Null-A Continuum — John C. Wright

In this heart-stopping sequel to A.E. van Vogt's World of Null-A, Gilbert Gosseyn, the superhuman amnesiac with a double brain, must pit his wits once more against the remorseless galactic dictator Enro the Red and the mysterious shadow-being known as The Follower.  And he must do it while he is being hurled headlong through unimaginable distances in space, in time, and through alternate eternities to fend off the death and complete the rebirth of the Universe itself!