Going Around Light Speed Through Complex Velocity
Relativity's equations blow up at v = c, so the book's FTL scheme never crosses that point on the real axis. Instead, ships 'invert' by adding an imaginary component to their speed. That lets them route around the singularity through the complex plane and come back out onto the real axis above light speed. The trick is to reinterpret the forbidden quantity (imaginary mass and energy) as a detour rather than a wall, and the appendix supplies the supporting equations.
