A few minutes after he began his exercise routine he was joined by Luisa Soter, who had just awakened, as she was on the first shift. She liked to do her "jogging" first thing in the morning, so it was not the first time they had intersected in this way. Six treadmills had been mounted to the walls of this cylindrical module; the users’ feet pointed outward and their heads projected in toward the center like spokes converging on a hub, bringing them rather close together and making conversation easy. For extroverted, social people like Doob and Luisa, this was a great setup; more solitary exercisers would don headphones and pointedly focus on a tablet or a book.