In her essay “Against Interpretation,” published a decade before “Einstein,” Susan Sontag contends that “to interpret is to impoverish.” Interpretation turns the world as it is, “the world,” as Sontag puts it, into “this world,” the dimmer one of our making. What is needed, she concludes, is to recover our senses. “We must learn to see more, hear more, feel more.” That is “Einstein on the Beach” in a nutshell, an opera that is all container and no content.