rules or devises new ones. In doing so, the star revitalizes pop and creates the illusion-however fragile-that a cohesive music community still exists. Circa 1954 the instigator was Elvis; a decade later, the Beatles. Around 1974 it was arguably Bruce Springsteen-who, in his first flush of success with Born to Run, reminded everyone that rock was inherently a working-class form of expression. And in 1983-84, Madonna's explicit sensuality and heightened media savvy (read: self-promotion) forced millions of people to rethink their notions of how a pop star should look, behave, and, of course, dress. Following that line of thinking, the next Next Big Thing should be within periscope distance. Or is it? Since sales figures play a stadium-size role in determining such trends, let's start with them-specifically, with the best- selling albums of 1993. The list is headed by the 5.5 million-selling soundtrack of The Bodyguard, also a leading contender at this year's Grammy Awards (March 1). Yet the album doesn't really qualify, since it's a multi- artist collection and an all-media event (a movie, a video, an album, and, inevitably, a virtual-reality game-protect Whitney yourself!). The year's second-biggest hit-Janet Jackson's sonic overload, janet.-sold 4.3 million copies, hatched several top 10 singles of varying quality, and spawned an arena-filling tour. But did it feel like an Event with a capital E? Did it $ seem like another Meet the Beatles or Born to Run or Like a Virgin (or, to bring her family into it, another Thriller)? Even the most casual pop observer has to answer no. Brash and meticulously overproduced, janet. felt like just another superstar album in an already crowded playing field. The same feeling runs through last year's remaining top 10 sellers. Kenny G's Breathless (No. 4) appealed mostly to audiophiles and fans of chill-out background music; Pearl Jam's Vs. (No. 3) and Stone Temple Pilots' Core (No. 9), to angst-ridden, air-guitaring twentysomethings; Mariah Carey's Music Box (No. 5), to admirers of the most predictable pop hooks; Dr. Dre's The Chronic (No. 6), to followers of the funkiest gangsta rap; Eric Clapton's Unplugged (No. 7), to white music fans of nearly all ages; Garth Brooks' In Pieces (No. 8), to disenfranchised boomers who like a little old- time rock with their country; and Meat Loaf's Bat Out of Hell II: Back Into Hell (No. 10), to anyone nostalgic for the first album and the heyday of the power ballad. Culturally, none of them truly claimed the biggest piece of the pie; even their sales figures are not that far apart, averaging 3.5 million. This splintering process within the pop community has been developing, gradually but inexorably, for more than 20 years. But that preliminary split is nothing compared with what's occurring in the '90s. More than ever before, pop music amounts to a huge mobile-home park with dozens of self-contained trailers. The few musicians who have approached Next Big Thing status-Pearl Jam, Nirvana-don't even seem to want the mantle; they're suspicious of success and its accompanying responsibilities. Add it all up, and the very concept of one artist who can unite a large pop audience and help shape and define it seems about as dead as the 45-rpm spindle. Next Big Thing? More like Next Modest Thing That Might Affect the Lives of a Portion of the Demographic.