Five years after his death, Michael Jackson stole the show. He always did when he was alive, and it was no different during Sunday night's Billboard Music Awards (BBMA), when a holographic MJ joined a five-piece band and 16 dancers onstage.

He wasn't the first. When hologram technology emerged two years ago, it seemed like a fad. Now it's a trend of resurrection so common it might just be the future of the industry.

It began in April 2012, when a virtual Tupac Shakur took the stage at the Coachella Valley Music and Arts Festival with Snoop Dogg and Dr. Dre. It was the first time a hologram had been used in a live performance for such a huge American crowd, and the first time hologram technology was used to ressurrect a dead singer. It made a mark. Artists weighed in on Twitter, and reactions varied from Rihanna's awestruck "#TupacBACK #unbelievable #IWASTHERE #STORY4myGrandKidz" to Tyler The Creator's sheer terror:

Since that performance, old favorites have been returning to us with increasing regularity. The deal behind the concert was relatively simple: Dr. Dre went to Tupac's mother to get permission to use his likeness, then he paid electronics firm AV Concepts $400,000 to recreate the rapper from old footage. In an interview with NPR a few months after the concert, MTV's James Montgomery reflected, "Once this becomes a little less cost-prohibitive, given the wild popularity of deceased stars like Elvis or Michael Jackson, I can see Las Vegas shelling out a lot of money to have these sort of 'live revues.'"

It was almost prophetic. Among the dead legends now returning to earth, hologram Ol' Dirty Bastard will make appearances at the Rock the Bells 10th anniversary shows this fall. People who were too young for a Wu-Tang show before ODB died from an overdose in 2004 can now see him rip through "Shame on a Nigga."

These deals all involve similar work and technology. A producer finds a dead artist's estate and obtains the necessary rights. In Jackson's case, the producers of the BBMAs sought permission from John Branca, the coexecutor of MJ's estate. Typically the performances are done by the same animation and production firms, places like Play Gig-It, Pulse Evolution and Tricycle Logic. "It's like walking on the moon for the first time,” Chris "Broadway" Romero, one of the digital artists that worked on the hologram ODB for Rock The Bells, told Pitchfork about his work crafting hologram performances. "You hope it works. You hope you don't die in front of a bunch of people. But you just go."

After rights are obtained, it takes an enormous amount of time and effort to make each performance. It took half a year to compose the MJ sequence, and BBMA producers didn't even see footage until eight days before the nationally broadcast show. Months of work go into every detail, from choreographed dancing to how the sweat will bead on MJ's head to the angle of his hand after he sticks a spin move. The likenesses are built off careful study of old film, but the performances are composed using motion capture technology. If the artist is still alive, they'll don the motion capture suit themselves, but when the artist has already passed, that duty often falls to their children. In the case of the ODB hologram, his son, Young Dirty Bastard, donned the motion capture suit. Eazy-E's hologram was made from combining performances from his three children — one for his voice, one for his body and one for his face.

Once the performance is complete, the technology behind projecting these apparitions is fairly simple — it's not even technically a hologram, actually. A projector is positioned above the stage, and it casts an image down onto a mirror placed at a specific angle on the floor of the stage. That image is then reflected onto a foil screen, where it appears to hover onstage, moonwalking around like MJ or traipsing about like Tupac.

The technology is widely celebrated, but the principle is a little more troubling. Bringing back the dead has always been treacherous ground to tread. In robotics, there's a concept called the "uncanny valley," where a digital or robotic likeness of a human is cool until it looks just enough like a real person, at which point it becomes terrifying. Think about any of Pixar's human caricatures, and now think about the Polar Express.

There's also the disturbing symbolism of the whole practice. This may be the future of entertainment, but perhaps it will never sit well. It takes months and long hours to create a likeness (and we will get faster), but it takes years of full life to build the real thing. According to Pitchfork, famed '90s group TLC has considered incorporating a hologram Lisa "Left-Eye" Lopes into their show. Lopes was one of the group's most magnetic personalities before she died in a car crash in 2002. The band was hesitant; T-Boz remembered how difficult it was just to have Lisa appear on the giant LED screens behind them after her death. "It took us 10 years just to be able to look back [at the screen]," she said. "I have to have tunnel vision, because it's a constant reminder that she's not there."

The technology, though, is looking to become an integral part of the future in music and beyond. Narendra Modi, the new prime minister of India, used the technology to reach more voters in the country's recent elections. Galaxy Chocolate used a similar technology to recreate Audrey Hepburn (in a likeness that came dangerously close to the "uncanny valley") to sell candy. The biggest pop star in Japan, Hatsune Miku, isn't actually a real person: She's a "digitally synthesized voice encapsulated in a crowd-sourced humanoid persona" — a projection of national preferences.

Admittedly, it's all a bit creepy, but she has more than 1.8 million Facebook followers, and more than 100,000 original songs. Her impact is real, even though she is, arguably, not. The draw is even bigger for dead artists. Fame often only amplifies once a star dies and becomes a legend. If those legends can return to us, they may well begin replacing real life performers with all the flaws that accompany a real live life. At Coachella in 2012, Tupac may not have been there, but his fame was: