Where do Diane and Tyler go at the end of the book? What was the ultimate purpose of the Spin membrane?

Diane, Tyler and the rest of the emigrants cross the Alien Bridge across an unknown distance and into a new life. Far from condemning the human race to burn under a mad red sun, the Hypotheticals used the Spin to preserve the human civilization and provide the inhabitants of the blue planet with a new world that would allow them to continue to evolve.