Maria Callas, who died in 1977, has been showing up in concert halls since the autumn of 2018, though her appearances are ephemeral. The immortal diva’s only remaining U.S. date in 2019 is at Chicago’s Lyric Opera House, once a favored stage, after which she heads to Barclona, Athens and other European climes. Her program features “Vissi d’arte” and other famous opera arias, which a live orchestra performs while sharing the stage with her incorporeal self. To make this magic, BASE Hologram company hired opera director Stephen Wadsworth to help a body double master the star’s iconic gestural routine. The face is altered digitally, and the recorded voice is, of course, real. “Wierdly tantalizing,” admitted one critic who saw the show in development. Another pointed out the obvious value of a soprano who won’t ever catch cold.