There are no scene or costume changes or props. “It moves through time,” says the playwright Duncan MacMillan, “in a way that breaks the conventions of what people expect from a play.” Yet Lungs asks that most eternal of questions: Why would you bring a child into a world of such political and environmental trouble? In this new “socially distanced” version, Claire Foy (the young Queen in television’s The Crown) stars with Matt Smith, and the pair perform six feet apart to an empty auditorium. Ticket proceeds go towards saving this iconic theater. —L.J.