The artist Elizabeth McTernan and the mathematician Luke Wolcott collaborated on A Tree Calls , in which Wolcott chopped down a tree in the United States and McTernan simultaneously led a group in Copenhagen to walk toward the arrival of the sound of the tree falling. How does the sound of this tree falling, and the story of its journey and reception, help us walk into a framed void, alone together? In its faint vibration, how can we hear both the idea’s persistent unity and the silent physical arrival of absence?