Scene Context: Will explains to Les that nothing is "pushing" the lifeboat—it is essentially "sliding down" an inclined geometry created by the stringlet pairs.
Essence of the Phenomenon: In General Relativity, a free-falling body moves not because a "force" is pulling it, but because it follows a geodesic—the straightest possible path in curved spacetime. This logic is expanded here: the two stringlet pairs do not merely contain the soliton; they generate a controlled metric gradient inside it—the very "slope" along which the convoy slides. While not modern engineering, the core concept of propulsion via geometric manipulation rather than classical thrust is firmly rooted in the physics of geodesics in curved spacetime.
Theoretical Extrapolation: The scenario assumes a soliton bubble can sustain a localized metric "slope" for extended periods. If the synchronization of the stringlet pairs degrades, this slope flattens or warps, and the ship no longer travels along its intended vector.