The Frame Shift Drive is based on an astrophysical process called Frame-Dragging. Frame in this context does not mean “single image captured by your eyes”, it is the "a basic structure that underlies or supports a system" concept of frame. This “frame” is used in Special Relativity to determine the position of an object in regards to 4 variables: time and 3 coordinates in space and time. The frame-dragging refers to the fact that this frame affects space around it and space affects the frame, in essence dragging each other. This happens because space is elastic, and every particle exchanges energy with it, exerting force – but the catch is, the moment that force is removed, space returns to its original shape and energy state. While frame-dragging usually works only in massive objects big enough to generate a strong gravitational field, the FSD works by generating that same kind of effect artificially by shifting that frame around Spacetime, compressing space and moving it’s particles around by the same principle of frame-dragging. But instead of dragging space around with it and exchanging energy, it shifts energy around the frame, essentially moving things and particles around the ship while the ship itself stays intact. This huge ballet of cosmic energy swinging around is also responsible for sensors picking up ships in SC from far away – the compression bubble greatly increases gravitational effects, and the distortion can be picked up from far away just as easily as a planet’s gravity well.
This frameshifting bubble created by the FSD is what allows the ship to move so fast but also turn direction and reverse speed – the compression field works the same way all around you, shifting space around the ship. This ability to change course mid-flight and even reverse direction is the main indicative of the FSD being a different kind of tech than the ones currently known.
