Four words protrude, stigmata-like, from a patch of white wall above the gallery’s double doors: “Sign reads: euphoria only.” That they appear next to a glowing emergency-exit sign seems apposite. Lou Lou Sainsbury, in her debut London solo, “Earth Is a Deadname,” unravels the means by which vocabularies created without our consent structure how we relate to our environments. The “interplanetary poetics” devised by Sainsbury and her collaborators articulate strategies of imagining that can surmount the claustrophobic logic of quotidian language, fixating on how narratives of trans being and