Chapter Two: Coordinates of the Wing Bone

Su fell toward the wall. Lin caught her hand, and both struck the white membrane. Golden lines that had crossed the wall now formed a road beneath their feet. The door waited "below" them. "It doesn't want an equation," Lin said, rising through the pain. "Newton describes the result. The third figure is standing on a curved grid. It wants geometry." "Mass curves spacetime." "Yes. The third dial isn't a multiplier. It's curvature." They walked along the wall. Symbols on the dial had become components of a Riemann tensor. Lin had modeled gravity-satellite trajectories for six months. Eyes closed, he mapped mass distribution to curvature and curvature to observed motion. When the final symbol aligned, the entire wing bone sang. The door opened.