Tupac hologram performs at Coachella 2012. Photo by evsmitty via flickr.com.

The illusionists behind that Tupac cameo at last month’s Coachella music festival can absolutely take credit for changing the game: While high-tech visual projections of the human form weren’t new to concert stages, none had ever caused as big a stir as the visitation of a murdered rapper.

It’s possible that none had ever been deployed so effectively: during a nighttime set in the California desert by West Coast rap icons Snoop Dogg and Dr. Dre, to the astonishment of a crowd of 100,000 people. Seemingly 3-D and free of video-screen boundaries, the pixelated Tupac Shakur banged out rhymes, punched the air and yanked on his gold neck chain in the presence of old gangsta buddies Snoop and Dre. He also reduced the rest of the festival to framing. Is anyone talking excitedly about who else played Coachella?

The living have always had to compete a little harder against the dead in popular music. More so than in movies or books, nostalgia is easily expressed and indulged through the quick-hitting medium of pop. No field cycles faster through fads and revivals or has built as big an infrastructure around its oldies. Meanwhile, instant online access to pretty much everything ever recorded has made music-sharing increasingly “atemporal,” according to the novelist William Gibson. (That songs are still closely tied to their times, and used as shorthand to define decades and eras, is a conundrum for another day.)

Pop always lives in a state of unresolved tension with its ghosts. Forward-looking musicians who complain about the mind share their deceased colleagues enjoy also know there’s fresh sonic ground to be plowed in smart quotation of old recordings. Critics who rail at fetishization of the past will themselves go nuts over a great re-issue or a classic album tour.

But something about Tupac materializing mid-stage for an event that didn’t exist in his lifetime — he even name-checked “Coachella” — has given people pause. Commentators admiring the technical achievement, and the show-stopping dramatic effect, also wonder if the late Tupac hasn’t just permanently tipped the scales against flesh-and-blood music-making.

Probably not. At least not yet. There is still a continuum that runs from honoring tradition (new stagings of great operas) to flogging nostalgia (oldies tours featuring no original band members) to committing necrophilia (Graceland). But the question of when and whether we collapse the space between the poles is worth posing. A culture that commits the majority of its resources — money, ingenuity, expertise — to resurrecting its dead idols is headed for extinction. A society needs to invest in the living beings who grow our art forms’ vocabularies.

So what to make of the news that virtual Tupac might tour? If it happens, it will be interesting, and scary, to see whether a binary creation can hit the road and pull a paying audience night after night.

Some observers are wary. The veteran band manager Danny Goldberg told MTV News that it’s one thing to spring a hip-hop ghost on a crowd for a few minutes as part of an old-school rap celebration, but another thing to expect that people will settle in for an evening with a publicized novelty.

It’s a safe bet, however, that somebody’s going to test the proposition. Sales of Tupac albums soared after Coachella. One assumes that record executives, tour promoters, producers of musical reality shows and the estates of dead pop stars are already on it. And the technology behind these re-animations will only improve.

California, Coachella, Coachella 2012, Dr. Dre, MTV, nostalgia, Snoop Dogg, Tupac, Tupac hologram, William Gibson