At one point, another train traveling in the same direction swept onto an adjoining line, and when she looked across and into the other carriage, it appeared stationary beside her. There was a man sitting adjacent and their eyes met, and Lucy fell to thinking about time and motion and speed, and began to glimpse the possibility that they weren’t actually moving at all—that it was the earth instead that had started to spin rapidly beneath them. Her knowledge of the fixed laws of physics suddenly loosened and her mind exploded with possibilities.
