The Transformer: Twyla Tharp Dives Into the Future

It could be the middle of the ocean on a starless night, but it’s a stage. An arm reaches up, glowing like a beacon of light. It lowers — slowly, deliberately — sliding into the darkness.

A piece of movement is nothing without context. Twyla Tharp created that arm gesture nearly 40 years ago as the emphatic closing image of her celebrated “In the Upper Room” (1986), in which two women — the “stompers” — yank down a fist in victory. It’s as much a physical movement as a celebration of making it to the top of a choreographic Mount Everest.

During a recent interview, Tharp, 83, hopped from a chair to her feet to illustrate its emphatic power. “Where that came from is the notion of pulling down a shade,” she said. “Blackout!”

That dance unspools to a propulsive mix of ballet, modern dance and even calisthenics to music by Philip Glass. It ends with the sense of an exhalation, a release.

But what if that final exhalation from “In the Upper Room” turned into an inhalation? What if an ending became a beginning? “Slacktide,” Tharp’s newest dance, is also set to Glass, his “Aguas da Amazonia,” in a new arrangement created and performed by Third Coast Percussion. It starts where “In the Upper Room” left off.

“I take that last move and make it go incredibly slow into the future,” Tharp said. “Into another place, and that other place is a transformation.”