What do You think about Hegira (1989)?
A good, solid work, although very early for Greg Bear. I'm not sure he had quite found his footing yet as influences from Dune and the Riverworld novels was pretty obvious. Written in 1979, it tells of 3 mens journey/quest/hegira (meaning flight or migration) from their current areas to the ends of the earth, literally. The main character Kiril is a writer who has lost his beloved and there is a prophecy that our loved ones can be returned to those who make this journey. What they find on their way and what happens to them, it would cause too many spoilers to say but the wikipedia article on the book lists AI and cyclic time as themes - and to say that it is influenced by the Riverworld books is probably enough to tell you what you might expect.I did like it quite a bit - not his strongest work - but very good considering how early it is for him.
—Stuart Lutzenhiser