Alcubierre-Roman drive

The Alcubierre-Roman drive, mostly referred to as warp drive, FTL drive or superluminal drive, is the sole type of propulsion which allows a spacecraft to achieve velocities surpassing that of light. It fundamentally works by bending space-time in such a way that the space in front of the ship is reduced, while that behind the vessel is expanded, creating a torus-shaped warp bubble between the two deformations.

The spacecraft itself doesn't move, but is subjected to a mechanism similar to riding a wave or slingshotting, where the water wave is replaced by the warp bubble. Since the warp bubble represents an island of unbent space-time on a "sea" of distorted space-time, it does not abide by the cosmic lightspeed limit, considering that bending space does not have a limit.

So far, the warp drive has been kept a secret by the United Nations. Not even the colonists that had registered for departure towards Alpha Centauri via the Alpha Centauri Initiative knew the propulsion system of the arks they boarded.