BECKET, Mass. — The dancer Wendy Whelan and the cellist Maya Beiser are towering figures in their respective fields. But in their multimedia collaboration “The Day,” they are overshadowed by another pair. It’s not the project’s two behind-the-scenes luminaries: David Lang, who wrote the music, and Lucinda Childs, who did the choreography. The pair whose absence looms over everything is the twin towers .

“The Day,” which had its world premiere at the Jacob’s Pillow Dance Festival here on Wednesday (it comes to the Joyce Theater in New York, Oct. 22-27), is Ms. Beiser’s brainchild. It combines two pieces of music that Mr. Lang wrote for her: “the day” (2016) and “world to come” (2003). Recording those works recently, she said she imagined a dancer, and who better to fill that role than Ms. Whelan, the former star (and now associate artistic director) of New York City Ballet turned contemporary experimenter. But the enormity and awfulness of Sept. 11, to which “world to come” responds, make this handsomely meditative production feel inadequate.

It is elegant and artful, though. The set design by Sara Brown resembles a memorial. The floor gleams like a reflecting pool. Two special zones — like the two waterfalls that now fill the footprint of the twin towers at ground zero — are demarcated, one of them raised, with a ramp. The two women, mostly onstage together, occupy the zones separately, their contrastive presences balanced: Ms. Beiser hot and more sedentary, Ms. Whelan cool but mobile.